A solid-state pH transducer fabricated from a self-plasticized methacrylic-acrylic membrane for potentiometric acetylcholine chloride biosensor

Abstract

A solid-state pH sensor based on a self-plasticizing film of methacrylic-acrylic copolymer was developed. The sensor was able to detect changes in pH after tridodecylamine ionophore was immobilized together with a lipophilic anionic salt. The pH sensor exhibited almost a Nemstian response (57.6 mV pH−1) with a linear pH response range of 6–10. It demonstrated a fast response (<2 min) to changes in pH and good selectivity against other common cations such as sodium, potassium, magnesium, lithium, and calcium. The sensor has a shelf life of at least 30 days without an obvious deterioration in response. By depositing a layer of poly(hydroxylethymethacrylate) immobilized with enzyme acetylcholinesterase on top of the pH selective methacrylic-acrylic film, the pH sensor was able to detect acetylcholine chloride (AChCl). The linear response range of the potentiometric biosensor to AChCl was dependent on the buffer concentrations used, and for a buffer concentration less than 1 mM, the linear response range obtained was 3.98–31.62 μM.