Synthesis and characterization of organo-soluble aniline oligomer-based electroactive doped with gold nanoparticles, and application to electrochemical sensing of ascorbic acid

Organo-soluble aniline oligomer-based electroactive polyimide (EPI) doped with gold nanoparticles (GNPs) applied in sensing ascorbic acid (AA) was presented. Conjugated aniline trimer (AT3) and aniline tetramer (AT4) were synthesized and characterized via 1H NMR, FTIR, and MS spectroscopic studies. Subsequently, the organo-soluble electroactive polyimide (EPI) was prepared by chemical imidization of electroactive poly(amic acid) (EPAA), followed by characterization through FTIR and GPC analyses. Moreover, formation of reduced gold nanoparticles (GNPs) upon the surface of EPI was confirmed by XRD, SEM-EDS, TEM and ICP-OES. Based on CV studies, the redox capability of as-prepared materials was found to show a decreasing trend of EPI-4G > EPI-4 > EPI-3. The as-prepared EPI-4G modified carbon paste electrode (CPE) turned out best in sensing AA at lower oxidative potential with good sensitivity, relative low detection limit, broad linear dynamic range and best selectivity for a tertiary mixture of ascorbic acid (AA)/dopamine (DA)/uric acid (UA) compared to the other tested electrodes.