Quantitative Cellular Uptake Of Gold Nanorods By Single Cell Mass Spectrometry

Gold nanoparticles(Au NPs)are widely used in biological research because of their unique properties.As Au NPs enters the biological system or cell culture medium,phenomena such as protein adsorption are bound to occur,resulting in particle dispersion,agglomeration and particle surface functionalization.These phenomena may interact with cells and affect their uptake of Au NPs to a certain extent.At the same time,the traditional way to quantify cellular uptake of Au NPs via ICP-MS measurement after the acidic digestion of cell populations can not specifically and accurately reflect how the changes in nano-properties affect the cellular uptake of NPs at the single-cell level.Therefore,understanding the heterogeneity in cellular uptake of NPs is fundamentally important to wide-ranging fields nanotoxicology and drug delivery.In this paper,rod-like Au NPs(Au NRs)were selected as research objects,and mouse macrophage line(RAW264.7)and mouse breast cancer cell line(4T1)were used as cell model.The time-dependent uptake of Au NRs and Au NRs-protein complex in the two kinds of cells,the spatial distribution of uptake,and the heterogeneity in cellular uptake of Au NRs were studied by single-cell quantification with Single-Cell Inductively Coupled Plasma Mass Spectrometer(SC-ICP-MS)and Laser Ablation Inductively Coupled Plasma Mass Spectrometer(LA-ICP-MS).The main work is as follows:(1)Scanning electron microscope(SEM)and Transmission electron microscope(TEM)were used to characterize the dispersion state of Au NRs and the BSA(bovine serum albumin)-precoated Au NRs,and then UV-Vis was used to characterize the agglomeration and sedimentation of BSA-coated Au NRs in pure water and cell medium.The results showed that Au NRs showed a completely different dispersion state after BSA pre-coating with different mass ratio.The high mass ratio BSA-precoated Au NRs kept monodispersed in pure water.While the low mass ratio BSA-precoated Au NRs appeared agglomeration.(2)The cellular uptake of protein-precoated Au NRs was quantified by SC-ICP-MS.The results showed that the particle dispersion state caused by protein pre-coating significantly affected the cellular uptake.The heterogeneity in cellular uptake of Au NRs in monodispersing state was lower than that of Au NRs agglomerated.(3)The heterogeneity in cellular uptake of Au NRs and Au NRs-protein complex was absolutely quantified by LA-ICP-MS.The results revealed time-dependent,agglomeratesdistribution-dependent,and sampling-location-dependent heterogeneities in cellular uptake of Au NRs.To sum up,the cellular uptake of protein-precoated Au NRs was analyzed by single-cell analysis by SC-ICP-MS.The results showed that particle aggregation significantly affected cellular uptake and changed the intercellular heterogeneity.Absolute quantitative analysis of NPs uptake by cells was carried out by LA-ICP-MS,which further showed the effects of cell uptake time,agglomerates distribution and sampling location on the heterogeneity of Au NRs uptake.The results provide an important basis for the understanding of NPs uptake heterogeneity at the single-cell level as well as the impacts of protein-coating.