Recognition of the Enzymatically Active and Inhibitive Oxygenous Groups on WO_3–x Quantum Dots by Chemical Deactivation and Density Functional Theory Calculations

Abstract

The design and construction of efficient nanozymes are vital for bio/chemo-sensing applications, while the systematic catalytic mechanism study is the prerequisite. Tungsten oxide (WO3–x ) quantum dots (QDs), an alternative to conventional heavy metal-containing semiconductor QDs, possess peroxidase-like activity but limited catalytic efficiency. Therefore, the functions of the typical oxygenous groups in determining the enzymatic activity of the WO3–x QDs by target-specifically shielding the carboxyl (COOH), hydroxyl (OH), or carbonyl (CO) groups, respectively, using a chemical titration method. The results show that the CO groups could accelerate the nanozymatic catalysis kinetically, while the OH ones were the catalytically inhibitive sites, which were further corroborated by the density functional theory (DFT) computations. The application potential of the WO3–x derivatives with an enhanced catalytic ability was verified via the colorimetric cholesterol sensing. The proposed method based on the benzoic anhydride (BA)-modified WO3–x QDs with deactivated OH groups showed a wider linear range and higher sensitivity than those based on the unmodified ones.

Malic acid-coated iridium nanoparticle-induced cascade enzymatic reactions for norepinephrine detection

“…Furthermore, in contrast to carboxyl groups, the presence of hydroxyl groups in the coating agent is beneficial for the nucleophilicity of the nanozymes. 15,16 Malic acid (2-hydroxybutanedioic acid, MA) has two carboxyl groups and small molecular weight, and hence it is selected as the stabilizer in the present work. As expected, the resultant MA-IrNPs exhibited excellent oxidase, peroxidase, catalase and laccase activities.…”

Spectrophotometric detection of uric acid with enzyme-like reaction mediated 3,3′,5,5′-tetramethylbenzidine oxidation

“…Huang's group established a colorimetric sensing platform for H2O2, ascorbic acid and dopamine detection based on WO3 nanowires (NWs) with peroxidase-like activity [29]. As a peroxidase mimetic, WO3 quantum dots (QDs) have been applied to construct cholesterol colorimetric sensor [30]. Because of its excellent peroxidase activity, WO3 nanosheets (NSs) were also applied for the colorimetric determination of xanthine [31].…”