A novel metal-organic framework of Ba-hemin with enhanced cascade activity for sensitive glucose detection.

Early glucose detection is important in both healthy people and diabetic patients. Glucose biosensing based on glucose oxidase (GOX) is a common method. However, native proteins are mostly membrane impermeable and are prone to degradation in complex sample environments. Herein, we report a facile one-step biomineralization method by simply mixing aqueous solutions of hemin and barium nitrate with glucose oxidase (GOX) to form Ba-hemin@GOX composites. Glucose (Glu) is introduced through self-driven sampling to trigger the GOX-catalysed production of hydrogen peroxide, which could help the subsequent 3,3',5,5'-tetramethylbenzidine (TMB) oxidation reaction catalysed by Ba-hemin to yield the blue-coloured product. The sensor exhibited a detection limit as low as 3.08 μM. The operability and accuracy of the Ba-hemin@GOX biosensor were confirmed by the quantitative determination of glucose in real samples, such as tap water, serum and drinks. Moreover, the Ba-hemin@GOX-based colorimetric biosensor showed good selectivity, storage stability and recoverability. The experimental results reveal that a GOX activity of more than 90% was still maintained even after being incubated at 60 °C for 30 minutes, and Ba-hemin@GOX could be reused for glucose detection at least six times. Even after 30 days of storage, the relative activity was still more than 90%. Overall, the developed Ba-hemin@GOX biosensor provides a valuable and general platform for applications in colorimetric biosensing and medical diagnostics.