Unraveling the binding interaction between polyvinyl chloride microplastics and bovine hemoglobin: Multi-spectroscopic studies

In this paper, the interaction between polyvinyl chloride microplastics (PVC MPs) and bovine hemoglobin (BHb), a carrier of oxygen in the blood circulation system, has been investigated by multi-spectroscopic techniques. The UV-vis absorption and steady state fluorescence spectroscopy prove that BHb molecules can be bound to the surface of PVC MPs by their electrostatic force interaction, and the up-conversion fluorescence measurements confirm that the lifetimes of BHb remain unperturbed in this process. Circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy further demonstrate that the BHb-PVC MPs binding has clearly changed the secondary structures of BHb. Moreover, the interactions between PVC MPs with different sizes (0.5, 1 and 2 µm) and BHb have been studied and compared, indicating that the binding affinity decreased with the increasement of particle size of PVC MPs. Those results have implied that microplastics could enter the human blood circulatory system and organs, and might be potentially toxic to the human body.