Portable glucose biosensor based on polynorepinephrine@magnetite nanomaterial integrated with a smartphone analyzer...

This work describes a novel nanoplatform based on polynorepinephrine (PNE) grafted on magnetite nanoparticles (Fe₃O₄) with glucose oxidase (GOx) from Aspergillus niger (Fe₃O₄@PNE-GOx). The system was integrated with a smartphone analyzer as a potential point-of-care testing (POCT) biosensor for glucose measurement. Covering the magnetite surface with the biomimetic polymer polynorepinephrine significantly increased the effectiveness of enzyme immobilization which was 38.40 mg g^-1, compared with 17.30 mg g^-1 on the bare surface of magnetite. The Fe₃O₄@PNE-GOx nanoplatform was deposited on a screen-printed electrode (SPE) and then used with the world's smallest ready-to-go potentiostat and a smartphone in tandem for glucose measurement. This biosensor displayed abroad range of linearity (0.2-24 mM), a low detection limit (6.1 μM), and good sensitivity (97.34 μA mM^-1 cm^-2). Moreover, it exhibited a fast electrocatalytic response (8 s), and long-term stability (up to 20 weeks). It was used to detect glucose in real samples such as human serum, human blood, infusion fluid, and commercial glucose solutions. The results obtained indicate that the proposed biosensor may be an attractive system for point-of-care testing (POCT), or in various industries, using asmartphone and potentiostat in tandem.