CN112326760A - Preparation and detection method of epitaxial gate field effect transistor sensor for detecting chiral tryptophan - Google Patents
Preparation and detection method of epitaxial gate field effect transistor sensor for detecting chiral tryptophan Download PDFInfo
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- QIVBCDIJIAJPQS-UHFFFAOYSA-N Tryptophan Natural products C1=CC=C2C(CC(N)C(O)=O)=CNC2=C1 QIVBCDIJIAJPQS-UHFFFAOYSA-N 0.000 title claims abstract description 46
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N27/4145—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for biomolecules, e.g. gate electrode with immobilised receptors
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Abstract
The invention relates to a preparation method and a detection method of an epitaxial gate field effect transistor sensor for chiral tryptophan detection. And soaking the epitaxial grid in a bovine serum albumin solution to form a layer of ordered bovine serum albumin molecules on the surface of the grid, and fixing the chiral separation medium to obtain the chiral sensing chip which is the bovine serum albumin epitaxial grid. The method is applied to constructing an MOS tube sensor, is a bovine serum albumin epitaxial gate field effect transistor biosensor, and reduces the damage of a liquid environment to a device by utilizing the structure of the bovine serum albumin epitaxial gate field effect transistor, and can realize efficient, sensitive and differentiated response to the chiral enantiomer of pM concentration level under low pressure. The detection sensitivity is obviously higher than that of detection methods such as chromatography, electrochemistry and the like, the time consumption is short, the real-time online detection is realized, and the method is expected to be used as a novel field detection application platform.
Description
Technical Field
A preparation method and a detection method of an epitaxial grid field effect transistor sensor for detecting chiral tryptophan relate to the field of chiral molecular sensors.
Background
Chirality is a natural attribute of nature, chiral molecules have wide application prospects in the fields of medicine, pharmacy, food chemistry, chiral synthesis and the like, but the physiological and pharmacological activities of chiral enantiomers may be quite different. For example, the dextro isomer of thalidomide has sedative effects, while the levo isomer is responsible for teratogenicity. Levodopa is the first choice drug for treating Parkinson's disease, and dextrodrugs cause granular leucopenia, so that the differential resolution of chiral enantiomers is particularly important. Amino acid, a typical chiral compound, plays an important role in maintaining normal physiology, immunity and metabolism of the human body. Wherein, tryptophan (Trp) is an essential amino acid for human bodies, is a precursor of 5-hydroxytryptamine as a monoamine neurotransmitter in brain, the content of the tryptophan is closely related to depression, and when the livestock and poultry lack the tryptophan, the problems of growth retardation, weight loss and the like can be caused. In view of the similar physicochemical properties of the optical isomers, chiral recognition of amino acids is still considered to be one of the most problematic problems.
Most biological macromolecules, such as proteins, nucleic acids and natural polysaccharides, have chiral building blocks, and in particular proteins consisting of chiral subunits (L-amino acids) are capable of specifically binding small molecules. Proteins such as bovine serum albumin, human serum albumin and the like are widely used for constructing a chiral sensing interface to realize chiral resolution, wherein the bovine serum albumin has low price, is easy to modify and fix, and has unique chiral recognition capability, so that the bovine serum albumin becomes the first choice of a chiral separation medium. At present, bovine serum albumin is commonly used as a chiral separation medium in the fields of chromatography, capillary electrophoresis, mass spectrometry, fluorescence and the like, but the detection means has great limitation in practical application because the equipment has large volume, long time consumption and low sensitivity and is difficult to realize online real-time detection and the like. The inherent signal amplification and signal conduction capabilities of field effect transistors have received much attention in the field of biosensing, and detection of gases, antigens, glucose and the like has been achieved. Most of sensing layer construction is based on devices such as organic field effect transistor sensors, organic semiconductor layers of the devices are probably very sensitive to water system environment, so liquid environment can cause irreversible damage to device performance, and the devices cannot work normally, so the devices usually have complex preparation processes or semiconductor layer material modification processes for achieving stable testing performance. The commercial MOS transistor has the advantages of low cost, small and exquisite equipment, sensitive signal, high stability and the like, and particularly arouses great interest of researchers.
On the basis of stable output performance of a commercial MOS tube, the invention separates a sensitive driving element from a device in order to reduce the damage to equipment, adopts an epitaxial grid structure, can conveniently replace a sensing chip and realizes the reutilization of the device. The bovine serum albumin field effect transistor sensor and the detection method provided by the invention integrate the advantages of field effect transistor amplified signals and bovine serum albumin chiral identification, realize rapid, sensitive and real-time online detection of chiral tryptophan molecules in a low concentration range, and construct a novel application carrier for chiral enantiomer identification.
