CN106111974A - A kind of preparation method and application of gold silver core-shell particles gold nanorods self-assembled structures - Google Patents

Abstract

A preparation method and application of a gold-silver core-shell particle-gold nanorod self-assembly structure, belonging to the field of analytical chemistry. The invention includes synthesis of gold and silver core-shell nanoparticles, synthesis of gold nanorods, nucleic acid modification of gold and silver core-shell nanoparticles, fluorescent dye and nucleic acid aptamer modification of gold nanorods, gold and silver core-shell particles-gold nanorods Self-assembly of dimers, Raman beacon modification, and bimodal quantitative detection of dopamine. The self-assembled structure integrates surface-enhanced Raman scattering (SERS) and fluorescence signals, forming a gold-silver core-shell particle-gold nanorod dimer with surface-enhanced Raman scattering and fluorescence signals; Dopamine can be accurately quantified by monitoring the changes in the distance between the gold and silver core-shell particles and the surface plasmon resonance properties of the assembled structure by monitoring the changes in its SERS and fluorescence signal intensity.

Description

Preparation method and application of a gold-silver core-shell particle-gold nanorod self-assembled structure

technical field

The invention relates to a preparation method and application of a gold-silver core-shell particle-gold nanorod self-assembly structure, belonging to the field of analytical chemistry.

Background technique

Since the birth of nanomaterials, due to their excellent quantum size effect, surface effect, and quantum tunneling effect, they have attracted extensive attention from many scientists and researchers, and have had a profound impact on various fields of science and society. Based on the synergistic effect of assembly primitives, the assembly of nanomaterials not only has the characteristics of nanoparticles, but also produces new coupling effects, showing unique optical, electrical and magnetic properties, and has become an important component of analytical chemistry, optical devices, It is an ideal material in many fields such as catalysis, chemical industry, environment and medicine. Dopamine (DA) is an important neurotransmitter, the change of its content can lead to Alzheimer's disease and schizophrenia, etc. Therefore, the study of its determination method has important practical significance for the research of disease mechanism and clinical application. Current detection methods for dopamine include HPLC, ultraviolet-visible spectrophotometry, electrochemistry, capillary electrophoresis, and chemiluminescence. Although these quantitative detection methods have certain sensitivity and specificity, they are all single-modal response signals, which cannot ensure accurate analysis.

Based on the gold-silver core-shell particles-gold nanorod self-assembly structure, the invention realizes the ultrasensitive quantitative detection of dopamine in dual modes of SERS and fluorescent signals.

Contents of the invention

The purpose of the present invention is to provide a preparation method and application of a gold-silver core-shell particle-gold nanorod self-assembled structure. At present, there is no report on the preparation of a gold-silver core-shell particle-gold nanorod self-assembled structure. The self-assembly structure of the present invention is different from other existing structures in that the end faces of gold nanorods are modified with dye-functionalized nucleic acid aptamers, and nucleic acid-modified gold-silver core-shell particles are self-assembled, and at the same time, Raman Finally, a gold-silver core-shell particle-gold nanorod dimer with surface-enhanced Raman scattering and fluorescence signals is formed.

The object of the present invention is also to provide a method for dual-mode detection of dopamine at the same time, that is to say, by monitoring the SERS And the change of fluorescence signal intensity can accurately quantify dopamine.

The technical solution of the present invention, a method for preparing a gold-silver core-shell particle-gold nanorod self-assembly structure, comprises the following steps:

(1) Synthesis of gold nanoparticles: Take 97.5mL of ultrapure water in a clean round bottom flask, add 2.5mL of 4g/L chloroauric acid solution, stir and mix with constant temperature magnetic force and heat to boiling, and keep boiling for 5 After -6 min, quickly add 2.0 mL of 1% trisodium citrate solution to the above mixed solution, continue heating and stirring for 10 min, until the solution is stable and bright wine red, and finally, the reaction solution is cooled to room temperature, and stored at 4 °C for later use , that is, gold nanoparticles with a particle size of 18nm are prepared;

(2) Synthesis of gold-silver core-shell particles: firstly, centrifuge and resuspend 100 μL of pre-synthesized gold nanoparticles in 5 mM phosphate buffer solution containing 0.5% polyvinylpyrrolidone (PVP), and then add 30 μL of 2.75 mM silver nitrate solution, while adding 20 μL of 0.1M ascorbic acid as a reducing agent, stirred at room temperature for 3 hours, centrifuged, washed the precipitate three times with ultrapure water, resuspended in 100 μL of ultrapure water, and kept at 4 °C Preserve it for later use, and obtain the gold-silver core-shell structure nanomaterial;

