阅读说明：本技术 一种石墨烯管/Au纳米颗粒微流体通道及其制备方法和声表面波生物传感器 (Graphene tube/Au nanoparticle microfluidic channel and preparation method thereof and surface acoustic wave biosensor ) 是由 李翠平 田树珍 赵晨曦 李明吉 李红姬 钱莉荣 杨保和 于 2021-08-18 设计创作，主要内容包括：本发明提供了一种石墨烯管/Au纳米颗粒微流体通道及其制备方法和声表面波生物传感器,属于生物传感器技术领域。本发明提供的石墨烯管/Au纳米颗粒微流体通道,由石墨烯管和分布于所述石墨烯管内表面的Au纳米颗粒组成。本发明提供的石墨烯管/Au纳米颗粒微流体通道中,石墨烯具有大的比表面积,具有很强的表面吸附作用；Au纳米颗粒具有很好的生物相容性,可以和蛋白质等生物分子结合,形成活性位点,且不破坏其生物活性。故本发明提供的石墨烯管/Au纳米颗粒微流体通道能够同时具有微流体通道和敏感元件的作用,可以用于构建生物传感器,实现不同浓度的氨基酸检测；且Au纳米颗粒和石墨烯管结合紧密,使生物传感器的使用寿命增加。(The invention provides a graphene tube/Au nanoparticle microfluidic channel, a preparation method thereof and a surface acoustic wave biosensor, and belongs to the technical field of biosensors. The graphene tube/Au nanoparticle microfluidic channel provided by the invention is composed of a graphene tube and Au nanoparticles distributed on the inner surface of the graphene tube. In the graphene tube/Au nanoparticle microfluidic channel provided by the invention, graphene has a large specific surface area and a strong surface adsorption effect; the Au nano-particles have good biocompatibility, can be combined with biomolecules such as protein and the like to form active sites, and does not destroy the bioactivity of the Au nano-particles. Therefore, the graphene tube/Au nanoparticle microfluidic channel provided by the invention can simultaneously have the functions of a microfluidic channel and a sensitive element, and can be used for constructing a biosensor and realizing the detection of amino acids with different concentrations; and the Au nano-particles and the graphene tube are tightly combined, so that the service life of the biosensor is prolonged.)

1. A graphene tube/Au nanoparticle microfluidic channel is composed of a graphene tube and Au nanoparticles distributed on the inner surface of the graphene tube.

2. The graphene tube/Au nanoparticle microfluidic channel of claim 1, wherein the graphene tube has an inner diameter of 0.6-0.8 mm and an outer diameter of 0.75-1 mm.

3. The graphene tube/Au nanoparticle microfluidic channel of claim 1, wherein the Au nanoparticles have a particle size of 50-300 nm.

4. The method for preparing the graphene tube/Au nanoparticle microfluidic channel of any one of claims 1to 3, comprising the following steps:

(1) growing graphene on the surface of the tantalum wire by adopting a hot wire chemical vapor deposition method, and then separating the graphene from the tantalum wire to obtain a graphene tube;

(2) electroplating Au in the graphene tube obtained in the step (1) by adopting a double-electrode system to obtain a graphene tube/Au nanoparticle microfluidic channel; the double-electrode system comprises a reference electrode, a counter electrode, electroplating liquid and a working electrode; the reference electrode and the counter electrode are platinum wires, the electroplating solution is a tetrachloroauric acid solution, and the graphene tube is a working electrode.

5. The method according to claim 4, wherein the deposition parameters of the hot wire chemical vapor deposition method in the step (1) are as follows: the hydrogen flow is 20-50 sccm, the methane flow is 10-25 sccm, the output current of the AC filament power supply is 50-100A, the vacuum degree is 30-45 Torr, and the deposition time is 20 min-1 h.

6. The method for preparing a two-electrode system according to claim 4, wherein the assembly method of the two-electrode system in the step (2) comprises: slightly inserting a tantalum wire into one end of the graphene tube for fixing; introducing a tetrachloroauric acid solution into the graphene tube by using an injector; inserting a platinum wire into the graphene tube from the other end of the graphene tube in parallel, and immersing the platinum wire and the graphene tube into a tetrachloroauric acid solution; the platinum wire is not in contact with the graphene tube.

