阅读说明：本技术 一种用于循环肿瘤细胞捕获与检测的太赫兹器件 (Terahertz device for capturing and detecting circulating tumor cells ) 是由 张留洋 沈忠磊 陈雪峰 徐亚飞 韩东海 王中兴 李胜男 于 2020-06-02 设计创作，主要内容包括：本公开揭示了一种用于循环肿瘤细胞捕获与检测的太赫兹器件,包括：二氧化硅基底、涂覆于所述二氧化硅基底上的石墨烯薄膜；所述石墨烯薄膜上刻蚀有多个环状纳米间隙,所述多个环状纳米间隙呈阵列式排列,构成周期性环状纳米间隙阵列；每个环状纳米间隙的环状区域为捕获及检测区域,用于对循环肿瘤细胞进行捕获以及用于对被捕获的循环肿瘤细胞进行检测。本公开利用石墨烯同轴孔构成太赫兹等离激元镊实现对肿瘤细胞的近场捕获,同时结合石墨烯可调谐的光学特性以迎合不同尺寸、不同折射率的肿瘤细胞对捕获性能的要求,实现对循环肿瘤细胞的特异性捕获。(The present disclosure discloses a terahertz device for capturing and detecting circulating tumor cells, comprising: the graphene film comprises a silicon dioxide substrate and a graphene film coated on the silicon dioxide substrate; a plurality of annular nanometer gaps are etched on the graphene film and arranged in an array manner to form a periodic annular nanometer gap array; the annular region of each annular nanogap is a capture and detection region for capturing circulating tumor cells and for detecting captured circulating tumor cells. According to the method, the terahertz plasmon tweezers are formed by the graphene coaxial holes to capture the near field of the tumor cells, and meanwhile, the tunable optical characteristics of the graphene are combined to meet the requirements of the tumor cells with different sizes and different refractive indexes on the capturing performance, so that the specific capture of the circulating tumor cells is realized.)

1. A terahertz device for circulating tumor cell capture and detection, comprising: the graphene film comprises a silicon dioxide substrate and a graphene film coated on the silicon dioxide substrate;

a plurality of annular nanometer gaps are etched on the graphene film and arranged in an array manner to form a periodic annular nanometer gap array;

the annular region of each annular nanogap is a capture and detection region for capturing circulating tumor cells and for detecting captured circulating tumor cells.

2. The terahertz device of claim 1, wherein preferably the periodic annular nanogap array obtains near-field trapping force by localizing terahertz waves within the trapping region.

3. The terahertz device of claim 1, wherein the detection of the captured circulating tumor cells is performed by detecting an amount of shift in a resonant frequency of the terahertz device.

4. The terahertz device of claim 1, wherein the periodic annular nanogap array has a period of 2-20 μ ι η.

5. The terahertz device of claim 1, wherein an inner diameter of each annular nanogap is 1-10 μ ι η.

6. The terahertz device of claim 1, wherein the gap width of each annular nanogap is 1-200 nm.

7. A method of preparing the terahertz device of any one of claims 1 to 6, comprising the steps of:

s100: generating a graphene film on a silicon dioxide substrate through chemical vapor deposition;

s200: and forming a plurality of annular nanometer gaps on the graphene film through focused ion beam etching.

8. The method of claim 7, wherein the plurality of annular nanogaps are arranged in an array to form a periodic array of annular nanogaps.

9. The method of claim 7, wherein the periodic circular nanogap array has a period of 2-20 μ ι η.

10. The method of claim 7, wherein each annular nanogap has an inner diameter of 1-10 μ ι η.

Technical Field

The disclosure relates to a terahertz device, in particular to a terahertz device for capturing and detecting circulating tumor cells and a preparation method thereof.

Background

Cancer, as a global public health problem, greatly endangers human life health. It is noted that a large number of cancer patients have developed tumor distant metastasis at the initial diagnosis, and thus the optimal treatment period is missed, and therefore, early diagnosis of cancer is of great significance for prolonging the life of the patients. At present, the clinical detection of cancer mainly comprises imaging and pathological detection, however, the imaging information has hysteresis, so that the imaging detection cannot carry out early detection and diagnosis; the tissue biopsy technology based on pathology has the advantages of accurate diagnosis and the like, but has the limitations of large invasiveness, difficult sampling, limited sampling window period, possible increase of metastasis risk and the like, and has very limited effects on early diagnosis, metastasis, prognosis evaluation and the like of cancer.

