阅读说明：本技术 一种金包硫化铜sers纳米基底的制备方法 (Preparation method of gold-coated copper sulfide SERS nano-substrate ) 是由 韩方源 唐彬 胡梦竹 罗宗昌 朱立平 梁沁沁 喻敏 徐兆丹 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种金包硫化铜SERS纳米基底的制备方法,通过空心硫化铜纳米溶胶的合成、玻璃片的前处理、空心硫化铜纳米粒子在玻璃片表面的吸附、纳米基底的循环生长四个步骤,在平面玻璃表面形成金包硫化铜纳米粒子二维团簇结构,从而得到一种金包硫化铜SERS纳米基底；本发明的金包硫化铜SERS纳米基底制备方法简单,所制备的金包硫化铜SERS纳米基底重复性好,并且具有显著的光热富集效果,通过近红外激光辐照基底10分钟就可以完成微区富集,从而大幅提高检测灵敏度。(The invention discloses a preparation method of a gold-coated copper sulfide SERS nano substrate, which comprises the following four steps of synthesis of hollow copper sulfide nano sol, pretreatment of a glass sheet, adsorption of hollow copper sulfide nano particles on the surface of the glass sheet and cyclic growth of the nano substrate, wherein a gold-coated copper sulfide nano particle two-dimensional cluster structure is formed on the surface of a plane glass, so that the gold-coated copper sulfide SERS nano substrate is obtained; the preparation method of the gold-coated copper sulfide SERS nano substrate is simple, the prepared gold-coated copper sulfide SERS nano substrate has good repeatability and obvious photo-thermal enrichment effect, and micro-area enrichment can be completed by irradiating the substrate for 10 minutes through near-infrared laser, so that the detection sensitivity is greatly improved.)

1. A preparation method of a gold-coated copper sulfide SERS nano substrate is characterized by comprising the following steps:

s1, synthesizing a hollow copper sulfide nano sol:

s11, sequentially adding 18-22% of polyvinylpyrrolidone solution and 0.08-0.12 mol/L of copper acetate solution into deionized water, and stirring to obtain a first mixed solution;

s12, adding a sodium hydroxide solution with the concentration of 0.8-1.2 mol/L into the first mixed solution at a constant speed, and stirring for reaction; then adding an ascorbic acid solution with the concentration of 0.08-0.12 mol/L, and stirring for reaction to obtain a cuprous oxide suspension;

s13, standing the cuprous oxide suspension, adding a sodium sulfide solution with the concentration of 0.04-0.06 mol/L into the cuprous oxide suspension, heating to 85-95 ℃, and stirring for reaction to obtain a second mixed solution; centrifuging the second mixed solution, removing supernatant, and resuspending with equal volume of deionized water to obtain hollow copper sulfide nanosol;

in the synthesis process of the hollow copper sulfide nano sol: the addition amount of the polyvinylpyrrolidone solution in each 100ml of deionized water is 0.8-1.2 ml, the addition amount of the copper acetate solution is 400-600 mu L, the addition amount of the sodium hydroxide solution is 800-1000 mu L, the addition amount of the ascorbic acid solution is 1.4-1.6 ml, and the addition amount of the sodium sulfide solution is 2.3-2.7 ml;

s2, pretreatment of the glass sheet:

s21, soaking the clean glass sheet in a saturated sodium hydroxide ethanol solution, taking out, and washing with deionized water to obtain a once-treated glass sheet;

s22, soaking the once-treated glass sheet in an adsorbent solution with the mass fraction of 0.08-0.12%, taking out, and washing with deionized water to obtain a pretreated glass sheet;

s3, adsorption of the hollow copper sulfide nano particles on the surface of the glass sheet: soaking the pretreated glass sheet in the hollow copper sulfide nano sol, adsorbing the hollow copper sulfide nano particles through electrostatic action, taking out, and cleaning the surface of the glass sheet by using deionized water to remove the unadsorbed hollow copper sulfide nano particles to obtain a primary adsorbed glass sheet;

s4, cyclic growth of the nano substrate:

s41, preparing a solution required by primary growth: adding 50-70 mu L of chloroauric acid solution with the mass fraction of 0.1-0.3% and 25-35 mu L of hydroxylamine hydrochloride solution with the concentration of 0.03-0.05 mol/L into every 3ml of deionized water, and mixing to obtain a solution required by primary growth;

s42, placing the glass sheet subjected to primary adsorption into a centrifugal tube, adding the prepared solution required for primary growth, oscillating for 8-12 min in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm, taking out the glass sheet, and cleaning with deionized water to complete primary growth circulation; repeating the growth cycle for a plurality of times to obtain the gold-coated copper sulfide SERS nano substrate.

2. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: synthesizing hollow copper sulfide nano sol in the step S1:

s11, sequentially adding 18-22% of polyvinylpyrrolidone solution and 0.08-0.12 mol/L of copper acetate solution into deionized water, and stirring for 4.5-5.5 min to obtain a first mixed solution;

s12, adding a sodium hydroxide solution with the concentration of 0.8-1.2 mol/L into the first mixed solution at a constant speed, and stirring and reacting for 1.5-2.5 min; then adding an ascorbic acid solution with the concentration of 0.08-0.12 mol/L, and stirring and reacting for 1.5-2.5 min to obtain a cuprous oxide suspension;

s13, standing the cuprous oxide suspension for 20-25 min, adding a sodium sulfide solution with the concentration of 0.04-0.06 mol/L into the cuprous oxide suspension, heating to 85-95 ℃, and stirring for reaction for 1.8-2.2 h to obtain a second mixed solution; centrifuging the second mixed solution at the rotating speed of 6000-7000 rpm for 15-20 min, discarding the supernatant, and resuspending with isovolumetric deionized water to obtain the hollow copper sulfide nanosol.

3. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: in the step S1, in the synthesis process of the hollow copper sulfide nano sol: the addition amount of the polyvinylpyrrolidone solution in each 100ml of deionized water is 1ml, the addition amount of the copper acetate solution is 500 muL, the addition amount of the sodium hydroxide solution is 900 muL, the addition amount of the ascorbic acid solution is 1.5ml, and the addition amount of the sodium sulfide solution is 2.5 ml.

4. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: the surface area of the glass sheet used in the step S2 is 30-60 mm²。

5. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: pretreatment of the glass sheet in the step S2:

s21, putting the clean glass sheet into a saturated sodium hydroxide ethanol solution to be soaked for 3.8-4.2 hours, taking out the glass sheet, and washing the glass sheet with deionized water to obtain a once-treated glass sheet;

s22, putting the glass sheet subjected to primary treatment into an adsorbent solution with the mass fraction of 0.08-0.12%, soaking for 28-32 min, taking out, and washing with deionized water to obtain a pretreated glass sheet.

6. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: the adsorbent in the adsorbent solution in step S2 is trimethoxysilane, polyetherimide or polydopamine.

7. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: and S3, soaking the pretreated glass sheet in the hollow copper sulfide nano sol for 3-24 hours, adsorbing the hollow copper sulfide nano particles through electrostatic action, taking out, and cleaning the surface of the glass sheet by using deionized water to remove the unadsorbed hollow copper sulfide nano particles to obtain the primary adsorbed glass sheet.

8. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: placing the glass sheet subjected to primary adsorption into a centrifugal tube in the step S4, adding the prepared solution required for primary growth, oscillating for 8-12 min in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm, taking out the glass sheet, and cleaning with deionized water to complete a primary growth cycle; and repeating the growth cycle for 5-11 times to obtain the gold-coated copper sulfide SERS nano substrate.

9. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: placing the glass sheet subjected to primary adsorption into a centrifugal tube in the step S4, adding the prepared solution required for primary growth, oscillating for 8-12 min in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm, taking out the glass sheet, and cleaning with deionized water to complete a primary growth cycle; repeating the growth cycle for 9 times to obtain the gold-coated copper sulfide SERS nano substrate.

10. The preparation method of the gold-coated copper sulfide SERS nano-substrate according to claim 1, wherein the preparation method comprises the following steps: placing the glass sheet subjected to primary adsorption into a centrifugal tube in the step S4, adding the prepared solution required for primary growth, oscillating for 10min in a constant-temperature mixer at a rotating speed of 1500rpm, taking out the glass sheet, and cleaning with deionized water to complete a primary growth cycle; repeating the growth cycle for 9 times to obtain the gold-coated copper sulfide SERS nano substrate.

Technical Field

The invention relates to the technical field of surface-enhanced Raman detection, in particular to a preparation method of a gold-coated copper sulfide SERS nano-substrate.

Background

In recent years, Surface Enhanced Raman Spectroscopy (SERS) has been widely used for analysis and detection of various objects such as bacteria, biomolecules, metal ions, and pollutants, and has attracted attention because of its characteristics of convenience in testing, high sensitivity, and molecular fingerprint recognition. It is well known in the industry that only when an object to be measured enters a hot spot region of the SERS substrate can a raman spectrum signal be sharply amplified. In practical application, many samples to be detected are solution samples, and when the SERS substrate of liquid phases such as nano sol is adopted, the nano particles in the sol state and the object to be detected are in an uncontrollable state, so that the difficulty of capturing optical signals of the object to be detected at a hot point is high, the reproducibility of detection is seriously influenced, and the SERS substrate of a solid phase is more reliable for practical application. In practical applications, the preparation of solid phase substrates also has the following problems: first, in addition to ensuring the detection sensitivity, the reproducibility of detection must be ensured, which requires that the solid-phase SERS substrate must have high repeatability, and the preparation of high-quality solid-phase SERS substrates meeting the above requirements at present often requires complex and expensive operations, such as capillary reaction, electron beam lithography, metal deposition, and the like. Secondly, compared with a liquid-phase SERS substrate, the solid-liquid two-phase substance transfer process is time-consuming, and the application of the solid-phase SERS substrate in the field of instant detection is limited to a certain extent.

