Abstract

Accurate detection of NADH levels plays a critical role in the diagnosis and management of conditions ranging from metabolic disorders to neurodegenerative diseases such as Parkinson and Alzheimer. It also holds potential for therapeutic interventions targeting mitochondrial function and energy metabolism. Herein, we designed the miniaturized sharp-edged hyper-branched gold microneedles (Au MNDs) decorated with pencil graphitic microelectrodes (PGME) via single-step, green electrochemical deposition strategy in the absence of any redox mediators, organic solvents and enzymes, etc. The as-prepared Au microneedles demonstrate impressive direct electrocatalytic properties for NADH oxidation. Their sharp edges of the microneedles and the optimized transducers ionic mobility effectively enhance electrochemically active surface area and intrinsic charge transfer efficiency, making this electrode a powerful enzyme-mimic platform for detecting NADH. This morphology, combined with the unique surface features, fosters a highly ideal conditions for the rapid electron transfer from NADH to the Au MNDs @PGME. The nanostructures improve the mobility directly influences the speed and efficiency of electronic charge carriers, which accelerates the rate of electron transfer. This enhances the electrochemical kinetics of the system, contributing to rapid and sensitive detection of NADH. These attributes indicate that Au MNDs-modified microsensor holds great potential for high sensitivity (62.80 mu A/mu M cm(-2)), two distinct linear ranges: 0.1-4.5 mu M and 4.5-54.5 mu M, fast response (<2 s), and lower LOD for the reliable NADH detection. The miniaturized microsensors had a strong ability to prevent anti-interference from sensing of NADH. Notably, the current micro sensing platform, which is based on Au MNDs @PGME, has proven to be useful in clinical diagnostics by successfully testing for NADH sensing in human serum and urine samples in biomedical application.