Preparation Of Drug Carriers Based On Cell Surface Coating

A drug carrier is a medium that is mainly used to load drugs,but it has certain special properties that will change the way the drug entering the human body,its distribution in the body,and its specific role in the lesion.The drug controlled release system can control the release of the drug after it reaches the lesion,further improving the utilization and effectiveness of the drug,and greatly reducing the frequency of drug administration,so it has attracted widespread attention.As the controlled release system,most of the drug carriers are polymer materials,but there are still some disadvantages,such as poor biocompatibility,complex synthesis,uneven particle size distribution,and slow degradation rate in human body.Nano-inorganic materials have achieved good research results in controlled drug release systems.Many materials,such as calcium phosphate,silicon oxide and zinc oxide,have been used as drug carriers,but their applications may be limited due to the complex preparation process.Based on the technology of cell surface shelling and layer by layer self-assembly,we explored a new drug carrier with hollow porous structure.In chapter 2,we reported a simple self-assembly method to prepare Ca CO₃-HNPs by using yeast as biological template,Poly（dimethyl diallyl ammonium chloride）（PDDA）/Poly（sodium-p-styrenesulfonate）（PSS）as polyelectrolyte.At the same time,FT-IR,XRD,SEM and other testing methods were used to characterize the microparticles.The results showed that the prepared Ca CO₃-HNPs had a small uniform particle size,good dispersibility,and high crystalline calcite spherical calcium carbonate.Then,doxorubicin hydrochloride（DOX）,a typical hydrophilic anticancer drug,was used as a model drug to investigate the drug loading,DOX release mechanism under different p H conditions,and the degradation of Ca CO₃-HNPs under different p H conditions.The results showed that Ca CO₃-HNPs had good drug loading rate,good biocompatibility and p H sensitivity.In general,Ca CO₃-HNPs has a good application prospect as a p H sensitive sustained-release drug carrier.In chapter 3,in order to give drug carriers more functions,we explored the feasibility of surface modification by layer by layer self-assembly method.In this paper,Fe₃O₄ nanoparticles were prepared by coprecipitation method,and then Fe₃O₄ was modified on the surface of yeast cells by layer by layer self-assembly method with PDDA/PSS as polycation/polyanion.The results showed that in the process of preparing magnetic Fe₃O₄,the best Fe₃O₄ was prepared by mechanical agitation and PEG4000 as the active agent.In addition,when using PDDA/PSS as polyelectrolyte to modify Fe₃O₄ on the surface of yeast cells,with the increase of the number of layers of polyelectrolyte,the adsorbed Fe₃O₄ particles also increased,but the more layers of polyelectrolyte,the more irregular the shape of yeast cells,so it is the best choice to wrap three layers of polyelectrolyte on the surface of yeast cells.In short,with the method of layer by layer self-assembly,the functional inorganic materials can be modified to the surface of yeast cells by using polyelectrolyte,and the corresponding functions of yeast cells can be given successfully.This can be combined with the calcium carbonate drug carrier in chapter 2,which is expected to achieve the preparation of multi-functional drug carrier.In chapter 4,we tried to use this method to deposit the inorganic material shell on the yeast surface,and prepare calcium phosphate microspheres and silica microspheres by high-temperature calcination.The results showed that this method was not successful in the preparation of calcium phosphate microspheres,It may be that some factors in the reaction process lead to the formation of dicalcium hydrogen phosphate or calcium pyrophosphate,and the prepared sample does not have a hollow porous structure,so it cannot be used as a drug carrier for research.However,this method can successfully prepare silica microspheres.The prepared silica microspheres have high purity,good dispersion,small particle size and pore on the surface,which can be used as drug carriers for further study.To sum up,the preparation of drug carrier based on cell surface shelling and layer by layer self-assembly technology is simple and easy to operate.The prepared carrier has hollow porous structure,and the drug loading rate is considerable without expensive equipment and materials.In addition,it can also be combined with a variety of functional materials to prepare multi-functional drug carriers,so it has a broad application prospect.