In order to improve the mass transfer efficiency of solid-liquid two phases, various solid-phase SERS substrate improvement strategies are currently available. One strategy is to introduce extra energy to cause disturbance of a solution system, accelerate thermal diffusion circulation of the object to be measured in the solution, and accelerate the capture rate of the SERS hot spot to the object to be measured. For example, thermal effects are generated by laser irradiation on the solid-phase SERS substrate, and it is found that when the solute moves in solution due to concentration gradient and temperature gradient to reach dynamic equilibrium under continuous irradiation, the concentration of the target in the vicinity of the laser irradiation region on the solid-phase SERS substrate is higher than that in other regions, resulting in a micro-region enrichment effect. However, for a common solid-phase SERS substrate, the photothermal enrichment effect is not strong enough, and the improvement of the detection sensitivity of a trace amount of an object to be detected is limited.

Therefore, from the perspective of practical application of SERS detection, it is necessary to provide a method with simple operation to prepare a solid-phase SERS substrate with high sensitivity, good repeatability and strong light-heat enrichment effect.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide the preparation method of the gold-coated copper sulfide SERS nano substrate, which is simple in preparation method, good in product repeatability, obvious in photo-thermal enrichment effect and capable of greatly improving the detection sensitivity.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a preparation method of a gold-coated copper sulfide SERS nano substrate comprises the following steps:

s1, synthesizing a hollow copper sulfide nano sol:

s11, sequentially adding 18-22% of polyvinylpyrrolidone solution and 0.08-0.12 mol/L of copper acetate solution into deionized water, and stirring to obtain a first mixed solution;

s12, adding a sodium hydroxide solution with the concentration of 0.8-1.2 mol/L into the first mixed solution at a constant speed, and stirring for reaction; then adding an ascorbic acid solution with the concentration of 0.08-0.12 mol/L, and stirring for reaction to obtain a cuprous oxide suspension;

s13, standing the cuprous oxide suspension, adding a sodium sulfide solution with the concentration of 0.04-0.06 mol/L into the cuprous oxide suspension, heating to 85-95 ℃, and stirring for reaction to obtain a second mixed solution; centrifuging the second mixed solution, removing supernatant, and resuspending with equal volume of deionized water to obtain hollow copper sulfide nanosol;

in the synthesis process of the hollow copper sulfide nano sol: the addition amount of the polyvinylpyrrolidone solution in each 100ml of deionized water is 0.8-1.2 ml, the addition amount of the copper acetate solution is 400-600 mu L, the addition amount of the sodium hydroxide solution is 800-1000 mu L, the addition amount of the ascorbic acid solution is 1.4-1.6 ml, and the addition amount of the sodium sulfide solution is 2.3-2.7 ml;

s2, pretreatment of the glass sheet:

s21, soaking the clean glass sheet in a saturated sodium hydroxide ethanol solution, taking out, and washing with deionized water to obtain a once-treated glass sheet;

s22, soaking the once-treated glass sheet in an adsorbent solution with the mass fraction of 0.08-0.12%, taking out, and washing with deionized water to obtain a pretreated glass sheet;

s3, adsorption of the hollow copper sulfide nano particles on the surface of the glass sheet: soaking the pretreated glass sheet in the hollow copper sulfide nano sol, adsorbing the hollow copper sulfide nano particles through electrostatic action, taking out, and cleaning the surface of the glass sheet by using deionized water to remove the unadsorbed hollow copper sulfide nano particles to obtain a primary adsorbed glass sheet;

s4, cyclic growth of the nano substrate:

s41, preparing a solution required by primary growth: adding 50-70 mu L of chloroauric acid solution with the mass fraction of 0.1-0.3% and 25-35 mu L of hydroxylamine hydrochloride solution with the concentration of 0.03-0.05 mol/L into every 3ml of deionized water, and mixing to obtain a solution required by primary growth;

s42, placing the glass sheet subjected to primary adsorption into a centrifugal tube, adding the prepared solution required for primary growth, oscillating for 8-12 min in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm, taking out the glass sheet, and cleaning with deionized water to complete primary growth circulation; repeating the growth cycle for a plurality of times to obtain the gold-coated copper sulfide SERS nano substrate.

