阅读说明：本技术 负载金银纳米膜的复合结构阵列及其制备方法和应用 (Composite structure array loaded with gold and silver nano-film and preparation method and application thereof ) 是由 张洪文 魏懿 崔锡荣 蔡伟平 于 2021-08-25 设计创作，主要内容包括：本发明涉及纳米材料技术领域,尤其是一种负载金银纳米膜的复合结构阵列及其制备方法和应用。负载金银纳米膜的复合结构阵列由位于硅基底上有序排列的复合结构单元组成,复合结构单元由纳米硅几何体和从里到外依次包覆在纳米硅几何体上的银膜、金膜组成。硅基底在提供高度粗糙的表面的同时作内标信号的来源,可以有效避免复杂背景的干扰；银起到增强复合衬底SERS活性的作用,覆盖在银膜上的金膜可以有效防止银层在空气中氧化,起到保护银层的作用。本发明通过设计负载金银纳米膜的Si内标纳米结构阵列作为SERS基底来进行定量SERS分析,不仅活性高,结构稳定,而且以硅信号作为内标,具有定量检测的效果。(The invention relates to the technical field of nano materials, in particular to a composite structure array loaded with a gold and silver nano film, and a preparation method and application thereof. The composite structure array loaded with the gold and silver nano-films consists of composite structure units which are orderly arranged on a silicon substrate, wherein the composite structure units consist of a nano-silicon geometric body, and a silver film and a gold film which are sequentially coated on the nano-silicon geometric body from inside to outside. The silicon substrate provides a highly rough surface and is used as a source of an internal standard signal, so that the interference of a complex background can be effectively avoided; the silver plays a role in enhancing the SERS activity of the composite substrate, and the gold film covered on the silver film can effectively prevent the silver layer from being oxidized in the air, so that the silver layer is protected. The Si internal standard nano structure array loaded with the gold and silver nano film is designed to be used as the SERS substrate for quantitative SERS analysis, so that the method is high in activity and stable in structure, and has the effect of quantitative detection by taking a silicon signal as an internal standard.)

1. A composite structure array loaded with gold and silver nano films is characterized by comprising composite structure units which are sequentially arranged on a silicon substrate, wherein each composite structure unit comprises a nano silicon geometric body, and a silver film and a gold film which are sequentially coated on the nano silicon geometric body from inside to outside, the thickness of the silver film is 30-50nm, the thickness of the gold film is 2-5nm, the total thickness of the silver film and the gold film is 35-55nm, and the distance between every two adjacent composite structure units is 100-500 nm.

2. The gold-silver-loaded nanomembrane composite structural array according to claim 1, wherein the nano-silicon geometry is one of a nano-cone, a nano-pillar, and a nano-sphere.

3. The composite structure array loaded with gold and silver nano-films as claimed in claim 2, wherein the height of the nano-cone is 80-400nm, the diameter of the root is 100-500nm, the diameter of the tip of the cone is 20-200nm, the angle of the cone at the top is 10-50 degrees, and the central axis of the nano-cone is perpendicular to the silicon substrate.

4. A method for preparing a composite structure array loaded with gold and silver nano-films as claimed in claim 1, 2 or 3, which is characterized by comprising the following steps:

s1, preparing orderly arranged nano silicon geometric array on a silicon substrate;

s2, depositing a layer of 30-50nm silver film on the surface of the silicon substrate where the nano silicon geometric array and the nano silicon geometric array are located by using a deposition coating technology;

and S3, depositing a gold film with the thickness of 3-5nm on the silver film by using a deposition coating technology to obtain the composite structure array loaded with the gold and silver nano film.

5. The method for preparing a composite structure array loaded with gold and silver nano-films according to claim 4, wherein the nano-silicon geometric array in the step S1 is prepared by a mask assisted reactive ion etching method.

6. The method for preparing a composite structure array loaded with gold and silver nano-films according to claim 4, wherein the deposition coating technology is one of magnetron sputtering, thermal evaporation and electron beam evaporation.

7. Use of the gold and silver nanofilm-supported composite structure array of claim 1, 2 or 3 as an active substrate for surface enhanced raman scattering.

