Poly(vinyl chloride) microplastics induce structural and functional alterations in myoglobin

Microplastics (MPs) pollution represents a global concern for biodiversity conservation, ecosystem and public health. The poly(vinyl chloride) Microplastics (PVC-MPs) are one of the dominant pollutants in both terrestrial and aquatic ecosystem. Myoglobin (Mb) is an important intracellular oxygen-binding protein found in mammals' hearts and skeletal muscles. Mb act as an oxygen transporter and storage material in muscle cells. Due to molecular inertness and excellent accessibility to organisms, PVC-MPs are degraded slowly in the atmosphere and can accumulate in the mammalian bloodstream, posing major health risks. In this study, under simulated physiological conditions, the interaction between the emerging pollutant PVC-MPs and Mb was analysed using multispectroscopic studies. From these studies, it has been found that PVC-MPs may bind to Mb during transportation and metabolic activities. Because of their tiny size, PVC-MPs may bind with Mb once they enter the bloodstream, altering the structure and physiological function of Mb. These results also suggest that electrostatic forces were the primary factor behind the interaction between PVC-MPs and Mb. Additionally, the results further showed that PVC-MPs significantly altered the microenvironment and secondary structure of Mb, which decreased the α-helix. This study clarifies the possible molecular toxicity of PVC-MPs in addition to provide crucial insight into the intermolecular interaction between PVC-MPs and Mb.