Lysine-Functionalized Tungsten Disulfide Quantum Dots as Artificial Enzyme Mimics for Oxidative Stress Biomarker Sensing

The color generating from the biochemical reaction between 3,3',5,5'-tetramethylbenzidine and Lysine@WS2 QDs was used a signal for the detection of hydrogen peroxide. The QDs were prepared using a combination of techniques, that is, probe sonication and hydrothermal treatment. Analysis via UV-vis spectroscopy, Fourier transform infrared and Raman spectroscopy, X-ray diffraction, energy-dispersive spectroscopy, and transmission electron microscopy yielded detailed information on the nature and characteristics of these quantum dots. Furthermore, as-synthesized quantum dots were studied for their capability to mimic peroxidase enzyme using 3,3',5,5'-tetramethylbenzidine as a substrate. Consequently, a colorimetric sensor utilizing Lysine@WS2 QDs could detect hydrogen peroxide in a range of 0.1-60 mu M with a response time of 5 min. The same material was used for H2O2 detection using impedance spectroscopy, which yielded a dynamic range of 0.1-350 mu M with a response time of 30-40 s.