▎ 摘　　要

The good mechanical and biological performance of natural biopolymers is important factor in biomedical science. In metabolism, nicotinamide adenine dinucleotide (NAD) is involved in redox reactions, carrying electrons from one reaction to another. On such a basis, much attention has been devoted to developing procedures to monitoring the presence of NAD at very low concentrations in a physiological environment and biological fluids. The good mechanical and biological performance of natural biopolymers is important factor in bone tissue engineering. Herein, a new platform based on silver nanoparticles (Ag NPs) and nitrogen doped graphene quantum dots (N-GQD(s)) is developed for sensitive voltammetric detection of NAD in human plasma samples. N-GQD(s)-Ag NPs film were prepared by the full electrochemically method onto the surface of GCE. Ag NPs were covalently bonded to N-GQDs films and used to bind of NAD biomarker. The novel detection scheme is a suitable electrochemical assay, which makes the NAD detection simple and rapid. The engineered electrochemical sensor showed a linear dynamic range and low limit of quantification limit of 1.45-7.9 mu M and 1.45 mu M, respectively. The proposed sensor showed excellent analytical performance for the detection of NAD with high sensitivity and reproducibility. The prepared sensor detected NAD ion human plasma samples with high recovery values. We hope that this platform has the potential to be used in clinical applications and point of -care diagnosis of disease.