Surface-enhanced Raman Spectroscopy (SERS）
Owing to the fingerprinting energy resolution and near-single-molecule sensitivity, surface-enhanced Raman spectroscopy (SERS) has been regarded as an important surface analysis tool in the field of environmental monitoring, food safety and clinical diagnosis. Our group has currently carried out the following work on the development of SERS:
1、For colloidal-based SERS substrate, employing the conventional Au and Ag NPs (citrate as capping agent) as SERS substrates, we discovered that the key for realizing the sensitively SERS measurement relies the trade-off between competitive and coadsorption behaviors of the target molecules and the anion and cation of the agglomerating agent on the surface of the SERS substrate. Based on the guidance, an induced-coadsorption strategy was proposed to improve the accurately qualitative and quantitative SERS analysis for different types of positively charged (e.g., tropane alkaloids and antibiotics) and electro-neutral molecules (e.g., PAHs and PCBs) at trace-level.
2、We also developed a low-energy cost method to prepare positively charged Au/Ag NPs with different types of capping agents. Through a deep-understanding for the positively charged Au/Ag NPs surface micro-circumstance (including capillary force, electrostatic and strongth steric effect) how accelerated or restrained the kinetic process of target species approaching hotspots region, we have realized the SERS detection of negatively charged species (e.g., sunset yellow and sulfate) with too much high sensitivity.
3、SERS is a highly surface-sensitive technique, providing fingerprint identification and near-single molecule sensitivity. In addition to surfactant on the substrate and photochemical reactions, we found that the ultrarace impurities significantly distorted the SERS spectra of high-purity reagents. Therefore, in the qualitative analysis of the target substance SERS, especially for weakly adsorbed molecules, while avoiding photochemical reactions and concentration titration in a large scale, it is also necessary to strictly exclude the interference of impurities.
4、During the testing process, we found that matrix effects in real world hinder the SERS signals of targets.Therefore, efficient and rapid sample pretreatment is the prerequisite for rapid qualitative and quantitative analysis of trace targets in complex samples by SERS. With the aid of different interaction forces by means of extraction, we are gearing up to develop the sample pretreatment methods with both separation and purification capabilities towards SERS.