7. The production method according to claim 4 or 6, wherein the concentration of the tetrachloroauric acid solution is 10^-3～10^-1mol/L。

8. A surface acoustic wave biosensor comprises a substrate, interdigital electrodes arranged on the surface of the substrate and a graphene tube/Au nanoparticle microfluidic channel arranged on the surface of the interdigital electrodes; the graphene tube/Au nanoparticle microfluidic channel is the graphene tube/Au nanoparticle microfluidic channel in any one of claims 1to 3 or the graphene tube/Au nanoparticle microfluidic channel prepared by the preparation method in any one of claims 4 to 6.

9. A surface acoustic wave biosensor as set forth in claim 8, wherein said substrate is a piezoelectric single crystal.

10. A surface acoustic wave biosensor as set forth in claim 8, wherein said interdigital electrode is made of aluminum, platinum, or gold.

Technical Field

The invention relates to the technical field of biosensors, in particular to a graphene tube/Au nanoparticle microfluidic channel, a preparation method thereof and a surface acoustic wave biosensor.

Background

Amino acids are basic units constituting protein molecules, play an important role in the human body through metabolism, and are closely related to life activities and health conditions of organisms. At present, the detection methods of amino acid comprise capillary electrophoresis, high performance liquid chromatography, spectroscopy, fluorescence and the like, and the methods all have the defects of time consumption, complex structure and low precision in detection. The surface acoustic wave is a sound wave propagating along the surface of an object, and is sensitive to perturbations on the surface of the object, so that the surface acoustic wave biosensor has high sensitivity. In addition, the acoustic surface biosensor also has the advantages of small volume, low cost and the like.

The microfluid technology is a technology for processing a small amount of fluid by using a tiny channel with a tiny size, can be applied to various fields from biology, chemistry to information technology, optics and the like, and has great application prospect in a surface acoustic wave biosensor. However, when the current microfluid technology is used for the surface acoustic wave biosensor, the sensitive film is often required to be combined into a microfluid channel, and the microfluid channel is required to be prepared first, and then the sensitive film is combined with the microfluid channel to form a sensitive element of the surface acoustic wave biosensor. However, the preparation method of the surface acoustic wave biosensor is complex, and the surface acoustic wave biosensor cannot be suitable for detection of amino acids with different concentrations due to the fact that the sensitive membrane is not tightly combined with the microfluidic channel, and the service life of the surface acoustic wave biosensor is short.

Therefore, it is desirable to provide a microfluidic channel that can be used in saw biosensors to detect amino acids with different concentrations and has a long service life.

Disclosure of Invention

The invention aims to provide a graphene tube/Au nanoparticle-based microfluidic channel, a preparation method thereof and a surface acoustic wave biosensor.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a graphene tube/Au nanoparticle microfluidic channel which is composed of a graphene tube and Au nanoparticles distributed on the inner surface of the graphene tube.

Preferably, the inner diameter of the graphene pipe is 0.6-0.8 mm, and the outer diameter of the graphene pipe is 0.75-1 mm.

Preferably, the particle size of the Au nano-particles is 50-300 nm.

The invention also provides a preparation method of the graphene tube/Au nanoparticle microfluidic channel in the technical scheme, which comprises the following steps:

(1) growing graphene on the surface of the tantalum wire by adopting a hot wire chemical vapor deposition method, and then separating the graphene from the tantalum wire to obtain a graphene tube;

(2) electroplating Au in the graphene tube obtained in the step (1) by adopting a double-electrode system to obtain a graphene tube/Au nanoparticle microfluidic channel; the double-electrode system comprises a reference electrode, a counter electrode, electroplating liquid and a working electrode; the reference electrode and the counter electrode are platinum wires, the electroplating solution is a tetrachloroauric acid solution, and the graphene tube is a working electrode.

Preferably, the deposition process parameters of the hot filament chemical vapor deposition method in the step (1) are as follows: the hydrogen flow is 20-50 sccm, the methane flow is 10-25 sccm, the output current of the AC filament power supply is 50-100A, the vacuum degree is 30-45 Torr, and the deposition time is 20 min-1 h.

