Temperature-sensitive intelligent response SERS substrate and preparation method and application thereof

Abstract

The invention relates to a temperature-sensitive intelligent response SERS substrate and a preparation method and application thereof. The preparation method comprises the following steps of taking azodiisobutyronitrile as an initiator, methanol as a solvent and 1-vinyl-3-ethylimidazolium bromide and N-isopropylacrylamide as monomers to carry out copolymerization reaction;re-dispersing the copolymer into the deionized water after precipitation, filtering and drying; adding an excessive amount of a tetrachloroauric acid solution, carrying out an ion exchange reaction, removing the unreacted tetrachloroauric acid, carrying out in-situ reduction by using sodium borohydride to generate poly (NIPAm-co-ViEtImBr)-AuNPs, continuously immobilizing probe molecules by using an ion exchange effect, and carrying out a Raman signal test. According to the invention, the intelligent polymer PNIPAM with temperature-sensitive response, the gold nanoparticles with enhancement effect on Raman signals andthe probe molecules are successfully integrated through a bridging effect of the ionic liquid.

Description

technical field [0001] Since the discovery of surface-enhanced Raman scattering in 1979, it has become an important means of material analysis. This technique significantly enhances the Raman scattering cross section of molecules adsorbed on the surface of metal nanostructures, making it a great potential for applications in the fields of analytical chemistry and biology. Background technique [0002] Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical detection tool that enables ultrasensitive analytical detection in the fields of chemistry and biochemistry. The preparation technology and application of common gold-silver sol SERS substrates are mature, and the current work mainly focuses on the following aspects: First, specific adjustments are made to the experimental conditions of each specific analyte. For example, the enhancement factors of organic acids and alcohols are several orders of magnitude smaller than those of thiols and amines. The reason is...

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Problems solved by technology

Another strategy is to control the charge on the surface of nanoparticles, and adsorb the analytes on the surface of nanoparticles through electrostatic attraction. This method is very effective in enhancing the Raman signals of acids and amines, but for alcohols, ethers and other Detection of oxygen-containing groups as well as non-functionalized molecules is of little help

The second is that in the SERS effect, the electromagnetic field enhancement effect is particularly obvious in the nano-gap between the coupling structures, in which the region with a strong enhanced electromagnetic field is called a "hot spot". When the analyte is on the "hot spot", its SERS signal will be greatly enhanced, so people have begun to use various methods to synthesize gold, silver, and copper nanoparticles of various shapes and sizes, and even synthesize assemblies of different structures. It is expected that the synthesized SERS substrate will have more "Hot spots", unfortunately, many composite metal nanomaterials have more hot spots that enhance the SERS signal. Applications are very limited

Based on this, there are currently many research groups dedicated to research in this direction, constructing smart response substrates such as solvents, pH, etc., but in the field of SERS, the application of smart response substrates is relatively scarce, because the reproducibility of SERS signals is very important The distance between the analyte and the plasmonic nanoparticles and the distance between the plasmonic nanoparticles are very high, so the position where the analyte is coupled with the plasma field, that is, the location of the hot spot is very important. SERS signal is also very important

At the same time, external stimuli such as acid-base stimuli usually have an irreversible effect on the material system, making the response signal not fully reversible

Therefore, a research group proposed to construct a SERS intelligent substrate with intelligent response to temperature, which can obtain a reversible, intelligent response SERS signal that changes with temperature. Unfortunately, the steps to prepare the substrate are too cumbersome and require fine-tuning of the process. control, making it limited in the field of practical application

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