Microtubule Sensors and Sensor Array Based on Polyaniline Synthesized in the Presence of Poly(styrene sulfonate)

Microtubule sensors for glucose, urea, and triglyceride were fabricated based on poly(styrene sulfonate)-polyaniline (PSSPANI) composites synthesized within the pores of track-etched polycarbonate membranes. The synthesis of a sufficiently thick and conducting PSS-PANI film at pH 5 provided the advantage of immobilizing enzymes during polymerization. This resulted in the improvement of sensor response for urea and triglyceride by a factor of ~10^2 with a significant increase in the linear region of response compared to polyaniline-based sensors, where the enzymes were immobilized by physical adsorption after the polymerization. The sensors based on urea and triglyceride were found to have a higher linear range of response, better sensitivity, improved multiple use capability, and faster response time compared to the potentiometric and amperometric sensors based on polyaniline. A microtubule sensor array for glucose, urea, and triglyceride based on PSS-PANI was fabricated by immobilization of three different sets of enzymes on three closely spaced devices and its response was found to be free from cross-interference when a sample containing a mixture of the above analytes was analyzed in a single measurement.