(3) Synthesis of gold nanorods:

①Seed crystal synthesis: Take 0.1mL of 4g/L chloroauric acid solution in a clean Erlenmeyer flask and add it into 1mL of 0.2M cetyltrimethylammonium bromide (CTAB) solution while stirring. The color changes from colorless to yellowish brown; then add 0.12mL of newly prepared 0.01M sodium borohydride solution and stir rapidly for 2 minutes, the color of the solution changes from yellowish brown to light brown;

②Gold nanorod growth: Add 5mL of 4g/L chloroauric acid solution to 5mL of 0.2M CTAB solution, and add 4mL of ultrapure water; another 0.125mL of 0.01M silver nitrate solution and 65µL of 0.1M ascorbic acid The solution was added to the above mixing system respectively, stirred and reacted at 28°C for 2min, the solution turned from brown to colorless; finally, 0.05mL of the seed crystal solution obtained in step ① was added and stirred for 20s, and then allowed to stand at 30°C for 3h to obtain a gold nanorod solution;

(4) Nucleic acid modification of gold-silver core-shell particles: Take 100 μL of gold-silver core-shell particles synthesized in step (2) and centrifuge at 10,000 rpm for 10 minutes. After removing the supernatant, resuspend the pellet in 100 μL of 10 mM PB solution, add DNA1, and massage The concentration ratio of gold and silver core-shell particles: DNA1 was coupled at a coupling ratio of 1:2, left to stand for 12 hours, centrifuged, and resuspended in 100 μL of 10mM PB solution to obtain the Au@Ag-DNA1 complex;

(5) Nucleic acid modification of gold nanorods: take the dispersed 10mL gold nanorods synthesized in step (3) and centrifuge at 7000rpm for 10min. The dopamine nucleic acid aptamer DNA2 modified by the Cy5 dye at the 'end was coupled according to the molar concentration ratio of gold nanorods: DNA2 as a coupling ratio of 1:2, left to stand for 12 hours, centrifuged, and resuspended in 10mL 10mM PB solution, Obtain the GNR-DNA2 complex;

(6) Gold-silver core-shell particles-gold nanorod self-assembly: Take 100 μL of the complexes of Au@Ag-DNA1 and GNR-DNA2 obtained in steps (4) and (5) and mix them in equal volumes, and statically Leave it for 12 hours, then add the Raman beacon molecule ATP so that the final concentration reaches 15 μM, and then the self-assembled structure of gold-silver core-shell particles-gold nanorod dimer with SERS and fluorescence signals can be obtained;

The DNA1: 5'-GGG CCT CAT TCT GTG CGA ACG CTT TTG TAC CGC ACA GCC TCT GGCGCA CAC AGA GAC -3';

DNA2 is DA-aptamer: 5′-SH-GTC TCT GTG TGC GCC AGA GAC ACT GGG GCA GAT ATGGGC CAG CAC AGA ATG AGG CCC-Cy5-3′.

(7) Dual-modal quantitative determination of dopamine: Take 100 μL of the complexes of Au@Ag-DNA1 and GNR-DNA2 obtained in steps (4) and (5) and mix them in equal volumes, and add 5 μL of dopamine to be tested at the same time The sample solution was left to stand for 12 hours, and then the Raman beacon molecule ATP was added to make the final concentration reach 15 μM, and then the Raman signal and the fluorescence signal of the dopamine sample system were measured respectively, thus, the changes of the Raman signal and the fluorescence signal can be The concentration of dopamine is measured.

Dual-modality quantification of dopamine concentration; the lower detection limit of dopamine concentration in fluorescence mode is 0.05fM, and the lower detection limit of dopamine concentration in Raman mode is 0.03fM.

Beneficial effects of the present invention: the present invention self-assembles the dye-functionalized nucleic acid aptamer on the end surface of gold nanorods, and nucleic acid-modified gold-silver core-shell particles, and at the same time introduces Raman beacons to finally form a Gold-silver core-shell particles-gold nanorod dimers with enhanced Raman scattering and fluorescence signals; with the change of the distance between gold nanorods and gold-silver core-shell particles and the regulation of the surface plasmon resonance properties of the assembled structure, by monitoring its SERS And the change of fluorescence signal intensity can accurately quantify dopamine.

