Processible polyaniline as an advanced potentiometric pH transducer. Application to biosensors

An advanced potentiometric pH transducer based on processible polyaniline ( PCPAn) is reported on. Both glassy carbon and screen-printed carbon electro des modified with PCPAn by dip-coating exhibited a fully reversible potenti ometric response of approximately 90 mV/pH unit over the range from pH 3 to 9. Such a significantly higher potentiometric response of PCPAn-modified e lectrodes as compared with those of existing devices is explained on the ba sis of the thermodynamics of polyaniline redox reactions. The PCPAn-based p H transducers exhibit both good operational stability and prolonged shelf l ife and display a negligible response toward singly charged cations. The ne w thick-film pH transducer was employed for designing a potentiometric bios ensor for urea. Zn the model solution which mimics blood serum, the urea-se nsitive electrode has a detection limit of 10(-5) M urea and a maximum resp onse of similar to 120 mV, The attractive performance characteristics are a dvantageous over those of existing pH sensors and offer great promise for s ensing and biosensing applications.