CN118169097A - Ordered localized nanostructure capable of realizing enrichment detection and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of nanocomposite materials, in particular to a preparation method for realizing enrichment detection by an ordered localized nanostructure. The method mainly comprises the following steps of 1, self-assembling PS balls; 2. removing ball corrosion; 3. electrochemical deposition; 4. and (3) modification of PDMS. The localized enrichment SERS array has the characteristics of simple preparation and strong repeatability, and has the excellent performance of conducting surface plasmons; ag ₇O₈NO₃ is a multivalent Ag compound, and reduced Ag has good SERS detection performance; the experimental steps are simple, and the preparation period is short; the preparation cost is low; the enrichment SERS detection can realize low-concentration SERS detection, and the operation space is widened for the subsequent single-molecule detection.

Description

Ordered localized nanostructure capable of realizing enrichment detection and preparation method and application thereof

Technical Field

The invention relates to the technical field of nanocomposite materials, and in particular to an ordered localized nanostructure capable of realizing enrichment detection, a preparation method and application thereof.

Background technique

Surface-Enhanced Raman Scattering (SERS) is a surface physics phenomenon based on the principle of Raman scattering. When molecules approach a rough metal surface or nanostructure, the Raman signal is significantly enhanced. This signal enhancement makes SERS an extremely sensitive spectroscopic technique that can be used to detect extremely low concentrations of chemicals.

Electrochemical deposition is a technique that generates and deposits metals or other substances on a conductive substrate through an electrolytic reaction. This method has been widely used in materials science and industrial production due to its advantages such as simple operation, low cost, strong controllability and the ability to coat the surface of objects with complex shapes. In recent years, with the development of nanotechnology, the application of electrochemical deposition at the nanoscale has attracted particular attention.

Ag ₇ O ₈ NO ₃ has unique electrochemical and optical properties and is considered to have great potential in SERS applications. Therefore, it can be used as a new type of SERS substrate material to provide high-density "hot spots" in the form of ordered nanoarrays, thereby greatly enhancing the Raman signal.

By constructing a SERS detection substrate in a limited area and combining it with a PDMS super-hydrophobic surface around the substrate, it can, to a certain extent, enrich the pyridine molecules in the object to be detected to the central detection area to the greatest extent. Therefore, it is necessary to construct an enrichment-SERS detection platform with high enrichment efficiency, especially suitable for conventional organic solvents, and independent of the type of molecules to be detected. This structure has application prospects in reducing single molecule detection, self-cleaning surface design, and microfluidic devices.

Summary of the invention

The present invention aims at the deficiencies of the prior art and proposes a preparation method based on an ordered localized nanostructure array. By electrochemically depositing noble metals in the nanostructure array and combining it with PDMS modification, the molecules to be detected can be enriched in the localized nanostructure for SERS detection. This provides a technical means based on an ordered localized nanostructure array with simple steps and strong operability to achieve single molecule detection.

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

A method for preparing an ordered localized nanostructure capable of realizing enrichment detection, characterized in that it comprises the following steps:

(A) PS spheres are self-assembled in the upper limit area of a silicon wafer, and the size of the PS spheres is reduced by etching to leave a certain distance between the PS spheres, thereby obtaining a PS sphere array on the silicon wafer;

(B) A layer of Cr is magnetron sputtered on the surface of the silicon wafer as a mask to remove the PS balls from the surface of the silicon wafer, and a bare silicon wafer area is generated after the PS balls are removed; the silicon wafer is heated and immersed in a NaOH solution to obtain an ordered array of concave pyramid structures on the surface of the silicon wafer;

(C) growing a layer of material for improving SERS performance in the concave pyramid structure, thereby obtaining a SERS site area on the surface of the silicon wafer;

(D) A layer of PDMS film is disposed on the surface of the silicon wafer in an area other than the SERS site area to form an ultra-smooth surface; the ultra-smooth surface is used to enable the sample to be tested to be concentrated in the central SERS site area on the ultra-smooth surface. As the water molecules in the sample to be tested evaporate, the molecules to be tested in the sample to be tested are continuously gathered and enriched under the action of PDMS, so that the molecules to be tested in the sample to be tested are continuously gathered in the SERS site area.

Preferably, in step (A), the confined self-assembly specifically comprises: controlling the range of the close-packed hexagonal stacked single-layer PS ball array to a confined area with a length and width of 200 μm-300 μm, and the diameter of the PS ball is 500 nm.

Preferably, in step (B), the heating and soaking with NaOH solution specifically includes placing in 80° C. NaOH solution for 1 to 3 minutes, so that the exposed silicon wafer area obtains a depressed pyramid structure; as the soaking time increases, the depth of the depressed pyramid gradually increases.

Preferably, in step (C), the method of growing a layer of a substance that improves SERS performance specifically comprises:

First, the concave pyramid structure is treated with Au by magnetron sputtering;

Then, Ag ₇ O ₈ NO ₃ is electrochemically deposited in the concave pyramid structure, and then Ag ₇ O ₈ NO ₃ is reduced to Ag, so that single-substance Ag with nano-scale holes on the surface is obtained in the concave pyramid.

