Liquid-liquid interface detection method for surface-enhanced Raman spectroscopy

Abstract

The invention provides a liquid-liquid interface detection method for surface-enhanced Raman spectroscopy. The method comprises: first, preparing an oil phase solution containing acetone and noble metal nano sol respectively; dissolving a to-be-detected substance in the oil phase solution or noble metal nano sol; then mixing the oil phase solution and the noble metal nano sol to form a liquid-liquid two-phase interface; and finally, detecting target molecules in the to-be-detected substance by a Raman spectrometer by utilizing a noble metal nano-particle array self-assembled on the liquid-liquid interface as an active substrate for Raman scattering. The method provided by the invention uses an insoluble liquid-liquid two-phase interface self-assembled noble metal nano-particle array as theRaman scattering active substrate for detection, can be used for single-phase or two-phase, single-component or multi-component detection of water-soluble / oil-soluble substances to be detected, breaks the bottleneck of detection of substances to be detected with different solubility in complex samples, and realizes high-throughput quantitative detection.

Description

technical field [0001] The invention relates to the field of sensitive analysis and detection, in particular to a liquid-liquid interface detection method with high reproducibility, ultra-stable and rapid surface-enhanced Raman spectroscopy. Background technique [0002] Surface-enhanced Raman scattering (SERS) is based on the special nano-size effect exhibited by noble metal nanoparticles, which solves the problem of weak conventional Raman scattering signals and achieves ultra-high sensitivity detection. Therefore, it is widely used in the fields of life science, environmental biology and public food safety. At present, the commonly used SERS substrate is in the state of colloidal solution, by adding anion (such as Cl - 、Br - etc.) to promote the agglomeration of nanoparticles in the solution, so that these agglomerated or complex-structured noble metal nanoparticles tend to generate more hot spots. However, the agglomeration phenomenon is uncontrollable and random, res...

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Problems solved by technology

However, due to the complex structure and high cost of the micro-nano processing equipment used, the time-consuming and high-cost fabrication process, and the difficulty in mass production limit the wide application of this type of SERS active substrate.

Common substrate materials are also rigid materials such as porous alumina, silicon wafers or glass slides, however these are usually not portable and not suitable for complex surface analysis in the field

[0003] Using SERS as a quantitative detection technique is still a big challenge, because SERS is essentially a near-field phenomenon, and only molecules located at hot spots can be detected. In addition, the field enhancement at hot spots is closely related to the local structure and the coupling between them, so even though the molecules can be evenly distributed on the metal surface, the SERS signal may still be inhomogeneous

For the solid-gas interface, sensitivity and reproducibility are two irreconcilable indicators. The use of internal standards can solve the above problems. However, in the same physical and chemical environment, the positioning of internal standards and target molecules has the following problems: The standard molecule will compete for the adsorption site to replace the target molecule; the second is that the microenvironment will affect the stability of the signal of the internal standard molecule, resulting in changes and fluctuations in intensity

This method cannot guarantee the continuity and regularity of the assembled membrane, and has disadvantages such as insufficient rapidity, susceptibility to interference, and low consistency of large-scale assembly.

In Au@SiO 2 Adding ethanol to the two-phase system of particle sol and n-hexane induces the self-assembly of nanoparticles. This method has obvious shortcomings: the treatment of noble metal particles is cumbersome; more assembly volume is required; the rapid addition of ethanol will affect the flatness of the assembled film sexual density

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