| Surface-enhanced Raman scattering(SERS)is one of the most popular techniques in the field of biomedicine,environmental contaminant detection and food safety,as it is highly sensitive,requires only a small amount of sample and enables fingerprinting and non-destructive detection of molecular.However,achieving sensitive,selective,and accurate detection of contaminants raises higher requirements for SERS detection technology as the contaminants in real environmental samples exist in complex matrices and are trace present and prone to transformation.There are a number of effective ways to address this challenge,such as separation of analytes from complex sample matrices,adsorption and enrichment of analytes,and in situ detection and analysis.In particular,enriched SERS substrates have significant advantages in achieving enrichment and separation of contaminants as well as sensitive detection.In this paper,we have conducted literature research and metrological analysis on enriched SERS substrates,and developed three enriched substrates in response to actual environmental issues under the guidance of research hotspots.Through nanoparticle surface functionalization,nanoparticle assembly,and substrate tuning,we ultimately realize the detection and analysis of environmental pollutants such as uranyl and atmospheric fine particulate fractions.Works were carried out as follows:(1)A bibliometric analysis was carried out on the 805 relevant literature in the field of magnetically enriched substrates included in the Web of Science core database to analyze the current development and the changes in research hotspots.A co-occurrence analysis showed that the most influential journals in this field are Journal of the American Chemical Society,Analytical Chemistry,etc.And the countries and institutions that have contributed most to this field are China and the University of Chinese Academy of Sciences,respectively.The research hotspots in recent years are nanostructure tuning and the study of methods to enhance Raman scattering signals.(2)Experimental,computational and simulation studies were combined to investigate how the applied magnetic field affects the performance of enriched Fe3O4@SiO2@Au substrate.The results showed that the intensity and homogeneity of the signal were enhanced by the applied magnetic field,with hot spot density,probe molecular density,and near-field enhancement found to be the main regulating factors.It has also been found that excessive aggregation on the substrate results in a light-thermal transition that results in a reduction in signal intensity,as observed by stereomicroscopic image.This provides guidance for signal regulation of enriched SERS substrates.(3)Prepared magnetically enriched SERS substrate Fe3O4@SiO2@Au@ZIF-8 for detection of uranyl.Firstly,the successful synthesis of the substrates was demonstrated by transmission electron microscopy characterisation,and the detection conditions(adsorption time,ratio of solution to the substrate)were optimised to obtain the optimal results.Secondly,the detection limit for uranyl solutions reached 10-7 M,which is below the minimum standard required for drinking water.X-ray photoelectron spectroscopy and Zeta potential detection were applied to explain the mechanism of uranyl adsorption and detection.(4)The Cu-Au substrates with both viscous,flexible and surface plasmonic properties were prepared for enrichment and detection of particulate matter.The SERS properties of the substrate was evaluated using 4-mercaptopyridin as the probe molecule with good sensitivity,uniformity,stability,and reproducibility.Scanning electron microscopy,atomic force microscopy characterisation results showed that the gold nanoparticles were semi-embedded in the Cu viscous layer.Finally,the granular samples were collected by the "paste-and-peel" method,and the characteristic peaks at 973 cm-1 and 1045 cm-1 were identified for ammonium sulphate and ammonium nitrate,common components of atmospheric fine particulate matter. |
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