High-performance non-enzymatic glucose sensing on nanocomposite electrocatalysts of nickel phthalocyanine nanorods and nitrogen doped-reduced graphene oxide nanosheets

Highly stable and efficient electrocatalytic materials are essential for developing high-performance non-enzymatic fourth-generation glucose biosensors. In this regard, hybrid materials incorporating metallophthalocyanines and carbon-based nanostructures are particularly interesting. A nanocomposite of nitrogen-doped reduced graphene oxide nanosheets and nickel phthalocyanine nanorods (N-rGONs|NiPcNRs) was prepared. N-rGONs|NiPcNRs were highly efficient and stable electrocatalysts for non-enzymatic d-glucose electrooxidation in alkaline media. Spectroscopic, microscopic, and electrochemical methods were used to characterize and evaluate the electrocatalytic performance of the N-rGONs|NiPcNRs. The remarkable electrocatalytic activity of N-rGONs|NiPcNRs originated from the in-situ transformation and formation of polymeric O-Ni-O oxo-bridge in alkaline electrolyte and the excellent electroconductivity of the N-rGONs. The N-rGONs|NiPcNRs with the optimum ratio of NiPcNRs to N-rGONs presented an efficient formation of the Ni-O-Ni oxo-bridge and d-glucose electrooxidation compared to N-rGONs and NiPcNRs alone. Thus, the fabricated GCE|N-rGONs|NiPcNRs glucose sensor showed an excellent analytical performance with a high sensitivity of 1458 µA.mM−1.cm−2 and a detection limit of 1.43 µM (S/N = 3) using cyclic voltammetry. For online glucose detection using chronoamperometry, a sensitivity of 358.9 µA.mM−1.cm−2 with a detection limit of 5.0 µM (the lowest concentration that could be discriminated from the buffer using GCE|N-rGONs|NiPcNRs) and a fast response time of 0.80 s was obtained. The high sensitivity of CV (1458 µA.mM−1.cm−2) allowed for lower limits of detection (1.34 µM). The fabricated sensor was successfully applied for the determination of d-glucose levels in serum samples, demonstrating its potential for monitoring glucose levels in diabetes patients.