Polyvinylpyrrolidine-functionalized silver nanoparticles for SERS based determination of copper(II)

A simple, rapid and ultrasensitive surface-enhanced Raman scattering (SERS) assay was developed for detection of Cu²⁺. It is based on the use of polyvinylpyrrolidine-functionalized silver nanoparticles (AgNPs). Detection is enabled because of the presence of N and O atoms in PVP which have specific coordination capability for Cu²⁺. Coordination is accompanied by the appearance of the change in the intensity ratio of the 845 cm^-1 and 899 cm^-1 peaks (I₈₄₅/I₈₉₉) that is associated with pyrrolidinone ring torsion in PVP. The intensity of the band increases linearly in the 0.01 to 2 μM Cu²⁺ concentration range, and the limit of detection is as low as 3 nM. The assay potentially is a promising tool for monitoring of Cu²⁺ in environmental water. Graphical abstract Schematic representation of a method for determination of Cu²⁺ using polyvinylpyrrolidone-functionalized AgNPs as a SERS nanoprobe. Cu²⁺ can coordinate with PVP through the N and O atoms. This effect induces AgNP aggregation and affects the electronic structure of PVP. The changes of the Raman spectra are proportional to the Cu²⁺ concentration.