Liquid biopsy is an emerging noninvasive detection technology, and the method monitors malignant tumors in vivo by collecting body fluids (including blood, saliva, sweat, secretion and the like) of a patient, and has become a research hotspot for individualized and accurate diagnosis in the field of cancers. Currently, the most studied blood markers include: micrornas, circulating tumor DNA, and circulating tumor cells. Wherein, the circulating tumor cells are cells which are spontaneously or in the course of treatment shed from the primary focus tumor to enter the peripheral blood, and enter other tissues and organs along with the blood circulation to grow into new tumor tissues. If circulating tumor cells are present in the blood, this indicates that a tumor is present in the body and that metastasis may have occurred, which is often a major factor leading to high mortality in cancer patients. Therefore, circulating tumor cells have become important markers for monitoring dynamic development of tumors in real time, and the number and type of the circulating tumor cells can be effectively used for early diagnosis, treatment and prognosis evaluation of cancers. However, the circulating tumor cells are present in very low levels in the blood, which are only a part per million of the total blood cells, and this requires that the detection technique can efficiently and accurately separate and detect a very small number of target cells from a large number of cells.

The detection technology based on the terahertz wave plasma resonance sensor is expected to solve the detection problem of the circulating tumor cells, the terahertz wave plasma resonance sensor is very sensitive to the change of the refractive index of the surrounding environment, the refractive index is the inherent property of media, and different media have different refractive indexes, so that any one of the media attached to the structure of the plasma resonance sensor corresponds to different resonance frequencies in transmission characteristics, and the detection of different media can be realized. At present, terahertz plasma resonance sensors are widely applied to sensing and detection of various cells, biomolecules and viruses. The terahertz wave is an electromagnetic wave with the frequency range of 0.1-10 THz, and because the photon energy of the terahertz wave is far less than the energy of X rays, harmful ionization can not be generated on biological macromolecules, biological cells, tissues and the like, and the requirement of liquid biopsy of circulating tumor cells is perfectly met. In addition, the rotation and vibration frequency of biomacromolecules such as lipid, nucleic acid, protein, saccharide and the like are just in the THz waveband, and resonance absorption can be effectively generated under the excitation of terahertz wave energy, so that a specific characteristic identification fingerprint spectrum is provided, and therefore, the terahertz wave has great application potential in the fields of nondestructive and unmarked sensing and cancer detection.

At present, the traditional tumor cell separation and enrichment technology based on physical properties is often adopted in the circulating tumor cell detection technology, and the technology is mainly used for separating cancer cells according to the size difference of the cancer cells and normal blood cells, wherein the circulating tumor cells (10-30 mu m), white blood cells (8-10 mu m) and red blood cells (less than 7 mu m). The method has the advantages of simple operation, better maintenance of cell integrity and activity and the like, but has the defects of poor specificity, easy loss of tumor cells beyond a specific size and the like, and is difficult to realize high-efficiency and specific separation and enrichment of circulating tumor cells. In addition, the terahertz plasma resonance sensor formed by taking noble metal as a plasma material has the problems of limited sensitivity, untuneability and the like, and is difficult to meet the requirement of high-sensitivity detection on different types of trace circulating tumor cells.

Disclosure of Invention

Aiming at the defects in the prior art, the disclosure aims to provide a terahertz device for capturing and detecting circulating tumor cells, wherein the graphene coaxial holes are used for forming terahertz plasmon tweezers to achieve near-field capture of the tumor cells, and meanwhile, the graphene tunable optical characteristics are combined to meet the requirements of the tumor cells with different sizes and different refractive indexes on the capturing performance, so that the circulating tumor cells are captured specifically. In addition, the obvious plasma enhancement effect of the graphene in the terahertz wave frequency band, the hydrophobic property of the multilayer graphene and the tunability of the graphene are utilized, so that the interaction between electromagnetic waves and substances is improved, and the high-sensitivity detection of different types of circulating tumor cells is realized.

