The Preparation Of Au NanoShells And Immunoassay Detection Based On This SERS Substrate

In recent years, surface-enhanced Raman spectroscopy (SERS) as a very importantanalytical technique for biomedical detection has received increasing attention. Owing tohigh sensitivity, SERS has been widely researched in ultrasensitive detection of variouschemical and biological molecules. The SERS detection exhibits unique and excellentproperties for the biological system. Compared with traditional fluorescence detection, SERSshows lower effect on environment and its narrow bandwidth can be used to detectmulticomponent samples.However, the intensity of signals is important for applying SERS.It is currently widely accepted that SERS enhancement comes from the formation of hotspots.Hot spots are formed in the nanoscale junctions and interstices of SERS substrates, andcould greatly increase the Raman cross section of biomolecules. The signal intensity of themolecules could be enhanced by orders of magnitudes on the proper SERS substrates. SERSsubstrates with large enhancement factor and good reproducibility are essential for thebiomedical applications. In order to realize the use of SERS, fabrication of active substrateshas become the major aspect in SERS field. Traditional SERS substrates such as colloidalmetal nanoparticles, metal islands, complex nanostructures such as dimmers, trimers,core@shell, bimetallic nanoparticles have also been prepared and can provide SERSenhancement. Although Au nanoparticles with such size have high SERS ability,corresponding optimum excitation wavelength used for SERS analysis is not appropriate forbiological and biomedical applications. Thus, in order to obtain the most critical aspects inpreparation of SERS active substrates are the controllable distance between adjacent metalnanostructures and the increase of Raman-scattering cross section gained more attention. Asimple and highly selective labeled immunoassay was developed for ultrasensitive detectionof protein using surface enhanced Raman scattering (SERS) method based on Au nanoshellsas active substrate. Au nanoshells with different Au aggregations show various SERSenhancement.