Development of a Colorimetric Sensor Based on Cu-MOFs: WO3 Nanorods for H2O2 and Glucose Detection with High Sensitivity and Selectivity

Abstract

A colorimetric sensor was developed based on the mixture of hydrothermally synthesized tungsten oxide nanorods (WO3 NRs) and copper-based metal-organic frameworks (Cu-MOFs) in order to detect hydrogen peroxide (H2O2) and glucose with high sensitivity and selectivity. By changing pH, temperature and Cu-MOFs: WO3 NRs concentrations, the perox idase-like enzymatic activity of Cu-MOFs: WO3 NRs was investigated to find optimum conditions of the oxidization of 3,3’,5,5’ tetramethylbenzidine (TMB) in the presence of H2O2. Moreover, TMB oxidation steady-state kinetics studies are performed in the presence of Cu-MOFs: WO3 NRs in order to obtain Michaelis-Menten constant value (Km) as a kinetic parameter using Lineweaver-Burk plot. The Km value of the sensor for H2O2 substrate (0.694 mM) is found to be less than that for horseradish peroxidase enzyme (3.7 mM), indicating its higher affinity towards H2O2 with a detection limit of 1.66 µM due to the effective intimate mixing of WO3 NRs and Cu-MOFs. The proposed sensor is also used for colo rimetric detection of sugar such as glucose, galactose, sucrose, lactose, fructose and ribose, resulting in a linear range up to 100 µM and low detection limit of 0.42 µM with short response time for glucose detection. The mixture of WO₃ NRs and Cu-MOFs is intended to synergistically enhance the catalytic activity by improving electron transfer efficiency and light absorption properties. Accordingly, Cu-MOFs: WO3 NRs with low-cost synthesis and ease of modification exhibits good peroxidase-like activity, being suitable to serve as a high performance substitute for natural peroxidases in biosen sors, medicines, catalysis and food industry applications.