Electrogenerated Chemiluminescence of Phosphate-Modified Polymeric Carbon Nitride for Sensing of NADH: Role of Luminophore–Coreactant Interactions in Enhancing the Signal

Abstract

Graphitic carbon nitride (GCN) is a potential material that has attracted a large attention for its application in electrogenerated chemiluminescence (ECL) due to its unique optical and electronic properties. Nanostructured and modified forms of GCN shows highly stable and intense ECL signals than the bulk counterpart. We report here that introducing phosphate species with different amounts during the synthesis of bulk GCN alters its morphology, surface area, bandgap and ECL properties. Interestingly, the phosphate (0.125%)-modified polymeric carbon nitride on glassy carbon electrode (PCN-0.125/GCE) showed an enhanced ECL intensity which is four times higher than that of the bulk GCN. Also, the ECL intensity shows a dependence on the phosphate content. Among the different coreactants tested, use of tri-propylamine (TPrA) resulted in the higher ECL intensity. The interaction between PCN-0.125 and TPrA could play an important role by forming an ion-pair that was revealed from 1H MAS-NMR spectroscopic results. The significance of this work lies in the gradual increase in the ECL intensity of PCN-0.125/GCE with each addition of nicotinamide adenine dinucleotide (NADH) in the range of 10 to 70 nM with 5.2 nM as the limit of detection (LOD). Our work demonstrates a new ECL sensing platform using an earth-abundant, easy-to-synthesize material, PCN, to detect NADH at lower level and this will be more useful in clinical diagnostics.