Preparation of water dispersible, fluorescent Ag–PAA–PVP hybrid nanogels and their optical properties

A simple method of synthesizing hybrid silver–polyacrylic acid–poly(N-vinylpyrrolidone) (Ag–PAA–PVP) nanogels was demonstrated through in situ reducing Ag+ inside PAA–PVP nanogels, which were formed by polymerization of acrylic acid in the PVP solution. Due to the ion exchange between Ag+ and acid protons of PAA, stable Ag+ clusters were formed inside the PAA–PVP nanogels, and hybrid nanogels were obtained by reducing Ag+ by ascorbic acid. Transmission electronic microscopic (TEM) images clearly showed the existence of silver nanoparticles inside the Ag–PAA–PVP nanogels. These hybrid nanogels showed typical surface plasma resonance absorption peak around 420 nm, and the size of the silver nanoparticles inside the Ag–PAA–PVP nanogels could be controlled from 9.5 ± 1.6 nm to 1.9 ± 0.4 nm by increasing the feeding amount of Ag+. In addition, these hybrid nanogels showed photoluminescent properties in fluorescent spectra. Considering the pH sensitive property of these hybrid nanogels, they will have potential application in drug delivery and biomedical imaging systems.