Description of drawings

Fig. 1 Transmission electron microscope image of gold-silver core-shell particle-gold nanorod assembly.

Figure 2 Raman spectrum of quantitative dopamine based on gold-silver core-shell particle-gold nanorod assembly.

Fig. 3 Fluorescence spectrum of quantitative dopamine based on gold-silver core-shell particle-gold nanorod assembly.

detailed description

Example 1

All glass instruments were soaked in aqua regia for 24h, washed with double distilled water, and dried for later use. The water used in the experiment was 18.2 MΩ Milli-Q ultrapure water.

(1) Synthesis of gold nanoparticles: Take 97.5mL of ultrapure water in a clean round bottom flask, add 2.5mL of 4g/L chloroauric acid solution, stir and mix with constant temperature magnetic force and heat to boiling, and keep boiling for 5 After -6 min, quickly add 2.0 mL of 1% trisodium citrate solution to the above mixed solution, and continue heating and stirring for 10 min until the solution is stable and translucent wine red. Finally, the reaction solution was cooled to room temperature and stored at 4 °C for future use, and gold nanoparticles with a particle size of about 18 nm were prepared.

(2) Synthesis of gold-silver core-shell particles: firstly, pre-synthesized 100 μL gold nanoparticles were centrifuged and resuspended in 5 mM phosphate buffer solution containing 0.5% PVP. After that, add 30 μL of 2.75 mM silver nitrate solution, and at the same time add 20 μL of 0.1 M ascorbic acid as a reducing agent, stir and react for 3 hours at room temperature, centrifuge, wash the precipitate with ultrapure water three times, and resuspend in 100 μL of ultrapure water Store in pure water at 4°C for later use, and the core-shell structure of gold and silver nanomaterials can be obtained.

(3) Synthesis of gold nanorods:

①Synthesis of seed crystals: Take 0.1mL of 4g/L chloroauric acid solution in a clean Erlenmeyer flask and add it into 1mL of 0.2M cetyltrimethylammonium bromide (CTAB) solution while stirring. The color changed from colorless to yellow-brown; then, 0.12 mL of newly prepared 0.01M sodium borohydride solution was added and stirred rapidly for 2 minutes, and the color of the solution changed from yellow-brown to light brown.

②Gold nanorod growth: Add 5mL of 4g/L chloroauric acid solution to 5mL of 0.2M CTAB solution, and add 4mL of ultrapure water; another 0.125mL of 0.01M silver nitrate solution and 65µL of 0.1M ascorbic acid The solution was added to the above mixing system respectively, stirred and reacted at 28°C for 2min, and the solution turned from brown to colorless; finally, 0.05mL of the seed crystal solution obtained in step ① was added and stirred for 20s, then stood at 30°C for 3h to obtain a gold nanorod solution.

(4) Nucleic acid modification of gold-silver core-shell particles: Take 100 μL of gold-silver core-shell particles synthesized in step (2) and centrifuge at 10,000 rpm for 10 minutes. After removing the supernatant, resuspend the pellet in 100 μL of 10 mM PB solution, add DNA1, and massage The concentration ratio of gold and silver core-shell particles: DNA1 was coupled at a coupling ratio of 1:2, left to stand for 12 hours, centrifuged, and resuspended in 100 μL of 10mM PB solution to obtain the Au@Ag-DNA1 complex;

(5) Nucleic acid modification of gold nanorods: take the dispersed 10mL gold nanorods synthesized in step (3) and centrifuge at 7000rpm for 10min. The dopamine nucleic acid aptamer DNA2 modified by the Cy5 dye at the 'end was coupled according to the molar concentration ratio of gold nanorods: DNA2 as a coupling ratio of 1:2, left to stand for 12h, centrifuged, and resuspended in 10mL 10mM PB solution, A GNR-DNA2 complex is obtained.

DNA1: 5′-SH-GGG CCT CAT TCT GTG CGA ACG CTT TTG TAC CGC ACA GCC TCTGGC GCA CAC AGA GAC -3′;

DNA2 (DA-aptamer): 5'-GTC TCT GTG TGC GCC AGA GAC ACT GGG GCA GAT ATG GGCCAG CAC AGA ATG AGG CCC-Cy5 -3'.