Disclosure of Invention
The invention aims to provide a preparation method of an epitaxial gate field effect transistor biosensor for detecting chiral tryptophan molecules, namely a bovine serum albumin epitaxial gate, aiming at the technical analysis, combining the output signal amplification capacity of a field effect transistor and the chiral recognition characteristic of bovine serum albumin, and applying the preparation method to the construction of an MOS (metal oxide semiconductor) tube sensor to realize efficient, sensitive and differential response to chiral enantiomers at pM concentration level under low pressure. The detection sensitivity is obviously higher than that of detection methods such as chromatography, electrochemistry and the like, the time consumption is short, the real-time online detection is realized, and the method is expected to be used as a novel field detection application platform.
The technical scheme of the invention is as follows:
an epitaxial grid field effect transistor sensor for detecting chiral tryptophan molecules is characterized in that an epitaxial grid is soaked in a bovine serum albumin solution, a layer of ordered bovine serum albumin molecules is formed on the surface of the grid, fixing of a chiral separation medium is completed, and a chiral sensing chip is manufactured and is a bovine serum albumin epitaxial grid field effect transistor biosensor.
The invention discloses a preparation method of an epitaxial gate field effect transistor sensor for detecting chiral tryptophan molecules, which comprises the following steps of:
(1) preparing an epitaxial grid: the glass substrate is ultrasonically cleaned by acetone, ethanol, isopropanol or other organic solvents to achieve the effect of removing surface dirt; then boiling in ethanol solution, drying by blowing with nitrogen, and evaporating an Au film on the glass substrate;
(2) modifying the epitaxial gate: preparing 1-10 mg/mL protein solution, soaking the epitaxial grid electrode in the protein solution for 1-12 h, taking out, washing with deionized water, removing the physically adsorbed bovine serum albumin, and forming a protein molecular layer on the surface of Au;
(3) preparation of PDMS sample cells for storage of assay solutions: and uniformly mixing the glue A and the glue B, vacuumizing to remove bubbles, pouring into a container containing a mold, heating and curing to obtain a sample cell, and fixing on the modified epitaxial gate by utilizing the adhesive force of PDMS and Au.
The length of the glass sheet in the step (1) is 0.5 cm-2.5 cm, the width is 0.5 cm-2.5 cm, the height is 0.2 cm-0.5 cm, the ultrasonic cleaning time is 10-20 min, the ethanol boiling time is 10-20 min, and the vacuum degree is 10-4Pa, the thickness of the Au film is 80-100 nm, and the evaporation rate is
The concentration of the phosphate buffer solution used in the step (2) is 10mM, the pH value is 7.2, the concentration of the bovine serum albumin solution is 1-10 mg/mL, and the soaking time is 1-12 h.
The glue in the step (3) A: the colloid content ratio of B is 10: 1-1: 1, the temperature is 20-100 ℃, and the curing time is 30-60 min.
A method for detecting a chiral tryptophan molecule using the sensor of the present invention; the method comprises the following steps:
(1) preparing a chiral tryptophan analysis solution: preparing D-or L-tryptophan into standard solutions with different concentrations by using a phosphate buffer solution, wherein the concentration is 0-10 mu M;
(2) testing the transfer characteristic curve of the device: testing the transfer characteristic curve of the epitaxial gate field effect transistor after the bovine serum albumin is modified;
(3) and (3) real-time baseline test: fixing the grid voltage and the source-drain voltage, adding PBS buffer solution into the sample cell, and testing the obtained real-time drain current curve as a baseline I0；
(4) Real-time detection of chiral tryptophan: fixing and testing grid voltage and source-drain voltage, adding D-or L-tryptophan with the concentration of 0-10 mu M into the sample cell, and using MOS tube drain electrode current variation (I-I)0) And the evaluation sensor senses the results of chiral tryptophan solutions with different concentrations in real time.
The test repetition frequency of the step (2) is 3 times.
The concentration of the phosphate buffer solution used in the step (1), the step (3) and the step (4) is 0.1 mM-10 mM.
And (4) setting the grid voltage and the source-drain voltage to be 1-2V.
The volume of the analysis solution used in each concentration in the step (3) and the step (4) is 10-30 mu L.
