Fabrication of flower-like silver nanostructures for rapid detection of caffeine using surface enhanced Raman spectroscopy

Abstract

Flower-like silver nanoparticles, with diameters of 450–500nm and protrusions on the surface up to 10–15nm, have been successfully synthesized via liquid phase reduction method, by using ascorbic acid as a reductant and polyvinyl pyrrolidone (PVP) as a surfactant. It is found that the proper coating degree of PVP on silver nuclei leads to anisotropic growth of the silver nuclei resulting in the formation of flower-like structure with more protrusions. Furthermore, when the obtained flower-like silver nanostructure is used as Surface Enhanced Raman Scattering(SERS) substrates, SERS signal is still clearly even if the concentration of R6G solution is reduced down to 10−8M. The SERS enhancement mechanism of flower-like silver nanostructures in SERS spectroscopy has been further discussed. SERS technology based on the obtained flower-like silver nanostructure substrates can be also used as an effective way to detect caffeine. In this work, it is found that the average intensity of SERS signals at 807cm−1(NCH), 958cm−1(Pyrimidine ring) and 1327cm−1(Imidazole trigonal ring) linear decreased with the −log10C (C is the concentration of caffeine), and the coefficient of determination (R2) is as high as 0.975. This work provides a new way for the quantitative detection of caffeine based on SERS spectroscopy.