Further, in the step S1, synthesis of hollow copper sulfide nano sol:

s11, sequentially adding 18-22% of polyvinylpyrrolidone solution and 0.08-0.12 mol/L of copper acetate solution into deionized water, and stirring for 4.5-5.5 min to obtain a first mixed solution;

s12, adding a sodium hydroxide solution with the concentration of 0.8-1.2 mol/L into the first mixed solution at a constant speed, and stirring and reacting for 1.5-2.5 min; then adding an ascorbic acid solution with the concentration of 0.08-0.12 mol/L, and stirring and reacting for 1.5-2.5 min to obtain a cuprous oxide suspension;

s13, standing the cuprous oxide suspension for 20-25 min, adding a sodium sulfide solution with the concentration of 0.04-0.06 mol/L into the cuprous oxide suspension, heating to 85-95 ℃, and stirring for reaction for 1.8-2.2 h to obtain a second mixed solution; centrifuging the second mixed solution at the rotating speed of 6000-7000 rpm for 15-20 min, discarding the supernatant, and resuspending with isovolumetric deionized water to obtain the hollow copper sulfide nanosol.

Further, in the step S1, in the synthesis process of the hollow copper sulfide nano-sol: the addition amount of the polyvinylpyrrolidone solution in each 100ml of deionized water is 1ml, the addition amount of the copper acetate solution is 500 muL, the addition amount of the sodium hydroxide solution is 900 muL, the addition amount of the ascorbic acid solution is 1.5ml, and the addition amount of the sodium sulfide solution is 2.5 ml.

Further, the surface area of the glass sheet used in the step S2 is 30-60 mm²。

Further, the pretreatment of the glass sheet in the step S2:

s21, putting the clean glass sheet into a saturated sodium hydroxide ethanol solution to be soaked for 3.8-4.2 hours, taking out the glass sheet, and washing the glass sheet with deionized water to obtain a once-treated glass sheet;

s22, putting the glass sheet subjected to primary treatment into an adsorbent solution with the mass fraction of 0.08-0.12%, soaking for 28-32 min, taking out, and washing with deionized water to obtain a pretreated glass sheet.

Further, the adsorbent in the adsorbent solution in step S2 is trimethoxysilane, polyetherimide or polydopamine.

Further, in the step S3, the pre-treated glass sheet is soaked in the hollow copper sulfide nano sol for 3-24 hours, the hollow copper sulfide nano particles are adsorbed through electrostatic action, the glass sheet is taken out, and the surface of the glass sheet is cleaned by deionized water to remove the unadsorbed hollow copper sulfide nano particles, so that the first-time adsorbed glass sheet is obtained.

Further, the glass sheet subjected to primary adsorption in the step S4 is placed into a centrifuge tube, a prepared solution required for primary growth is added, the solution is oscillated in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm for 8-12 min, the glass sheet is taken out and washed by deionized water, and a primary growth cycle is completed; and repeating the growth cycle for 5-11 times to obtain the gold-coated copper sulfide SERS nano substrate.

Further, the glass sheet subjected to primary adsorption in the step S4 is placed into a centrifuge tube, a prepared solution required for primary growth is added, the solution is oscillated in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm for 8-12 min, the glass sheet is taken out and washed by deionized water, and a primary growth cycle is completed; repeating the growth cycle for 9 times to obtain the gold-coated copper sulfide SERS nano substrate.

Further, the glass sheet subjected to primary adsorption in the step S4 is placed into a centrifuge tube, the prepared solution required for primary growth is added, the solution is oscillated in a constant-temperature blending machine at the rotating speed of 1500rpm for 10min, the glass sheet is taken out and washed by deionized water, and a primary growth cycle is completed; repeating the growth cycle for 9 times to obtain the gold-coated copper sulfide SERS nano substrate.

The invention relates to a preparation method of a gold-coated copper sulfide SERS nano substrate, which comprises the following four steps of synthesis of hollow copper sulfide nano sol, pretreatment of a glass sheet, adsorption of hollow copper sulfide nano particles on the surface of the glass sheet and cyclic growth of the nano substrate, wherein a gold-coated copper sulfide nano particle two-dimensional cluster structure is formed on the surface of a plane glass, so that the gold-coated copper sulfide SERS nano substrate is obtained; the preparation method of the gold-coated copper sulfide SERS nano substrate has the following beneficial effects:

(1) the preparation method of the gold-coated copper sulfide SERS nano-substrate disclosed by the invention is simple, after the hollow copper sulfide nano-sol is synthesized, the preparation can be completed only by simple steps of soaking different solutions and simple conventional operations such as oscillation, cleaning and the like, and the prepared gold-coated copper sulfide SERS nano-substrate has good repeatability;

(2) the gold-coated copper sulfide SERS nano substrate prepared by the invention has a remarkable photo-thermal enrichment effect, and micro-area enrichment can be completed by irradiating the substrate with near-infrared laser for 10 minutes, so that the detection sensitivity is greatly improved.

