CN106404840A - Method for realizing surface modification of nanowire biosensor - Google Patents

Abstract

The invention provides a method for realizing the surface modification of the nanowire biosensor. In the method, the plasma treatment of ammonia gas or nitrogen-hydrogen mixed gas is performed on the surface of the nanowire biosensor to be modified, and the surface of the nanowire biosensor to be modified is modified with amino groups; Titrate the solution mixed with the cross-linking agent and the biomolecules to be modified onto the surface of the nanowire biosensor to be modified. biological modification. The plasma treatment method proposed by the invention can form more uniform and higher-density amino groups on the surface of the nanowire to be modified, so that the modification density of subsequent molecules to be modified is also greatly improved; the sensitivity and signal intensity of biosensing are greatly improved.

Description

A method for surface modification of nanowire biosensors

technical field

The invention relates to biosensors, in particular to a method for realizing surface modification of nanowire biosensors.

Background technique

Since the invention of the integrated circuit, the performance of the chip can be effectively improved by continuously reducing its feature size and integrating other micro-mechanical system components. In recent years, the combination of micro-nano technology and biotechnology has attracted widespread attention from academia and industry. Miniature biosensors are components that use biologically active units (such as enzymes, antibodies, nucleic acids, cells, etc.) as sensitive units to convert biological information into electrical signals to monitor biological signals in the environment. Nanowires have a high surface area to volume ratio and meet the sensitivity requirements of biosensing, so they are considered as one of the most promising biosensing devices.

At present, the method for modifying the surface of nanowires in the industry mainly adopts the method of solution titration to modify the surface. For protein modification, specifically titrate a solution mixed with APTES, a cross-linking agent (such as pentylene glycol) and protein onto the surface of silica with hydroxyl groups on the nanowires, and APTES in the solution acts as an intermediate acceptor, and the nanowires The hydroxyl group on the surface undergoes a coupling reaction to form a covalent bond, and at the same time exposes the amino group at one end of APTES. Under the action of a cross-linking agent such as pentanediol, the carboxyl end of the protein dehydrates and condenses with the amino end of APTES to form a peptide bond. So far, the purpose of protein modification on the surface of nanowires has been achieved. This method has low coupling efficiency, and the enrichment degree of the biomolecules to be modified on the surface of the nanowire is not enough. At the same time, APTES is an organic macromolecule, and using it as an intermediate acceptor will increase the Debye ratio between the molecule to be modified and the surface of the nanowire. The length cannot meet the requirements of high sensitivity and high signal strength for biosensing.

Contents of the invention

Aiming at the above problems, the present invention proposes a modification method for introducing amino groups on the surface of nanowire biosensors based on plasma treatment. This method can meet the requirements of high sensitivity and high signal intensity for biosensing.

Technical scheme of the present invention is as follows:

A method for surface modification of a nanowire biosensor, comprising the following steps:

1. Remove the natural oxide layer and organic contamination on the surface of the nanowire biosensor to be modified, exposing the hydrogen bond of the nanowire;

2. Plasma treatment of ammonia or nitrogen-hydrogen mixed gas on the surface of the nanowire biosensor to be modified, and the surface of the nanowire is modified with amino (-NH ₂ );

3. Titrate the solution mixed with the cross-linking agent and the biomolecules to be modified onto the surface of the nanowire biosensor to be modified. Surface biomodification.

Further, the nanowires described in step 1 can be prepared by semiconductor materials such as silicon and germanium, or by two-dimensional materials such as graphene;

Further, the method for removing surface organic contamination in step 1 may be organic cleaning, concentrated sulfuric acid cleaning, fuming nitric acid cleaning, ammonia water and hydrogen peroxide mixed cleaning, etc.;

Further, the method for removing the surface oxide layer in step 1 may be hydrochloric acid cleaning, hydrofluoric acid cleaning, etc.;

Further, the gas used for plasma treatment in step 2 can be ammonia, or a mixed gas of nitrogen and hydrogen;

Further, the plasma treatment process in step 2 is as follows: inject ammonia gas or nitrogen-hydrogen mixed gas into the plasma reaction chamber, ammonia gas or nitrogen-hydrogen mixed gas decomposes into nitrogen ions and hydrogen ions, nitrogen ions combine with hydrogen ions to form amino groups group (-NH ₂ ) to replace the hydrogen ions on the surface of the nanowire to be modified; the plasma reaction chamber can be an inductively coupled plasma (ICP) chamber, or any other chamber that can generate plasma;

Further, in the plasma treatment described in step 2, the gas flow rate is 5-100sccm, the air pressure is 8-200mTorr, the power used to generate plasma is 20-1500W, the plasma treatment time is 5s-60min, and the treatment temperature is room temperature;

Further, the linking agent described in step 3 can be pentanediol, SMCC (succinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate), EDC ( 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride)/NHS (N-hydroxysuccinimide), etc. can make the amino terminal on the surface of the nanowire and the carboxyl group of the molecule to be modified Organic reagents that undergo dehydration reactions.

Advantage of the present invention and positive effect are as follows:

a) Compared with the introduction of amino groups by APTES solution titration, the plasma treatment method proposed by the present invention can form more uniform and higher density amino groups on the surface of the nanowire biosensor to be modified, so that the modification density of subsequent molecules to be modified also greatly improved;

b) Compared with using organic macromolecules such as APTES as intermediate receptors, using plasma to directly introduce amino groups on the surface of nanowire biosensors can reduce the Debye length of the molecules to be modified for biosensing and greatly improve the biosensing efficiency. Sensitivity and signal strength;

c) The process is simple and the cost is small.

Description of drawings

1-4 is a schematic flow chart of a method for surface modification of a nanowire biosensor proposed by the present invention, wherein:

Figure 1 Removal of contamination and natural oxide layer;

Figure 2 uses plasma treatment to introduce amino groups on the surface of the nanowire biosensor to be modified;

Fig. 3 titrates the mixed solution of cross-linking agent and protein to the surface to be modified of nanowire biosensor;

Figure 4 The carboxyl group of the protein undergoes a dehydration reaction with the amino group under the action of a cross-linking agent to form a peptide bond and complete the protein modification;

Fig. 5 is a legend of Fig. 1 to Fig. 4 .

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific examples.

According to the following steps, protein modification can be realized on the surface of the nanowire biosensor. The substrate of the biosensor is silicon oxide, and the nanowire is monocrystalline silicon:

1) The surface of the single crystal silicon nanowire is washed with fuming nitric acid to remove organic contamination, and then the natural oxide layer is washed with hydrofluoric acid to expose the hydrogen bonds on the surface of the nanowire. As shown in Figure 1;

2) Put the nanowire biosensor substrate to be modified into an inductively coupled plasma (ICP) chamber, then feed ammonia gas into the chamber, the flow rate of ammonia gas is 12 sccm, the air pressure is 10 mTorr, and the power used to generate plasma is 500W, the plasma treatment time is 2min, the treatment temperature is room temperature, and the surface of the nanowire is modified with amino (-NH ₂ ), as shown in Figure 2;

3) titrate the solution mixed with pentanediol and protein to the surface of the nanowire to be modified, as shown in Figure 3;

4) The carboxyl terminal (-COOH) of the protein molecule undergoes a dehydration reaction with the amino group on the surface of the single crystal silicon nanowire under the cross-linking action of pentanediol to form a peptide bond to complete the modification of the protein on the surface of the single crystal silicon nanowire ,As shown in Figure 4;

Finally, high-density and high-uniform protein molecular modification is realized on the surface of silicon-based nanowires.

The embodiments of the present invention are not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. a kind of method realizing nanowire biosensor surface modification, comprises the following steps：

1) remove nanowire biosensor natural oxidizing layer surface to be modified and organic contaminations, expose the hydrogen of nanowire surface Key；

2) corona treatment that carry out ammonia or nitrogen hydrogen mixeding gas surface to be modified to nanowire biosensor, nano wire Surface is modified amino；

3) being blended with the solution of crosslinking agent and biomolecule to be finished, to be titrated to nanowire biosensor surface to be modified, raw Thing molecule forms covalent bond with the amino of nanowire surface in the presence of crosslinking agent, completes to nanowire biosensor surface Bio-modification.

2. the method for claim 1 is it is characterised in that step 1) described in nano wire adopt silicon or Germanium semiconductor material It is prepared, or be prepared with grapheme two-dimension material.

3. the method for claim 1 is it is characterised in that step 1) in remove that nanowire biosensor surface is organic to be stained with Dirty method is organic washing, concentrated sulfuric acid cleaning, fuming nitric aicd cleaning, ammoniacal liquor and hydrogen peroxide mixing cleaning.

4. the method for claim 1 is it is characterised in that step 1) in remove the nature on nanowire biosensor surface The method of oxide layer is hydrochloric acid cleaning or hydrofluoric acid clean.

5. the method for claim 1 is it is characterised in that step 2) in for plasma treatment gas be ammonia or Nitrogen and the mixed gas of hydrogen.

6. the method for claim 1 is it is characterised in that step 2) in plasma treatment process as follows：Inject a gas into To in plasma reaction chamber, gas is decomposed into Nitrogen ion and hydrogen ion, and Nitrogen ion is combined generation amino group with hydrogen ion, takes For nano wire hydrogen ion surface to be modified.

7. the method for claim 1 is it is characterised in that step 2) in plasma reaction chamber be inductively coupled plasma Chamber.

8. the method for claim 1 is it is characterised in that step 2) described in corona treatment in gas flow be 5-100sccm, air pressure is 8-200mTorr, and the power for producing plasma is 20-1500W, plasma treatment time For 5s-60min, treatment temperature is room temperature.

9. the method for claim 1 is it is characterised in that step 3) described in crosslinking agent be that pentanediol, succinyl are sub- Amido 4- (N- maleimidomehyl) hexamethylene -1- carboxylate, 1- (3- dimethylamino-propyl) -3- ethyl carbodiimide hydrochloride Salt/NHS (N-hydroxy-succinamide).