Preparation of Poly(Acrylic Acid) Crosslinked-Gold Nanoparticles for Colorimetric Detection of Analytes

The aims of this study are to synthesize and characterize gold nanoparticles (AuNPs) crosslinked by pH-responsive polymer poly (acrylic acid) (PAA) and its application for detection of some analytes in herbal medicine product. In this study, a pH-responsive polymer, poly (acrylic acid) was prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization method. The polymer was then cross-linked by gold nanoparticles, which was synthesized by the Turkevich method. The response of the AuNPs-crosslinked PAA was observed by the color change from red to blue at a specific pH (4-5) and was characterized by TEM. The reversible color change was resulted from aggregation and disaggregation of the AuNPs due to the shrinking and swelling of the polymer when different pH was introduced as a stimulant. This sensor has the capability of recognizing analytes such as aspirin and tolbutamide added in the herbal medicine product at the concentration of 0.04-0.05 M.