A polymer dot-based NADH-sensitive electrochemiluminescence biosensor for analysis of metabolites in serum

Nicotinamide adenine dinucleotide (NADH) plays a pivotal role in metabolism. Convenient detection of NADH and its related metabolites has the pursuit of point-of-care and clinical analysis. Here, we propose a polymer dots (Pdots)-based NADH-sensitive electrochemiluminescence (ECL) biosensor for detection of NADH and three metabolites. Pdots acted as the efficient ECL emitters without additional modification to construct this biosensor. Specially, NADH both acted as the final detection target and at the same time as the bio-coreactants to sensitively influence the ECL intensities, in which NADH was generated or consumed in the presence of the target analyte and their specific enzyme. For glucose and lactic acid detection, NAD⁺ was reduced to NADH to generate an enhanced ECL signal. Conversely, for pyruvate detection, NADH was consumed to further decrease the ECL. The designed Pdots-based ECL biosensor showed wide detection ranges, high selectivity and low limits of detection of 4.6 μM, 0.7 μM and 0.5 μM for the analysis of three analytes, respectively. This strategy was successfully applied in quantifying the concentrations of glucose, lactic acid and pyruvate in human serum, which also has the potential to be implemented as a powerful and fast tool for ECL sensing of NADH and other related metabolites for point-of-care use and disease monitoring.