The invention relates to an epitaxial gate field effect transistor sensor for detecting chiral tryptophan molecules, which is a bovine serum albumin epitaxial gate field effect transistor biosensor. The sensor uses a commercial MOS tube, does not need to prepare a device, only needs to prepare an epitaxial grid, and builds a sensing platform, and comprises the preparation of the epitaxial grid and the construction of a detection method.
The sensor structure comprises an MOS (metal oxide semiconductor) tube (1), a PDMS (polydimethylsiloxane) sample pool (2), an epitaxial grid (5) chip modified by copper wires (3) and bovine serum albumin (4).
The epitaxial grid (5) is obtained by vacuum evaporation of a gold film on a glass sheet, the glass sheet is soaked in bovine serum albumin solution, S-Au chemical bonds are formed by protein sulfydryl and gold, and a layer of ordered protein molecules is formed on the surface of the grid to obtain the epitaxial grid chiral sensing chip. The PDMS sample pool (2) is obtained by uniformly mixing the glue A (main agent) and the glue B (hardening agent), pouring the mixture into a mold, heating and curing the mixture, and can be fixed on an epitaxial grid by utilizing the adhesive force between PDMS and gold.
The sensor detection method comprises the following steps: the liquid in the sample cell is contacted with the fixed and suspended copper wire, and the chiral discrimination is realized according to the variable quantity of the real-time current of the MOS tube caused after the chiral molecules act with the bovine serum albumin by adding the analysis liquid with different configurations and concentrations into the sample cell.
The epitaxial gate field effectThe transistor sensor is characterized in that the drain current of the field effect transistor presents very obvious gradient change to the change of the concentration of D-, L-tryptophan along with time, and compared with an epitaxial gate field effect transistor without modified bovine serum albumin, the leakage current change amount under different concentrations is increased. When the concentration gradient of the analysis solution changes, the current changes by an amount (I-I)0) Gradient reduction is achieved, the current change caused by the L-Trp is more obvious, and the change rate is-10% -40%, so that the L-Trp and the bovine serum albumin have stronger acting force, and the chiral microenvironment provided by the bovine serum albumin plays an important role in the chiral enantiomer differential response aspect. And the epitaxial grid structure reduces the damage of the liquid environment to the device, can realize the repeated use of the device and the sensing chip, has simple and convenient operation, and lays a foundation for practical application.
An epitaxial gate field effect transistor sensor detection method for chiral tryptophan detection comprises the following steps:
preparing chiral tryptophan analysis solution: d-or L-tryptophan is prepared into standard solutions with different concentrations by using a phosphate buffer solution, wherein the concentration is 0-10 mu M.
Testing a device transfer characteristic curve in the step (2): the transfer characteristic curve of the epitaxial gate field effect transistor after bovine serum albumin modification is tested, and the attached figure 3 is a stability test chart of the transfer characteristic curve, and whether the device works normally is checked.
Step (3), real-time baseline test: fixing the grid voltage and the source-drain voltage, adding PBS buffer solution into the sample cell, and testing the obtained real-time drain current curve as a baseline I0。
Step (4), real-time detection of chiral tryptophan: fixing and testing grid voltage and source-drain voltage, adding D-or L-tryptophan with the concentration of 0-10 mu M into the sample cell, and using MOS tube drain electrode current variation (I-I)0) And the evaluation sensor senses the results of chiral tryptophan solutions with different concentrations in real time. As shown in fig. 4, it can be seen that the sensing performance of the modified device is better than that of the unmodified device, and the response to the tryptophan concentration is more obvious. As can be seen from FIG. 5, the detection platform can still be used when the concentration of the analysis solution is as low as pM levelRealizing chiral discrimination of tryptophan. In summary, when the concentration gradient of the analysis solution is changed, the current changes by an amount (I-I)0) The current variable caused by the L-Trp is more obvious, the change rate is-10% -40%, the acting force of the L-Trp and the bovine serum albumin is stronger, and the constructed real-time analysis platform can realize the identification of the chiral molecules according to the current variable caused by different configurations.
The invention has the advantages that: 1. by utilizing the bovine serum albumin epitaxial gate field effect transistor structure, the damage of a liquid environment to a device is reduced, quick, simple, convenient and sensitive differential response to the chiral tryptophan can be realized under low voltage, and the lowest detection concentration is in the pM level. 2. The traditional reference electrode is eliminated, the contact with the analysis liquid in the sample cell is realized by only one fixed copper wire, the electric signal is conducted and amplified through the epitaxial grid, the response is obvious, the detection sensitivity is high, and the consumed time is short. 3. The sensor has simple structure and detection method, can realize repeated use of devices and sensing chips, is suitable for large-scale preparation and application, and is expected to be used as a novel application carrier for field detection.