In order to achieve the above purpose, the present disclosure provides the following technical solutions:

a terahertz device for circulating tumor cell capture and detection, comprising: the graphene film comprises a silicon dioxide substrate and a graphene film coated on the silicon dioxide substrate;

a plurality of annular nanometer gaps are etched on the graphene film and arranged in an array manner to form a periodic annular nanometer gap array;

the annular region of each annular nanogap is a capture and detection region for capturing circulating tumor cells and for detecting captured circulating tumor cells.

Preferably, the periodic ring-shaped nanogap array obtains a near-field trapping force by localizing the terahertz waves within the trapping region.

Preferably, the detecting of the captured circulating tumor cells is performed by detecting a moving amount of a resonance frequency of the terahertz device.

Preferably, the periodic circular nanogap array has a period of 2 to 20 μm.

Preferably, the inner diameter of each annular nanogap is 1 to 10 μm.

Preferably, the gap width of each annular nanogap is 1 to 200 μm.

The present disclosure also provides a method for manufacturing a sensor based on terahertz waves, including the steps of:

s100: generating a graphene film on a silicon dioxide substrate through chemical vapor deposition;

s200: and forming a plurality of annular nanometer gaps on the graphene film through focused ion beam etching.

Preferably, the plurality of annular nanogaps are arranged in an array to form a periodic annular nanogap array.

Preferably, the periodic circular nanogap array has a period of 2 to 20 μm.

Preferably, each annular nanogap has an inner diameter of 1 to 10 μm.

Compared with the prior art, the beneficial effect that this disclosure brought does:

1. a novel circulating tumor cell separation and capture technology is provided, namely the circulating tumor cell capture technology based on terahertz plasmon tweezers, specificity lossless capture of circulating tumor cells is realized by combining tunable optical characteristics of graphene, and compared with the traditional circulating tumor cell separation technology, the method has the advantages of simplicity and convenience in operation, high specificity and the like;

2. a new circulating tumor cell enrichment technology based on multilayer graphene is provided, the concentration of circulating tumor cells in blood can be indirectly improved by utilizing the hydrophobic characteristics of the surface of the multilayer graphene, and the enrichment effect and the detection sensitivity of the circulating tumor cells are improved;

3. compared with the traditional plasma resonance sensor formed by noble metals, the novel terahertz plasma resonance sensor based on graphene has the advantages of simple structure, tunability, high sensitivity and the like, and can realize high-sensitivity detection on different kinds of trace circulating tumor cells.

Drawings

Fig. 1 is a schematic structural diagram of a terahertz device for capturing and detecting circulating tumor cells according to an embodiment of the present disclosure;

fig. 2 is a top view of a terahertz device for capturing and detecting circulating tumor cells according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a single graphene coaxial hole in a terahertz device for capturing and detecting circulating tumor cells according to an embodiment of the present disclosure;

fig. 4(a) and 4(b) are schematic views of the shape of blood droplets on the surfaces of a graphene film and a noble metal film, respectively;

FIG. 5 is a schematic illustration of a circulating tumor cell captured at a nanogap, provided by an embodiment of the disclosure;

fig. 6 is a schematic diagram of a reflectivity curve of a sensor based on terahertz waves according to another embodiment of the present disclosure.

Detailed Description

Specific embodiments of the present disclosure will be described in detail below with reference to fig. 1 to 6. While specific embodiments of the disclosure are shown in the drawings, it should be understood that the disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

It should be noted that certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, various names may be used to refer to a component. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present disclosure is to be determined by the terms of the appended claims.

To facilitate an understanding of the embodiments of the present disclosure, the following detailed description is to be considered in conjunction with the accompanying drawings, and the drawings are not to be construed as limiting the embodiments of the present disclosure.

In one embodiment, as shown in fig. 1, a terahertz device for capturing and detecting circulating tumor cells comprises: the graphene film is etched with a plurality of annular nanometer gaps, and the annular nanometer gaps are arranged in an array form to form a periodic annular nanometer gap array; the annular region of each annular nanogap is a capture and detection region for capturing circulating tumor cells and for detecting captured circulating tumor cells.