Preferably, the assembly method of the two-electrode system in the step (2) comprises: slightly inserting a tantalum wire into one end of the graphene tube for fixing; introducing a tetrachloroauric acid solution into the graphene tube by using an injector; inserting a platinum wire into the graphene tube from the other end of the graphene tube in parallel, and immersing the platinum wire and the graphene tube into a tetrachloroauric acid solution; the platinum wire is not in contact with the graphene tube.

Preferably, the concentration of the tetrachloroauric acid solution is 10^-3～10^-1mol/L。

The invention also provides a surface acoustic wave biosensor, which comprises a substrate, interdigital electrodes arranged on the surface of the substrate and a graphene tube/Au nanoparticle microfluidic channel arranged on the surface of the interdigital electrodes; the graphene tube/Au nanoparticle microfluidic channel is the graphene tube/Au nanoparticle microfluidic channel in the technical scheme or the graphene tube/Au nanoparticle microfluidic channel prepared by the preparation method in the technical scheme.

Preferably, the substrate is a piezoelectric single crystal.

Preferably, the material of the interdigital electrode is aluminum, platinum or gold.

The invention provides a graphene tube/Au nanoparticle microfluidic channel which is composed of a graphene tube and Au nanoparticles distributed on the inner surface of the graphene tube. In the graphene tube/Au nanoparticle microfluidic channel provided by the invention, graphene has a large specific surface area and a strong surface adsorption effect; the Au nano-particles have good biocompatibility, can be combined with biomolecules such as protein and the like to form active sites, and does not destroy the bioactivity of the Au nano-particles. Therefore, the graphene tube/Au nanoparticle microfluidic channel provided by the invention can simultaneously have the functions of a microfluidic channel and a sensitive element, and can be used for constructing a biosensor and realizing the detection of amino acids with different concentrations; and the Au nano-particles and the graphene tube are tightly combined, so that the service life of the biosensor is prolonged. The data of the embodiment shows that the L-lysine solutions with different concentrations are introduced into the graphene tube/Au nanoparticle microfluidic channel in the surface acoustic wave biosensor, so that the detection can be effectively carried out, the cyclic multiple use can be realized, and the service life is longer.

Drawings

Fig. 1 is an SEM image of a cross section of a graphene tube prepared in example 1 of the present invention;

fig. 2 is an SEM image of the internal structure of the graphene tube/Au nanoparticle microfluidic channel prepared in example 1 of the present invention, enlarged by 2K times;

FIG. 3 is an SEM image of the internal structure of the graphene tube/Au nanoparticle microfluidic channel prepared in example 1 of the present invention, magnified 20K times;

FIG. 4 is a biological detection system employed in an embodiment of the present invention, wherein: a1 is a network analyzer, A2 is a peristaltic pump, A3 is a carbon nanotube/Au nanoparticle microfluidic channel, A4 is a test fixture, A5 is a delay line type surface acoustic wave device, and A6 is a beaker;

FIG. 5 is a graph showing the variation of the center frequency of the device with the L-tyrosine concentration when the SAW biosensor of example 2 of the present invention detects L-tyrosine;

FIG. 6 is a graph showing the change of the center frequency of the device with the L-lysine concentration when the SAW biosensor of example 3 of the present invention detects L-lysine.

Detailed Description

The invention provides a graphene tube/Au nanoparticle microfluidic channel which is composed of a graphene tube and Au nanoparticles distributed on the inner surface of the graphene tube.

In the invention, the inner diameter of the graphene tube is preferably 0.6-0.8 mm, and more preferably 0.7-0.8 mm; the outer diameter of the graphene tube is preferably 0.75-1 mm, and more preferably 0.9-1 mm. In the invention, the graphene tube is a hollow tube with the inner diameter and the outer diameter in the ranges, which is composed of graphene, and can form a microfluidic channel for micro fluid to pass through, and when the graphene tube is used in a surface acoustic wave biosensor, the sensitivity of the sensor can be improved.

In the invention, the particle size of the Au nanoparticle is preferably 50-300 nm, and more preferably 100-200 nm. In the invention, the Au nano-particles have good biocompatibility, can be combined with biomolecules such as proteins and amino acids to form active sites, and does not destroy the bioactivity of the Au nano-particles. In the invention, when the particle size of the Au nanoparticle is in the range, more active sites can be formed in the graphene tube to adsorb amino acid to be detected, and the sensitivity of the sensor can be improved when the Au nanoparticle is used in a surface acoustic wave biosensor.

