Graphene non-covalent surface modified chemical varactor-based sensor
阅读说明：本技术 石墨烯非共价表面改性的基于化学变容二极管的传感器 (Graphene non-covalent surface modified chemical varactor-based sensor ) 是由 甄学 菲利普·皮埃尔·约瑟夫·布尔曼 史蒂芬J.科斯特 张遥 贾斯廷·西奥多·尼尔森 于 2019-02-20 设计创作，主要内容包括：一种医疗装置,其可以包括石墨烯变容二极管(100)。所述石墨烯变容二极管(100)可以包括石墨烯层(108a,108b)和通过π-π堆积相互作用设置在所述石墨烯层的外表面上的自组装单层。所述自组装单层可以提供至少0.9的朗缪尔θ值。所述自组装单层可以包括多环芳烃、四苯基卟啉或其衍生物、金属四苯基卟啉或芳族环糊精。还披露了相应的制造方法和利用所述医疗装置检测患者的气态样本中的分析物的方法。(A medical device may include a graphene varactor (100). The graphene varactor (100) may include graphene layers (108a, 108b) and a self-assembled monolayer disposed on an outer surface of the graphene layers through pi-pi stacking interactions. The self-assembled monolayer may provide a langmuir θ value of at least 0.9. The self-assembled monolayer may include a polycyclic aromatic hydrocarbon, tetraphenylporphyrin or a derivative thereof, a metal tetraphenylporphyrin, or an aromatic cyclodextrin. Corresponding methods of manufacture and methods of detecting an analyte in a gaseous sample of a patient using the medical device are also disclosed.)
1. A medical device, comprising:
a graphene varactor, the graphene varactor comprising:
a graphene layer;
a self-assembled monolayer disposed on an outer surface of the graphene layer by pi-pi stacking interactions; and is
Wherein the self-assembled monolayer provides a Langmuir θ value of at least 0.9.
2. The medical device of any one of claims 1 or 3-12, the self-assembled monolayer comprising one or more hydrocarbons comprising from 3 to 10 aromatic rings.
3. The medical device of any of claims 1-2 or 4-12, the self-assembled monolayer comprising one or more polycyclic aromatic hydrocarbons comprising 3 to 10 aromatic rings.
4. The medical device of any of claims 1-3 or 5-12, wherein the polycyclic aromatic hydrocarbon comprises anthracene, benzanthracene, phenanthrene, phenalene, tetracene, benzanthracene, phenanthrene, phenanthracene, phenanthrene,
5. The medical device of any one of claims 1-4 or 6-12, the self-assembled monolayer comprising:
wherein X1、X2、X3And X4Including any straight, branched or cyclic C covalently bonded directly to the underlying aromatic ring structure1-C10Alkyl, -H, -R1OH，-R2COOH，-R3COOR4，-R5NH3 +，-R6NH2，-R7NR8，-R9NR10R11+，-R12B(OH)2Or any combination thereof; and R is1To R12Including any straight, branched or cyclic C1-C10Alkyl groups or combinations thereof, or may be absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the base aromatic ring structure.
6. The medical device of any one of claims 1-5 or 7-12, wherein the self-assembled monolayer comprises one or more of fully benzylated a-cyclodextrin, fully benzylated β -cyclodextrin, or fully benzylated γ -cyclodextrin, or a derivative thereof.
7. The medical device of any one of claims 1-6 or 8-12, the self-assembled monolayer comprising:
wherein n is an integer from 6 to 8, and each X can independently be-H, hydroxy, amino, any straight or branched C1-C10Alcohol, any straight or branched C1-C10Amine, phenyl, benzyl or naphthyl, provided that each repeating unit in the above structure contains at least one functionality that is aromaticX of the cluster.
8. The medical device of any one of claims 1-7 or 9-12, wherein the self-assembled monolayer comprises one or more tetraphenylporphyrins, metal tetraphenylporphyrins, or derivatives thereof.
9. The medical device of any one of claims 1-8 or 10-12, the self-assembled monolayer comprising:
wherein n is any integer from 1 to 5; m is 1 or 2; r1To R8comprises-H; -X, wherein X comprises a halogen atom; -R9；-R10OH；-R11COOH；-R12COOR13；-R14OR15；-R16COH；-R17COR18；-R19NH3 +；-R20NH2；-R21NR22；-R23NR24R25+；-R26X or-R27COX, where X is any halogen atom; -R28SH or any combination thereof; and R is9To R28Including any straight or branched C1-C12Alkyl radical, C1-C12Alkenyl radical, C1-C12Alkynyl groups, or any combination thereof, or may be absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the base aromatic ring structure.
10. The medical device of any one of claims 1-9 or 11-12, the self-assembled monolayer comprising:
wherein M is any metal including aluminum, calcium, magnesium, manganese, iron, cobalt, nickel, zinc, ruthenium, palladium or derivatives thereofAn atom; wherein n can be any integer from 1 to 5; m may be 1 or 2; r1To R8comprises-H; -X, wherein X is any halogen atom; -R9；-R10OH；-R11COOH；-R12COOR13；-R14OR15；-R16COH；-R17COR18；-R19NH3 +；-R20NH2；-R21NR22；-R23NR24R25+；-R26X or-R27COX, where X is any halogen atom; -R28SH or any combination thereof; and R is9To R28Including any straight or branched C1-C12Alkyl radical, C1-C12Alkenyl radical, C1-C12Alkynyl groups, or any combination thereof, or may be absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the base aromatic ring structure.
11. The medical device of any one of claims 1-10 or 12, wherein the self-assembled monolayer provides a langmuir θ value of at least 0.98.
12. The medical device of any one of claims 1-11, wherein the self-assembled monolayer provides from 50% to 150% graphene-on-coverage by surface area.
13. A method of surface modifying graphene to produce a graphene varactor, the method comprising:
forming a self-assembled monolayer on an outer surface of a graphene layer of the graphene varactor by pi-pi stacking interaction;
quantifying the degree of surface coverage of the self-assembled monolayer using contact angle goniometry, raman spectroscopy, or X-ray photoelectron spectroscopy;
selecting a derivatized graphene layer exhibiting a langmuir θ value of at least 0.9.
14. The method of claim 13, wherein selecting a derivatized graphene layer comprises selecting a derivatized graphene layer that exhibits a langmuir θ value of at least 0.98.
15. A method for detecting an analyte, comprising:
collecting a gaseous sample of a patient;
contacting a graphene varactor with the gaseous sample, the graphene varactor being according to any one of claims 1 to 12 herein.
Technical Field
Embodiments herein relate to chemical sensors, devices and systems including the same, and related methods. More specifically, embodiments herein relate to graphene-based non-covalent surface-modified chemical sensors.
Background
Accurate detection of disease may enable clinicians to provide appropriate therapeutic intervention. Early detection of disease may lead to better therapeutic outcomes. Many different techniques can be used to detect disease, including analysis of tissue samples, analysis of various bodily fluids, diagnostic scans, gene sequencing, and the like.
Some disease states lead to the production of specific chemical compounds. In some cases, Volatile Organic Compounds (VOCs) released into a patient's gaseous sample may be a marker of certain diseases. The detection of these compounds or differential sensing of them may allow early detection of specific disease states.
Disclosure of Invention
In a first aspect, a medical device is included. The medical device may include a graphene varactor. A graphene varactor may include a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer by pi-pi stacking interactions. The self-assembled monolayer may provide a Langmuir theta value of at least 0.9.
In a second aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may comprise one or more polycyclic aromatic hydrocarbons having from 3 to 10 aromatic rings.
In a third aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the polycyclic aromatic hydrocarbon can include anthracene, benzanthracene, phenanthrene, phenalene, naphthacene, benzanthracene (benzanthracene), benzanthracene,Pentacene, diphenylanthracene, triphenylene, pyrene, benzopyrene, picene, perylene, benzoperylene, pentaphene (pentaphene), pentacene, anthanthrone, coronene, ovalene or one or more of their derivatives.
In a fourth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the polycyclic aromatic hydrocarbon can include one or more hydroxyl, carboxyl, ester, ammonium, amino, diethylamino, or boronic acid functional groups.
In a fifth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may comprise one or more of a fully benzylated α -cyclodextrin, a fully benzylated β -cyclodextrin, or a fully benzylated γ -cyclodextrin or a derivative thereof.
In a sixth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may comprise one or more tetraphenylporphyrins or derivatives thereof.
In a seventh aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may comprise one or more metallotetraphenylporphyrins or derivatives thereof.
In an eighth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the medical device may include a plurality of graphene varactors arranged in an array.
In a ninth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the plurality of graphene varactors may be configured to detect the same analyte in a gaseous sample.
In a tenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the plurality of graphene varactors may be configured to detect different analytes in a gaseous sample.
In an eleventh aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer can provide a langmuir θ value of at least 0.95.
In a twelfth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may provide a langmuir θ value of at least 0.98.
In a thirteenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may be homogeneous.
In a fourteenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may be heterogeneous.
In a fifteenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the medical device may comprise an endoscope, a bronchoscope, or a bronchoscope.
In a sixteenth aspect, a method-a method of surface modifying graphene to produce a graphene varactor is included. The method may include forming a self-assembled monolayer on an outer surface of a graphene layer of the graphene varactor by pi-pi stacking interactions. The method may comprise quantifying the degree of surface coverage of the self-assembled monolayer using contact angle goniometry, raman spectroscopy or X-ray photoelectron spectroscopy. The method may comprise selecting a derivatized graphene layer that exhibits a langmuir θ value of at least 0.9.