Drawings
FIG. 1 is a diagram illustrating a real-time testing structure of an epitaxial gate MOS transistor sensor modified by bovine serum albumin according to the present invention
FIG. 2 shows the surface cyclic voltammetry test patterns of bare gold film and gold film modified with BSA
FIG. 3 is a graph of stability of transfer characteristic curve of an epitaxial gate MOS transistor modified by a protein
FIG. 40, 100nM, 1. mu.M, 10. mu.M concentration range of D-or L-tryptophan real-time test chart
FIG. 50, 100pM, 1nM, 10nM, 100nM, 1. mu.M concentration range of D-or L-tryptophan real-time test plots
Detailed Description
The invention is further illustrated by the following specific figures and examples. The scope of the invention is not limited to the following examples.
Example 1
Bovine serum albumin modified epitaxial gate field effect transistor sensor structure
The invention provides a detection method of an epitaxial gate field effect transistor sensor for chiral tryptophan detection, and the implementation scheme mainly covers the preparation of a sensing chip and a specific method for detecting chiral tryptophan molecules in real time. The structure of the epitaxial grid MOS tube sensor is shown in the attached figure 1 and comprises an MOS tube (1), a PDMS sample pool (2), a copper wire (3) and an epitaxial grid (5) chip modified by Bovine Serum Albumin (BSA) (4). The sensor uses commercial MOS tubes, does not need a complex device preparation process, and only needs to prepare an epitaxial grid.
Secondly, preparing an epitaxial grid, comprising the following steps:
step (1) preparation of epitaxial grid
The glass substrate has a length of 1.5cm, a width of 0.5cm and a height of 0.2cm, and is ultrasonically cleaned with acetone, ethanol and isopropanol for 15min, the glass sheet is boiled with ethanol for 15min, and dried with nitrogen. At a vacuum degree of 10-4Under the condition of Pa, a 100nm Au film is evaporated at the evaporation rate of
Step (2) modifying the epitaxial gate
30mg BSA was dissolved in 3mL 10mM phosphate buffer solution to prepare 10mg/mL solution, the epitaxial gate was immersed for 12h, rinsed with a large amount of deionized water to remove the physically adsorbed BSA and form a self-assembled molecular layer on the Au surface, and FIG. 2 shows the surface modification result by cyclic voltammetry. The reference electrode is a saturated calomel electrode, the auxiliary electrode is a platinum wire electrode, and the prepared epitaxial gate is a working electrode. The electrolyte solution was 5mM [ Fe (CN)6]3-/4-1M KCl, the scanning range is-0.2V-0.6V, and the scanning speed is 0.02V/s. As is apparent from fig. 2, the peak current is significantly reduced after the BSA modification, which is because BSA obstructs the electron transfer process on the Au surface, indicating that BSA is successfully loaded on the epitaxial gate.
Step (3) preparing PDMS sample pool
And (3) gluing A: the glue B is prepared according to the following steps of 10: 1, putting the mixture into a vacuum drying oven, vacuumizing the vacuum drying oven to remove bubbles, pouring the mixture into a container filled with a mold, curing the mixture for 40min at 90 ℃ in the vacuum drying oven, stripping the mold, cutting redundant parts to obtain a sample cell, and fixing the sample cell on a modified epitaxial gate by utilizing the adhesion force of PDMS and Au.
The sensor prepared by the invention is applied to real-time detection of chiral tryptophan molecules, and the specific detection method comprises the following steps:
step (1) preparation of chiral tryptophan analysis solution
0.0041g D-and L-tryptophan are respectively dissolved in 20mL0.1mM PBS buffer solution to prepare 1mM standard solution, and are sequentially diluted according to the proportion, and D-and L-tryptophan are prepared into standard solutions with different concentrations, wherein the concentrations are 0, 100nM, 1. mu.M and 10. mu.M.
Step (2) testing transfer characteristic curve of device
The MOS tube source electrode, the MOS tube drain electrode and the modified epitaxial grid electrode are connected to a source meter, the MOS tube grid electrode is connected with the epitaxial grid electrode through a lead, a transfer characteristic curve is repeatedly tested for 3 times, and the attached figure 3 is a transfer characteristic curve stability test chart, so that the real-time test platform built by the invention is stable in performance and can be used for the subsequent real-time sensing test of the enantiomer analysis liquid.
