Reactivity of Poly(anilineboronic acid) with NAD⁺ and NADH

The complexation of poly(anilineboronic acid) with β-nicotinamide adenine dinucleotide (NADH) and its oxidized form, NAD +, has been investigated using electrochemical and spectroscopic techniques. At neutral pH, cyclic voltammetry of poly(anilineboronic acid) exhibits redox activity in the presence of NADH and NAD + characteristic of self-doping. While complexation of both NADH and NAD + with poly(anilineboronic acid) is confirmed with polarization-modulated infrared reflection absorption spectroscopic measurements, a significant difference in redox behavior is observed. 11 B NMR studies suggest that the nature of species responsible for self-doping is different in the case of NAD + and NADH, where the presence of NAD + complex appears to facilitate the formation of the pernigraniline form of the polymer. In addition, a distinct difference in the sensitivity of open-circuit potential measurements is observed upon complexation with NADH and NAD + as a function of the oxidation state of polymer suggesting that reduction of the polymer occurs upon complexation of NADH. The mechanism responsible for the observed behavior is supported by quartz crystal microbalance measurements.