Drawings

FIG. 1 is a Scanning Electron Microscope (SEM) image of a gold-coated copper sulfide SERS nano-substrate prepared in example 1 of the present invention;

FIG. 2 is an SEM image of the distribution of the vacancy-centered copper sulfide nano-particles on the surface of a glass sheet when different adsorbents are selected in example 2 of the present invention;

FIG. 3 is an SEM image of the distribution of hollow copper sulfide nano particles on the surface of a glass sheet after the glass sheet in example 3 of the present invention is soaked in the hollow copper sulfide nano sol for different periods of time;

FIG. 4 is an SEM image of gold-coated copper sulfide SERS nano-substrates at different growth cycle times in example 4 of the present invention;

FIG. 5 is a graph showing the enhancement effect of Raman signal of the gold-coated copper sulfide SERS nano-substrate under different growth cycle number in example 4 of the present invention;

fig. 6 is a graph showing the reproducibility evaluation of 5 different batches of the gold-coated copper sulfide SERS nano-substrates prepared under each growth condition in example 5 of the present invention.

Detailed Description

The following examples may help one skilled in the art to more fully understand the present invention, but are not intended to limit the invention in any way.

The polyvinylpyrrolidone solution in the invention is the aqueous solution of polyvinylpyrrolidone; the polyvinylpyrrolidone has various specifications, and the polyvinylpyrrolidone with the viscosity grade of K15 and the average molecular weight of 10000 is used in the invention, wherein the polyvinylpyrrolidone has different dissolving capacity in water according to different polymerization degrees.

In the present invention, it is common practice in chemistry that no particular solvent is substituted by default for an aqueous solution, i.e., a solution other than an ethanol saturated solution of sodium hydroxide is referred to as an aqueous solution. The chemical reagents used in the present invention are all analytically pure.

A preparation method of a gold-coated copper sulfide SERS nano substrate comprises the following steps:

s1, synthesizing a hollow copper sulfide nano sol:

s11, sequentially adding 18-22% of polyvinylpyrrolidone solution and 0.08-0.12 mol/L of copper acetate solution into deionized water, and stirring for 4.5-5.5 min to obtain a first mixed solution;

s12, adding a sodium hydroxide solution with the concentration of 0.8-1.2 mol/L into the first mixed solution at a constant speed, and stirring and reacting for 1.5-2.5 min; then adding an ascorbic acid solution with the concentration of 0.08-0.12 mol/L, and stirring and reacting for 1.5-2.5 min to obtain a cuprous oxide suspension;

s13, standing the cuprous oxide suspension for 20-25 min, adding a sodium sulfide solution with the concentration of 0.04-0.06 mol/L into the cuprous oxide suspension, heating to 85-95 ℃, and stirring for reaction for 1.8-2.2 h to obtain a second mixed solution; centrifuging the second mixed solution at the rotating speed of 6000-7000 rpm for 15-20 min, removing supernatant, and carrying out heavy suspension with equal volume of deionized water to obtain hollow copper sulfide nanosol;

in the synthesis process of the hollow copper sulfide nano sol: the addition amount of the polyvinylpyrrolidone solution in each 100ml of deionized water is 0.8-1.2 ml, the addition amount of the copper acetate solution is 400-600 mu L, the addition amount of the sodium hydroxide solution is 800-1000 mu L, the addition amount of the ascorbic acid solution is 1.4-1.6 ml, and the addition amount of the sodium sulfide solution is 2.3-2.7 ml;

s2, pretreatment of the glass sheet:

s21, soaking the clean glass sheet in a saturated sodium hydroxide ethanol solution, taking out, and washing with deionized water to obtain a once-treated glass sheet;

s22, soaking the once-treated glass sheet in an adsorbent solution with the mass fraction of 0.08-0.12%, taking out, and washing with deionized water to obtain a pretreated glass sheet; s3, adsorption of the hollow copper sulfide nano particles on the surface of the glass sheet: soaking the pretreated glass sheet in the hollow copper sulfide nano sol, adsorbing the hollow copper sulfide nano particles through electrostatic action, taking out, and cleaning the surface of the glass sheet by using deionized water to remove the unadsorbed hollow copper sulfide nano particles to obtain a primary adsorbed glass sheet;

s4, cyclic growth of the nano substrate:

s41, preparing a solution required by primary growth: adding 50-70 mu L of chloroauric acid solution with the mass fraction of 0.1-0.3% and 25-35 mu L of hydroxylamine hydrochloride solution with the concentration of 0.03-0.05 mol/L into every 3ml of deionized water, and mixing to obtain a solution required by primary growth;

s42, placing the glass sheet subjected to primary adsorption into a centrifugal tube, adding the prepared solution required for primary growth, oscillating for 8-12 min in a constant-temperature mixing instrument at the rotating speed of 1000-2000 rpm, taking out the glass sheet, and cleaning with deionized water to complete primary growth circulation; repeating the growth cycle for a plurality of times to obtain the gold-coated copper sulfide SERS nano substrate.

