Pt-Decorated\nBoron Nitride Nanosheets as Artificial\nNanozyme for Detection of Dopamine

Abstract

Over the past decade,\nnanosized metal oxides, metals, and bimetallic\nparticles have been actively researched as enzyme mimetic nanomaterials.\nHowever, the common issues with individual nanoparticles (NPs) are\nstabilization, reproducibility, and blocking of active sites by surfactants.\nThese problems promote further studies of composite materials, where\nNPs are spread on supports, such as graphene derivatives or dichalcogenide\nnanosheets. Another promising type of support for NPs is the few-layered\nhexagonal boron nitride (hBN). In this study, we develop surfactant-free\nnanocomposites containing Pt NPs dispersed on chemically modified\nhydrophilic hBN nanosheets (hBNNSs). Ascorbic acid was used as a reducing\nagent for the chemical reduction of the Pt salt in the presence of\nhBNNS aqueous colloid, resulting in Pt/hBNNS nanocomposites, which\nwere thoroughly characterized with X-ray diffraction, transmission\nelectron microscopy, dynamic light scattering, and X-ray\nphotoelectron and infrared spectroscopies. Similar to graphene\noxide binding the metal NPs more efficiently than pure graphene, hydrophilic\nhBNNSs well stabilize Pt NPs, with particle size down to around 8\nnm. We further demonstrate for the first time that Pt/hBNNS nanocomposites\nexhibit peroxidase-like catalytic activity, accelerating the oxidation\nof the classical colorless peroxidase substrate 3,3′,5,5′-tetramethylbenzidine\n(TMB) to its corresponding blue-colored oxidized product in the presence\nof H₂O₂. Kinetic and mechanism studies involving\nterephthalic acid and isopropanol as a fluorescent probe and an ^•OH radical scavenger, respectively, proved that Pt/hBNNSs\nassist H₂O₂ decomposition to active oxygen species\n(^•OH), which are responsible for TMB oxidation.\nThe Pt/hBNNS nanocomposite-assisted oxidation of TMB provides an effective\nplatform for the colorimetric detection of dopamine, an important\nbiomolecule. The presence of increased amounts of dopamine gradually\ninhibits the catalytic activity of Pt/hBNNSs for the oxidation of\nTMB by H₂O₂, thus enabling selective sensing\nof dopamine down to 0.76 μM, even in the presence of common\ninterfering molecules and on real blood serum samples. The present\ninvestigation on Pt/hBNNSs contributes to the knowledge of hBN-based\nnanocomposites and discovers their new usage as nanomaterials with\ngood enzyme-mimicking activity and dopamine-sensing properties.