According to the graphene tube/Au nanoparticle microfluidic channel provided by the invention, graphene has a large specific surface area and a very strong surface adsorption effect, can adsorb Au nanoparticles, and is tightly combined with the Au nanoparticles; the Au nano-particles have good biocompatibility, can be combined with biomolecules such as protein and the like to form active sites, and does not destroy the bioactivity of the Au nano-particles. Therefore, the graphene tube/Au nanoparticle microfluidic channel provided by the invention can simultaneously have the functions of the microfluidic channel and a sensitive element, can be used for constructing a biosensor, realizes the detection of amino acids with different concentrations, and has the advantages of stable structure and long service life.

The invention also provides a preparation method of the graphene tube/Au nanoparticle microfluidic channel, which comprises the following steps:

(1) growing graphene on the surface of the tantalum wire by adopting a hot wire chemical vapor deposition method, and then separating the graphene from the tantalum wire to obtain a graphene tube;

(2) electroplating Au in the graphene tube obtained in the step (1) by adopting a double-electrode system to obtain a graphene tube/Au nanoparticle microfluidic channel; the double-electrode system comprises a reference electrode, a counter electrode, electroplating liquid and a working electrode; the reference electrode and the counter electrode are platinum wires, the electroplating solution is a tetrachloroauric acid solution, and the graphene tube is a working electrode.

According to the method, graphene grows on the surface of a tantalum wire by a hot wire chemical vapor deposition method, and then the graphene is separated from the tantalum wire to obtain the graphene tube.

In the invention, the diameter of the tantalum wire is preferably 0.6-0.8 mm, and more preferably 0.7-0.8 mm; the length of the tantalum wire is preferably 5-10 cm, and more preferably 6-8 cm. In the present invention, the diameter of the tantalum wire determines the inner diameter of the graphene tube.

In the invention, the hot wire chemical vapor deposition takes a tantalum wire as a hot wire, a support template for depositing the graphene tube is deposited, and the graphene tube is grown on the surface of the hot wire chemical vapor deposition.

The present invention preferably cleans the tantalum wire prior to hot wire chemical vapor deposition. The method for cleaning the tantalum wire is not particularly limited, and the cleaning method known to those skilled in the art can be adopted to remove the pollutants on the surface of the tantalum wire. In the invention, the method for cleaning the tantalum wire is preferably to polish the tantalum wire by using 100-300-mesh sand paper to remove surface oxides and impurities; and then ultrasonically cleaning the mixture in ultrapure water, absolute ethyl alcohol and ultrapure water for 5-10 min respectively, and drying the mixture at room temperature. In the invention, the method for cleaning the tantalum wire can remove pollutants on the surface of the tantalum wire and simultaneously roughen the surface of the tantalum wire so as to attach the modified particles.

In the invention, the deposition process parameters of the hot wire chemical vapor deposition method are as follows: the hydrogen flow rate is preferably 20 to 50sccm, more preferably 30 to 40 sccm; the flow rate of the methane is preferably 10-25 sccm, and more preferably 15-20 sccm; the output current of the alternating current filament power supply is preferably 50-100A, and more preferably 60-80A; the degree of vacuum is preferably 30 to 45Torr, more preferably 35 to 40 Torr; the deposition time is preferably 20min to 1h, and more preferably 30min to 50 min. In the invention, when the deposition process parameters of the hot wire chemical vapor deposition method are in the range, a more continuous graphene layer can be formed on the surface of the tantalum wire.

After the hot wire chemical vapor deposition is finished, the graphene is separated from the tantalum wire, and the graphene tube is obtained. The method for separating graphene from tantalum wire is not particularly limited, and graphene can be separated from tantalum wire by a method well known to those skilled in the art.

After the graphene tube is obtained, Au is electroplated in the graphene tube by adopting a double-electrode system, so that the graphene tube/Au nanoparticle microfluidic channel is obtained.

In the present invention, the two-electrode system preferably comprises a reference electrode and a counter electrode, an electroplating solution and a working electrode; the reference electrode and the counter electrode are preferably platinum wires, the electroplating solution is preferably a tetrachloroauric acid solution, and the graphene tube is a working electrode.

