Multi-signal information increment sensing system for point-of-care testing of NADH based on cobalt oxyhydroxide nanoflakes

Herein, an innovative multi-signal information increment sensor was proposed to achieve sensitive and immediate detection of nicotinamide adenine dinucleotide (NADH) (just-in-time detection (POCT)) by measuring a series of values such as pressure, temperature and weight without the need for complex instrumentation. Hydrogen peroxide (H2O2) can be decomposed to O2 by cobalt hydroxide (CoOOH) nanosheets in a sealed bottle, accompanied by a significant pressure and a significant temperature increase due to the exothermic effect of the reaction (ΔH =−98.2 kJ mol−1). The increase in pressure forces a certain amount of H2O to spill out from the drainage bottle into the water collection bottle pre-filled with ammonium chloride (NH4Cl), resulting in a significant decrease in the bottle temperature due to the good heat absorption effect of NH4Cl (ΔH=14.8 kJ mol−1). In contrast, NADH can significantly inhibit the catalytic activity of CoOOH and a significant decrease in the pressure, overflow water weight, and temperature response was observed. The changes in response signal can be easily obtained by barometer, electronic balance and thermometer. Importantly, signal amplification is achieved by coupled superposition of incremental and decremental temperature signals to improve the sensitivity of the platform. The obtained barometric pressure difference, temperature difference, weight change and NADH concentration showed good linearity. With a linearity range of 0.9–19 mg mL−1 and a sensor detection limit of 0.26 mg mL−1 NADH, the quantification results of this multi-signal sensor were consistent with those of high-performance liquid chromatography (HPLC).