Studies On Factors Influencing The Interactions Of Magnetic Iron Oxide Nanoparticles With Cells And Their Application In Drug Delivery

Magnetic iron oxide nanoparticles?IONPs?are promising advanced materials for various biomedical applications due to their unique physicochemical properties and biocompatibility.In order to fully exploit the potential of IONPs for theranostic applications,an understanding of how these materials react to physiological conditions and critical factors that impact the interactions of these materials with cells is still needed.In this work,influences of size and surface chemistry of IONPs along with the biological fluid composition on the interactions of IONPs with cells were investigated.Furthermore,utilization of IONPs with different surface modifications as drug carriers was comparatively studied regarding to the drug loading capacity,drug release profile and in vitro anticancer performance.The major contributions are as follows:1.Particle size is a crucial factor that influences the interactions of IONPs with cellsHuman breast cancer cells?MDA-MB-231?were exposed to IONPs of 205 nm and 486nm in diameter,respectively,and then cell viability,endocytic efficiency,as well as autophagosomes accumulation were analyzed.Results demonstrated the critical role of particle size in the interactions of IONPs with MDA-MB-231 cells.Compared with 486 nm IONPs,205 nm IONPs showed higher endocytic efficiency by MDA-MB-231 cells,and also induced more autophagosomes accumulation.However,486 nm IONPs exhibited stronger cytotoxicity than 205 nm IONPs,which was due to 486 nm IONPs caused more serious damage to cell membrane.Results also showed that microscopic method that combines light scattering and fluorescence was a simple but effective method for observing the endocytic processes of IONPs by cells.2.Biological fluid composition significantly affects the interactions of IONPs with cellsEnergy dispersive spectrometry?EDS?analyses were performed to confirm the presence of protein corona on the surface of IONPs that were incubated in serum-containing cell culture medium.MDA-MB-231 cells were exposed to IONPs in serum-containing medium and serum-free medium,respectively,and then endocytic efficiency and endocytic pathways of IONPs by cells were investigated.In order to identify the role of serum proteins and salt ions in the interactions of IONPs with cell membrane,giant unilamillar vesicles?GUVs?were prepared and utilized as cell membrane model to interact with IONPs under various conditions.Results showed that serum in medium exerted an inhibitory effect on the endocytosis of IONPs by MDA-MB-231 cells.Furthermore,serum proteins modulated the endocytic pathways of IONPs by MDA-MB-231 cells.However,medium salt ions exhibited a promoting role in the non-specific interactions of IONPs with GUVs.3.Particle surface chemistry and serum in medium play critical roles in the interactions of IONPs with cellsIONPs coated with citric acid?CA-IONP?,IONPs coated with chitosan?CS-IONP?and IONPs coated with folic acid conjugated chitosan?FA-g-CS-IONP?were prepared,and then their physicochemical properties were characterized.Effects of medium pH and ionic strength on the dispersity of IONPs with different coatings were studied.Breast cancer cells?MDA-MB-231?and normal fibroblast?L929?were exposed to IONPs with different coatings,respectively,and then cell viability was analyzed.MDA-MB-231 cells and L929 cells were exposed to IONPs with different coatings in serum-containing medium and serum-free medium,respectively,and then endocytic efficiencies of IONPs by cells were analyzed.Results demonstrated that CA-IONP,CS-IONP and FA-g-CS-IONP all possessed Fe₃O₄ cubic inverse spinel structure and superparamagnetism,whereas the saturation magnetization of IONPs decreased with the increase in weight ratio of organic coatings.IONPs were well-dispersed in medium with low ionic strength and low pH value,however,IONPs tended to agglomerate into larger clusters when the medium ionic strength and pH increased.Results also demonstrated that cytotoxicity of IONPs remarkably decreased after their surfaces were modified with biocompatible chitosan as well as chitosan derivative.Furthermore,both particle surface chemistry and serum in medium play critical roles in the endocytosis of IONPs by cells.4.Particle surface modifications affect the performance of IONPs as drug carriersCA-IONP loaded with doxorubicin?DOX@CA-IONP?,CS-IONP loaded with doxorubicin?DOX@CS-IONP?and FA-g-CS-IONP loaded with doxorubicin?DOX@FA-g-CS-IONP?were prepared respectively.DOX loading capacities of different DOX-loaded IONPs were analyzed.Influences of medium pH on the DOX release profile of DOX-loaded IONPs were investigated.In vitro anticancer efficiency of these DOX-loaded IONPs was studied.Endocytic efficiencies of these DOX-loaded IONPs by MDA-MB-231 cells and L929 cells were analyzed,respectively.Results demonstrated that IONP surface chemistry significantly affects their DOX loading capacity,DOX release profile and in vitro anticancer efficiency.Compared with positively charged IONPs,negatively charged IONPs exhibited higher DOX loading capacity.Compared with IONPs coated with small molecules,IONPs coated with polysaccharide exhibited slower DOX release profile,it might be due to that the DOX in the polysaccharide coated IONPs was more deeply embedded.Compared with DOX@CS-IONP,DOX@FA-g-CS-IONP showed stronger inhibitory effect on the proliferation of MDA-MB-231 cells,it was due to the higher affinity of FA-g-CS-IONP with membrane of MDA-MB-231 cell that overexpressed the folate receptor.Particle surface chemistry,serum in medium and cell line type all affect the endocytosis of IONPs by cells.