Competitive adsorption of residual polyvinylpyrrolidone and detection molecular on flower liked silver nanoparticles

The silver nanoparticles have been frequently used in SERS detection, for their unique optical properties and sensitive surface Raman enhancement properties. However, as the preparation of silver nanoparticles will use polyvinylpyrrolidone (PVP) to achieve the effect of reducing agent and surfactant, the surface of the prepared silver nanoparticles will be wrapped by PVP, forming an insulating layer and an ill-defined AgNPs interface, which limits the plasmonic coupling between the laminates of AgNPs. This paper reported a simple method to remove PVP for high performance and reusable SERS substrate, and the residue of PVP was studied after clean centrifugal by ethanol or water. When the number of cleaning times reached 10, there was basically no residual of PVP. The cleaned AgNPs interface effectively enhanced the plasma resonance of the local surface (LSPR) and greatly improved the SERS activity of the substrate. Moreover, probe molecules (R6G) are introduced to study the influence of single molecule PVP on subsequent detection. Through the competitive relationship between the two, it can be concluded that residual PVP has basically no influence on detection of the molecular which absorbed stronger than PVP, and the remaining PVP can be ignored.