Example 1:

a preparation method of a gold-coated copper sulfide SERS nano substrate specifically comprises the following steps:

100mL of deionized water, 1mL of a polyvinylpyrrolidone solution with a mass fraction of 20% and 500. mu.L of a copper acetate solution with a concentration of 0.1mol/L were sequentially added to a round-bottom glass flask, and the mixture was stirred at room temperature for 5 min. Then 900 mu L of sodium hydroxide solution with the concentration of 1mol/L is slowly added into the solution at a constant speed to react for 2 min. Then, 1.5mL of ascorbic acid solution with the concentration of 0.1mol/L was added, and stirring was stopped after 2min of reaction to obtain cuprous oxide suspension. After standing for 23min, 2.5mL of 0.05mol/L sodium sulfide solution is added into the cuprous oxide suspension, and then the temperature is raised to 90 ℃ and stirring reaction is carried out for 2 h. Centrifuging the obtained product at the rotating speed of 6600rpm for 17min, removing supernatant, and resuspending with isovolumetric deionized water to obtain hollow copper sulfide nano sol for later use.

Soaking clean glass sheet with size of 6mm × 6mm in saturated sodium hydroxide ethanol solution for 4hr, taking out, and washing with deionized water. Then soaking the mixture in 0.1 mass percent of trimethoxy silane solution for 30min, taking out the mixture, and washing the mixture with deionized water. And (3) vertically soaking the hollow copper sulfide nano sol prepared in the previous step for 10 hours, and adsorbing the hollow copper sulfide nano particles on a glass sheet through electrostatic action. And then deionized water is used for cleaning the surface of the glass sheet to remove the unadsorbed hollow copper sulfide nano particles.

Putting the glass sheet with the surface adsorbed with the hollow copper sulfide nano particles into a 5mL centrifuge tube, adding 3mL deionized water, adding 60 muL of chloroauric acid solution with the mass fraction of 0.2% and 30 muL of hydroxylamine hydrochloride solution with the concentration of 0.04mol/L into the centrifuge tube as solutions required by primary growth, oscillating the solution in a constant-temperature mixer at the rotating speed of 1500rpm for 10min, taking out the solution, and cleaning the solution with deionized water to finish primary growth circulation. And repeating the growth cycle for 10 times to obtain the gold-coated copper sulfide SERS nano substrate. A Scanning Electron Microscope (SEM) image of the substrate is shown in fig. 1.

Example 2:

a preparation method of a gold-coated copper sulfide SERS nano substrate specifically comprises the following steps:

100mL of deionized water, 1mL of a polyvinylpyrrolidone solution with a mass fraction of 20% and 500. mu.L of a copper acetate solution with a concentration of 0.1mol/L were sequentially added to a round-bottom glass flask, and the mixture was stirred at room temperature for 5 min. Then 900 mu L of sodium hydroxide solution with the concentration of 1mol/L is slowly added into the solution at a constant speed to react for 2 min. Then, 1.5mL of ascorbic acid solution with the concentration of 0.1mol/L was added, and stirring was stopped after 2min of reaction to obtain cuprous oxide suspension. After standing for 23min, 2.5mL of 0.05mol/L sodium sulfide solution is added into the cuprous oxide suspension, and then the temperature is raised to 90 ℃ and stirring reaction is carried out for 2 h. Centrifuging the obtained product at the rotating speed of 6600rpm for 17min, removing supernatant, and resuspending with isovolumetric deionized water to obtain hollow copper sulfide nano sol for later use.

Soaking clean glass sheet with size of 6mm × 6mm in saturated sodium hydroxide ethanol solution for 4hr, taking out, and washing with deionized water. Then soaking the mixture in an adsorbent solution with the mass fraction of 0.1% for 30min, taking out the mixture, and washing the mixture with deionized water. The hollow copper sulfide nano sol prepared in the previous step is vertically soaked for 11 hours, and the hollow copper sulfide nano particles are adsorbed on a glass sheet through electrostatic action. And then deionized water is used for cleaning the surface of the glass sheet to remove the unadsorbed hollow copper sulfide nano particles.

Putting the glass sheet with the surface adsorbed with the hollow copper sulfide nano particles into a 5mL centrifuge tube, adding 3mL deionized water, adding 60 muL of chloroauric acid solution with the mass fraction of 0.2% and 30 muL of hydroxylamine hydrochloride solution with the concentration of 0.04mol/L into the centrifuge tube as solutions required by primary growth, oscillating the solution in a constant-temperature mixer at the rotating speed of 1500rpm for 10min, taking out the solution, and cleaning the solution with deionized water to finish primary growth circulation. And repeating the growth cycle for 10 times to obtain the gold-coated copper sulfide SERS nano substrate.

To compare the effect of different adsorbents on the adsorption effect of copper sulfide nanoparticles on the surface of the glass sheet, three different adsorbents were selected in the adsorption step of example 2, and the distribution of the hollow copper sulfide nanoparticles on the surface of the glass sheet was compared, as shown in fig. 2. The SEM images of the distribution of the hollow copper sulfide nanoparticles on the surface of the glass sheet are shown in fig. 2(a), fig. 2(b), and fig. 2(c), respectively, by selecting trimethoxysilane, polyetherimide, and polydopamine as the adsorbent. By comparison, it is found that, under fixed conditions, the adsorption of copper sulfide nanoparticles on the surface of glass flakes using polyetherimide as the adsorbent is the most dense. In addition, the raman scattering cross section of polyetherimide is small and does not interfere with subsequent tests, so among the above three adsorbents, polyetherimide is the most preferable adsorbent.