In the present invention, the outer diameter of the platinum wire is preferably lower than the inner diameter of the graphene tube. In the invention, the platinum wire is used as a reference electrode and a counter electrode, and is inserted into the graphene tube during electroplating, and when the outer diameter of the platinum wire is smaller than the inner diameter of the graphene tube, the platinum wire can be prevented from contacting with the graphene tube to cause short circuit.

In the present invention, the concentration of the tetrachloroauric acid solution is preferably 10^-3～10^-1mol/L, more preferably 10^-2～10^-1mol/L. In the present invention, when the concentration of the tetrachloroauric acid solution is within the above range, it is more advantageous to form Au nanoparticles that are uniformly distributed and not accumulated inside the graphene tube.

In the invention, the length of the graphene tube is preferably 10-20 mm, and more preferably 15-20 mm. In the present invention, when the length of the graphene tube is within the above range, the operation of electroplating is facilitated.

In the present invention, the method for assembling the two-electrode system preferably includes: slightly inserting a tantalum wire into one end of the graphene tube for fixing; introducing a tetrachloroauric acid solution into the graphene tube by using an injector; inserting a platinum wire into the graphene tube from the other end of the graphene tube in parallel, and immersing the platinum wire and the graphene tube into a tetrachloroauric acid solution; the platinum wire is not in contact with the graphene tube.

In the invention, the graphene tube is brittle and is easy to break when directly used as a working electrode to be connected with a circuit. According to the invention, one end of the graphene tube is slightly inserted into the tantalum wire to be fixed, and then the tantalum wire is connected with the circuit, so that the operation problem of electroplating interruption caused by graphene breakage when the circuit is directly connected with the graphene tube can be prevented, and the smooth electroplating can be further promoted.

In the invention, the graphene tube is filled with the electroplating solution by introducing the tetrachloroauric acid solution into the graphene tube by using the injector, so that the graphene tube is filled with the electroplating solution when the platinum wire is inserted into the graphene tube, and uniform Au particles are formed in the graphene tube.

In the invention, the platinum wire is inserted into the graphene tube from the other end of the graphene tube in parallel, so that Au particles can be distributed in the graphene tube during electroplating.

In the invention, the platinum wire is not in contact with the graphene tube, so that short circuit can be prevented.

In the invention, the platinum wire and the graphene tube are immersed in the tetrachloroauric acid solution to the same depth, preferably 8-18 mm, and more preferably 10-15 mm. In the present invention, when the depth of the platinum wire and the graphene tube immersed in the tetrachloroauric acid solution is within the above range, the Au particles can be more uniform.

In the electroplating process, the tetrachloroauric acid solution is preferably introduced into the graphene tube by using an injector. In the invention, as the Au nanoparticles are formed in the graphene tube by the gold ions in the electroplating process, the concentration of the tetrachloroauric acid solution in the graphene tube is reduced, and the tetrachloroauric acid solution is introduced into the graphene tube, so that the reduction of the electroplating efficiency caused by the concentration change of the tetrachloroauric acid solution in the graphene tube can be prevented, and the more uniform distribution of the Au nanoparticles in the graphene tube can be promoted.

In the present invention, the plating is preferably Au plating inside the graphene tube using an electrochemical workstation step method.

In the present invention, the electroplating of Au in the graphene tube by using the electrochemical workstation step method is preferably divided into three stages:

in the 1 st stage, the electroplating potential is preferably-3-0V, and more preferably-2-0V; the deposition time is preferably 0-2 s, and more preferably 1-2 s;

in the 2 nd stage, the electroplating potential is preferably 0-3V, more preferably 1-2V; the deposition time is preferably 2-8 s, and more preferably 4-6 s;

in the 3 rd stage, the electroplating potential is preferably-2-1V, more preferably-1-0V; the deposition time is preferably 0-2 s, and more preferably 1-2 s;

the number of electroplating turns is preferably 20-50 turns, and more preferably 30-40 turns;

the sensitivity is preferably 1X 10^-3～1×10^-1More preferably 1X 10^-2～1×10^-1；

After 3-6 min of electroplating each time, injecting a tetrachloroauric acid solution into the graphene tube by using an injector;

the step method of the electrochemical workstation is used for electroplating Au in the graphene tube preferably for repeating 3-8 times, and more preferably for 4-6 times.

