Spectroscopic analysis of the interaction between Co₃O₄ nanoparticles and acid phosphatase

In this study, the structure and stability of acid phosphatase in its interaction with Co₃O₄ nanoparticles are evaluated through absorbance, enzyme activity assay, fluorescence, thermal stability, and circular dichroism spectroscopy. It had been found that with the enhancement of Co₃O₄ nanoparticle concentration, the intensity of the enzyme's ultraviolet spectrum was increasing. In fact, under these conditions (pH 4.8, T = 310 K), the activity of acid phosphatase was raised too. Also, it was revealed that by enhancing the concentration of the nanoparticles, the enzyme thermal stability increased from 342.0 to 346.0 K. Also, far-UV CD investigations illustrated that the Co₃O₄ nanoparticles could alter the secondary structure of acid phosphatase through an increase in the value of the α-helix structure (from 10.8 to 13.9%) and a decrease in the β-sheet (from 30.2 to 28.0%). By raising the temperature from 298 to 308 K, the Stern–Volmer constant decreased from 5.72 × 10⁴ to 4.39 × 10⁴ M⁻¹. Also, it was found which Co₃O₄ nanoparticles quenched the intrinsic fluorescence of acid phosphatase by the static quenching mechanism. Therefore, the thermodynamic parameters showed that the binding process was spontaneous because the value of ∆G was negative. Also, van der Waals forces and hydrogen bonding interactions had the main effects on the interaction of Co₃O₄ nanoparticles with acid phosphatase because the values of ∆H and ∆H were negative. So, Co₃O₄ nanoparticles increased the stability and activity of acid phosphatase. Graphic abstract: