Enhanced peroxidase-like activity of platinum nanoparticles decorated on nickel- and nitrogen-doped graphene nanotubes: colorimetric detection of glucose

A nanostructured catalyst is introduced that demonstrates peroxidase mimicking activity. It consists of nickel- and nitrogen-doped graphene nanotubes loaded with platinum nanoparticles. Pt-decorated Ni-doped nitrogen-rich graphitic nanotube (Pt/Ni@NGT) was synthesized using a two-step procedure in which the precursors were first refluxed to form a supramolecular assembly followed by a pyrolysis and leaching step to form nanotubes. Afterwards, Pt was decorated on the outer surface of nanotube by an ultrasound assisted method. Pt/Ni@NGT was characterized by XPS, TEM, SEM, and HAADF–STEM. The as-prepared Pt/Ni@NGT nanostructure was used for the detection of glucose via catalyzing the oxidation of a substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), to form a blue product (ox-TMB), thereby enabling colorimetric assay for enzymatically generated H₂O₂. The nanostructure exhibited excellent biocompatibility and led to highly efficient immobilization and retention of GOx. The method has a linear response in the 43 pM to 220 μM glucose concentration range, a detection limit as low as 1 pM and a limit of quantification of 3.4pM, along with good reproducibility(< 3%). A paper based visual microfluidic assay was also worked out that has an analytical range that extends from 0.1–50 mM. It is simple and rapid enough to be useful as a glucose home test.. The method was successfully applied to the determination of glucose in tear and saliva samples.

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