In a seventeenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the step of selecting a derivative graphene layer may comprise selecting a derivative graphene layer that exhibits a langmuir θ value of at least 0.95.
In an eighteenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the step of selecting a derivatized graphene layer may include selecting a derivatized graphene layer that exhibits a langmuir θ value of at least 0.98.
In a nineteenth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer can include one or more polycyclic aromatic hydrocarbons having from 3 to 10 aromatic rings.
In a twentieth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the polycyclic aromatic hydrocarbon can include anthracene, benzanthracene, phenanthrene, phenalene, naphthacene, benzanthracene, and/or a pharmaceutically acceptable salt,
In a twenty-first aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the polycyclic aromatic hydrocarbon can include one or more hydroxyl, carboxyl, ester, ammonium, amino, diethylamino, or boronic acid functional groups.
In a twenty-second aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer may comprise one or more of a fully benzylated α -cyclodextrin, a fully benzylated β -cyclodextrin, or a fully benzylated γ -cyclodextrin or a derivative thereof.
In a twenty-third aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer can include one or more tetraphenylporphyrins or derivatives thereof.
In a twenty-fourth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the self-assembled monolayer can include one or more metallotetraphenylporphyrins or derivatives thereof.
In a twenty-fifth aspect, a method for detecting an analyte is included. The method may include collecting a gaseous sample from a patient and contacting the gaseous sample with one or more graphene varactors. Each graphene varactor may include a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer by pi-pi stacking interactions. The self-assembled monolayer may provide a langmuir θ value of at least 0.9.
In a twenty-sixth aspect, in addition to or in lieu of one or more of the preceding or subsequent aspects, the method may further comprise measuring a capacitance differential response of the one or more graphene varactors resulting from binding of the one or more analytes present in the gaseous sample.
In a twenty-seventh aspect, a medical device is included. The medical device may include a chemical sensor element. The chemical sensor element may include a first measurement region, wherein the first measurement region may include a graphene varactor including a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer by pi-pi stacking interactions. The self-assembled monolayer may cover at least 90% of the graphene layer surface.
In a twenty-eighth aspect, the chemical sensor element can include a second measurement zone in addition to or in place of one or more of the preceding or subsequent aspects.
This summary is an overview of some of the teachings of the present application and is not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details can be found in the detailed description and the appended claims. Other aspects will be apparent to those skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which is not in a limiting sense. The scope herein is defined by the appended claims and their legal equivalents.
Drawings
Various aspects may be more fully understood with reference to the following drawings, in which:
fig. 1 is a schematic perspective view of a graphene varactor, according to various embodiments herein.
Fig. 2 is a schematic cross-sectional view of a portion of a graphene varactor, according to various embodiments herein.
Fig. 3 is a schematic top plan view of a chemical sensor element according to various embodiments herein.
Fig. 4 is a schematic illustration of a portion of a measurement zone according to various embodiments herein.
Fig. 5 is a circuit diagram of a passive sensor circuit and a portion of a read circuit according to various embodiments herein.
Fig. 6 is a schematic diagram of a system for sensing a gaseous analyte according to various embodiments herein.
Fig. 7 is a schematic diagram of a system for sensing a gaseous analyte according to various embodiments herein.
Fig. 8 is a schematic cross-sectional view of a portion of a chemical sensor element according to various embodiments herein.
Fig. 9 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
FIG. 10 is a representative graph of relative surface coverage as a function of the log of concentration shown in FIG. 9 according to various embodiments herein.
Fig. 11 is a representative high resolution XPS spectrum and was fitted according to various embodiments herein.
Figure 12 is a representative high resolution XPS spectrogram and fit according to various embodiments herein.
Figure 13 is a representative high resolution XPS spectrogram and fit according to various embodiments herein.
Figure 14 is a representative high resolution XPS spectrogram and fit according to various embodiments herein.
Fig. 15 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
Fig. 16 is a representative graph of relative surface coverage as a function of the log of concentration shown in fig. 15 according to various embodiments herein.
FIG. 17 is a reaction pathway for synthesizing pyrene derivatives, according to various embodiments herein.
FIG. 18 is a reaction pathway for synthesizing pyrene derivatives, according to various embodiments herein.
Figure 19 is a reaction pathway for synthesizing cyclodextrin derivatives according to various embodiments herein.
Fig. 20 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
Fig. 21 is a representative graph of relative surface coverage as a function of the log of concentration shown in fig. 20, according to various embodiments herein.
Fig. 22 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
Fig. 23 is a representative graph of relative surface coverage as a function of the log concentration shown in fig. 22 according to various embodiments herein.
Fig. 24 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
Fig. 25 is a representative graph of relative surface coverage as a function of the log concentration shown in fig. 24, according to various embodiments herein.
Fig. 26 is a representative graph of relative surface coverage as a function of concentration according to various embodiments herein.
Fig. 27 is a representative graph of relative surface coverage as a function of the log concentration shown in fig. 26, according to various embodiments herein.
Fig. 28 is a representative plot of raman spectra according to various embodiments herein.
While the embodiments are susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example and drawings and will be described in detail. It should be understood, however, that the scope of the present disclosure is not limited to the particular embodiments described. On the contrary, the intention is to cover modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.
Detailed Description
Embodiments herein relate to chemical sensors, medical devices and systems including the sensors, and related methods for detecting chemical compounds in gaseous samples, such as, but not limited to, respiration of a patient. In some embodiments, the chemical sensors herein may be based on non-covalent surface modification of graphene.
Graphene is a form of carbon that comprises a monolayer of carbon atoms in a hexagonal lattice. Graphene due to its close packed sp2Hybrid orbitals with high strength and stability, in which each carbon atom forms a sigma (σ) bond with each of its three adjacent carbon atoms, and one p-orbital is flat from a hexagonThe surface is extended. The p orbitals of the hexagonal lattice can hybridize to form pi bands suitable for noncovalent pi-pi stacking interactions with other pi electron rich molecules.
Non-covalent functionalization of graphene with self-assembled monolayers does not significantly affect the atomic structure of graphene and provides stable graphene-based sensors with high sensitivity to many Volatile Organic Compounds (VOCs) at parts per billion (ppb) or parts per million (ppm) levels. As such, the embodiments herein can be used to detect VOCs and/or differential binding patterns of VOCs, which in turn can be used to identify disease states.
Referring now to fig. 1, a schematic diagram of a graphene-based variable capacitor (or graphene varactor) 100 is shown, according to embodiments herein. It will be understood that the graphene varactor can be fabricated in various geometries in various ways, and that the graphene varactor shown in fig. 1 is only one example according to embodiments herein.
The graphene varactor 100 may include an insulator layer 102, a gate electrode 104 (or "gate contact"), a dielectric layer (not shown in fig. 1), one or more graphene layers (e.g., graphene layers 108a and 108b), and a contact electrode 110 (or "graphene contact"). In some embodiments, one or more of the graphene layers 108a-b may be continuous, while in other embodiments, one or more of the graphene layers 108a-b may be discontinuous. The gate electrode 104 may be deposited within one or more recesses formed in the insulator layer 102. The insulator layer 102 may be formed of an insulating material such as silicon dioxide formed on a silicon substrate (wafer) or the like. The gate electrode 104 may be formed of a conductive material such as chromium, copper, gold, silver, tungsten, aluminum, titanium, palladium, platinum, iridium, and any combination or alloy thereof, which may be deposited on top of or embedded in the insulator layer 102. A dielectric layer may be disposed on the surface of the insulator layer 102 and the gate electrode 104. One or more graphene layers 108a-b may be disposed on the dielectric layer. The dielectric layer will be discussed in more detail below with reference to fig. 2.
The graphene varactor 100 includes eight gate electrode fingers 106a-106 h. It will be understood that although the graphene varactor 100 shows eight gate electrode fingers 106a-106h, any number of gate electrode finger configurations are contemplated. In some embodiments, a single graphene varactor may include less than eight gate electrode fingers. In some embodiments, a single graphene varactor may include more than eight gate electrode fingers. In other embodiments, a single graphene varactor may include two gate electrode fingers. In some embodiments, a single graphene varactor may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more gate electrode fingers.
The graphene varactor 100 may include one or more contact electrodes 110 disposed on a portion of the graphene layers 108a and 108 b. The contact electrode 110 may be formed of a conductive material such as chromium, copper, gold, silver, tungsten, aluminum, titanium, palladium, platinum, iridium, and any combination or alloy thereof. Additional aspects of exemplary graphene varactors can be found in U.S. patent No. 9,513,244, the contents of which are incorporated herein by reference in their entirety.
Graphene varactors described herein may include those in which a single graphene layer has been surface modified by non-covalent pi-pi stacking interactions between graphene and pi-electron rich molecules (such as, for example, pyrene derivatives and other compounds having aromatic groups). In some embodiments, the surface of a single graphene layer may be surface modified by non-covalent pi-pi stacking interactions between graphene and any of a number of cyclodextrins and derivatives thereof. In some embodiments, the surface of a single graphene layer may be surface modified by non-covalent pi-pi stacking interactions between graphene and any of a number of tetraphenylporphyrins and derivatives thereof. Details regarding graphene varactors and pi-electron rich molecules suitable for use herein are discussed more fully below.
Referring now to fig. 2, a schematic cross-sectional view of a portion of a graphene varactor 200 is shown, in accordance with various embodiments herein. The graphene varactor 200 may include an insulator layer 102 and a gate electrode 104 recessed into the insulator layer 102. The gate electrode 104 may be formed by depositing a conductive material in a recess in the insulator layer 102, as discussed above with reference to fig. 1. A dielectric layer 202 may be formed on the surface of the insulator layer 102 and the gate electrode 104. In some examples, the dielectric layer 202 may be formed of a material such as silicon dioxide, aluminum oxide, hafnium dioxide, zirconium dioxide, hafnium silicate, or zirconium silicate.