In the present invention, the inside of the graphene tube can be filled with the tetrachloroauric acid solution by injecting the tetrachloroauric acid solution into the graphene tube with a syringe after each plating. According to the invention, the graphene tube is preferably taken down when the tetrachloroauric acid solution is introduced into the graphene tube by using the injector, so that the tetrachloroauric acid solution can be conveniently injected.

The preparation method provided by the invention can form Au particles which are uniformly distributed and not accumulated on the surface of the graphene.

The invention also provides a surface acoustic wave biosensor, which comprises a substrate, interdigital electrodes arranged on the surface of the substrate and a graphene tube/Au nanoparticle microfluidic channel arranged on the surface of the interdigital electrodes; the graphene tube/Au nanoparticle microfluidic channel is the graphene tube/Au nanoparticle microfluidic channel in the technical scheme or the graphene tube/Au nanoparticle microfluidic channel prepared by the preparation method in the technical scheme.

In the present invention, the substrate is preferably a piezoelectric single crystal; the piezoelectric single crystal is preferably lithium niobate, quartz, bismuth germanate or lithium tantalate. In the invention, the substrate plays a role in supporting the interdigital electrode and the graphene tube/Au nanoparticle microfluidic channel.

In the present invention, the material of the interdigital electrode is preferably aluminum, platinum, or gold. In the present invention, when the interdigital electrode is made of the above material, the sensitivity of the sensor can be improved.

The preparation method of the surface acoustic wave biosensor is not particularly limited, and the method for preparing the surface acoustic wave biosensor, which is well known by the technical personnel in the field, can be adopted.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The medicine purchase sources in the embodiment of the invention are as follows:

3 tetrachloroauric acid hydrate, purchased from alfa aesar (china) chemical ltd;

the model of the electrochemical workstation is 660e, which is purchased from Shanghai Chenghua apparatus Co., Ltd;

the anhydrous disodium hydrogen phosphate is purchased from Dache chemical reagent factory in Tianjin;

anhydrous sodium dihydrogen phosphate was purchased from Dache chemical reagent factory, Tianjin;

the pH meter is PhS-3C and is purchased from Shanghai apparatus and electronic science instruments, Inc.;

l-lysine is purchased from Guang-Shen-Fine chemical research institute in Tianjin;

l-tyrosine is purchased from Guangdong chemical research institute of Guangdong province in Tianjin.

(II) in the following examples, when the time-current curve was measured by using the two-electrode system, the length of the working electrode, the reference electrode and the counter electrode inserted into the measured liquid was 15mm, and the distance between the working electrode, the reference electrode and the counter electrode was 15 mm.

(III) a preparation method of the graphene tube/Au nanoparticle microfluidic channel comprises the following steps:

(1) cleaning the tantalum wire: a tantalum wire having a diameter of 0.60mm and a length of 8cm was prepared. Polishing tantalum wires by 180-mesh abrasive paper to remove surface oxides and impurities, then respectively ultrasonically cleaning the tantalum wires in ultrapure water, absolute ethyl alcohol and ultrapure water for 10min, and drying the tantalum wires at room temperature;

(2) preparing a graphene tube by hot wire chemical vapor deposition: growing a graphene tube on the surface of the tantalum wire cleaned in the step (1) by adopting a hot wire chemical vapor deposition method, wherein the deposition process parameters are as follows: the hydrogen flow is 50sccm, the methane flow is 25sccm, the output current of the alternating current filament power supply is 100A, the vacuum degree is 41Torr, and the deposition time is 40 min;

(3) cutting off a tantalum wire at one end, drawing out a graphene tube, dividing the graphene tube into 17mm lengths, electroplating Au by adopting a double-electrode system, taking the graphene tube as a working electrode, connecting the working electrode with the tantalum wire, inserting one section of the graphene tube into the tantalum wire for fixing, taking a platinum wire as a reference electrode and a counter electrode, inserting the graphene tube onto the platinum wire, wherein the platinum wire and the graphene tube are immersed into a tetrachloroauric acid solution to the same depth, and the immersion lengths are both 15 mm;

(4) introducing a tetrachloroauric acid solution (with the concentration of 10) into the graphene tube by using an injector^-2mol/L), inserting the graphene tube on a tantalum wire, electroplating Au by using an electrochemical workstation step method, wherein the electroplating is divided into three stages:

in the 1 st stage, the electroplating potential is-2V, and the deposition time is 1 s;

step 2, the electroplating potential is 2V, and the deposition time is 5 s;

step 3, the electroplating potential is-1V, and the deposition time is 1 s;

the number of plating turns is 43 turns, and the sensitivity is 1 multiplied by 10^-2After 5min of electroplating each time, taking down the graphene tube;

(5) and (5) repeating the step (4)6 times, and carrying out Au electroplating for 30 min.

