Elucidation of the Critical Role of Core Materials in PM_(2.5)-Induced Cytotoxicity by Interrogating Silica- and Carbon-Based Model PM_(2.5) Particle Libraries

摘要

An insoluble core with adsorbed pollutants constitutes the most toxic part of PM_(2.5) particles. However, the toxicological difference between carbon and silica cores remains unknown. Here, we employed 32-membered carbon- and silica-based model PM_(2.5) libraries that each was loaded with four toxic airborne pollutants including Cr(Ⅵ), As(Ⅲ), Pb~(2+), and BaP in all possible combinations to explore their contributions to cytotoxicity in normal human bronchial cells. The following three crucial findings were revealed: (1) more adsorption of polar pollutants in a silica core (such as Cr(Ⅵ), As(Ⅲ), and Pb~(2+)) and nonpolar ones in a carbon core (such as BaP); (2) about 41% more cell uptake of carbon- than silica-based particles; and (3) about 59% less toxicity in silica- than carbon-based particles when pollutants other than Cr(Ⅵ) were loaded. This was reversed after Cr(Ⅵ) loading (silica particles were 56% more toxic). The difference maker is that compared to stable silica, carbon particles reduce Cr(Ⅵ) to less toxic Cr(Ⅲ). Our findings highlight the different roles of carbon and silica cores in inducing health risks of PM_(2.5) particles.