8. Use of the gold-silver nanofilm-loaded composite structure array as a surface-enhanced raman scattering active substrate according to claim 7, wherein when the gold-silver nanofilm-loaded composite structure array is used as a surface-enhanced raman scattering active substrate to measure the raman spectrum of a target molecule attached thereon, the excitation light of the laser raman spectrometer has a wavelength of 532, 633 or 785nm, a power of 0.1-10mW, and an integration time of 1-30 s.

Technical Field

The invention relates to the technical field of nano materials, in particular to a composite structure array loaded with a gold and silver nano film, and a preparation method and application thereof.

Background

The Surface Enhanced Raman Spectroscopy (SERS) technology can amplify Raman signals of surface adsorption molecules at high power, can be used for identifying target molecules and carrying out quantitative detection, has the advantages of rapidness, sensitivity, no damage and trace detection, and has important application in the fields of chemical analysis, bioscience, environmental monitoring and the like. In the application of SERS detection based on a noble metal solid substrate, due to the equipment or operation problems of substrate structure difference, unstable molecular adsorption, laser energy fluctuation, focusing and the like, the repeatability and reproducibility of SERS signals are poor. At present, reliable quantitative analysis based on SERS technology is always a problem recognized by academia. Currently, there are two main methods for improving the quantitative analysis capability of SERS. Firstly, by constructing a highly ordered array substrate, such as a structural array of a nanocone, a nanocolumn, a nanocube and the like of two-dimensional ordered raman active metal (such as gold, silver, copper and the like), compared with an unordered nanoparticle film, the uniformity of the structure greatly improves the uniformity of the intensity of the SERS signal. However, during field testing, it is still difficult to avoid signal intensity fluctuations due to operational differences when different personnel use raman spectrometers. The other method is to introduce an internal standard to calibrate the collected SERS characteristic peak intensity so as to reduce the influence caused by the difference of the substrate structure, the instrument parameters, the test conditions and the like as much as possible. The commonly used internal standard method is to embed organic molecules with high raman activity into the interface of the inner core or shell of the noble metal nanoparticle, and since the internal standard molecule and the analyte are in similar microenvironment, the raman signal intensity of the internal standard molecule and the analyte can change synchronously when the measurement parameters are different. The Raman characteristic peak intensity of the target substance is normalized on the basis of the Raman signal of the internal standard molecule, so that the signal reproducibility can be effectively improved. However, in practical operation, it is difficult to realize one-to-one correspondence between the internal standard molecules and the analytes on the noble metal substrate, and the internal standard molecules usually have a plurality of characteristic peaks to form complex background signals, so that the difficulty of identifying the target molecules is increased, thereby reducing the sensitivity of detection.

Disclosure of Invention

The invention provides a composite structure array loaded with a gold and silver nano-film, a preparation method and application thereof, aiming at overcoming the defects that the repeatability and reproducibility of SERS signals are poor, organic molecules of an internal standard method can generate complex background interference peaks and the like in the prior art.

In order to solve the technical problem, the technical scheme is that the composite structure array loaded with the gold and silver nano-films comprises composite structure units which are sequentially arranged on a silicon substrate, each composite structure unit comprises a nano-silicon geometric body, and a silver film and a gold film which are sequentially coated on the nano-silicon geometric body from inside to outside, the thickness of the silver film is 30-50nm, the thickness of the gold film is 2-5nm, the total thickness of the silver film and the gold film is 35-55nm, and the distance between every two adjacent composite structure units is 100-500 nm.

The composite structure array loaded with gold and silver nano films is further improved:

preferably, the nano-silicon geometric body is one of a nano-cone, a nano-column and a nano-sphere.

Preferably, the height of the nano-cone is 80-400nm, the diameter of the root is 100-500nm, the diameter of the tip of the cone is 20-200nm, the cone angle of the top is 10-50 degrees, and the central axis of the nano-cone is perpendicular to the silicon substrate.

In order to solve the technical problem, the invention adopts another technical scheme that the preparation method of the composite structure array loaded with the gold and silver nano-film comprises the following steps:

s1, preparing orderly arranged nano silicon geometric array on a silicon substrate;

s2, depositing a layer of 30-50nm silver film on the surface of the silicon substrate where the nano silicon geometric array and the nano silicon geometric array are located by using a deposition coating technology;

and S3, depositing a gold film with the thickness of 3-5nm on the silver film by using a deposition coating technology to obtain the composite structure array loaded with the gold and silver nano film.