(6) Gold-silver core-shell particle-gold nanorod self-assembly: Take 100 μL of the complexes of Au@Ag-DNA1 and GNR-DNA2 obtained in steps (4) and (5) and mix them in equal volumes, statically Leave it for 12 hours, and then add the Raman beacon molecule ATP so that the final concentration reaches 15 μM, and then a gold-silver core-shell particle-gold nanorod dimer with SERS and fluorescent signals integrated can be obtained. The transmission electron microscope image of the gold-silver core-shell particle-gold nanorod assembly is shown in Figure 1.

(7) Dual-modal quantitative determination of dopamine: Take 100 μL of the complexes of Au@Ag-DNA1 and GNR-DNA2 obtained in steps (4) and (5) and mix them in equal volumes, and add 5 μL of dopamine to be tested at the same time The sample solution was left to stand for 12 hours, and then the Raman beacon molecule ATP was added to make the final concentration reach 15 μM, and then the Raman signal and the fluorescence signal of the dopamine sample system were measured respectively, thus, the changes of the Raman signal and the fluorescence signal can be The concentration of dopamine is measured.

The Raman spectrum of quantitative dopamine based on gold-silver core-shell particle-gold nanorod assembly is shown in Figure 2; the fluorescence spectrum of quantitative dopamine based on gold-silver core-shell particle-gold nanorod assembly is shown in Figure 3.

Claims (4)

1. the preparation method of gold silver core-shell particles-gold nanorods self-assembled structures, it is characterised in that step is as follows:

(1) nucleic acid of gold silver core-shell particles is modified: takes the gold silver core-shell particles that 100 μ L prepare and is centrifuged with 10000 rpm 10min, after removing supernatant, precipitation is resuspended in the 10mM PB solution of 100 μ L, adds DNA1, and molar concentration is than gold silver core Shell particles DNA1 be 12 coupling ratio carry out coupling, stand 12h, centrifugal, be resuspended in 100 μ L 10mM PB solution, obtain Au@Ag-DNA1 complex；

(2) nucleic acid of gold nanorods is modified: takes the scattered 10mL gold nanorods prepared and is centrifuged 10min with 7000rpm, goes After supernatant, precipitation is resuspended in the 5mM CTAB solution of 10mL, adds 5 ' end sulfydryl modifications, the DOPA of 3 ' end Cy5 dyestuffs modifications Amine aptamer DNA2, and molar concentration carries out coupling than the coupling ratio that gold nanorods DNA2 is 12, stands 12h, from The heart is resuspended in 10mL 10mM PB solution, obtains GNR-DNA2 complex；

(3) gold silver core-shell particles-gold nanorods self-assembly: Au@Ag-DNA1 step (1) prepared and step (2) prepare GNR-DNA2 complex respectively takes 100 μ L and carries out equal-volume mixing, stands 12h, adds afterwards and makes final concentration reach 15 μMs draw Graceful beacon molecule ATP, i.e. obtains SERS and fluorescence signal in the gold silver core-shell particles-gold nanorods self-assembled structures of one.

The preparation method of gold silver core-shell particles-gold nanorods self-assembled structures the most according to claim 1, it is characterised in that: Described DNA1:5 '-GGG CCT CAT TCT GTG CGA ACG CTT TTG TAC CGC ACA GCC TCT GGC GCA CAC AGA GAC -3′；

DNA2 i.e. DA-aptamer:5 '-SH-GTC TCT GTG TGC GCC AGA GAC ACT GGG GCA GAT ATG GGC CAG CAC AGA ATG AGG CCC-Cy5 -3′。

3. the application of gold silver core-shell particles-gold nanorods self-assembled structures that prepared by method described in claim 1, its feature exists In: it is applied to dopamine detection, specifically comprises the following steps that what Au@Ag-DNA1 step (1) prepared and step (2) prepared GNR-DNA2 complex respectively takes 100 μ L and carries out equal-volume mixing, is simultaneously introduced 5 μ L dopamine to be measured sample solution, stands 12h, adds the Raman beacon molecule ATP making final concentration reach 15 μMs afterwards, measures drawing of dopamine sample system the most respectively Graceful signal and fluorescence signal, thus, detected the concentration of dopamine by the situation of change of Raman signal and fluorescence signal.

The application of gold silver core-shell particles-gold nanorods self-assembled structures the most according to claim 3, it is characterised in that: bimodulus The quantitative dopamine concentration of state；Under fluorescence mode, the Monitoring lower-cut of dopamine concentration is 0.05fM, dopamine concentration under Raman modes Monitoring lower-cut be 0.03fM.