The graphene varactor 200 may include a single graphene layer 204, which may be disposed on a surface of a dielectric layer 202. Graphene layer 204 may be surface modified with self-assembled monolayer 206. The self-assembled monolayer 206 may be formed from a homogenous population of pi-electron rich molecules disposed on the outer surface of the graphene layer 204 by non-covalent pi-pi stacking interactions. Exemplary pi-electron rich molecules are described more fully below. The self-assembled monolayer 206 may provide at least 90% surface coverage (by area) of the graphene layer 204. In some embodiments, the self-assembled monolayer 206 may provide at least 95% surface coverage of the graphene layer 204. In other embodiments, the self-assembled monolayer 206 may provide at least 98% surface coverage of the graphene layer 204.
In some embodiments, the self-assembled monolayer may provide at least 50%, 60%, 70%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% surface coverage (by area) of the graphene layer. It will be understood that the self-assembled monolayer may provide surface coverage falling within a range, wherein any of the foregoing percentages may be used as either a lower or upper limit of the range, provided that the value of the lower limit of the range is less than the upper limit of the range.
In some embodiments, it will be understood that self-assembly of pi-electron rich molecules on the surface of a graphene layer may include self-assembly into more than one monolayer, such as a multilayer. Multilayers can be detected and quantified by techniques such as Scanning Tunneling Microscopy (STM) and other scanning probe microscopes. References herein to a percentage of coverage of greater than 100% shall refer to the case where a portion of the surface area is covered by more than one monolayer, such as by two, three, or more layers of the compound used. Thus, reference herein to a coverage of 105% will indicate that about 5% of the surface area comprises more than a monolayer coverage on the graphene layer. In some embodiments, the graphene surface may comprise 101%, 102%, 103%, 104%, 105%, 110%, 120%, 130%, 140%, 150%, or 175% surface coverage of the graphene layer. It will be understood that the multi-layer surface coverage of the graphene layers may fall within a range of surface coverage, where any of the above percentages may be used as either a lower or upper limit of the range, provided that the value of the lower limit of the range is less than the upper limit of the range. For example, coverage ranges may include, but are not limited to, 50% to 150% by surface area, 80% to 120% by surface area, 90% to 110% by surface area, or 99% to 120% by surface area.
In some embodiments, self-assembled monolayers suitable for use herein can provide graphene surface coverage using monolayers, as quantified by a langmuir θ value of at least some minimum threshold, but avoid covering most surfaces of graphene with multiple layers thicker than a monolayer. Details regarding langmuir θ values and the determination of specific self-assembled monolayers using langmuir adsorption theory are described more fully below. In some embodiments, self-assembled monolayers suitable for use herein provide langmuir θ values of at least 0.95. In some embodiments, self-assembled monolayers suitable for use herein provide langmuir θ values of at least 0.98. In some embodiments, the self-assembled monolayer may provide a langmuir θ value of at least 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1.0. It will be understood that the self-assembled monolayer may provide a range of langmuir theta values, wherein any of the foregoing langmuir theta values may be used as either a lower limit or an upper limit of the range, provided that the value of the lower limit of the range is less than the upper limit of the range.
Referring now to fig. 3, a schematic top plan view of a
A
In some embodiments, a third measurement region (drift control region or witness zone) 308 may also be disposed on the substrate. The
The first measurement region, the second measurement region, and the third measurement region may have the same size or may have different sizes. The
In some embodiments, chemical sensor elements embodied herein may include electrical contacts (not shown) that may be used to provide power to components on
It will be understood that chemical sensor elements embodied herein may include those that are compatible with passive wireless sensing. A schematic diagram of a portion of the passive sensor circuit 502 and the read circuit 522 is shown in fig. 5 and discussed in more detail below. In a passive wireless sensing arrangement, one or more graphene varactors may be integrated with the inductor such that one terminal of the graphene varactor contacts one end of the inductor and a second terminal of the graphene varactor contacts a second terminal of the inductor. In some embodiments, the inductor may be located on the same substrate as the graphene varactor, while in other embodiments, the inductor may be located in an off-chip location.
Referring now to fig. 4, a schematic diagram of a portion of a
In some embodiments, the discrete graphene varactors may be heterogeneous in that they all differ from each other in their binding behavior or specificity with respect to a particular analyte. In some embodiments, some discrete graphene varactors may be duplicated for verification purposes, but otherwise heterogeneous with other discrete graphene varactors. In yet other embodiments, the discrete graphene varactors may be homogenous. While the
In some embodiments, the order of the particular
The number of discrete graphene varactors within a particular measurement region may be from about 1 to about 100,000. In some embodiments, the number of discrete graphene varactors may be from about 1 to about 10,000. In some embodiments, the number of discrete graphene varactors may be from about 1 to about 1,000. In some embodiments, the number of discrete graphene varactors may be from about 2 to about 500. In some embodiments, the number of discrete graphene varactors may be from about 10 to about 500. In some embodiments, the number of discrete graphene varactors may be from about 50 to about 500. In some embodiments, the number of discrete graphene varactors may be from about 1 to about 250. In some embodiments, the number of discrete graphene varactors may be from about 1 to about 50.
Each of the discrete graphene varactors suitable for use herein may include at least a portion of one or more electrical circuits. For example, in some embodiments, each of the discrete graphene varactors may include one or more passive circuits. In some embodiments, graphene varactors may be included such that they are integrated directly on the electronic circuit. In some embodiments, graphene varactors may be included such that they are wafer bonded to the circuit. In some embodiments, the graphene varactor may include integrated readout electronics, such as a readout integrated circuit (ROIC). The electrical characteristics of the circuit (including resistance or capacitance) may change upon binding (e.g., specific and/or non-specific binding) with a component from the gas sample.
Referring now to fig. 5, a schematic diagram of a portion of a passive sensor circuit 502 and a read circuit 522 is shown, in accordance with various aspects herein. In some embodiments, passive sensor circuit 502 may include a metal oxide graphene varactor 504 coupled to an inductor 510 (where RS represents a series resistance and CG represents a varactor capacitor). Graphene varactors can be fabricated in various ways and in various geometries. For example, in some aspects, the gate electrode can be recessed into the insulator layer, as shown by gate electrode 104 in fig. 1. The gate electrode may be formed by etching a recess in the insulator layer and then depositing a conductive material in the recess to form the gate electrode. A dielectric layer may be formed on the insulator layer and the surface of the gate electrode. In some examples, the dielectric layer may be formed of a metal oxide such as aluminum oxide, hafnium oxide, zirconium dioxide, silicon dioxide, or another material such as hafnium silicate or zirconium silicate. A surface modified graphene layer may be disposed on the dielectric layer. A contact electrode may also be provided on the surface of the surface-modified graphene layer, as also shown in fig. 1 as contact electrode 110.
Additional aspects of exemplary graphene varactor constructions can be found in U.S. patent No. 9,513,244, the contents of which are incorporated herein by reference in their entirety.
In various embodiments, a functionalized graphene layer (e.g., functionalized to contain an analyte-binding receptor), which is part of a graphene varactor and thus part of a sensor circuit, such as a passive sensor circuit, is exposed to a gas sample flowing over the surface of a measurement region. The passive sensor circuit 502 may also include an inductor 510. In some embodiments, each passive sensor circuit 502 includes only a single varactor. In some embodiments, each passive sensor circuit 502 includes (e.g., in parallel) a plurality of varactors.
In the passive sensor circuit 502, the capacitance of the circuit changes after an analyte in the gas sample combines with the graphene varactor. The passive sensor circuit 502 may be used as an LRC resonator circuit, where the resonant frequency of the LRC resonator circuit changes after combination with the constituents of the gas sample.
The read circuit 522 may be used to detect an electrical characteristic of the passive sensor circuit 502. For example, the read circuit 522 may be used to detect the resonant frequency of the LRC resonator circuit and/or changes therein. In some embodiments, the read circuit 522 may include a read coil having a resistance 524 and an inductance 526. The phase versus frequency plot of the impedance of the read circuit has a minimum (or phase tilt frequency) when the sensor side LRC circuit is at its resonant frequency. Sensing may occur when the varactor capacitance changes in response to binding of the analyte, which changes the value of the resonant frequency, and/or the phase tilt frequency.
Referring now to fig. 6, a schematic diagram of a system 600 for sensing a gaseous analyte is shown, in accordance with various embodiments herein. The system 600 may include a housing 618. The system 600 may include a mouthpiece 602 into which a subject to be evaluated may insufflate a breath sample. A gaseous breath sample may pass through inflow conduit 604 and through an evaluation sample (patient sample) input port 606. The system 600 may also include a control sample (environment) input port 608. The system 600 may also include a sensor element chamber 610 in which disposable sensor elements may be placed. The system 600 may also include a display 614 and a user input device 616, such as a keyboard. The system may also include a gas outflow port 612. The system 600 may also include a flow sensor in fluid communication with an air flow associated with one or more of the evaluation sample input port 606 and the control sample input port 608. It will be appreciated that many different types of flow sensors may be used. In some embodiments, a hot wire anemometer may be used to measure air flow. In some embodiments, the system may include a CO in fluid communication with the gas stream2A sensor associated with one or more of the evaluation sample input port 606 and the control sample input port 608.
