Tailoring properties of polyaniline for simultaneous determination of a quaternary mixture of ascorbic acid, dopamine, uric acid, and tryptophan

In this study, ion-exchange property and mesoporosity of polyaniline were exploited in the simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), and tryptophan (Trp), which is very important in the clinical diagnosis. Mesoporous polyaniline synthesized by the self-assembly of mixed (ionic and non-ionic) soft template was ion-exchanged to form transition metal ion-exchanged mesoporous polyaniline (M-Meso-PANI). Materials were characterized by X-ray diffraction, nitrogen sorption, scanning electron microscopy, UV–vis, and FT-IR spectroscopic methods. M-Meso-PANI based electrochemical sensors were fabricated for the simultaneous determination studies. For comparative electrochemical studies, transition metal exchanged polyaniline (M-PANI) were also investigated. Fe-Meso-PANI exhibited higher sensitivity and volumetric response for these bio-molecules compared to Fe-PANI, which is due to the highly dispersed Fe2+ in high surface area Meso-PANI matrix. Fe-Meso-PANI exhibited the highest sensitivity, selectivity among the M-Meso-PANI materials. The analytical performance of this sensor was also demonstrated for the blood serum and urine samples. The reliability and stability of the modified electrode provides a good possibility for applying the technique in routine analysis for a selected class of electroactive bio-molecules.