GOX-hemin nanogels with enhanced cascade activity for sensitive one-step glucose detection

Early glucose detection is important in both healthy people and diabetic patients. The glucose colorimetric detection techniques usually consist of multiple steps and their preparation processes are time consuming. In this work, we fabricate a GOX-hemin nanogel (GHN) that could be used for one-step colorimetry detection of glucose. The GHN was prepared by carrying out polymerization on the surface of GOX. Each GOX-hemin nanogel consists of a single GOX encapsulated with a thin polymer network containing hemin. The proximity of hemin to GOX facilitates two reactions, i.e. the oxidation of glucose catalysed by GOX to yield H₂O₂, and the subsequent 3,3',5,5'-tetramethylbenzidine (TMB) oxidation reaction catalysed by hemin to yield the blue colored product. These processes work in tandem, which greatly enhances the efficacy, sensitivity and stability of the detection system. The limit of detection in our system was determined to be as low as 4 μM. Furthermore, the glucose detection activity still maintained more than 70% even after being incubated at 55 °C for 30 minutes, or in 20% (v/v) aqueous solution of DMF, CH₃CN or THF for 25 minutes at room temperature. It is anticipated that this work can provide a method for developing diverse functional materials based on proteins.