In various embodiments, system 600 may also include other functional components. For example, the system 600 may include a humidity control module 640 and/or a temperature control module 642. The humidity control module may be in fluid communication with the gas streams associated with one or more of the evaluation sample input port 606 and the control sample input port 608 to adjust the humidity of one or both gas streams so that the relative humidity of the two streams is substantially the same to prevent adverse effects on the readings obtained by the system. The temperature control module may be in fluid communication with the gas streams associated with one or more of the evaluation sample input port 606 and the control sample input port 608 to adjust the temperature of one or both gas streams so that the temperatures of the two streams are substantially the same to prevent adverse effects on readings taken by the system. For example, the air flowing into the control sample input port may be raised to 37 degrees celsius or higher to match or exceed the air temperature from the patient. The humidity control module and the temperature control module may be located upstream of the input port, within the input port, or downstream of the input port in the housing 618 of the system 600. In some embodiments, the humidity control module 640 and the temperature control module 642 may be integrated.
In some embodiments (not shown), a control sample input port 608 of the system 600 may also be connected to the mouthpiece 602. In some embodiments, mouthpiece 602 may include a switched airflow valve such that when the patient is inhaling, air flows from the control sample input port 608 to the mouthpiece, and the system is configured such that ambient air is caused to flow through the appropriate control measurement zone (e.g., the second measurement zone). Then, when the patient exhales, the switching airflow valve may be switched such that a breath sample from the patient flows from the mouthpiece 602 through the inflow conduit 604 into the evaluation sample input port 606 and across an appropriate sample (patient sample) measurement zone (e.g., first measurement zone) on the disposable sensor element.
In an embodiment, a method of manufacturing a chemical sensor element is included. The method may include depositing one or more measurement zones on a substrate. The method may further include depositing a plurality of discrete graphene varactors within the measurement region on the substrate. The method may include creating one or more discrete graphene varactors by modifying a surface of a graphene layer with pi-electron rich molecules to form a self-assembled monolayer on an outer surface of the graphene layer through pi-pi stacking interactions. The method may comprise quantifying the degree of surface coverage of the self-assembled monolayer using contact angle goniometry, raman spectroscopy or X-ray photoelectron spectroscopy. The method may include selecting a derivatized graphene layer that exhibits a langmuir θ value of at least 0.9, as will be discussed more fully below. The method may further comprise depositing a component for storing the reference data onto the substrate. In some embodiments, the measurement zones may all be placed on the same side of the substrate. In other embodiments, the measurement zones may be placed on different sides of the substrate.
In an embodiment, a method of analyzing one or more gas samples is included. The method may include inserting the chemical sensor element into a sensing machine. The chemical sensor element can include a substrate and a first measurement region including a plurality of discrete graphene varactors. The first measurement zone may define a portion of the first gas flow path. The chemical sensor element may further comprise a second measurement zone separate from the first measurement zone. The second measurement region may also include a plurality of discrete graphene varactors. The second measurement zone may be disposed outside of the first gas flow path.
The method may further comprise prompting the subject to blow air into the sensing machine to follow the first gas flow path. In some embodiments, the CO of air from the subject is monitored2In a content of CO2Sampling is performed with disposable sensor elements during the plateau of content, since it is believed that the air originating from the patient's alveoli has the most abundant content of chemical compounds (e.g., volatile organic compounds) for analysis. In some embodiments, the method may include monitoring the total mass flow of the breath sample and the control (or ambient) air sample using a flow sensor. The method may further comprise interrogating the discrete graphene varactors to determine their analyte binding state. The method may further comprise discarding the disposable sensor element after sampling is complete.
Referring now to fig. 7, a schematic diagram of a
In some embodiments, one of the measurement regions may be configured to indicate a change (or drift) in the chemical sensor element that may occur during storage and handling due to aging and exposure to changing conditions (e.g., heat exposure, light exposure, molecular oxygen exposure, moisture exposure, etc.) prior to use. In some embodiments, a third measurement zone may be configured for this purpose.
Referring now to fig. 8, a schematic cross-sectional view of a portion of a
In embodiments, methods for detecting one or more analytes are included. The method may include collecting a gaseous sample from a patient. In some embodiments, the gaseous sample may comprise breath. In other embodiments, the gaseous sample may comprise a breath (break) obtained from the patient's lungs via a catheter or other similar extraction device. In some embodiments, the extraction device may comprise an endoscope, a bronchoscope, or a bronchoscope. The method may further include contacting a graphene varactor with the gaseous sample, wherein the graphene varactor includes a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer by pi-pi stacking interactions. In some embodiments, the self-assembled monolayer may provide a langmuir θ value of at least 0.9. The langmuir θ values will be discussed more fully below. In some embodiments, the method may include measuring a capacitive differential response of the graphene reactor due to binding of one or more analytes present in the gaseous sample, which in turn may be used to identify a disease state.
Graphene varactor
The graphene varactors described herein may be used to sense one or more analytes in a gaseous sample (e.g., such as a breath of a patient). The graphene varactors embodied herein may exhibit high sensitivity to Volatile Organic Compounds (VOCs) found in gaseous samples at or near parts per million (ppm) or parts per billion (ppb) levels. Adsorption of VOCs on the surface of graphene varactors can change the resistance, capacitance, or quantum capacitance of such devices, and can be used to detect VOCs and/or their combination patterns, which in turn can be used to identify disease states such as cancer, heart disease, infection, multiple sclerosis, alzheimer's disease, parkinson's disease, and the like. Graphene varactors can be used to detect individual analytes in gas mixtures, as well as response modes in highly complex mixtures. In some embodiments, one or more graphene varactors may be included to detect the same analyte in a gaseous sample. In some embodiments, one or more graphene varactors may be included to detect different analytes in a gaseous sample. In some embodiments, one or more graphene varactors may be included to detect multiple analytes in a gaseous sample.
An exemplary graphene varactor may include a graphene layer and a self-assembled monolayer disposed on an outer surface of the graphene layer that interacts with the latter through pi-pi stacking interactions, as shown and discussed above with reference to fig. 2. Self-assembled monolayers suitable for use herein can provide langmuir θ values of at least 0.9. The determination of langmuir θ values for particular self-assembled monolayers using langmuir adsorption theory is described in more detail below. In some embodiments, self-assembled monolayers suitable for use herein provide langmuir θ values of at least 0.95. In some embodiments, self-assembled monolayers suitable for use herein provide langmuir θ values of at least 0.98.
Graphene varactors described herein may include those in which a single graphene layer has been surface modified by non-covalent pi-pi stacking interactions between the graphene layer and pi-electron rich molecules.
An exemplary class of pi-electron rich molecules includes polycyclic aromatic hydrocarbons. Examples of polycyclic aromatic hydrocarbons suitable for use in the graphene varactors described herein may include, but are not limited to, those having from 3 to 10 aromatic rings. For example, polycyclic aromatic hydrocarbons having from 3 to 10 aromatic rings may include anthracene, benzanthracene, phenanthrene, phenalene, naphthacene, benzanthracene, benzanth,
As described herein, polycyclic aromatic hydrocarbons may be described by the following formula:
wherein X1May be any substituent, including but not limited to any straight, branched or cyclic C covalently bonded directly to the underlying aromatic ring structure1-C10Alkyl, -H, -R1OH，-R2COOH，-R3COOR4，-R5NH3 +，-R6NH2，-R7NR8，-R9NR10R11+，-R12B(OH)2Or any combination thereof; n is any integer from 3 to 10, from 3 to 15, or from 3 to 20; and R is1To R12May include, but is not limited to, any straight chain, branched chainOr cyclic C1-C10An alkyl group, or a combination thereof, or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the underlying aromatic ring structure.
In some embodiments, polycyclic aromatic hydrocarbons may include pyrene and pyrene derivatives described by the following formula:
wherein X1、X2、X3And X4May be any substituent, including but not limited to any straight, branched or cyclic C covalently bonded directly to the underlying aromatic ring structure1-C10Alkyl, -H, -R1OH，-R2COOH，-R3COOR4，-R5NH3 +，-R6NH2，-R7NR8，-R9NR10R11+，-R12B(OH)2Or any combination thereof; and R is1To R12May include, but is not limited to, any straight, branched or cyclic C1-C10An alkyl group, or a combination thereof, or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the underlying aromatic ring structure. In some embodiments, pyrene (Pyr) derivatives suitable for use herein include, but are not limited to Pyr-CH2OH、Pyr-CH2COOH、Pyr-CH2COOCH3、Pyr-CH2NH2、Pyr-CH2NH2·HCl、Pyr-CH2N(CH2CH3)2And Pyr-B (OH)2。
In some embodiments, functional groups suitable for use herein may include polar functional groups containing at least one oxygen atom, including but not limited to-R1OH、-R2COOH and-R3COOR4Or any combination thereof, wherein R1、R2、R3And R4May include, but is not limited to, any straight, branched or cyclic C1-C10An alkyl group or a combination thereof,or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the base aromatic ring structure. In some embodiments, functional groups suitable for use herein may include polar functional groups containing at least one nitrogen atom, including but not limited to-R5NH3 +、-R6NH2、-R7NR8、-R9NR10R11+、-R12B(OH)2Or any combination thereof, wherein R5、R6、R7、R8、R9、R10、R11And R12May include, but is not limited to, any straight, branched, or cyclic C1-C10An alkyl group or a combination thereof, or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the underlying aromatic ring structure. In other embodiments, the functional group may include a combination of a polar functional group containing at least one oxygen atom and a polar functional group containing at least one nitrogen atom.
