Study On The Formation Mechanism And Cytotoxicity Of Aromatic Organic Aeroso

Aromatic compounds are an important precursor of secondary organic aerosols（SOA）,which are emitted into the atmosphere by biomass combustion,fossil fuel evaporation,combustion release etc.Aerosols are formed through photooxidation,causing harmful effects on the atmospheric environment and human health.Toluene and PCBs are the main components of aromatic compounds,but the aerosol formation mechanism is not fully understood.To address this issue,an atomistic molecular dynamics（MD）approach and density functional theory（DFT）are coupled to study the molecular chemistry of toluene SOAs by examining their structural characteristics and thermodynamic properties.Besides in this paper,polychlorinated biphenyls（PCBs）with high toxicity was taken as an example to systematically study the cytotoxicity mechanism of SOA.Here,we propose a hierarchical-multiscale framework for analyzing the cellular translocation and cytotoxicity of PCBs by consolidating experimental techniques,density functional theory,and microsecond-long molecular dynamics simulations motivated by adaptively enhanced 1D-and 2D-free-energy samplings.Our results suggest that the molecular hierarchical synergistic effects majorly determine the formation of core–shell SOA nanoparticles.In the toluene photooxidation production,H₂SO₄–H₂O clusters are nuclear structures,pyruvic acid acts as a“bridge”that promotes the concentration of benzaldehyde and benzoic acid at the surface of H₂SO₄–H₂O clusters.Besides,the chemical composition and environmental temperature have a key role in the probability distribution and lifetime of hydrogen bonds of toluene SOAs,the number of hydrogen bonds and the probability of hydrogen bond existence of the simulation system lacking pyruvate are lower than other simulation systems,thus altering the formation energy barrier of gas-to-nanoparticle conversion.When compared with van der Waals interactions,electrostatic interactions are found to be the central driving force that yields stable toluene SOA nanoparticles.Our results reveal the molecular chemistry of the atmospheric aerosol and highlight the need to account for molecular hierarchical synergistic effects when assessing the atmospheric aerosol.Besides,our findings show that the trade-off effect derived from the differentiated non-covalent bindings pervades the translocational events both dynamically and thermodynamically.Specifically,well-compensated non-covalent bondings（binding affinity difference<14.5 kcal/mol）cooperatively result in a five-stepwise pathway of“flipping（Ⅰ→Ⅲ）-insertion-uptake”for PCBs across biological membranes,whereas badly-deviated non-covalent bondings exacerbate the competitively active-binding of PCBs onto biological membrane surfaces.In addition,the solution dispersion and cytotoxicity of PCBs nanoparticles were characterized by zeta potential and cytotoxicity experiments,which were positively correlated with the PCBs transmembrane transport energy barrier,and the experimental results were consistent with the simulation results in thermodynamics and thermodynamics.In this paper,based on experimental techniques,density functional theory and molecular dynamics simulation methods,the mechanism of aromatic compounds is the formation mechanism of secondary organic aerosols,and then the related cytotoxicity mechanism is studied,which provides theoretical guidance for air pollution and prevention.