Facile fabrication of FeN nanoparticles/nitrogen-doped graphene core-shell hybrid and its use as a platform for NADH detection in human blood serum

• A novel strategy for the synthesis of FeN NPs/NG core-shell hybrid has been proposed.
• The FeN NPs-NG/GCE demonstrates as direct and mediatorless responses to NADH oxidation at low potential.
• FeN NPs-NG/GCE displays a high sensitivity, selectivity, reproducibility, and long term stability.  .
• FeN NPs-NG/GCE offers innovative platform for the electrochemical detection of NADH in human blood serum.

Herein, we present a novel strategy for the synthesis of an iron nitride nanoparticles-encapsulated nitrogen-doped graphene (FeN NPs/NG) core-shell hierarchical nanostructure to boost the electrochemical performance in a highly sensitive, selective, reproducible, and stable sensing platform for nicotinamide adenine dinucleotide (NADH). This core-shell hierarchical nanostructure provides an excellent conductive network for effective charge transfer and avoids the agglomeration and restacking of NG sheets, which provides better access to the electrode material for NADH oxidation. The FeN NPs/NG core-shell hierarchical nanostructure demonstrates direct and mediatorless responses to NADH oxidation at a low potential. This material displays a high sensitivity of 0.028 μA/μM cm2, a wide linear range from 0.4 to 718 μM, and a detection limit of 25 nM with a fast response time of less than 3 s. The interferences from common interferents, such as glucose, uric acid, dopamine, and ascorbic acid, are negligible. The fabricated sensor was further tested for the determination of NADH in human blood serum. The resulting high sensitivity, excellent selectivity, outstanding stability, and good reproducibility make the proposed FeN NPs/NG core-shell hierarchical nanostructure as a promising candidate for biomedical applications.