Another class of pi electron rich molecules suitable for modifying the surface of graphene by non-covalent pi-pi stacking interactions includes molecules having multiple aromatic groups (such as the polycyclic groups mentioned above), and also aromatic groups having one or more aromatic rings, such as phenyl, benzyl, or naphthyl groups and derivatives thereof. Examples of such molecules for use herein are aromatic cyclodextrins, such as benzylated cyclodextrins, and include, but are not limited to, alpha-, beta-, and gamma-cyclodextrin derivatives. In some embodiments, the cyclodextrin can include fully benzylated α -, β -, and γ -cyclodextrins. In some embodiments, the cyclodextrin may include partially benzylated α -, β -, and γ -cyclodextrins.
In some embodiments, the fully benzylated cyclodextrins and derivatives thereof can include, but are not limited to, those having the following formula:
wherein n can be an integer from 5-10, or any integer from 6 to 8, and X can includeBut are not limited to-H, hydroxy, amino, any straight, branched or cyclic C1-C10Alcohol, any straight, branched or cyclic C1-C10Any combination of any one of amine, phenyl, benzyl or naphthyl and derivatives thereof, provided that each repeating unit in the above structure comprises at least one X that is an aromatic functional group. In some embodiments, the presence of one or more hydroxyl or amino groups may facilitate hydrogen bonding between the cyclodextrin molecules and the graphene layer.
Another class of pi electron rich molecules suitable for modifying graphene surfaces through non-covalent pi-pi stacking interactions includes Tetraphenylporphyrins (TPPs) and derivatives thereof. The structure of tetraphenylporphyrin is as follows:
in various embodiments herein, tetraphenylporphyrins can be derivatized with various functional groups. Thus, in some embodiments, the tetraphenylporphyrins herein can be described by the formula:
wherein n can be any integer from 1 to 5; m may be 1 or 2; r1To R8May be any substituent, including but not limited to-H; -X, wherein X comprises any halogen atom; -R9；-R10OH；-R11COOH；-R12COOR13；-R14OR15；-R16COH；-R17COR18；-R19NH3 +；-R20NH2；-R21NR22；-R23NR24R25+；-R26X or-R27COX, where X may be any halogen atom; -R28SH or any combination thereof; and R is9To R28May include, but is not limited to, any straight or branched chain C1-C12Alkyl radical, C1-C12Alkenyl radical, C1-C12Alkynyl groups, or any combination thereof, or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the basic aromatic ring structure.
In some embodiments, the tetraphenylporphyrin is a metal tetraphenylporphyrin. The structure of the metal tetraphenylporphyrin is as follows:
in various embodiments herein, the metal tetraphenylporphyrins can be derivatized with various functional groups. Thus, in some embodiments, the metal tetraphenylporphyrins can be described by the formula:
wherein M is any metal atom including, but not limited to, aluminum, calcium, magnesium, manganese, iron, cobalt, nickel, zinc, ruthenium, palladium, or derivatives thereof; wherein n can be any integer from 1 to 5; m may be 1 or 2; r1To R8May be any substituent, including but not limited to-H; -X, wherein X comprises any halogen atom; -R9；-R10OH；-R11COOH；-R12COOR13；-R14OR15；-R16COH；-R17COR18；-R19NH3 +；-R20NH2；-R21NR22；-R23NR24R25+；-R26X or-R27COX, where X may be any halogen atom; -R28SH or any combination thereof; and R is9To R28May include, but is not limited to, any straight or branched chain C1-C12Alkyl radical, C1-C12Alkenyl radical, C1-C12Alkynyl groups, or any combination thereof, or absent such that the remainder of the functional group is covalently bonded directly to one or more carbon atoms of the basic aromatic ring structure.
Self-assembled monolayers may include both homogenous and heterogeneous (e.g., they may include layers of more than one type of compound). In some embodiments, the self-assembled monolayer may be monofunctional, and in other embodiments, the self-assembled monolayer may be difunctional, trifunctional, or the like. In some embodiments, the self-assembled monolayer may include at least about 5%, 10%, 15%, 20%, 25%, 30%, 40%, or 50% of a secondary compound (or an amount that falls within a range between these amounts), which may be any of the compounds described herein, but which is different from the primary compound which makes up the substantial balance of the graphene layer coverage.
In some embodiments, the graphene layer may be disposed on a surface of the substrate. Suitable substrate materials for use herein may include metals such as copper, nickel, ruthenium, platinum, iridium, and the like, as well as metal oxides such as copper oxide, zinc oxide, magnesium oxide, and the like. Substrate materials may also include silicon, quartz, sapphire, glass, ceramics, polymers, and the like.
Additional aspects of exemplary graphene varactors can be found in U.S. patent No. 9,513,244, the contents of which are incorporated herein by reference in their entirety.
Contact angle goniometry
Contact angle goniometry can be used to determine the wettability of a solid surface by a liquid. Wettability or wetting may be caused by intermolecular forces at the contact area between the liquid and the solid surface. The degree of wetting can be described by the value of the contact angle Φ formed between the contact area between the liquid and the solid surface and a line tangent to the liquid-vapor interface. When the surface of the solid is hydrophilic and water is used as the test liquid (i.e. high wettability), the value of Φ may fall in the range of 0 to 90 degrees. When the surface of the solid is moderately hydrophilic to hydrophobic (i.e., moderately wetting), the value of Φ of water as the test liquid may fall within the range of 85 to 105 degrees. When the surface of the solid is highly hydrophobic (i.e., low wettability), the value of Φ of water as the test liquid may fall within the range of 90 to 180 degrees. Thus, the change in contact angle may reflect a change in the surface chemistry of the substrate.
The graphene surface and the modification to the graphene surface can be characterized using a contact angle goniometry method. The contact angle goniometry method can provide quantitative information about the degree of graphene surface modification. Contact angle measurements are highly sensitive to the presence of functional groups on the sample surface and can be used to determine the formation and extent of surface coverage of self-assembled monolayers. The change in contact angle of the bare graphene surface compared to a graphene surface that has been immersed in a self-assembly solution containing pi-electron rich molecules can be used to confirm the formation of self-assembled monolayers on the graphene surface.
The type of solvent (also referred to as wetting solution) suitable for determining contact angle measurements is one that maximizes the difference between the contact angle of the solution on bare graphene and the contact angle on modified graphene, thereby improving the measurement data accuracy of the binding isotherm. In some embodiments, the wetting solution may include, but is not limited to, Deionized (DI) water, aqueous NaOH, borate buffer (pH 9.0), other pH buffers, CF3CH2OH and the like. In some embodiments, the wetting solution is polar. In some embodiments, the wetting solution is non-polar.
Langmuir theory of adsorption
Without wishing to be bound by any particular theory, it is believed that monolayer modification of graphene can be controlled by varying the concentration of the adsorbate in the bulk of the self-assembly solution according to langmuir adsorption theory according to the following formula:
where θ is the fraction of surface coverage, C is the concentration of the adsorbate in the bulk of the self-assembly solution, and K is the equilibrium constant for the adsorbate to adsorb onto the graphene. Experimentally, the surface coverage can be expressed by the change in contact angle between bare graphene and modified graphene according to the following formula:
where Φ (i) is the contact angle of the modified graphene as a function of concentration in the self-assembly solution, Φ (bare) is the contact angle of bare graphene, and Φ (saturated) is the contact angle of graphene modified with a monolayer of intact acceptor molecules (i.e., 100% surface coverage or θ ═ 1.0). Inserting θ from equation (2) into equation (1) and solving for Φ (i) yields equation (3)
Thus, experimentally observed values of Φ (i) can be fitted as a function of the concentration of the acceptor in the self-assembly solution using two fitting parameters K and Φ (saturation). Once these two parameters are determined, the relative surface coverage at different self-assembly concentrations can be extrapolated from equation (1) using K.
The data can be fitted with a langmuir adsorption model to determine the equilibrium constant for surface adsorption and the concentration of self-assembly solution required to form a dense monolayer on graphene with 90% or greater surface coverage (i.e., θ > 0.9). In some embodiments, it is desirable for the surface coverage to be at least 90% or greater. In some embodiments, it is desirable for the surface coverage to be at least 95% or greater. In some embodiments, it is desirable for the surface coverage to be at least 98% or greater.
For the formation of Pyr-CH2OH adsorption onto graphene, a representative langmuir adsorption isotherm is shown in figure 9 and described more fully in example 8 below. For the formation of Pyr-CH2OH adsorbs onto graphene, and the data shows relative monolayer coverage (dots) along with a fit based on langmuir adsorption theory (solid line) as determined by contact angle measurements. For the formation of Pyr-CH2OH adsorbs to the graphene, and the log concentration as a function of relative surface coverage is shown in table 10.
In the above example, K was determined from the contact angle data using the langmuir model. Instead of contact angle data, band intensities in the spectrum from surface spectroscopy, such as data obtained by infrared spectroscopy or raman spectroscopy, may be used.
x-ray photoelectron spectroscopy
X-ray photoelectron spectroscopy (XPS) is a highly sensitive spectroscopic technique that can quantitatively measure the elemental composition of a material surface. The process of XPS involves irradiating the surface with X-rays under vacuum while measuring the kinetic energy and electron release within the first 0 to 10nm of the material. Without wishing to be bound by any particular theory, it is believed that XPS may be used to demonstrate the presence of self-assembled monolayers formed on the graphene surface.
