Construction of an ultrasensitive non-enzymatic sensor to investigate the dynamic process of superoxide anion release from living cells.

In this work, a novel non-enzymatic superoxide anion (O•) sensor was constructed based on Ag nanoparticles (NPs) / poly (amidoamine) (PAMAM) dendrimers and used to investigate the dynamic process of O• release from living cells. The AgNPs/PAMAM nanohybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The fabricated electrode exhibited excellent catalytic activity toward the reaction of O• with a super low detection limit (LOD) of 2.530 × 10M (S/N = 3) and wide linear range of 8 orders of magnitude. It could fulfill the requirement of real-time measurement O• released from living cells. Furthermore, zymosan was chosen as the stimulant to induce O• generation from cancer cells (rat adrenal medulla pheochromocytoma cell (PC12)). The electrochemical experiment results indicated that the levels of intracellular O• depended on the amount of Zymosan. A large amount of O• generated in the living cells by added heavy stimulant could damage cells seriously. More importantly, a vitro simulation experiment confirmed the role of superoxide dismutase (SOD) for the first time because it could maintain the O• concentration at a normal physiological range. These findings are of great significance for evaluating the metabolic processes of O• in the biological system, and this work has the tremendous potential application in clinical diagnostics to assess oxidative stress.