Preparation Of The Camptothecin Loaded Vitamin A-decorated Mesoporous Hollow Silica Nanosphere And Its Anti-fibrotic Function Study

Liver fibrosis is an injury repair response to chronic liver damage and specifically manifested by excessive production and deposition of extracellular matrix(ECM)components,particularly collagen.A variety of cells and signaling molecules act in different ways in the formation of hepatic fibrosis,eventually resulting in imbalance of ECM synthesis and degradation and liver fibrosis.Activated hepatic stellate cells(HSC)synthesizes and secrete a large amount of ECM,which is an important cause of hepatic fibrosis.Therefore,inhibition of proliferation of the activated HSCs,promotion of their apoptosis,and reversal of their activated phenotype have become major anti-hepatic fibrosis approaches.At present,many anti-fibrotic drugs are poorly soluble in water,sparingly bioavailable and highly toxic.When made into salt,these drugs lower their activities and are easily cleared by the systemic circulatory system after entering into the body,which limits their clinical use.Nano drug-loading system has become a hotspot in the field of pharmaceutics and nanomedicine because of its characteristics of improved drug availability and controlled release rate.Hollow mesoporous silica nano(HMSN)particles,as a new type of drug delivery system,have the controllable particle size,large specific surface area and pore volume,high drug loading rate,and sustained release of drugs.Moreover,its internal and external surfaces are easily modified.HMSNs have good biocompatibility,and therefore have attracted wide attention.In this dissertation,we attempted to construct a HMSN drug delivery system coupled with VA for the carry of camptothecin.In vitro experiment was conducted to examine the specific targeting of the nano-vehicles at the activated HSCs,and the anti-fibrotic effects of the loaded camptothecin via inhibition of glycolysis of activated HSCs and reversal of the MF phenotype.First,We synthesized four types of nanocarriers: amino-modified silica,VA-coupled silica,chitosan-coated silica,and conjugate-coated silica(The letters SiO2-NH2,SiO2-CONH-VA,SiO2-CS,and SiO2-CS-VA respectively replace the previous four carriers),Then FTIR,DLS,Zeta,BET,TG,SEM,WB and other methods were used to investigate their physical and chemical properties to verify the successfμL preparation of these HMSN particles and the success of the retinol targeting ligand modification.At the same time,it was determined by the cytotoxicity and blood compatibility of the four nanocarriers that they all have good biocompatibility.Next,the engulfment of four HMSN particles loaded with Nile red fluorescent dye by the activated HSC T6 cells and Hela cells was examined using fluorescence microscopy and flow cytometry.The resμLts showed that T6 cells,but not HeLa cells,preferentially took up the two VA-decorated nano-systems.VA modification can effectively mediate the active targeting of nanocarriers at the activated hepatic stellate cells in vitro.Finally,four HMSN particles loaded with CPT were prepared and their physicochemical properties were evaluated.In vitro drug release analysis showed that chitosan coating significantly improved the pH-responsive sustained release function of the CPT loaded HMSN.Cytotoxicity evaluation and gene and protein expression analysis showed that the four CPT nanoparticles were quite toxic to HSCs and effectively reversed the activated phenotype of HSCs,and both the VA modification and the chitosan coating significantly improved these anti-fibrotic activities of the whole CPT nanomedicines.These results indicate that the CPT loaded VA modified HMSN spheres possess the good active targeting at HSCs,the excellent pH-responsive release control function and the expected activity to inhibit the activated HSCs,showing a nice potential as a novel anti-fibrosis therapeutic.