Fig. 20. (A) Fabrication of the iron nitride (FeN) NPs/NG core–shell hybrid. (B) NADH measurement mechanism involving a FeN NPs/NG core–shell hybrid-based electrode. (C) Selective amperometric response of FeN NPs/NG/GCE after adding (a) 1 mM NADH, (b) 1 mM glucose, (c) UA, (d) dopamine, and (e) AA at an applied potential of +0.35 V. (D) Stability of FeN NPs/NG/GCE based sensor in 0.5 mM NADH at an applied potential of +0.35 V showing 96.18% of initial current retention after 1000 cycles. [Reprinted with permission from ref. 429, J. Balamurugan, T. D. Thanh, N. H. Kim and J. H. Lee, Facile Fabrication of FeN Nanoparticles/Nitrogen-Doped Graphene Core-Shell Hybrid and Its Use as a Platform for NADH Detection in Human Blood Serum, Biosens. Bioelectron., 2016, 83, 68–76. Copyright© Elsevier.].