The surface concentration of the atomic species (as determined by XPS) of the monolayer, graphene and underlying substrate composition is dependent on the langmuir θ value of the monolayer, in other words, the surface density of the monolayer molecules on the graphene. For example, the surface concentration of carbon, oxygen, and copper (i.e., C%, O%, and Cu% as determined by XPS) for any given monolayer of cyclodextrin on a copper substrate depends on the concentration of the cyclodextrin in the self-assembly solution. Due to experimental errors, the equilibrium constant K, which results in surface adsorption, will be slightly different values when fitting the C%, O% or Cu% data, respectively. However, since the C%, O%, or Cu% data have the same equilibrium characteristics, K has only one true value. Thus, the XPS data can be fitted not only to C%, O%, and Cu% data, respectively, but also as a set of combined data. Fitting the combined data for the monolayer, graphene and underlying substrate composition of several types of atoms gives a more accurate estimate of the true value of K. For this purpose, the following equation may be used, where each data point consists of a vector (vector) that includes (i) the index, (ii) the concentration of the self-assembling solution and (iii) the carbon, oxygen or copper concentration as determined by XPS.
In the above example, the K values were fitted according to 3 adsorption isotherms (i.e. surface concentrations of 3 atoms). The same type of fit may also be made for adsorption isotherms of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more different types of atoms.
Bare graphene and graphene oxide coated with α -CDBn18Representative C1s and O1s spectra of modified graphene are shown in figures 10-13 and further described in example 14 below the equilibrium constant K as determined by fitting XPS data can be used in a langmuir adsorption model to determine the theta values for graphene surfaces modified with various molecules (such as cyclodextrins and cyclodextrin derivatives) that form monolayers on graphene for the fully benzylated β -cyclodextrin (β -CDBn)21) A representative Langmuir adsorption isotherm for the adsorption of modified graphene is shown in FIG. 15 for β -CDBn21Adsorption of modified graphene, the data showing relative monolayer coverage (dots) along with a fit based on langmuir adsorption theory (solid line) as determined by XPS data for β -CDBn21Adsorbing to graphene, and taking the relative surface coverage rate as β -CDBn in self-assembly solution21The function of the log concentration is shown in figure 16.
Aspects may be better understood with reference to the following examples. These examples are intended to be representative of particular embodiments, but are not intended to limit the overall scope of the embodiments herein.
Examples of the invention
Example 1: experimental Material
Experimental materials suitable for use in the synthesis of the reagents described in examples 2-6. for self-assembly of fully benzylated α -, β -and γ -cyclodextrins, single-layer graphene on Cu foil was purchased from Grapheneea (Donostia, Spain.) for all other self-assemblies, single-layer graphene was grown on 25 μm thick Cu foil (Alfa Aesar, Tewksbury, MA) at 1050 ℃ by chemical vapor deposition using 21sccm and 0.105sccm hydrogen and methane flow rates, respectively, pyrene, 1-pyrene acetic acid, 1-pyrenemethylammonium chloride, pyrenmethyl chloride, respectively, from Aldrich (Aldrich, St. Louis, Mo), Michelia1-pyreneboronic acid, β -cyclodextrin and PBr3And NaH (60% w/w dispersion in mineral oil) 1-pyrene methanol and α -and γ -cyclodextrin were purchased from TCI corporation (Cambridge, MA) before use α -, β -and γ -cyclodextrin were dried under vacuum overnight before use toluene, methanol and dimethyl sulfoxide (DMSO) were dried over molecular sieves before use purified by using Milli-Q PLUS reagent grade water system (Millipore, Billerica, MA, belerica) to obtain deionized water (DI water, specific resistance 0.18M) borate buffer (pH 9) was prepared from 50mL aqueous solution containing 0.1M boric acid and 0.1M KCl, 20.8mL 0.1M NaOH (aq) and 29.2mL DI water.
Example 2: surface modification of graphene by self-assembly
Graphene substrates were immersed overnight in solutions containing various concentrations (0, 0.03, 0.10, 0.30, 1.0, 3.0, or 10mM) of pyrene or cyclodextrin derivatives. The modified graphene substrate was then washed 3 times with a small portion of solvent to remove excess self-assembly solution. For Pyr-CH2COOH、Pyr-CH2COOCH3、Pyr-CH2NH2·HCl、Pyr-CH2NH2And Pyr-CH2N(CH2CH3)2Modification, ethanol was used as the self-assembly solvent. For pyrene and Pyr-CH2OH、Pyr-B(OH)2、α-CDBn18、β-CDBn21And gamma-CDBn24Modification was performed using acetonitrile instead, since pyrene and Pyr-CH2OH does not assemble well on graphene in ethanol and fully benzylated cyclodextrins are insoluble in ethanol.
The concentration required for 90% monolayer coverage of all pyrene derivatives was estimated to be in the range of 0.30-3.6mM, regardless of whether self-assembly to form acetonitrile or ethanol solutions was performed. The equilibrium constant (K) of all pyrene derivatives was 103.4And 104.6M-1α -CDBn18,β-CDBn21,andγ-CDBn24Has a cyclodextrin equilibrium constant (K) of 103.24、102.97And 102.95M-1. Table 1 reportsEquilibrium constant and monolayer concentration required for 90% surface coverage.
Table 1 equilibrium constants and monolayer concentrations for adsorption of pyrenyl or benzyl bearing acceptors onto graphene.
2 2Example 3: preparation of Pyr-CHNH & HCl
Suitable syntheses for Pyr-CH are described above in example 12NH2HCl test material. Briefly, 50mgPyr-CH2NH2HCl in 10mL CH2Cl2And washed 3 times with 10mM NaOH (aq; 3 × 10mL) and DI water (3 × 10mL), respectively, CH was collected2Cl2Phase, and passing through anhydrous Na2SO4Drying gave a yellow solid after evaporation of the solvent under vacuum (50% by weight yield).1H NMR (, ppm, deuterated dimethyl sulfoxide (DMSO-d)6):4.483(s,2H,Ar-CH2)；8.048-8.444(m,11H,Ar-H,NH2)。
2 3Example 4: synthesis of Pyr-CHCOOCH
Suitable syntheses for Pyr-CH are described above in example 12COOCH3The test material of (1). Briefly, 0.25mL of concentrated sulfuric acid was added to 5mL of dry methanol. 150mg Pyr-CH was added2COOH and the resulting solution was refluxed for 24 hours after methanol evaporation, the remaining suspension was added to 20mL ice cold DI water, the resulting suspension was extracted with diethyl ether (3 × 20mL), the combined ether phases were washed with DI water (3 × 60mL) and over anhydrous Na2SO4And (5) drying. The solvent was evaporated in vacuo to give a yellow solid (66% by weight yield).1H NMR(,ppm,DMSO-d6):3.645(s,3H,CH3)；4.476(s,2H,Ar-CH2) (ii) a 8.014-8.329(m,9H, Ar-H). Mass spectrum (ESI-TOF, MeOH), m/z:297.0961 (Pyr-CH)2COOCH3·Na+)。Pyr-CH2COOCH3The synthesis of (a) is shown in figure 17.
2 2 3 2Example 5: synthesis of Pyr-CHN (CHCH)
Suitable syntheses for Pyr-CH are described above in example 12N(CH2CH3)2The test material of (1). First, Pyr-CH is prepared2Br is added. 250mg Pyr-CH2OH was added to 5.35mL of dry toluene. The suspension was cooled to 0 ℃ and 125. mu.L of PBr was added dropwise using a syringe3. The mixture was stirred at 0 ℃ for 1h and at room temperature overnight. Then, 5mL of saturated Na was slowly added under ice-cooling2CO3An aqueous solution. The solid and toluene layers were combined and washed with Na2SO4And (5) drying. After removal of the solid by filtration, the solvent was evaporated from the liquid phase using vacuum to give a yellow solid (Pyr-CH)2Br, yield 75% by weight).1H NMR(,ppm,CDCl3):5.295(s,2H,Ar-CH2)；8.0-8.5(m,9H,Ar-H)。
In N2In an atmosphere, 125mg Pyr-CH2Br and 0.2mL diethylamine were added to 3mL toluene. The mixture was refluxed overnight. Toluene was evaporated and the solid obtained was added to 20mL CH2Cl2In a 10mM NaOH (aq) mixture (1:1, v/v), the mixture was subsequently stirred overnight. Collecting CH2Cl2The phases were washed with DI water (3 × 10mL) and anhydrous Na2SO4And (5) drying. Evaporation of the solvent in vacuo gave a yellow solid (Pyr-CH)2N(CH2CH3)2Yield 66% by weight).1H NMR(,ppm,DMSO-d6):1.037-1.072(t,6H,CH3)；2.562-2.615(m,4H,CH2)；4.229(s,2H,Ar-CH2) (ii) a 8.053-8.602(m,9H, Ar-H). Mass spectrum (ESI-TOF, MeOH), m/z:215.1125,288.2231 (Pyr-CH)2N(CH2CH3)2·H+)。Pyr-CH2N(CH2CH3)2The synthesis of (a) is shown in figure 18.
EXAMPLE 6 Synthesis of Perbenzylated α -, β -and γ -cyclodextrins
Experimental materials suitable for the synthesis of fully benzylated α -, β -, and γ -cyclodextrins are described above in example 1 briefly, 915mg NaH (60 wt% in mineral oil, 4 equivalents relative to the hydroxyl groups on the cyclodextrin) was added to a 2-neck round bottom flask in N2The mineral oil was removed by washing the NaH 5 times with hexane under protection. Then, 300mg of cyclodextrin was dissolved in 10ml of ldmso and the solution was degassed for 20 minutes and transferred to a round bottom flask. After stirring for 2 hours to react NaH with the hydroxyl groups of the cyclodextrin, 2.62mL of benzyl chloride (4 equivalents relative to the hydroxyl groups on the cyclodextrin) was added dropwise to the mixture. In N2The reaction was stirred at room temperature for 24 hours under protection then 15mL of water was added to the reaction mixture to neutralize excess NaH the resulting suspension was extracted with dichloromethane (4 × 30mL) then the combined dichloromethane phases were washed with water (1 × 120mL) and over anhydrous Na2SO4Drying, the solvent was evaporated in vacuo overnight the synthesis of fully benzylated α -, β -and γ -cyclodextrins is shown in FIG. 19.