Preferably, in step (D), the specific method of providing a layer of PDMS film comprises:

The surface of the silicon wafer except the SERS site area is hydrophilized, and the surface of the hydrophilized area is grafted with a PDMS precursor solution under an ambient humidity of 60% and acid catalysis to obtain a PDMS film.

By dropping the substance to be detected onto the sample, the ultra-slippery surface of PDMS can make the liquid more concentrated and gathered. During the continuous evaporation of the liquid, the pyridine molecules continue to gather in the central area until the water molecules in the solution are completely evaporated, and the molecules to be detected in the sample are enriched in the SERS site area to the greatest extent.

The present invention also provides an ordered localized nanostructure capable of realizing enrichment detection, wherein the ordered localized nanostructure capable of realizing enrichment detection comprises a SERS site region and an ultra-slippery surface; the length and width of the SERS site region are both within the range of 200 μm-300 μm, the periphery of the SERS site region is an ultra-slippery surface, and the ultra-slippery surface is composed of a PDMS film;

The SERS site area is composed of a concave pyramid array.

The spacing between the concave pyramid arrays is 20nm-100nm.

An Au layer is magnetron sputtered in the concave pyramid;

The Au layer is also provided with single substance Ag having nano-scale holes on its surface.

Preferably, the thickness of the Au layer is 5 nm.

The present invention also provides an ordered localized nanostructure capable of realizing enrichment detection, which is applied to the enrichment detection of a molecule to be detected in an aqueous solution, comprising the following steps:

An aqueous solution containing the molecule to be tested is used as a sample to be tested;

Placing the sample to be tested on the surface of the ordered localized nanostructure for achieving enrichment detection; utilizing the super-slippery surface to enable the sample to be tested to be concentrated to the central SERS site area on the super-slippery surface;

The water in the aqueous solution is evaporated. As the water molecules evaporate, the sample to be tested is continuously gathered and enriched in the SERS site area under the action of PDMS, so that the molecules to be tested in the sample to be tested are continuously gathered in the SERS site area;

After the molecules to be tested in the aqueous solution are enriched in the SERS site area, Raman spectroscopy test is performed on the molecules to be tested in the SERS site area.

Preferably, the spacing between the recessed pyramid arrays is 20 nm-100 nm, and the molecules to be detected are pyridine molecules.

Beneficial effects of the present invention:

In the present invention, an ordered localized nanostructure array is prepared. The preparation method is relatively simple and easy to operate. The prepared microstructure array has the characteristics of localized detection, strong SERS signal, enrichment effect, regular structure, etc.

The present invention can enrich the sample to be tested to the central detection area to the greatest extent, avoiding the "coffee ring" during the detection process.

The emergence of the effect increases the concentration limit of detection.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a flowchart of the experiment.

FIG2 is a schematic diagram of a confined ordered array of PS balls.

Figure 3 is a SEM image of the ordered structure.

FIG. 4 is a SEM image of Ag ₇ O ₈ NO ₃ after electrochemical deposition in an ordered structure.

Detailed ways

Embodiment 1:

Self-assembled PS ball

Here we use 500nm polystyrene microspheres and obtain PS ball arrays in a localized area on a silicon wafer by processing with a mask. Through RIE processing, under the parameters of 50W, 20Pa, and oxygen flux of 50sccm, the size of the PS balls is reduced to about 240nm after etching for 200s.

Ball removal corrosion

Here we magnetron sputtered a layer of Cr on the surface of the PS ball as a mask. The purpose of Cr plating is to protect the silicon wafer from NaOH corrosion. The PS ball was removed from the silicon wafer substrate and placed in 20mL NaOH solution heated to 80℃ for wet chemical etching for 1-2min to obtain pyramid-shaped nanostructures with different degrees of depression.

Electrochemical deposition

Here, we further modified the localized structure after corrosion by magnetron sputtering with 5nm Au and placed it in an electrolyte solution of AgNO ₃ and H ₃ BO ₃ for electrochemical deposition. The Au sputtered by magnetron is used to improve the conductivity, and the deposited Ag ₇ O ₈ NO ₃ is reduced to obtain a single Ag with a large number of nanoscale holes on the surface of the Ag ₇ O ₈ NO ₃ structure.

PDMS modification

Here we will use acid catalysis to graft the PDMS precursor dimethyldimethoxysilane onto the hydrophilic treated substrate surface. During the grafting process, the water in the air also participates in the reaction. Therefore, in order to obtain a better hydrophobic effect, it is also necessary to control the humidity in the air, so as to obtain a hydrophobic, super-slippery, and enriched PDMS film on the substrate surface.

Example 2

The method of applying the ordered localized nanostructure capable of realizing enrichment detection to the enrichment detection of the molecule to be detected in the aqueous solution comprises the following steps:

An aqueous solution containing pyridine molecules is used as a sample to be tested;

Placing the sample to be tested on the surface with the ordered localized nanostructure for achieving enrichment detection; utilizing the super-slippery surface to enable the sample to be tested to spontaneously concentrate on the central SERS site area on the super-slippery surface;

The water in the aqueous solution is further evaporated. As the water molecules evaporate, the sample to be tested is continuously gathered and enriched in the SERS site area under the action of PDMS, so that the pyridine molecules in the sample to be tested are continuously gathered in the SERS site area.

