Deciphering the mechanism of hafnium oxide nanoparticles perturbation in the bio-physiological microenvironment of catalase

Nanoparticles (NPs) are extensively being used in state-of-the-art nano-based therapies, modern electronics, and consumer products, so can be released into the environment with enhancement interaction with humans. Hence, the exposures to these multifunctional NPs lead to changes in protein structure and functionality, raising serious health issues. This study thoroughly investigated the interaction and adsorption of catalase (CAT) with HfO2-NPs by circular dichroism (CD), Fourier transform infrared (FTIR), absorption, and fluorescence spectroscopic techniques. The results indicate that HfO2 NPs cause fluorescence quenching in CAT by a static quenching mechanism. The negative values of Vant Hoff thermodynamic expressions (ΔHo, ΔSo, and ΔGo) corroborate the spontaneity and exothermic nature of static quenching driven by van der Waals forces and hydrogen bonding. Also, FTIR, UV-CD, and UV–visible spectroscopy techniques confirmed that HfO2 NPs binding could induce microenvironment perturbations leading to secondary and tertiary conformation changes in CAT. Furthermore, synchronous fluorescence spectroscopy confirmed the significant changes in the microenvironment around tryptophan (Trp) residue caused by HfO2 NPs. The time depending denaturing of CAT biochemistry through HfO2-NPs was investigated by assaying catalase activity elucidates the potential toxic action of HfO2-NPs at the macromolecular level. Briefly, this provides an empathetic knowledge of the nanotoxicity and likely health effects of HfO2 NPs exposure.