Interactions of Fly Ash Particles with Mucin and Serum Albumin

Fly ash particles can contribute to haze and adverse health outcomes. In this study, two mucins, one from bovine submaxillary glands (bovine submaxillary mucin, BSM) and one from porcine stomach (porcine gastric mucin), as well as bovine serum albumin (BSA), which served as the physical barriers against foreign substances entering the tissues and the blood protein, respectively, were chosen as models for the investigations of the interactions between the proteins and the fly ash particles. Their adsorption behaviors were studied using spectroscopy and a quartz crystal microbalance with a dissipation monitor (QCM-D). The results indicated that the fly ash particles can induce the loosening of mucins and BSA, probably via the formation of complexes. Further, the secondary structure of proteins changed in the presence of fly ash particles. The α-helix content decreased with an increasing fly ash particle concentration. The addition of fly ash particles into protein solutions led to fluorescence quenching, which suggested that there were interactions between these particles and the mucins and BSA. The association constants ( K_a) for BSM and BSA were 5.35 and 4.18 L/g, respectively. Furthermore, the results of QCM-D analyses showed that the amount decreased on the mucin surface but increased slightly on the BSA surface, which indicated that the fly ash particles disrupted the mucin layer upon adsorption. These findings provide clear evidence of the interactions between the fly ash particles and the mucins and BSA, which can lead to structural changes. This study contributes to a better understanding of the interactions and adsorptions of atmospheric particulate pollutants with the proteins in the human body.