“…Relative humidity barely affects the equilibrium structures of BaP agglomeration and adsorption on graphene, but promotes BaP agglomeration (Additional le 1: Fig. S3), possibly due to liquid bridging forces as previously reported [22]. Upon inhalation and deposition of graphene carrying BaPs in alveoli, the interfacial phenomenon is a result of multiple interactions of varying types, including graphene-BaP, BaP-BaP, BaP-PS, graphene-PS, and PS-PS.…”
Section: Discussionsupporting
confidence: 70%
“…By comparing time sequences of typical snapshots and evolutions of the BaP-BaP interaction energy, humidity was found to promote and stabilize BaP agglomeration (Additional le 1: Fig. S3), possibly due to liquid bridging forces which enhanced the agglomeration velocity as previously reported [22].…”
Section: Bap Agglomeration and Adsorption On Graphenesupporting
Background: Airborne nanoparticles can be inhaled and deposit in human alveoli, where pulmonary surfactant (PS) molecules line at the alveolar air-water interface to act as the first barrier against inhaled nanoparticles entering the body. Although considerable efforts have been made to elucidate the mechanisms underlying nanoparticle-PS interactions, our understanding on this important issue is limited due to the high complexity of the atmosphere, in which nanoparticles are believed to experience transformations that remarkably change the nanoparticles’ surface properties and states. By contrast with bare nanoparticles that have been extensively studied, relatively little is known about the interactions between PS and inhaled nanoparticles which already adsorb contaminants. In this combined experimental and computational effort, we investigate the joint interactions between PS and graphene with coexisting benzo[a]pyrene (BaP).Results: Depending on the BaP concentration and molecular agglomeration, different nanocomposite structures are formed via BaPs adsorption on graphene. Upon deposition of graphene carrying BaPs at the pulmonary surfactant (PS) layer, competition of interactions between different components determines the interfacial processes including BaP solubilization, graphene translocation and PS perturbation. Importantly, BaP adsorbed on graphene is solubilized to increase its bioavailability and inhibit the PS biophysical function. Translocation of graphene across the PS layer is facilitated by BaP adsorption through segregating it from contact with PS, while translocation of graphene oxide is suppressed due to increase of the surface hydrophobicity. Graphene extracts PS molecules from the layer, and the resultant PS depletion declines with graphene oxidation and BaP adsorption.Conclusion: Graphene showed high capacity of adsorbing BaPs to form nanocomposites, which were inhaled and deposit in alveoli, where competition of interactions between different components determined the interfacial processes of BaP solubilization, graphene translocation and PS perturbation.
“…Relative humidity barely affects the equilibrium structures of BaP agglomeration and adsorption on graphene, but promotes BaP agglomeration (Additional le 1: Fig. S3), possibly due to liquid bridging forces as previously reported [22]. Upon inhalation and deposition of graphene carrying BaPs in alveoli, the interfacial phenomenon is a result of multiple interactions of varying types, including graphene-BaP, BaP-BaP, BaP-PS, graphene-PS, and PS-PS.…”
Section: Discussionsupporting
confidence: 70%
“…By comparing time sequences of typical snapshots and evolutions of the BaP-BaP interaction energy, humidity was found to promote and stabilize BaP agglomeration (Additional le 1: Fig. S3), possibly due to liquid bridging forces which enhanced the agglomeration velocity as previously reported [22].…”
Section: Bap Agglomeration and Adsorption On Graphenesupporting
Background: Airborne nanoparticles can be inhaled and deposit in human alveoli, where pulmonary surfactant (PS) molecules line at the alveolar air-water interface to act as the first barrier against inhaled nanoparticles entering the body. Although considerable efforts have been made to elucidate the mechanisms underlying nanoparticle-PS interactions, our understanding on this important issue is limited due to the high complexity of the atmosphere, in which nanoparticles are believed to experience transformations that remarkably change the nanoparticles’ surface properties and states. By contrast with bare nanoparticles that have been extensively studied, relatively little is known about the interactions between PS and inhaled nanoparticles which already adsorb contaminants. In this combined experimental and computational effort, we investigate the joint interactions between PS and graphene with coexisting benzo[a]pyrene (BaP).Results: Depending on the BaP concentration and molecular agglomeration, different nanocomposite structures are formed via BaPs adsorption on graphene. Upon deposition of graphene carrying BaPs at the pulmonary surfactant (PS) layer, competition of interactions between different components determines the interfacial processes including BaP solubilization, graphene translocation and PS perturbation. Importantly, BaP adsorbed on graphene is solubilized to increase its bioavailability and inhibit the PS biophysical function. Translocation of graphene across the PS layer is facilitated by BaP adsorption through segregating it from contact with PS, while translocation of graphene oxide is suppressed due to increase of the surface hydrophobicity. Graphene extracts PS molecules from the layer, and the resultant PS depletion declines with graphene oxidation and BaP adsorption.Conclusion: Graphene showed high capacity of adsorbing BaPs to form nanocomposites, which were inhaled and deposit in alveoli, where competition of interactions between different components determined the interfacial processes of BaP solubilization, graphene translocation and PS perturbation.
