A bifunctional metal organic framework of type Fe(III)-BTC for cascade (enzymatic and enzyme-mimicking) colorimetric determination of glucose

A metal organic framework (MOF) of type Fe(III)-BTC (where BTC is 1,3,5-benzenetricarboxylic acid) was utilized to construct an integrated system for cascade colorimetric determination of glucose. The MOF performs a dual function in acting (a) as a peroxidase (POx) mimic, and (b) as a solid support for immobilization of glucose oxidase (GOx). The MOF was prepared by a one-pot method. Glucose is consumed while H2O2 is produced during the enzymatic oxidation by GOx. In the presence of H2O2, the POx mimic catalytically oxidizes 3,3′,5,5′-tetramethylbenzidine (TMB) to form a blue-green product. The absorbance of oxidized TMB (measured at 652 nm) increases linearly in the 5.0–100 μM glucose concentration range, and the detection limit is 2.4 μM. The GOx@Fe-BTC MOF was successfully applied to the determination of glucose in serum.