Study The Cytotoxicity Of Nanodrugs And Carriers Based On Atomic Force Microscopy

Synthetic macromolecular polymerization had enlightened the field of biomedical applications of drug delivery systems.In that perspective,polyamidoamine dendrimers（PAMAM）provide an essential scientific breakthrough in the structural designing of different bioactive materials to enhance and exposed their specific functions.However,most of the reported studies focused on the toxicity of cell membrane.It is of great importance to investigate the cytotoxicity to have a better understanding of the underlying mechanism that application of PAMAM in nanomedicine.In this study,atomic force microscopy（AFM）based nanoindentation technology can be used to measure the mechanical properties of individual cells under physiological conditions.By comparing the changes of cell mechanical properties（Young’s modulus）after different generations and different terminal groups of PAMAM,the cytotoxicity of PAMAM was analyzed.Meanwhile,the cell membrane adsorption on cytotoxicity was studied by nanoindentation technology and fluorescence microscopy.The research progress is as follows:1.Analysis of cell cytotoxicity treated with PAMAM by AFM-based nanoindentation.Studies have shown that the Young’s modulus of He La cells after coincubation with G5-PAMAM-NH₂（0.5μmol/L）for different time（0 h,0.5 h,1 h,and 2 h）become0.61±0.49 k Pa、0.45±0.33 k Pa、0.46±0.33 k Pa and 0.22±0.15 k Pa.However,the Young’s modulus o of He La cells after coincubation with G5-PAMAM-NH₂ for 2 h at different concentrations（0.5μmol/L,1μmol/L and 2μmol/L）.become 0.30 k Pa、0.20 k Pa、0.17 k Pa and 0.22 k Pa.It was found that for G5-PAMAM-NH₂,time was the dominant factor of cytotoxicity,while for G5-PAMAM-COOH,concentration was the dominant factor of cytotoxicity.2.Analysis of the effect of PAMAM cell membrane adsorption on cytotoxicity by AFM-based nanoindentation and fluorescence microscope.By comparing the Young’s modulus of He La cells after coincubation with G2-PAMAM-NH₂,G5-PAMAM-NH₂,G7-PAMAM-NH₂,G5-PAMAM-OH and G5-PAMAM-COOH after between 2 h and0.5+1.5 h.Similarly,Fluorescence imaging and nanoindentation experiments confirmed that the cell membrane absorption of G5-PAMAM-NH₂ and G7-PAMAM-NH₂ prolonged their cytotoxicity.3.Young’s modulus of He La cells after coincubation with paclitaxel（0.1μmol/L、1μmol/L、10μmol/L）for 2 h become 1.99±1.10 k Pa、2.57±1.53 k Pa and 1.68±1.53 k Pa.The stiffness of the treated cells for paclitaxel was larger than that of the untreated cell caused by microtubule polymerization.In contrast,it decreased for treatments 10μmol/L by cytotoxicity causes cell apoptosis.This study will provide an important theoretical basis for the better application of PAMAM in nanomedicine.