ZnO Nanoparticles/Lipid-coated ZnO Nanoparticles Synthesis,Characterization And Cytotoxicity Studies

ZnO nanoparticles(NPs)attract a lot of attention for fundamental studies and potential applications in different research areas.ZnO NPs represent a versatile functional material,and their superior properties find current and potential applications in physical chemistry,biomedical sciences,catalysts,microelectronics,textile,cosmetics,etc.Because of the large specific surface area,small size effect,and other physical and chemical properties.The size/morphology control and stability improvement of nanomaterials have also received extensive attention from researchers.Wherein,in the direction of nanomaterial morphology/size control,the crystal is grown by a non-classical crystal growth model to obtain nanoparticles of a desired morphology,and further,the self-assembly and encapsulation of ZnO NPs by phospholipid bilayer can enhance the stability of the solution and improve the biocompatibility,thereby achieving the purpose of reducing cytotoxicity,and is a feasible method.This paper is divided into three parts.In the first part,by exploring the synthesis conditions of ZnO NPs(pH value,reaction time and growth temperature and precursor concentration),ZnO NPs with good suspension in solution were obtained.The structural morphology,chemical properties and the morphology/size evolution of ZnO NPs was systematically discussed.In the second part,ZnO NPs with three different morphologies,such as spherical,columnar and rod-shaped,were prepared by using the developed conditions.According to the characteristics of the molecular structure of phospholipids,the three kinds of ZnO NPs were encapsulated,which significantly improved the stability of the material in solution.In the third part,the toxicological characteristics of the ZnO NPs and phospholipid encapsulated ZnO NPs,including cytotoxicity,apoptosis and cell morphology analysis,were studied from the perspective of morphology and concentration.(1)The ZnO NPs were synthesized by wet chemical method at low temperature,and ZnO NPs with good dispersion and suspension in solution were obtained by changing the reaction conditions.The morphology/size evolution of ZnO NPs in ethanol solution was analyzed,and ZnO NPs with different morphologies was obtained.The crystal nucleation and growth were analyzed and described,and proved to be consistent with the oriented attachment(OA)growth model.(2)Different morphologies/sizes of ZnO NPs(spherical⁷ nm,columnar¹8 nm,rod⁴9 nm)were synthesized.The samples were encapsulated with phospholipids to obtain three other phospholipids with different morphology/size(¹3 nm,²2 nm,⁵2 nm)and demonstrated the success of phospholipid bilayer encapsulation.The phospholipid bilayer can self-assemble on the surface of inorganic nanocrystals to form a complete and dense covering layer,thus prevent the reaction between ZnO nanocrystal and the aqueous solution.It also greatly enhances the colloidal and chemical stability of the particles in aqueous solution.(3)Phospholipid bilayer can improve the colloidal stability,prevent the aggregation and dissolution of nanocrystal particles in the solution,and avoid the dissolution of ZnO nanomaterials into Zn²⁺cations,thus,reduce cytotoxicity and stress response.Compared to the pristine ZnO NPs(⁷ nm,¹8 nm,⁴9 nm),lipid-coated ZnO NPs(¹3 nm,²2 nm,⁵2 nm)could improve the colloidal stability,prevent the aggregation and dissolution of nanocrystal particles in the solution,and avoid ZnO NPs dissolution into Zn²⁺cations,and thus reduce their cytotoxicity.Compared to Lipid-coated ZnO NPs group,pristine ZnO NPs(⁷ nm,¹8 nm,⁴9 nm)damaged the cells at lower concentrations,in a dose-dependent manner.At the same concentration,ZnO NPs(⁷ nm)exhibited the highest cytotoxicity.Noteworthily,for lipid-coated ZnO NPs,the higher level of concentration doesn't suggest higher cytotoxicity.