The preparation method of the composite structure array loaded with the gold and silver nano-film is further improved:

preferably, the nano-silicon geometric array in step S1 is prepared by a mask assisted reactive ion etching method.

Preferably, the deposition coating technology is one of magnetron sputtering, thermal evaporation and electron beam evaporation.

In order to solve the technical problem, the invention adopts another technical scheme that the composite structure array loaded with the gold-silver nano film is used as an active substrate for surface enhanced Raman scattering.

The application of the composite structure array loaded with the gold and silver nano-film as an active substrate for surface enhanced Raman scattering is further improved:

preferably, when the composite structure array loaded with the gold and silver nano-films is used as an active substrate for surface enhanced Raman scattering to measure the Raman spectrum of target molecules attached to the composite structure array, the wavelength of exciting light of a laser Raman spectrometer is 532, 633 or 785nm, the power is 0.1-10mW, and the integration time is 1-30 s.

Compared with the prior art, the invention has the beneficial effects that:

1) the silicon substrate has two roles: one is to provide a highly rough surface to obtain more SERS hot spots; secondly, as the source of the internal standard signal, the characteristic Raman peak of silicon (Si) is single (located at 520 cm)^-1) And outside the raman window of many organic analytes (typically 500 cm)^-1Above), if silicon is used as an internal standard substance, its raman signal will not overlap with that of the analyte, and interference of complex background can be effectively avoided.

2) The function of silver: the silver has a much stronger SERS enhancement effect than gold, so the silver layer in the middle is thicker, about 30-50nm, and the composite substrate has high SERS activity.

3) The function of gold: although silver has high activity, the silver is easy to oxidize in the air to reduce the activity, so that the surface of the silver is covered with gold with a thin layer of 2-5nm to prevent the silver layer from oxidizing in the air, thereby playing a role in protecting the silver layer.

4) The Si internal standard nano structure array loaded with the gold and silver nano film is designed to be used as the SERS substrate for quantitative SERS analysis, so that the method is high in activity and stable in structure, and has the effect of quantitative detection by taking a silicon signal as an internal standard.

Drawings

FIG. 1a is a cross-sectional view of a plasma metal coated silicon nanostructure array, with the top right side of the array showing the cells in the array; FIG. 1b illustrates the realization of a highly reliable quantitative SERS analysis in combination with a substrate homogenization and internal standard strategy;

FIG. 2 shows signals obtained after soaking SERS substrates in 4-ATP solutions of different concentrations;

FIG. 3 is a linear fit of normalized signal intensity before different analyte concentrations, where R represents a linear correlation coefficient.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to embodiments, and all other embodiments obtained by a person of ordinary skill in the art without any creative effort based on the embodiments of the present invention belong to the protection scope of the present invention.

Example 1

A preparation method of a composite structure array loaded with gold and silver nano films comprises the following steps:

s1, preparing a uniform polystyrene colloid ball single-layer mask plate on a silicon wafer with a single-side polished by an air-water interface self-assembly method: firstly, dispersing 0.5mL of polystyrene colloidal sphere suspension with the particle size of 150-500nm into 0.5mL of ethanol to obtain 1mL of mixed colloidal sphere suspension; then, slowly dripping 5-20 mu L of polystyrene colloid ball suspension liquid from the edge of a 0.5-4 inch silicon wafer covered by a deionized water film by using a liquid transfer gun to form a tightly-packed single-layer film, removing water from the edge by using filter paper, and naturally drying to prepare an ordered polystyrene colloid ball single-layer template on the silicon wafer;

s2, heating the silicon chip covered by the prepared polystyrene colloid sphere single-layer template at 70 ℃ for 20 minutes to ensure that the polystyrene colloid spheres are firmly fixed on the silicon chip, and using SF (sulfur hexafluoride) in a reactive ion etching machine₆And (3) performing gas etching with the etching power of 100W, the gas flow rate of 30sccm and the etching time of 200 seconds. And after the etching is finished, preparing a highly ordered silicon nano silicon geometric structure array, wherein the silicon nano silicon geometric structure comprises silicon nano cones, nano columns, nano spheres and other structures. Subsequently, the etched sample was rinsed with ethanol and annealed at 600 ℃ for 2 hours to remove the residual polystyrene colloidal spheres;

s3, sputtering and depositing a 30-50nm silver film on the surface of the silicon nanostructure array at a deposition rate of 0.5-2nm/S by using deposition and coating technologies such as magnetron sputtering, thermal evaporation, electron beam evaporation and the like, and then depositing a 2-5nm thin gold layer. The resulting gold/silver covered silicon nanocone array was trimmed to a size of 5mm by 5mm, resulting in a SERS substrate.

