A novel colorimetric assay based on the peroxidase-like properties of amino functionalized copper metal-organic framework nanoparticles for ascorbic acid sensing

A rapid and sensitive calorimetric strategy for the determination of ascorbic acid (AA) is presented, using amino functionalized copper metal-organic framework nanoparticles (Cu-BDC-NH(2)NPs) with effective intrinsic peroxidase-like properties. In our design, Cu-BDC-NH(2)NPs catalyze the H2O2 oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) generating blue-colored oxidized TMB (ox-TMB) with a significant absorbance at 655 nm in the UV-vis spectrum. AA can reduce ox-TMB, inducing a dramatic blue color fading and a decrease in absorbance. Under the optimal experimental conditions, this proposed system presents a good linear relationship (0.5-60 mu M) and the detection limit is 0.15 mu M. Repeatability, high selectivity and practicability are also well-studied, proving that the sensing system based on Cu-BDC-NH(2)NPs can be successfully applied for calorimetric detection of AA in human serum, food and pharmaceutical samples. The designed method can provide a highly selective and sensitive optical sensing system to detect AA and establish a new platform to develop extensive applications of metal- organic framework nanoparticles with enzyme-mimetic activity in calorimetric biosensing.