“…By comparing time sequences of typical snapshots and evolutions of the BaP-BaP interaction energy, humidity barely affected the equilibrium structure but promoted and stabilized BaP agglomeration (Additional file 1 : Fig. S3), possibly due to liquid bridging forces which enhanced the agglomeration velocity as previously reported [ 29 ]. Fig.…”
Background
Airborne nanoparticles can be inhaled and deposit in human alveoli, where pulmonary surfactant (PS) molecules lining at the alveolar air–water interface act as the first barrier against inhaled nanoparticles entering the body. Although considerable efforts have been devoted to elucidate the mechanisms underlying nanoparticle-PS interactions, our understanding on this important issue is limited due to the high complexity of the atmosphere, in which nanoparticles are believed to experience transformations that remarkably change the nanoparticles’ surface properties and states. By contrast with bare nanoparticles that have been extensively studied, relatively little is known about the interactions between PS and inhaled nanoparticles which already adsorb contaminants. In this combined experimental and computational effort, we investigate the joint interactions between PS and graphene-family materials (GFMs) with coexisting benzo[a]pyrene (BaP).
Results
Depending on the BaP concentration, molecular agglomeration, and graphene oxidation, different nanocomposite structures are formed via BaPs adsorption on GFMs. Upon deposition of GFMs carrying BaPs at the pulmonary surfactant (PS) layer, competition and cooperation of interactions between different components determines the interfacial processes including BaP solubilization, GFM translocation and PS perturbation. Importantly, BaPs adsorbed on GFMs are solubilized to increase BaP’s bioavailability. By contrast with graphene adhering on the PS layer to release part of adsorbed BaPs, more BaPs are released from graphene oxide, which induces a hydrophilic pore in the PS layer and shows adverse effect on the PS biophysical function. Translocation of graphene across the PS layer is facilitated by BaP adsorption through segregating it from contact with PS, while translocation of graphene oxide is suppressed by BaP adsorption due to the increase of surface hydrophobicity. Graphene extracts PS molecules from the layer, and the resultant PS depletion declines with graphene oxidation and BaP adsorption.
Conclusion
GFMs showed high adsorption capacity towards BaPs to form nanocomposites. Upon deposition of GFMs carrying BaPs at the alveolar air–water interface covered by a thin PS layer, the interactions of GFM-PS, GFM-BaP and BaP-PS determined the interfacial processes of BaP solubilization, GFM translocation and PS perturbation.
“…The extensive emission of particles into the atmosphere has caused environmental and health concerns. Adverse effects on the environment include the decline of air quality, reduction of atmospheric visibility and global climate change (Cui et al 2018;He et al 2019). Health hazards include an increase in asthma cases and even severe respiratory and cardiovascular diseases caused by the inhalation of fine particles that can travel to various organs beyond the lungs (Kecorius et al 2017;Chen et al 2018).…”
Heterogeneous condensation of water vapor on the aerosol particles is a very important phenomenon in natural and industrial processes such as the formation of cloud droplets, the measurement of aerosol number concentrations and particulate abatement. In the present work, a mixed surface is created, where the hydrophilic SiO 2 particles are dispersed on the super-hydrophobic substrate. The direct visualization of the heterogeneous condensation process on a smooth spherical single particle is realized by adopting an Environmental Scanning Electron Microscopy (ESEM) system. The time-resolved images captured by ESEM show that only one embryo drop formed at a random position of the particle surface, and the single particle could be gradually contained with the formation of an embryo drop, the enlargement of the spherical-cap shaped drop and the spherical drop. A physical model of heterogeneous condensation is established, and in good agreement with Fletcher's classical nucleation model. Meanwhile, the growth rate of a droplet is obtained experimentally based on the time-resolved images. Then the condensational growth of the droplet is numerically predicted by Kulmala's equations and the numerical results agree well with the experimental data. The growth rate of a droplet decreases with the increase of the droplet size. Finally Lee's condensation mechanisms and the concept of surface free energy are presented to explain the decrease of the growth rate of the droplet.
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