Toxical Effects Of PM2.5 On A549 Cells Investigated By Raman Spectroscopy And AFM Mechanics

PM2.5 is one of the major air contaminants,with complicated components.PM2.5 can seriously influence human health since it may lead to lung disease,cardiovascular disease,respiratory disease,etc.Studies on the effects of PM2.5 on cells are of great significance for an in-depth understanding of the development mechanisms of PM2.5-related diseases,as well as for helping figure out effective prevention strategies for PM2.5-induced diseases.In this work,human lung carcinoma epithelial cells(A549)were used as the model cells and the influences of PM2.5 on A549 cells were investigated with confocal Raman micro-spectroscopy and atomic force microscopy(AFM)on the single cell level,respectively.In combination with other techniques,the chemical and structural changes of cells upon exposure to PM2.5 were disclosed.The effects of PM2.5 from different regions(Chongqing,Chengdu and Suzhou)on A549 cells were investigated,respectively.Upon the treatment of the cell for 2 h at a PM2.5 concentration of average daily volume,the characteristic peaks of Raman spectra show that the contents of protein and nucleic acid of cells increase for both of these PM2.5 from different regions.AFM data indicate that PM2.5 from Suzhou region results in decreased cellular adhesion work and increased cellular elastic energy while PM2.5 from the other two regions have no significant influence on the mechanical properties measured.To serve the local environment research,the influence of PM2.5 from Chongqing region on A549 cells was further investigated.Raman spectrum show that the contents of cellular protein,nucleic acids and lipids increase with the exposure time.AFM results show that cells exposure to PM2.5 for 24 h have significantly decreased cellular adhesion work and increased cellular elastic energy than the control group,indicating PM2.5 induced structural changes of cells.TEM imaging and western blot techniques were employed to further confirm the structural changes.Western blot assays indicate that the content of the ?-tubulin and ?-actin of PM2.5 treated cells are higher than the control group,suggesting the amount of both microtubules and microfilaments in treated cells increased,which is consistent with the increase of elastic energy of treated cells.Taken all together,we established a method of using Raman spectroscopy and AFM mechanics to interrogate the influence of PM2.5 on A549 cells and found that the amount of chemicals such as protein,nucleic acid and lipids increased and the structures including microvilli and cytoskeleton changed,upon the treatment of cells by PM2.5.The present study demonstrated a new approach to explore the actions of PM2.5 on cells and can provide useful information on understanding the development mechanisms of PM2.5 related diseases.