In this embodiment, since the noble metal has fixed free electrons, once the sensor device made of the noble metal is manufactured, the working performance of the sensor device is difficult to change, and the requirements for capturing and detecting different types of circulating tumor cells cannot be met. In contrast, the carrier density of graphene can be regulated and controlled by the gate voltage, which provides a possibility for the preparation of tunable sensing devices. In addition, compared with noble metals, the graphene also has the advantages of high carrier concentration and mobility, low optical loss and the like, the field local area of electromagnetic waves can be remarkably improved, the interaction between terahertz waves and an object to be detected is enhanced, and conditions are provided for realizing high-sensitivity detection. Therefore, compared with the problems of untuneability and limited sensitivity of a sensor made of noble metal adopted in the prior art, the embodiment adopts the graphene-based terahertz device for analyzing and detecting the circulating tumor cells, and can obtain a better detection effect. For example, fig. 4(a) and 4(b) are schematic diagrams of shapes of a graphene thin film (hydrophobic interface) and a noble metal thin film surface (hydrophilic interface) respectively dropped with the same volume of blood, and as shown in fig. 4(a) to 4(b), the contact angle θ formed by the drop of blood on the surface of the multi-layer graphene and the surface of the noble metal thin film respectively₁And theta₂And theta₁＞θ₂. Larger contact angle theta₁Indicating that the blood drop has a smaller contact area and a higher height on the graphene surface. When the concentration of circulating tumor cells in the blood to be tested is highWhen the degree is fixed, the smaller contact area can indirectly improve the space density of the circulating tumor cells in unit area, and further increase the probability to be detected. Therefore, compared with the traditional sensor composed of a metal film, the sensor surface composed of the multilayer graphene has hydrophobicity, so that the concentration of circulating tumor cells in blood in unit area can be indirectly increased, the enrichment effect of the circulating tumor cells is enhanced, and the detection sensitivity of the sensor is improved.

In another embodiment, the periodic circular nanogap array obtains near-field trapping force by localizing terahertz waves within the trapping region.

In this embodiment, under the radiation effect of the terahertz electromagnetic wave, free electrons in the graphene film generate collective oscillation and are gathered at the boundary of the annular nanogap, so that the terahertz electromagnetic wave is strongly localized near the nanogap, a local hot spot is generated at the nanogap, and a huge electromagnetic field is enhanced, and as the electromagnetic field intensity is rapidly reduced along with the distance away from the center of the local hot spot, a near-field capture force applied to a cell is generated and a three-dimensional capture potential well is formed on the surface of the graphene, when the size of the three-dimensional capture potential well is enough to overcome the irregular brownian motion of the cell, the cell moves to the center of the local hot spot (i.e., the lowest point of potential energy) under the push of the capture force and is bound at the position. Since the magnitude of the near-field capture force is proportional to the electromagnetic field strength, the size and refractive index of the captured cells, and the size and refractive index parameters of circulating tumor cells are higher than those of other cells (e.g., red blood cells, white blood cells) in blood. Therefore, when the graphene plasma structure is determined, the capture capacity of the device can be regulated and controlled only by adjusting the Fermi energy level to control the resonance strength of the graphene plasma, so that the capture capacity enough for capturing the circulating tumor cells but not enough for capturing other cells is obtained, and finally the specificity lossless capture of the circulating tumor cells is realized. Compared with the traditional separation and enrichment technology based on the size difference of the circulating tumor cells, the method is based on the difference of two key physical properties of the size and the refractive index of the circulating tumor cells, and therefore, the method has higher specificity.

In another embodiment, the detection of the captured circulating tumor cells is performed by detecting the amount of shift of the resonant frequency of the terahertz device.