Soaking the prepared SERS substrate in a target molecule solution to be detected for a period of time, and taking out the SERS substrate, wherein the surface of the SERS substrate can uniformly adsorb the target molecule to be detected, and the target molecule and the silicon at the bottom have a one-to-one corresponding distribution relationship, as shown in FIG. 1 a; a raman test was then performed and the resulting spectra tested contained both the signal of the target analyte and the silicon internal standard signal, as shown in figure 1 b.

As can be seen from fig. 1a and 1b, due to the ordered structure of the SERS substrate, not only can the uniform distribution of the hot spot and the adsorbed analyte on the surface be ensured, but also due to the consistent structure, a one-to-one distribution of the analyte and the Si substance can be realized. In this case, Si signal intensity (I)₁) And adsorbed analyte signal intensity (I)₂) May vary synchronously with fluctuations in the measured parameter (insets of fig. 1a and 1 b). If Si signal intensity is used to normalize the adsorbed analyte signal intensity, orWill I₂/I₁The ratio is used as a Raman measured value, so that the interference caused by the fluctuation of the measured parameter can be effectively eliminated, highly repeatable measurement is realized, and reliable quantitative SERS detection is realized.

Example 2

A preparation method of a composite structure array loaded with gold and silver nano films comprises the following steps:

s1, preparing a uniform polystyrene colloid ball single-layer mask plate on a silicon wafer with a single-side polished surface by an air-water interface self-assembly method. Firstly, dispersing 0.5mL of polystyrene colloidal sphere suspension with the particle size of 500nm into 0.5mL of ethanol to obtain 1mL of mixed colloidal sphere suspension; then 5 μ L of polystyrene colloidal sphere suspension was slowly dropped from the edge of the 0.5 inch silicon wafer covered with deionized water film using a pipette gun. The polystyrene colloid ball is self-assembled on the air-water interface to form a tightly-packed single-layer film. After removing water from the edges with filter paper and drying naturally, an ordered polystyrene colloidal sphere single-layer template was prepared on a silicon wafer.

S2, heating the silicon chip covered by the prepared polystyrene colloid sphere single-layer template at 70 ℃ for 20 minutes to ensure that the polystyrene colloid spheres are firmly fixed on the silicon chip, and etching the silicon chip by using SF6 gas in a reactive ion etching machine. The etching power was 200W, the gas flow rate was 60sccm, and the etching time was 200 seconds. And after the etching is finished, preparing the highly ordered silicon nanocone array. Subsequently, the etched sample was rinsed with ethanol and annealed at 600 ℃ for 2 hours to remove the residual polystyrene colloidal spheres. Finally, a 30nm silver film is sputtered and deposited on the surface of the silicon nanocone array at a deposition rate of 0.5nm/s by utilizing deposition coating technologies such as magnetron sputtering, thermal evaporation, electron beam evaporation and the like, and then a 2nm thin gold layer is deposited. The resulting gold/silver covered silicon nanocone array was trimmed to 3mm by 3mm size to yield SERS substrates.

After soaking the SERS substrate prepared in example 2 in 50mL of p-aminophenol (4-ATP) solution with different concentrations for 6 hours, the obtained spectral data is shown in FIG. 2. Then using 520cm of silicon^-1The peak at (A) is strongly denormalized at 1075, 1140, 1390 and 1435cm^-1After the raman peak intensity, a very good linear relationship of concentration as a function of normalized intensity was obtained, as shown in fig. 3. As can be seen from fig. 2 and 3, the characteristic peak intensities of the analytes are normalized by the silicon signal intensity, so that highly reliable quantitative SERS analysis of analytes with different concentrations can be realized.

It should be understood by those skilled in the art that the foregoing is only illustrative of several embodiments of the invention, and not of all embodiments. It should be noted that many variations and modifications are possible to those skilled in the art, and all variations and modifications that do not depart from the gist of the invention are intended to be within the scope of the invention as defined in the appended claims.