Step (3) real-time baseline testing
Setting the grid voltage of the source meter to 1.5V, setting the source drain voltage to 1.5V, adding 30 microliter blank 0.1mM PBS buffer solution into the sample cell, and taking the obtained real-time drain current curve as a base line I0。
Step (4) real-time detection of chiral tryptophan
mu.L of D-, L-tryptophan at a concentration of 0, 100nM, 1. mu.M, 10. mu.M was added sequentially to the cuvette. The grid voltage of a source meter is set to be 1.5V, the source-drain voltage is set to be 1.5V, and the drain current I of the MOS tube is tested to change along with the concentration. Using MOS transistor drain electrode current variation (I-I)0) The evaluation sensor senses the results of chiral tryptophan solutions with different concentrations in real time, as shown in fig. 4, it can be seen that after the bovine serum albumin is modified, the drain current shows a regular step change trend along with the increase of the analyte concentration. As can be seen from FIG. 5, when the concentration of the analysis solution is as low as pM level, the detection platform can still realize chiral discrimination of tryptophanThe method realizes the detection of the chiral tryptophan molecules in a low concentration range under low pressure, and the sensitivity is obviously higher than that of the electrochemical test method and the like. In summary, when the concentration of the analyte solution is changed in a gradient manner, the amount of change in current (I-I)0) The gradient is reduced, the current variable quantity caused by the L-Trp is more obvious, the change rate is-10% -40%, the acting force of the L-Trp and the bovine serum albumin is stronger, the result shows that the chiral microenvironment of the bovine serum albumin plays an important role in the aspect of the differential response of chiral enantiomers, and the constructed real-time analysis platform can realize the identification of chiral molecules according to the current variable quantity caused by different configurations.
Example 2
First, the structure of the epitaxial gate field effect transistor sensor modified by bovine serum albumin is the same as that in example 1.
Secondly, preparing an epitaxial grid, comprising the following steps:
step (1) preparation of epitaxial grid
Changing the length of the glass sheet to 2cm, the width to 1.5cm, the height to 0.3cm, the ultrasonic cleaning time to 10min, the ethanol boiling time to 10min, the Au film thickness to 90nm, the evaporation rate to 90nm
The rest of the procedure was the same as in example 1.
Step (2) modifying the epitaxial gate
The BSA concentration was changed to 1mg/mL, the soaking time was changed to 6h, and the rest of the specific modification methods were the same as in example 1.
Step (3) preparing PDMS sample pool
The PDMS sample cell was prepared in the same manner as in example 1. Wherein, the glue A: the adhesive B is changed into 5: 1, changing the temperature to 100 ℃ and changing the curing time to 30 min.
The sensor prepared by the invention is applied to real-time detection of chiral tryptophan molecules, and the specific detection method comprises the following steps:
step (1) preparation of chiral tryptophan analysis solution
1mM PBS buffer was used, and the procedure was the same as in example 1.
Step (3) real-time baseline testing
The volume of the analysis solution was 20. mu.L, the gate voltage and the source-drain voltage were set to 1V, 1mM PBS buffer was used, and the other methods were the same as in example 1.
Step (4) real-time detection of chiral tryptophan
The volume of the assay solution was 20. mu.L, the gate voltage and the source-drain voltage were set to 1V, 1mM PBS buffer was used, and the tryptophan detection concentrations were 0, 40nM, 200nM, 1. mu.M, and 5. mu.M, in the same manner as in example 1.
Example 3
First, the structure of the epitaxial gate field effect transistor sensor modified by bovine serum albumin is the same as that in example 1.
Secondly, preparing an epitaxial grid, comprising the following steps:
step (1) preparation of epitaxial grid
The length of the glass sheet is changed to 2.5cm, the width is changed to 1cm, the height is changed to 0.5cm, the ultrasonic time is changed to 30min, the ethanol boiling time is changed to 30min, the thickness of the Au film is changed to 80nm, the evaporation rate is changed to 80nm
The rest of the procedure was the same as in example 1.
Step (2) modifying the epitaxial gate
The BSA concentration was changed to 5mg/mL, the soaking time was changed to 1h, and the rest of the specific modification methods were the same as in example 1.
Step (3) preparing PDMS sample pool
The preparation method of the PDMS sample cell was the same as in example 1, wherein the gel a: the proportion of the B glue is changed to 8: 1, the curing temperature is changed to 20 ℃, and the curing time is changed to 60 min.