A scanning electron microscope is used for testing the graphene tube prepared in the embodiment, and an SEM image of the cross section of the graphene tube is shown in fig. 1;

a scanning electron microscope is adopted to test the microfluidic channel of the graphene tube/Au nanoparticle prepared in the embodiment, and an SEM image with the internal structure magnified by 2K times is obtained and is shown in FIG. 2;

the graphene tube/Au nanoparticle microfluidic channel prepared in this example was tested with a scanning electron microscope to obtain an SEM image with an internal structure magnified 20K times as shown in fig. 3.

As can be seen from fig. 1, the graphene tube prepared by the present invention is a graphene tube with uniform thickness, and in the tube layer, the graphene tube is assembled by a plurality of layers of graphene.

As can be seen from fig. 2 and 3, Au nanoparticles are attached to the inner surface of the microfluidic channel of the graphene tube/Au nanoparticles prepared by the present invention, and the Au nanoparticles are not agglomerated and are uniformly distributed on the inner surface of the graphene tube.

Example 2

The graphene tube/Au nanoparticle microfluidic channel prepared in example 1 was assembled into a surface acoustic wave biosensor, using the graphene tube/Au nanoparticle microfluidic channel as a delay line type surface acoustic wave device, using quartz as a substrate material, and using Al metal as an interdigital electrode.

The surface acoustic wave biosensor obtained in the embodiment is used for constructing a biological detection system to detect L-tyrosine, and the specific process is as follows:

step 1, the biological detection system is shown in FIG. 4;

step 2, weighing 0.0906g of L-tyrosine, pouring the L-tyrosine into a 10mL volumetric flask, using PBS with pH 7.4 as a solvent to prepare the L-tyrosine with the concentration of 5 × 10^-2The L-tyrosine solution of mol/L is diluted into 1 × 10 respectively by taking a proper amount of the solution with the concentration by using a proper pipette^-2mol/L、3×10^-2mol/L、1×10^-3mol/L、3×10^-3mol/L、5×10^{- 3}L-tyrosine solution with each concentration of mol/L; then 0.4g of NaOH is weighed and poured into a 10mL volumetric flask, the volume is fixed by ultrapure water, 1mol/L NaOH solution is prepared, and the solution is diluted into 0.5mol/L solution.

Step 3, introducing a PBS solution into the microfluidic channel of the Au-plated graphene tube by using a peristaltic pump, placing the PBS solution on a delay line type surface acoustic wave device, testing the center frequency of the device by using a network analyzer, and introducing 1 multiplied by 10 into the microfluidic channel of the Au-plated graphene tube by using the peristaltic pump^-3And putting the microfluid channel of the graphene tube electroplated Au into which the L-tyrosine solution is introduced into a thermostat at 37 ℃ for half an hour after incubation, and then putting the microfluid channel on an interdigital of a surface acoustic wave device to record the central frequency at the moment.

Step 4, respectively and sequentially introducing 0.5mol/L NaOH solution and ultrapure water into the microfluidic channels of the graphene tube electroplated Au, cleaning the microfluidic channels, introducing PBS solution, then placing the microfluidic channels on the interdigital of the surface acoustic wave device to record the central frequency, and then introducing 5 multiplied by 10 concentration into the microfluidic channels of the graphene tube electroplated Au^-3Putting the mol/L-tyrosine solution into a thermostat at 37 ℃ as in the step 2, incubating for half an hour, and then putting the L-tyrosine solution on the interdigital of the surface acoustic wave deviceThe center frequency at this time is recorded.

And 5, repeating the operation of the step 3 to clean, and introducing the L-tyrosine solution with higher concentration to test, and repeating the steps until all the concentration tests are finished.

