Atomic Force Microscopy Investigation Of The Morphology And Mechanical Properties Of Cell Response To Antibiotic Treatment

The interaction between drugs and cells has attached increasing interest inbiochemistry, basic medicine, pharmaceutical engineering, for it will help clarify theaction mechanism and the effect of drug and it also provide theoretical basis for thedeveloping and screening of antibiotics. Compared with conventional microscopictechniques, atomic force microscope (AFM) has many advantages such as highspatial resolution, no complex sample pretreatment, and wide imaging conditions.AFM imaging has been widely used in the research of interaction between drugs andcells, since it can image living cells under physiological conditions in anon-destructive manner. More importantly, AFM force measurement technology canbe used to study the mechanical properties of cell, which is one of the key parametersof cell activity. So AFM force measurement technology is a effective means forevaluation the effects of cell.The result provided a direct observation of morphological and mechanicalproperties to investigate the action mechanism of drug. The main contents aresummarized as follows:1. Atomic force microscopy (AFM) was used to investigate the morphology andmechanical properties of HeLa cells in response to antibiotic treatment. The AFMimaging and force measurement results showed that there were at least three changesfor HeLa cells after they were treated with nystatin. First, the shape of the cellschanged from the full polygon to circle and the height of cells decreased; second, thesurface roughness of the cells increased; third, the cell membrane became softer andits elasticity decreased. The above results were consistent with the action mechanismof nystatin. This work demonstrated that AFM was a useful tool for studying theinteraction between drugs and cells.2. AFM imaging and force measuring were used to investigate the morphologyand mechanical properties of yeast in response to antibiotic treatment at living celllevel. After treatment with nystatin and caspofungin, the cell surface roughness hadno obvious change, while the cell size decreased and the elastic modulus decreasedobviously. At low drug concentration, the morphology and size of the yeast has notchanged, while the modulus of elasticity has been significantly reduced.The results show that the changes of cell mechanical properties were moresensitive than the change of morphology; force measuring technology is a kind of more effective means for the study of drug effects on cells. Compared with nystatin,the effect of caspofungin on yeasts is more obvious. At the same time, the effect ofpenicillin, chloramphenicol and rifampicin on yeast is not obvious. These results willprovide important information for the study of action mechanism of antibiotic.