| In recent years,environmental pollution,food and drug safety,major infectious diseases and other issues become increasingly serious.Human beings'life and health are seriously threatened.Timely and effective biochemical detection methods can provide a strong preventive monitoring and reliable follow-up treatments.Existing biochemical detection methods exhibit some disadvantages such as complex sample pretreatment,low detection sensitivity,expensive equipment,long detection time and so on.As a result,the rapid on-site detection technologies with high sensitivity,good specificity and convenient equipment are attracting more and more researchers'attention.Surface-Enhanced Raman Scattering?SERS?spectroscopy is a constantly developing vibration spectroscopy technique,which can detect analytes of low-concentration with high-sensitivity by amplifying the electromagnetic field generated by localized surface plasmon excitation.As a powerful analytical tool,SERS has been widely applied in chemical detection,bioanalysis and identification,biosensing and optoelectronics.Now,the bottleneck that limits the widespread application of SERS technology is the synthesis controlled of high-performance SERS substrates.By combining the prepared SERS substrates with a suitable experimental method and using a high-sensitivity Raman spectrometer,the SERS technology is further developed into a rapid on-site detection and analysis method with high specificity and low detection limit.In this work,based on the excellent SERS enhancement effect of Ag and Au nanoparticles,monodisperse spherical Au@Ag core-shell nanoparticles with the surface plasmon resonance?LSPR?optical properties were prepared by the seed growth method.The prepared nanoparticles colloid combined with Portable laser Raman spectrometer are applied for the detection of pesticide and herbicide residues which related to food safety.The experimental results showed that the detection limits of thiram and paraquat on the surface of apple were low to 4.51×10-6g/cm2 and 2.57×10-5g/cm2 respectively,which verified the practical application of Au@Ag nanoparticles as the SERS substrates in the field of rapidly food safety detection.There is a good linear relationship between the logarithm of SERS signals intensities and the logarithm of samples concentrations.Metal-Organic Frameworks?MOFs?are a new class of porous,highly crystalline materials,which are assembled together by coordination of metal ions and organic ligands in an orderly manner.Metal nanoparticles are encapsulated in MOFs to form new nanocomposites.MOFs are used as the stable matrix of metal nanoparticles which serve as SERS active sites.In this paper,Ag nanoparticles were encapsulated in MIL-101?Cr?.The large surface area and porous structure of the MOFs materials can preconcentrate the analyte molecules to be approaching to the metal surface.By optimizing the preparation conditions and characterizing by means of electron microscope,XRD,EDX and UV-vis,The sensitivity of the nanocomposites was investigated by employing 4-mercaptopyridine as Raman labeling molecules and the Enhancement Factor is about 1.17×106.The nanocomposites were used as SERS substrates to detect ultra-trace glucose in the PBS buffer solution.The experimental study laid the foundation of the semi-quantitative analysis of glucose by SERS technology. |
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