5,10,15,20-tetrakis(4-carboxyl phenyl)porphyrin-CdS nanocomposites with intrinsic peroxidase-like activity for glucose colorimetric detection.

Here, we describe the design of a novel mimic peroxidase, nanocomposites composed by 5,10,15,20-tetrakis(4-carboxyl phenyl)-porphyrin (H2TCPP) and cadmium sulfide (CdS). The H2TCPP-CdS nanocomposites can catalyze oxidation of substrate 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H2O2 and form a blue product which can be seen by the naked eye in 5 min. The mechanism of the catalytic reaction originated from the generation of hydroxyl radical (·OH), which is a powerful oxidizing agent to oxidize TMB to produce a blue product. Then, we developed a colorimetric method that is highly sensitive and selective to detect glucose, combined with glucose oxidase (GOx). The proposed method allowed the detection of H2O2 concentration in the range of 4×10(-6)-1.4×10(-5)M and glucose in the range of 1.875×10(-5)-1×10(-4)M with detectable H2O2 concentration as low as 4.6×10(-7)M and glucose as low as 7.02×10(-6)M, respectively. The results provided the theoretical basis of practical application in glucose detecting and peroxidase mimetic enzymes.