Investigation of the Interaction between Platinum Nanozymes and Serum Albumin by Multispectroscopic Approach and Molecular Docking Simulation

The interaction between platinum nanozymes (PtNZs) and serum albumin (SA), including human serum albumin (HSA) and bovine serum albumin (BSA), was comprehensively analyzed through a combination of ultraviolet-visible (UV-vis) absorption, fluorescence (FL), circular dichroism (CD) spectroscopy, and molecular docking simulation. The differences in the binding between SA and PtNZs were compared based on thermodynamic data. The spectral experimental results indicated that PtNZs interact with HSA and BSA to varying degrees, with BSA exhibiting a stronger binding affinity for PtNZs than HSA. The fluorescence results indicate that the fluorescence intensity of SA is quenched by platinum nanozymes, with static quenching being the main mechanism. The <i>K</i>_a values of HSA binding with PtNZs is smaller than that of BSA at the same temperature, indicating a relatively weak affinity between HSA and PtNZs. Negative Δ<i>G</i> values suggest that this interaction is a spontaneous process, while positive Δ<i>H</i> values are classified as endothermic processes. Δ<i>H</i> > 0 and Δ<i>S</i> > 0 proved that hydrophobic interactions were the primary driving forces in the binding processes. Synchronous fluorescence and excitation emission matrix spectroscopy indicated that the structure of tyrosine (Tyr) and tryptophan (Trp) residues in HSA/BSA had undergone slight changes, with their secondary structure also exhibiting subtle alterations. Molecular docking simulations yielded the number and type of amino acids bound to the surface of PtNZs within 3 Å as well as the energy of the binding system. Analysis of the CD spectra shows that the interaction with PtNZs causes secondary structural changes in HSA/BSA.