The yellow liquid crude product was washed with hexane to remove most of the remaining benzyl chloride, followed by chromatographic purification on alumina (using first ethyl acetate/hexane, 1:6 as eluent, then switching to 1:3) to give a white solid foam (40% yield by weight).1H NMR(β-CDBn21,,ppm,CDCl3) 7.233-7.020(m,105H, aromatic H),5.174(d,7H, H1),5.069-4.335(m,42H, CH)2-Ph),4.034-3.957(m,28H,H3,H4,H5,H6),3.551-3.454(m,14H,H2,H6)。13C NMR(β-CDBn21,,ppm,CDCl3) 139.268,138.341,138.197(3 × C aromatic without H substituents), 128.291-126.913(CH aromatic), 98.443(C1),80.900(C3),78.797(C2),78.678(C4),75.441,73.273,72.641(3 × CH)2-Ph),71.438(C5),69.294 (C6). Mass Spectrometry (MALDI,
2 2 2 2 2 3Example 7: graphene modified with Pyr-CHNH & HCl, Pyr-CHNH and Pyr-CHCOOCH
Bare graphene and bare graphene with Pyr-CH were performed with a contact angle goniometer (Erma, Tokyo, Japan)2NH2·HCl、Pyr-CH2NH2And Pyr-CH2COOCH3Contact angle measurement of modified graphene. 4, 8 or 12 μ Ι _ of the appropriate solvent was dropped onto the graphene surface and the average contact angle was obtained from 6 advancing contact angle readings of the two points. Bare graphene and graphene coated with Pyr-CH2NH2·HCl、Pyr-CH2NH2And Pyr-CH2COOCH3The contact angle measurement results of the modified graphene are shown in table 2.
After the graphene is immersed in a pure solvent, the contact angle of the bare graphene is obtained. Using DI water as the wetting liquid, the contact angle of the bare graphene was found to be 90 ° -92 °. After the graphene was immersed in the self-assembly solution containing the pyrene derivative, the contact angle was changed, confirming that a self-assembled monolayer was formed on the graphene surface. For example, contact angles of graphene when exposed to 10mM Pyr-CH2NH2The HCl solution is then reduced to 74.0 ℃.
Relative monolayer coverage as a function of self-assembly solution concentration (mM) was fitted to Pyr-CH independently2COOCH3、Pyr-CH2NH2HCl and Pyr-CH2NH2Langmuir adsorption model of modified graphene. For Pyr-CH2COOCH3Figure 22 shows a single data point (dot) and a fit based on langmuir adsorption theory (solid line). For the formation of Pyr-CH2COOCH3Adsorbing the graphene, and taking the relative surface coverage rate as Pyr-CH in the self-assembly solution2COOCH3The function of the log concentration is shown in figure 23. For Pyr-CH2NH2HCl, fig. 24 shows a single data point (dot) and a fit based on langmuir adsorption theory (solid line). For the formation of Pyr-CH2NH2HCl is adsorbed on graphene, and the relative surface coverage is taken as Pyr-CH in self-assembly solution2NH2The function of the logarithm of the HCl concentration is shown in fig. 25. For Pyr-CH2NH2Figure 26 shows a single data point (dot) and a fit based on langmuir adsorption theory (solid line). For the formation of Pyr-CH2NH2Adsorbing the graphene, and taking the relative surface coverage rate as Pyr-CH in the self-assembly solution2NH2The function of the log concentration is shown in figure 27.
TABLE 2 DI water on bare graphene and with Pyr-CH2NH2·HCl、Pyr-CH2NH2Or Pyr-CH2COOCH3Contact angle on modified graphene.
2 2 2 2 3 2Example 8: graphene modified with Pyr-CHCOOH, pyrene, Pyr-CHOH or Pyr-CHN (CHCH)
The contact angle was measured with a contact angle goniometer (Elma, Tokyo, Japan) using Pyr-CH2COOH, pyrene, Pyr-CH2OH and Pyr-CH2N(CH2CH3)2Contact angle measurement of modified graphene. 4, 8 or 12. mu.L of an appropriate solvent is dropped onOn the graphene surface, and the average contact angle was obtained from 6 advancing contact angle readings at two points. By Pyr-CH2COOH, pyrene, Pyr-CH2OH and Pyr-CH2N(CH2CH3)2The contact angle measurement results of the modified graphene are shown in table 3.
Relative monolayer coverage as a function of self-assembly solution concentration (mM) was fitted to Pyr-CH independently2COOH, pyrene, Pyr-CH2OH or Pyr-CH2N(CH2CH3)2Langmuir adsorption model of modified graphene. For pyrene, figure 20 shows a single data point (dot) and a fit based on langmuir adsorption theory (solid line). The log concentration as a function of relative surface coverage for pyrene adsorption onto graphene is shown in fig. 21. For Pyr-CH2OH, figure 9 shows a single data point (dot) and a fit based on langmuir adsorption theory (solid line). For the formation of Pyr-CH2OH is adsorbed on graphene, and the relative surface coverage rate is used as Pyr-CH in self-assembly solution2The function of the logarithm of the OH concentration is shown in FIG. 10.
TABLE 3 use of Pyr-CH2COOH, pyrene, Pyr-CH2OH and Pyr-CH2N(CH2CH3) Contact angle measurement of modified graphene
2Example 9: graphene modified with Pyr-B (OH)
The XPS microprobe (PHI 5000, Physical Electronics, Chanhassen, Minn.) was scanned by Versa Probe III and collected with Pyr-B (OH)2X-ray photoelectron spectroscopy (XPS) spectroscopy of the modified graphene. Table 4 shows the results obtained with Pyr-B (OH)2Elemental surface composition results for modified graphene.
TABLE 4 Pyr-B (OH) as determined by XPS2ModifiedElemental surface composition of graphene
Concentration of self-assembling solution (mM)
C％
O Si％
0
54.7±1.2
33.3±0.6
12.4±0.2
0.01
53.1±0.1
34.1±0.1
12.1±0.1
0.10
56.9±0.9
31.8±0.1
11.3±0.8
0.40
56.2±2.2
30.8±1.2
13±1.0
1.0
60.2±1.6
28.4±1.4
11.3±0.3
2.0
60.4±0.1
28.7±0.6
10.7±0.2
18Example 10 graphene modified with fully benzylated α -Cyclodextrin (α -CDBn)
α -Cyclodextrin (α -CDBn) fully benzylated was collected on a Versa Probe III scanning XPS microprobe (PHI 5000, Physical Electronics, Inc., Chanhassen, Minn.)18) X-ray photoelectron Spectroscopy (XPS) Spectroscopy of modified graphene Table 5 shows the use of α -CDBn18Elemental surface composition results for modified graphene.
TABLE 5 α -Cyclodextrin Perbenzylated with Perbenzylated (α -CDBn) as determined by XPS18) Elemental surface composition of graphene
Concentration of self-assembling solution (mM)
C％
O Si％
0
56.3±0.4
11.0±1.5
32.6±1.4
0.03
54.7±1.1
12.8±1.3
32.5±1.7
0.10
57.3±2.3
14.7±1.4
28.1±3.3
0.30
62.4±0.5
15.0±0.5
22.7±0.2
1.0
62.8±1.1
16.3±0.1
20.9±1.0
3.0
69.0±0.7
19.0±0.4
12.0±0.3
21Example 11 graphene modified with fully benzylated β -Cyclodextrin (β -CDBn)
β -Cyclodextrin (β -CDBn) fully benzylated was collected on a Versa Probe III scanning XPS microprobe (PHI 5000, Physical Electronics, Inc., Chanhassen, Minn.)21) XPS spectra of modified graphene Table 6 shows the use of β -CDBn21Elemental surface composition results for modified graphene.
TABLE 6 β -Cyclodextrin Perbenzylated with Perbenzylated (β -CDBn) as determined by XPS21) Elemental surface composition of modified graphene
24Example 12: graphene modified with fully benzylated gamma-cyclodextrin (gamma-CDBn)
Gamma-cyclodextrin (. gamma. -CDBn) with total benzylation was collected on Versa Probe III scanning XPS microprobe (PHI 5000, Physical Electronics, Inc., Chanhassen, Minn.)24) XPS spectra of modified graphene Table 7 shows the use of β -CDBn24Elemental surface composition results for modified graphene.
TABLE 7 Gamma-Cyclodextrin (Gamma-CDBn) with Total benzylation as determined by XPS24) Elemental surface composition of modified graphene
Concentration of self-assembling solution (mM)
C％
O Si％
0
58.2±0.5
10.5±0.7
31.3±1.1
0.03
57.4±1.3
10.5±1.2
32.0±2.5
0.10
59.0±0.9
12.1±1.8
28.9±1.4
0.30
62.2±0.1
12.3±1.4
25.4±1.5
1.0
61.6±1.0
13.5±0.4
24.9±0.8
3.0
66.7±2.4
15.8±0.7
17.6±3.0
Example 13: XPS of bare graphene
X-ray photoelectron spectroscopy (XPS) spectra of bare graphene on copper substrates were collected on a VersaProbe III scanning XPS microprobe (PHI 5000, Physical Electronics, Chanhassen, MN). The elemental surface composition of bare graphene on a copper substrate was found to be 56.3 mol% carbon, 11.0 mol% oxygen, and 32.6 mol% copper. High resolution C1s XPS spectra of bare graphene (fig. 11) reveal five types of carbon atoms that can be assigned to C ═ C (284.5eV), C — OH (285.4eV), C — O-C (286.4eV), C ═ O (287.4eV), and O — C ═ O (288.9 eV). As shown in the high resolution O1s XPS spectrum (fig. 12), four types of oxygen were observed, namely Cu — O (530.4eV), C — O (531.4eV), C ═ O (532.1eV), and O — C ═ O (532.9 eV). The Cu-O peak was maximal and the integration of these peaks indicated that 61.2% of the oxygen came from the underlying copper substrate (Cu-O).
Example 14: XPS of surface modified graphene
α -CDBn by XPS pairing18、β-CDBn21Or gamma-CDBn24α -Cyclodextrin fully benzylated (α -CDBn) was collected on Versa Probe III scanning XPS microprobe (PHI 5000, Physical Electronics, Chanhassen, Minn.) with a fully benzylated α -Cyclodextrin18) Fully benzylated β -cyclodextrins (β -CDBn)21) Or fully benzylated gamma-cyclodextrins (gamma-CDBn)24) XPS spectra of modified graphene.
This trend is consistent with the composition of the cyclodextrin monolayer, which for all three cyclodextrins was 84.4 mol% carbon and 15.6 mol% oxygen (see tables 5-7). high resolution XPS spectra of C1s and O1s confirmed with α -CDBn by showing a much smaller Cu-O peak compared to bare graphene and much larger peaks of sp3 carbon and C-O-C carbon and oxygen atoms belonging to the fully benzylated cyclodextrin (FIGS. 13-14)18Surface modification is carried out.
Example 15: stability and reversibility of surface modification to heat and vacuum
To ensure the stability of the surface modification of graphene under heat or vacuum, Pyr-CH will be used2NH2HCl-modified graphene in high vacuum (2 × 10)-5Torr) was baked at 100 ℃ overnight. Contact angle measurements were then made using DI water as the wetting liquid. Table 8 shows the results obtained with Pyr-CH by heating and vacuum exposure2NH2The contact angle of the HCl-modified graphene substrate did not change due to thermal and vacuum exposure, indicating Pyr-CH on graphene2NH2The HCl monolayer did not fail under these conditions.
TABLE 8 use of Pyr-CH2NH2Stability of HCl-modified graphene to Heat and vacuum treatment
Example 16: stabilization of toluene surface modificationSex and reversibility
Reacting Pyr-CH2NH2The HCl-modified graphene was immersed in toluene for 1 hour (after 0.5 hour the toluene was replaced once). Contact angle measurements were recorded before and after toluene immersion. The contact angle increased from 85.5 ° ± 1.4 ° in the case of monolayer modification to 91.6 ° ± 0.5 ° after toluene impregnation, indicating that, as expected, toluene removed the acceptor monolayer from the graphene, again revealing the bare graphene surface. A control experiment was also performed, immersing bare graphene in ethanol overnight and then in toluene for 1 hour. After ethanol impregnation and toluene impregnation, the contact angles were found to be 91.3 ° ± 1.5 ° and 92.5 ° ± 1.9 °, respectively, confirming that toluene did not damage the graphene-coated Cu substrate.
Example 17: 5,10,15, 20-tetraphenyl-21H, 23H-porphyrin manganese (III) chloride (Mn (III) TPPCl) in graphite Self-assembly on alkenes
wherein R is a phenyl group at each position on the molecule.
For self-assembly of mn (iii) TPPCl on graphene, graphene substrates grown on copper were immersed overnight in ethanol solutions containing various concentrations (0, 0.128, 0.64, 1.28, 3.0, or 10mM) of mn (iii) TPPCl. The modified graphene substrate was then washed 3 times with a small portion of ethanol to remove excess self-assembly solution. XPS was performed to determine C%, O%, N% and Cu% of the modified surface. Table 9 presents the surface compositions as determined by XPS.
TABLE 9 elemental surface composition of graphene modified with Mn (III) TPPCl as determined by XPS
Concentration of self-assembling solution (mM)
C％
Cu％
N O％
0
55.8±1.5
33.2±1.9
-
11.0±0.5
0.128
56.2±0.5
34.6±0.6
-
9.0±1.0
0.64
61.7±1.5
28.4±0.4
1.5±0.8
8.4±1.6
1.28
76.5±2.2
9.2±2.5
4.8±1.0
9.5±1.1
3.0
81.8±0.9
4.2±0.8
5.8±0.4
8.3±0.7
10
79.0±0.4
0.8±0.1
5.5±0.6
14.7±0.7
The C% and Cu% data were fitted simultaneously to determine the equilibrium constant K, as described above. The N% and O% data are not included in the fit because the maximum variation of O% and N% falls within the experimental background noise. Table 10 shows the equilibrium constant K and concentration of the self-assembly solution required to form at least a 90% monolayer with mn (iii) TPPCl.
TABLE 10 reaction of Mn (III) TPPCl and β -CDBn19(OH)2Equilibrium constant and monolayer concentration adsorbed onto graphene
A D 19 2Example 18 self-Assembly of 6, 6-Dihydroxybenzylated β Cyclodextrin on graphene (β -CDBn (OH))
6A,6D-dihydroxybenzylated β -cyclodextrin (β -CDBn)19(OH)2) Synthesis of 325mg of fully benzylated β -cyclodextrin (β -CDBn)21) Dissolved in 10mL of anhydrous toluene. The solution was degassed with argon for 20 minutes and transferred to a 2-neck round bottom flask with nitrogen blanket. Then, 6.5mL of diisobutylaluminum hydride solution (1M in toluene, Aldrich) was added dropwise to the flask and the solution was heated to 50 ℃. After 2 hours, another 6.5mL of diisobutylaluminum hydride solution (1M in toluene, Aldrich) was added to the solution and allowed to react for an additional 5.5 h. Then, in an ice bathTo the mixture was slowly added 20mL of 1M HCl (aq.) the resulting suspension was extracted with ethyl acetate (4 × 30mL), the combined ethyl acetate phases were washed with water (1 × 120mL) and over anhydrous Na2SO4Drying, evaporation of the solvent in vacuo overnight then the white crude product was purified by chromatography on silica (first using ethyl acetate/hexane 1:4 as eluent, then switching to 1:2) at 37% yield mass spectrometry (MALDI,
For self-assembly β -CDBn on graphene19(OH)2Graphene substrates grown on copper were immersed in β -CDBn containing various concentrations (0, 0.03, 0.1, 0.3, 1.0, or 3.0mM)19(OH)2Overnight. The modified graphene substrate was then washed 3 times with a small portion of acetonitrile to remove excess self-assembly solution. XPS was performed to determine C%, O% and Cu% of the modified surface. Table 11 presents the surface compositions as determined by XPS.
TABLE 11 determination by XPS with β -CDBn19(OH)2Elemental surface composition of modified graphene
Concentration of self-assembling solution (mM)
C％
Cu O％
0
63.2±0.4
25.1±1.0
11.4±0.8
0.03
64.5±2.6
24.2±3.3
11.3±0.8
0.1
63.0±1.5
25.6±1.5
11.3±1.2
0.3
74.1±1.0
12.1±0.6
13.8±0.5
1.0
76.5±1.1
6.8±1.7
16.7±0.8
3.0
81.1±1.0
3.0±0.6
15.9±0.8
As described above, C%, O%, and Cu% data were simultaneously fitted to determine the equilibrium constant K.Table 10 shows the use of β -CDBn19(OH)2The equilibrium constant K and the concentration of the self-assembly solution required to form at least a 90% monolayer.
2Example 19: raman spectroscopy of Pyr-B (OH) -modified graphene
After using Pyr-B (OH)2On modified grapheneAnd performing Raman spectroscopy. To estimate surface coverage, graphene was applied at different concentrations (including 1mM and 2mM) of Pyr-B (OH)2The modification is carried out in the solution. About 1286cm in Raman spectrum of the modified graphene surface corresponding to B-OH bending and B-O stretching vibration, respectively-1And 1378cm-1The peak at (c). The raman spectroscopy results are shown in fig. 28.
For 1mM and 2mM Pyr-B (OH)2Solution, B-OH Peak (1283 cm)-1) With graphene G peak (about 1600 cm)-1) The peak height ratios of (a) and (b) were 0.048 and 0.083, respectively. For 1mM and 2mM Pyr-B (OH)2Solution, B-OH (1283 cm)-1) And graphene 2D peak (2692 cm)-1) The peak height ratios of (a) and (b) were 0.045 and 0.098, respectively. The peak height ratio of the B-OH peak to the G/2D peak increases with self-assembly concentration from 1.0mM to 2.0mM, which is believed, without wishing to be bound by any particular theory, to indicate that the graphene surface is not fully saturated with 1.0mM self-assembly solution.
It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
It should also be noted that, as used in this specification and the appended claims, the phrase "configured to" describes a system, apparatus, or other structure that is constructed or arranged to perform a particular task or take a particular configuration. The phrase "configured" may be used interchangeably with other similar phrases such as "arranged and configured, constructed and arranged, constructed, manufactured and arranged, etc.
All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. All publications and patent applications herein are incorporated by reference in their entirety as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The embodiments described herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may understand and appreciate the principles and practices. Thus, the various aspects have been described with reference to various specific and preferred embodiments and techniques. It will be understood, however, that many variations and modifications may be made while remaining within the spirit and scope of the disclosure.
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