The impact of nano-polystyrene on human serum albumin–paracetamol interactions: understanding the impact on therapeutic development and safety

Abstract

Micro/nano-plastics have become a major threat to living beings. They have already made their way into the human body. In this study, we have elucidated the impact of nanopolystyrene (NPS) on paracetamol–human serum albumin (HSA) interaction. From fluorescence spectroscopic analysis, a dual quenching mechanism (static and dynamic) was identified. The stoichiometry of the binding between HSA and paracetamol decreased from 2 to 0.3 in the presence of NPS. Further, thermodynamic parameters suggested that the reaction is exothermic and spontaneous in the control and treatment groups. The changes in enthalpy (ΔH) and entropy (ΔS) remained negative but decreased with an increase in NPS concentration. This indicates a reduction of van der Waals and hydrogen bonding interactions. Synchronous spectroscopy (Δλ60 nm) in the presence of NPS showed an increase in changes in the tryptophan microenvironment and increased hydrophilicity. Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) spectroscopy results indicated an increase in β-sheets and random coils. The presence of NPS in the HSA–paracetamol interaction leads to significant structural changes. Molecular docking indicated the loss of binding sites for paracetamol on HSA in the presence of NPS. The conformational changes further support the simultaneous reduction in binding sites and increase in binding forces, indicating that the presence of NPS impedes the pharmacokinetics of the drug.