After the pyridine molecules in the aqueous solution are enriched in the SERS site area, Raman spectroscopy is performed on the molecules to be tested in the SERS site area. Due to the enrichment effect, the pyridine with a low content in the aqueous solution can be enriched to enhance the signal.

The above-described embodiment is only a preferred solution of the present invention and does not limit the present invention in any form. There are other variations and modifications without exceeding the technical solution described in the claims.

Claims (9)

1. A method for preparing an ordered localized nanostructure capable of realizing enrichment detection, characterized in that it comprises the following steps: (A) PS spheres are self-assembled in the upper limit area of a silicon wafer, and the size of the PS spheres is reduced by etching to leave a certain distance between the PS spheres, thereby obtaining a PS sphere array on the silicon wafer; (B) A layer of Cr is magnetron sputtered on the surface of the silicon wafer as a mask to remove the PS balls from the surface of the silicon wafer, and a bare silicon wafer area is generated after the PS balls are removed; the silicon wafer is heated and immersed in a NaOH solution to obtain an ordered array of concave pyramid structures on the surface of the silicon wafer; (C) growing a layer of material for improving SERS performance in the concave pyramid structure, thereby obtaining a SERS site area on the surface of the silicon wafer; (D) A layer of PDMS film is disposed on the surface of the silicon wafer in an area other than the SERS site area to form an ultra-smooth surface; the ultra-smooth surface is used to enable the sample to be tested to be concentrated in the central SERS site area on the ultra-smooth surface. As the water molecules in the sample to be tested evaporate, the molecules to be tested in the sample to be tested are continuously gathered and enriched under the action of PDMS, so that the molecules to be tested in the sample to be tested are continuously gathered in the SERS site area. 2. The preparation method according to claim 1 is characterized in that in step (A), the confined self-assembly specifically comprises: controlling the range of the close-packed hexagonal stacked single-layer PS ball array to a confined area with a length and width of 200μm-300μm, and the diameter of the PS ball is 500nm. 3. The preparation method according to claim 1 is characterized in that, in step (B), the heating and soaking with NaOH solution specifically includes placing in 80° C. NaOH solution for 1 to 3 minutes, so that the exposed silicon wafer area obtains a concave pyramid structure; as the soaking time increases, the depth of the concave pyramid gradually increases. 4. The preparation method according to claim 1, characterized in that in step (C), the method of growing a layer of a substance for improving SERS performance specifically comprises: First, the concave pyramid structure is treated with Au by magnetron sputtering; Then, Ag ₇ O ₈ NO ₃ is electrochemically deposited in the concave pyramid structure, and then Ag ₇ O ₈ NO ₃ is reduced to Ag, so that single-substance Ag with nano-scale holes on the surface is obtained in the concave pyramid. 5. The preparation method according to claim 4, characterized in that, in step (D), the specific method of providing a layer of PDMS film comprises: The surface of the silicon wafer except the SERS site area is hydrophilized, and the surface of the hydrophilized area is grafted with a PDMS precursor solution under an ambient humidity of 60% and acid catalysis to obtain a PDMS film. 6. An ordered localized nanostructure capable of realizing enrichment detection, wherein the ordered localized nanostructure capable of realizing enrichment detection is prepared by the preparation method as claimed in claim 5, characterized in that: The ordered localized nanostructure capable of realizing enrichment detection comprises a SERS site region and an ultra-slippery surface; the length and width of the SERS site region are both within the range of 200 μm-300 μm, the periphery of the SERS site region is an ultra-slippery surface, and the ultra-slippery surface is composed of a PDMS film; The SERS site area is composed of a concave pyramid array. The spacing between the concave pyramid arrays is 20nm-100nm. An Au layer is magnetron sputtered in the concave pyramid; The Au layer is also provided with single substance Ag having nano-scale holes on its surface. 7. An ordered localized nanostructure capable of realizing enrichment detection as described in claim 6, characterized in that the thickness of the Au layer is 5 nm. 8. The ordered localized nanostructure capable of realizing enrichment detection as claimed in claim 6 or 7 is applied to the enrichment detection of the molecule to be detected in the aqueous solution, characterized in that it comprises the following steps: An aqueous solution containing the molecule to be tested is used as a sample to be tested; Placing the sample to be tested on the surface of the ordered localized nanostructure for achieving enrichment detection; utilizing the super-slippery surface to enable the sample to be tested to be concentrated to the central SERS site area on the super-slippery surface; The water in the aqueous solution is evaporated. As the water molecules evaporate, the sample to be tested is continuously gathered and enriched in the SERS site area under the action of PDMS, so that the molecules to be tested in the sample to be tested are continuously gathered in the SERS site area; After the molecules to be tested in the aqueous solution are enriched in the SERS site area, Raman spectroscopy test is performed on the molecules to be tested in the SERS site area. 9. The use according to claim 8, characterized in that the spacing between the recessed pyramid arrays is 20 nm-100 nm, and the molecules to be detected are pyridine molecules.