Example 3:

to study the effect of the soaking time of the glass sheet in the hollow copper sulfide nanosol on the adsorption effect of the copper sulfide nanoparticles on the surface of the glass sheet, in example 1, polyetherimide was selected as an adsorbent, and 4 different soaking times were selected, as shown in fig. 3, to compare the distribution of the hollow copper sulfide nanoparticles on the surface of the glass sheet. When the soaking time is 3h, 6h, 12h and 24h, respectively, the SEM images of the distribution of the hollow copper sulfide nanoparticles on the surface of the glass sheet are shown in fig. 3(a), fig. 3(b), fig. 3(c) and fig. 3(d), respectively. Along with the lengthening of the soaking time of the glass sheet in the hollow copper sulfide nano sol, the density of the hollow copper sulfide nano particles adsorbed on the surface of the glass sheet is gradually increased and reaches the maximum value after 12 hours; after that, the soaking time is continuously increased, a part of the adsorbed nano particles are dissociated into the sol again due to the thermal motion, and the density of the hollow copper sulfide nano particles adsorbed on the surface of the glass sheet is reduced. Therefore, the optimal soaking time of the glass sheet in the hollow copper sulfide nano sol is 12 hours, and the better soaking time is 6-12 hours.

Example 4:

in order to study the influence of the growth cycle times on the appearance of the gold-coated copper sulfide SERS nano-substrate and the enhancement effect of a Raman signal, in example 1, 1-11 growth cycles are sequentially performed, and the distribution condition of nanoparticles on the surface of the glass sheet is represented by a Scanning Electron Microscope (SEM). FIG. 4 is an SEM image of the gold-coated copper sulfide SERS nano-substrate under different growth cycle times, and FIGS. 4(a) - (k) sequentially correspond to the gold-coated copper sulfide SERS nano-substrate obtained through 1-11 growth cycles. As can be seen, because the lattice mismatch exists between the hollow copper sulfide nano particles and the gold shell, the gold shell presents a plurality of island-shaped appearances on the surfaces of the hollow copper sulfide nano particles, and the thickness of the gold shell is increased and the inter-particle distance is gradually shortened along with the increase of the growth cycle times. When the growth cycle times are less, the distance between the nano particles is reduced due to the growth of the gold shell, the SERS hot point is increased along with the increase of the growth cycle times, and the Raman spectrum signal intensity is gradually enhanced; however, the overgrowth of the gold shell can cause the surface roughness of the nanoparticles to be reduced, and SERS hot spots are reduced, so that the Raman spectrum signal intensity can not be increased or inversely reduced after a certain growth cycle number is exceeded. And (3) actually testing the Raman signal enhancement effect of the gold-coated copper sulfide SERS nano substrate with small nano particle spacing obtained by 8 times, 9 times, 10 times and 11 times of growth circulation by using the 4-mercaptoboric acid standard solution with the concentration of 1 mu mol/L. Completely immersing the substrate in 1mL of standard solution, taking out after 1h, and carrying out the treatment on 4 substrates at 400-1800 cm under the same experimental conditions^-1The spectrum range was collected for raman signal and the resulting raman spectrum is shown in fig. 5. Experimental results show that the Raman signal enhancement effect of the gold-coated copper sulfide SERS nano substrate obtained by 9 growth cycles is optimal.

Example 5:

in order to verify the repeatability of the gold-coated copper sulfide SERS nano-substrate prepared by the invention, 5 batches of substrates with 6 pieces in each batch were prepared according to the conditions determined in examples 1-4. Then randomly selecting 4 pieces from each batch, and concentratingThe obtained 20 substrates were tested with 4-mercaptoboronic acid standard solutions of 1. mu. mol/L. Completely immersing the substrate in the standard solution for 1h, taking out, and carrying out the Raman spectroscopy on 20 substrates at 400-1800 cm under the same experimental conditions^-1Raman spectra were collected over the range and plotted for comparison as shown in figure 6. Each spectrum in the figure corresponds to a substrate, and the signal intensity of each substrate is basically the same, which shows that the reproducibility of the substrate is good.