The sensor prepared by the invention is applied to real-time detection of chiral tryptophan molecules, and the specific detection method comprises the following steps:
step (1) preparation of chiral tryptophan analysis solution
The same procedure as in example 1 was repeated except for using 10mM PBS buffer.
Step (3) real-time baseline testing
The volume of the analysis solution was 10. mu.L, the gate voltage and the source-drain voltage were set to 2V, 10mM PBS buffer was used, and the other methods were the same as in example 1.
Step (4) real-time detection of chiral tryptophan
The volume of the assay solution was 10. mu.L, the gate voltage and the source-drain voltage were set to 2V, 10mM PBS buffer was used, and the tryptophan detection concentrations were 0, 800pM, 4nM, 20nM and 100nM, and the rest of the procedure was the same as in example 1.
While the methods and techniques of the present invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and/or modifications of the methods and techniques described herein may be made without departing from the spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.
Claims (10)
1. An epitaxial grid field effect transistor sensor for detecting chiral tryptophan molecules is characterized in that an epitaxial grid is soaked in a bovine serum albumin solution, a layer of ordered bovine serum albumin molecules is formed on the surface of the grid, fixing of a chiral separation medium is completed, and a chiral sensing chip is manufactured and is a bovine serum albumin epitaxial grid field effect transistor biosensor.
2. A preparation method of an epitaxial gate field effect transistor sensor for detecting chiral tryptophan molecules is characterized by comprising the following steps:
(1) preparing an epitaxial grid: the glass substrate is ultrasonically cleaned by acetone, ethanol, isopropanol or other organic solvents to achieve the effect of removing surface dirt; then boiling in ethanol solution, drying by blowing with nitrogen, and evaporating an Au film on the glass substrate;
(2) modifying the epitaxial gate: preparing 1-10 mg/mL protein solution, soaking the epitaxial grid electrode in the protein solution for 1-12 h, taking out, washing with deionized water, removing the physically adsorbed bovine serum albumin, and forming a protein molecular layer on the surface of Au;
(3) preparation of PDMS sample cells for storage of assay solutions: and uniformly mixing the glue A and the glue B, vacuumizing to remove bubbles, pouring into a container containing a mold, heating and curing to obtain a sample cell, and fixing on the modified epitaxial gate by utilizing the adhesive force of PDMS and Au.
3. The method according to claim 2, wherein the glass sheet of step (1) has a length of 0.5cm to 2.5cm, a width of 0.5cm to 2.5cm and a height of 0.2cm to 0.5cm, and is ultrasonically cleaned for 10 to 20min, boiled in ethanol for 10 to 20min and in a vacuum of 10 to 20min-4Pa, the thickness of the Au film is 80-100 nm, and the evaporation rate is
4. The method according to claim 2, wherein the phosphate buffer solution used in step (2) has a concentration of 10mM, a pH of 7.2, a concentration of 1-10 mg/mL bovine serum albumin solution, and a soaking time of 1-12 h.
5. The method of claim 2, wherein step (3) a comprises: the colloid content ratio of B is 10: 1-1: 1, the temperature is 20-100 ℃, and the curing time is 30-60 min.
6. A method for detecting a chiral tryptophan molecule using the sensor of claim 1; the method is characterized by comprising the following steps:
(1) preparing a chiral tryptophan analysis solution: preparing D-or L-tryptophan into standard solutions with different concentrations by using a phosphate buffer solution, wherein the concentration is 0-10 mu M;
(2) testing the transfer characteristic curve of the device: testing the transfer characteristic curve of the epitaxial gate field effect transistor after the bovine serum albumin is modified;
(3) and (3) real-time baseline test: fixing the grid voltage and source-drain voltage, adding PBS buffer solution into the sample cell, and testing the obtained real-time drain current curve as the baseLine I0；
(4) Real-time detection of chiral tryptophan: fixing and testing grid voltage and source-drain voltage, adding D-or L-tryptophan with the concentration of 0-10 mu M into the sample cell, and using MOS tube drain current variation (I-I)0) And the evaluation sensor senses the results of chiral tryptophan solutions with different concentrations in real time.
7. The method of claim 6, wherein the step (2) is repeated 3 times.
8. The method according to claim 6, wherein the concentration of the phosphate buffer solution used in the step (1), the step (3) or the step (4) is 0.1 mM-10 mM.
9. The method of claim 6, wherein the gate voltage and the source-drain voltage set in the steps (3) and (4) are both 1-2V.
10. The method according to claim 6, wherein the volume of the analysis solution used in each concentration of the step (3) and the step (4) is 10 to 30. mu.L.
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