In this example, a PBS buffer solution was prepared from 0.1mol/L anhydrous sodium dihydrogen phosphate and 0.1mol/L anhydrous disodium hydrogen phosphate in a ratio of 19: 81, the PBS buffer solutions prepared in different proportions have different pH values, the pH value of the PBS buffer solution prepared in the proportion is 7.4, and the pH value of the PBS buffer solution is detected by a pH meter.

The curve of the center frequency of the device with the concentration of L-tyrosine when detecting L-tyrosine by using the surface acoustic wave biosensor is shown in FIG. 5.

As can be seen from FIG. 5, the surface acoustic wave biosensor prepared by the present invention can sensitively detect L-tyrosine with different concentrations, has a wide detection range, and can be suitable for the detection of amino acids with different concentrations. And, as long as do not artificially cause the graphite alkene pipe to take place the breakage, all can use, after recycling many times, still have excellent accuracy.

Example 3

The graphene tube/Au nanoparticle microfluidic channel prepared in example 1 was assembled into a surface acoustic wave biosensor, using the graphene tube/Au nanoparticle microfluidic channel as a delay line type surface acoustic wave device, using quartz as a substrate material, and using Al metal as an interdigital electrode.

The surface acoustic wave biosensor obtained in the embodiment is used for constructing a biological detection system and detecting L-lysine, and the specific process is as follows:

step 1, the biological detection system is shown in FIG. 4;

step 2, weighing 0.0731g of L-lysine, pouring into a 10mL volumetric flask, using PBS of pH 7.4 as solvent, preparing into a concentration of 5X 10^-2The L-lysine solution of mol/L is diluted into 1 × 10 by taking a proper amount of the solution of the concentration by using a proper pipette^-2mol/L、3×10^-2mol/L、1×10^-3mol/L、3×10^-3mol/L、5×10^{- 3}L-lysine solution with each concentration of mol/L; then 0.4g of NaOH is weighed and poured into a 10mL volumetric flask, the volume is fixed by ultrapure water, 1mol/L NaOH solution is prepared, and the solution is diluted into 0.5mol/L solution.

Step 3, introducing a PBS solution into the microfluidic channel of the Au-plated graphene tube by using a peristaltic pump, placing the PBS solution on a delay line type surface acoustic wave device, testing the center frequency of the device by using a network analyzer, and introducing 1 multiplied by 10 into the microfluidic channel of the Au-plated graphene tube by using the peristaltic pump^-3And putting the microfluid channel of the graphene tube electroplated Au into which the L-lysine solution is introduced into a thermostat at 37 ℃ for half an hour after the L-lysine solution is in an mol/L state, and putting the microfluid channel on an interdigital of a surface acoustic wave device to record the central frequency at the moment.

Step 4, respectively and sequentially introducing 0.5mol/L NaOH solution and ultrapure water into the microfluidic channels of the graphene tube electroplated Au, cleaning the microfluidic channels, introducing PBS solution, then placing the microfluidic channels on the interdigital of the surface acoustic wave device to record the central frequency, and then introducing 5 multiplied by 10 concentration into the microfluidic channels of the graphene tube electroplated Au^-3And (3) putting the L-lysine solution in mol/L into a thermostat at 37 ℃ as in the step 2, incubating for half an hour, and placing the L-lysine solution on the interdigital of the surface acoustic wave device to record the central frequency at the moment.

And 5, repeating the operation of the step 3 to clean, and introducing a higher-concentration L-lysine solution to perform testing, and repeating the steps until all concentration tests are finished.

In this example, the preparation method of the PBS buffer solution was the same as that of example 2.

The change curve of the center frequency of the device with the L-lysine concentration when detecting L-lysine using the SAW biosensor is shown in FIG. 6.

As can be seen from FIG. 6, the surface acoustic wave biosensor prepared by the present invention can sensitively detect L-lysine with different concentrations, has a wide detection range, and can be suitable for the detection of amino acids with different concentrations.

According to the embodiment, the acoustic surface wave biosensor prepared by the invention takes the graphene tube/Au nanoparticle microfluidic channel as the microfluidic channel and the sensitive element, can integrate the microfluidic channel and the sensitive element into a whole, and has a simple preparation method; and the obtained graphene tube/Au nanoparticle microfluidic channel has a stable structure, can adapt to amino acid detection in a wide concentration range, and has a long service life.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.