In the embodiment, the terahertz waves are very sensitive to the dielectric property of the surface of the graphene film due to the local and enhanced electromagnetic field of the terahertz waves, when the circulating tumor cells are stably captured in the capture area, red blood cells and white blood cells in blood are washed by PBS buffer solution to leave the captured circulating tumor cells, the dielectric property of the surface of the graphene film is disturbed due to the existence of the circulating tumor cells, so that the resonance frequency of the terahertz device is moved, and the biological information carried by the circulating tumor cells can be detected through the reflection spectrum/transmission spectrum resonance frequency and the moving amount of the detection device of the terahertz time-domain spectroscopy system. Exemplarily, as shown in fig. 5, when the period P of the graphene circular nanogap array is 3 μm, the gap inner diameter D is 2 μm, the gap width w is 20nm, and the graphene fermi level is 0.6eV, under the radiation of the terahertz wave, the circulating tumor cells in the blood will be captured at the nanogap, and at this time, the red blood cells and the white blood cells in the blood are washed with the PBS buffer solution, and finally the captured circulating tumor cells are left. Assuming that the sample does not contain circulating tumor cells, the refractive index n of the blood to be measured is 1.5, and the resonance frequency f of the device is at this time₀The THz is 5.0THz, and when the blood to be measured contains circulating tumor cells, the refractive index n is 2.0, that is, the refractive index disturbance Δ n is 0.5, as shown in fig. 6, the resonance frequency shift Δ f of the terahertz device is 0.9 THz. Because different biological cells have different absorption frequency bands for the terahertz waves, the information such as the number and the type of the circulating tumor cells can be obtained by comparing and analyzing the resonance frequency and the movement amount of the terahertz device so as to realize the disease diagnosis of the cancer patient. Normalized sensitivity S 'of terahertz device for capture and detection of circulating tumor cells'_fCan be expressed as S'_f＝Δf/(Δn·f₀) In the embodiment, the normalized sensitivity of the terahertz device can reach 0.36THz/RIU, while the normalized sensitivity of the traditional plasma resonance sensor is only 0.01-0.1 THz/RIU. In addition, according to the requirements of different circulating tumor cells on capture parameters and cellsResonance frequencies of internal biological molecules in a terahertz frequency range are different, the Fermi level of the graphene film is regulated and controlled through the external field voltage regulator, the capture capacity and the resonance frequency of the device are adjusted, the capture performance requirements of different circulating tumor cells and the resonance frequencies of molecules in the tumor cells are met, and finally the specific capture and high-sensitivity detection of different types of circulating tumor cells are realized.

In another embodiment, the periodic circular nanogap array has a period of 2 to 20 μm.

In another embodiment, the inner diameter of the annular nanogap is 1 to 10 μm.

In the embodiment, the characteristic size of the device based on the metamaterial structure is in a sub-wavelength scale (namely 0.1-1 time wavelength), and the wavelength range of the terahertz wave is 30-3000 μm, so that the inner diameter of the annular nanogap is selected to be 1-10 μm.

In another embodiment, the annular nanogap has a gap width of 1 to 200 nm.

In this embodiment, in order to realize the local area and enhancement of the terahertz wave, the width of the nanogap is selected to be 1-200 nm.

It should be understood that the width of the nanogap is set to be nanoscale to realize the local and strengthening of the terahertz wave, so as to excite the resonance of the device.

It should also be appreciated that when the circulating tumor cells are stably captured in the capture region, the field localization and enhancement effects of the electromagnetic wave become stronger as the nanogap width w decreases, so that the electromagnetic wave becomes more sensitive to changes in the dielectric properties of the interface, and thus the detection sensitivity of the sensor device can be improved by decreasing the nanogap width w.

In another embodiment, the present disclosure further provides a method for manufacturing a sensor based on terahertz waves, including the following steps:

s100: generating a graphene film on a silicon dioxide substrate through chemical vapor deposition;

s200: and forming a plurality of annular nanometer gaps on the graphene film through focused ion beam etching.

The foregoing describes the general principles of the present application in conjunction with specific embodiments, however, it is noted that the advantages, effects, etc. mentioned in the present application are merely examples and are not limiting, and they should not be considered essential to the various embodiments of the present application. Furthermore, the foregoing disclosure of specific details is for the purpose of illustration and description and is not intended to be limiting, since the foregoing disclosure is not intended to be exhaustive or to limit the disclosure to the precise details disclosed.

The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit embodiments of the application to the form disclosed herein. While a number of example aspects and embodiments have been discussed above, those of skill in the art will recognize certain variations, modifications, alterations, additions and sub-combinations thereof.