Example 6:

to verify that the gold-coated copper sulfide SERS nano-substrate prepared by the method can generate obvious photo-thermal effect under near-infrared laser irradiation, the gold-coated copper sulfide SERS nano-substrate obtained by 8 times, 9 times, 10 times and 11 times of growth cycles in example 4 is respectively placed in a sample cell, 250 mu L of ultrapure water is added, and then the gold-coated copper sulfide SERS nano-substrate is placed under 808nm near-infrared laser for continuous irradiation for 15min, wherein the irradiation area is 0.03cm²The laser power density is 1.4W/cm²And detecting and recording the temperature change of the water in the sample cell by using a thermocouple probe connected with a digital thermometer. For comparison, three additional materials were tested as controls, including a glass slide with a clean surface, a glass slide with hollow copper sulfide nanoparticles adsorbed on the surface prepared according to the adsorption conditions optimized in example 3, and a glass slide with a single-layer nanogold film covered on the surface. The temperature change data obtained in the experiment are shown in the following table 1, and it can be seen that after 808nm near-infrared laser irradiation, the water temperature in all sample cells rises, which indicates that the near-infrared laser can generate a certain degree of photothermal effect in all experimental materials; after irradiation for 10min, the water temperatures in all the sample cells reach a stable value, and the larger the difference value between the stable value and the initial value before irradiation, the more remarkable the photothermal effect generated by the experimental material under the irradiation of the near-infrared laser is. For the gold-coated copper sulfide SERS nano-substrate obtained by 8 times, 9 times, 10 times and 11 times of growth cycles, the difference values are respectively 20.9 ℃, 26.1 ℃, 21.1 ℃ and 20.5 ℃; for the three materials in the control group, the difference values are 5.4 ℃ (glass sheet), 8.3 ℃ (glass sheet with hollow copper sulfide nano particles adsorbed on surface) and 10.9 ℃ (glass sheet with single-layer nano gold film covered on surface), respectively, and it can be seen that the gold-coated copper sulfide SERS nano film prepared by the inventionThe photothermal effect of the nano-substrate under near-infrared laser irradiation is very significant and is indeed generated by the two-dimensional cluster structure of the gold-coated copper sulfide nano-particles on the surface of the glass sheet.

TABLE 1 photothermal effect data of gold-coated copper sulfide SERS nano-substrate and control group material under irradiation of near-infrared laser

Example 7:

in order to evaluate the photo-thermal enrichment effect of the gold-coated copper sulfide SERS nano-substrate prepared by the method, the substrate is prepared according to the conditions determined in the embodiments 1-4. Firstly, 4-mercaptoboric acid is selected as a probe molecule, an experimental group substrate is soaked in a 4-mercaptoboric acid solution with the concentration of 1 mu mol/L, and the power density is 1.4W/cm²The substrate was irradiated with 808nm laser for 10min, and the control substrate was not subjected to laser irradiation treatment. Selecting 4-mercaptoboric acid 1072cm^-1The Raman spectrum imaging test is carried out on the vibration peak intensity, and the size of a test area is 480 mu m multiplied by 480 mu m.

Further selecting crystal violet having electrostatic interaction with the surface of the gold shell as a probe molecule for experiment, and selecting the crystal violet 1616cm except that the solution concentration is 300nmol/L^-1Except for the imaging of the vibration peak intensity, other experimental conditions are the same as those when 4-mercaptoboric acid is used as a probe molecule.

The experimental result shows that under the irradiation of near-infrared laser, the intensity of the Raman signal of the 4-mercaptoboronic acid in the irradiation area is obviously higher than that in the area far away from the irradiation; compared with the control group, the intensity of the Raman signal of the irradiated area of the experimental group is more than 50 times of that of the control group in the highest value. Under the irradiation of near-infrared laser, the strength of a crystal violet Raman signal of an irradiation area is obviously higher than that of an area far away from the irradiation; due to the electrostatic interaction between the crystal violet molecules and the gold shells, Raman signals of the crystal violet molecules with certain intensity are detected in a control group which is not subjected to irradiation treatment, and the Raman signal intensity of an irradiation area of an experimental group is more than 4 times of that of the control group in the highest value. The experiment result shows that the gold-coated copper sulfide SERS nano substrate prepared by the invention has a good photo-thermal enrichment effect on a to-be-detected object in a liquid sample, and target molecules in a solution can be rapidly and effectively enriched to a laser irradiation area through a local photo-thermal effect generated under near-infrared laser irradiation.

Therefore, the preparation method of the gold-coated copper sulfide SERS nano substrate comprises four steps of synthesis of hollow copper sulfide nano sol, pretreatment of a glass sheet, adsorption of hollow copper sulfide nano particles on the surface of the glass sheet and cyclic growth of the nano substrate, and a gold-coated copper sulfide nano particle two-dimensional cluster structure is formed on the surface of a plane glass, so that the gold-coated copper sulfide SERS nano substrate is obtained; the preparation method of the gold-coated copper sulfide SERS nano-substrate is simple, after the hollow copper sulfide nano-sol is synthesized, the preparation can be completed only by simple steps of soaking different solutions and simple conventional operations such as oscillation, cleaning and the like, the prepared gold-coated copper sulfide SERS nano-substrate has good repeatability and obvious photo-thermal enrichment effect, and micro-area enrichment can be completed by irradiating the substrate for 10 minutes by near-infrared laser, so that the detection sensitivity is greatly improved.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.