Catalase-mimicking synthetic nano-enzymes can reduce lipopolysaccharide-induced reactive oxygen generation and promote rapid detection of hydrogen peroxide and l-cysteine

Abstract

Purpose Here, we present the fabrication of a novel molybdenum-based, synthetic blue nano-enzyme (Synz) as an in situ oxygenic catalase mimic for the reduction of H2O2 and the detection of hydrogen peroxide (H2O2) and l-cysteine (l-Cys). Methods Molybdenum-based synthetic nano-enzymes (Synz) were fabricated by the flash freeze-heating method. Field emission scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction analysis, X-ray photoelectron spectroscopy (HP-XPS) and Fourier transform infrared spectroscopy were used for the physicochemical characterization of the developed Synz. Ultraviolet-visible (UV-Vis) absorption spectra were used to detect both H2O2 and l-Cys. Digital photographs were taken to visualize the colour changes in Synz-coated paper incubated with both H2O2 and l-Cys. Results Synz was used as a colorimetric biosensor for the detection of both H2O2 and l-Cys. Furthermore, co-incubation with lipopolysaccharide and Synz reduced the levels of both H2O2 and reactive oxygen species in J77A4 macrophage cells. Additionally, the incubation of H2O2 on Synz-coated cellulose filter paper led to a substantial change in the paper's colour from blue to white with a low H2O2 detection limit of 10 mu M and, on the contrary, retained the blue colour with the addition of an l-Cys + H2O2 solution with l-Cys concentration detection limit of 70 mu M. Conclusion Collectively, our results show Synz to be a promising catalase-mimicking biomaterial that can alleviate H2O2 and be used to develop a low-cost colorimetric paper biosensor for prognostic or theranostic applications.