Construction Of Nano-drug-loading System Of Stigmasterol Derivative And Its Inhibition Effect On HT-29 Cells

Paclitaxel is widely used as a broad-spectrum antitumor drug.In order to improve its biocompatibility and reduce the toxicity to normal cells,there are more and more reports on its application in nanoparticles for treatment.Since natural plant sourced sterols have various physiological activities such as anti-tumor,anti-oxidation and hypolipidemic and good biocompatibility,they can be used as carriers to deliver drugs for better anti-tumor effects.In this study,stigmasterol was used as the structural nucleus,and 3,3'-dithiodipropionic acid containing disulfide bond was grafted by covalent bond to construct a nanocarrier with redox responsiveness to study its antitumor activity when loaded paclitaxel.The main contents of this study are as follows:First,the stigmasterol derivative?SD?is synthesized by covalently linking the hydroxyl group of stigmasterol with the carboxyl group of 3,3'-dithiodipropionate by ester condensation,and the formation of the target product is determined by thin layer chromatography.The SD was isolated and purified,and the structure of SD was identified by ¹H-NMR and ¹³C-NMR.The results showed that SD was successfully synthesized with a yield of 18%.Stigmasterol derivative nanoparticles?SDNs?were prepared by ultrasonic emulsification.The morphology of the phytosterols was optimized by scanning electron microscopy.The proportion of emulsifier,the type of organic solvent and the preparation method were optimized.Using CCl₄ as solvent and CCl₄:2.5%PVA=1:4,the morphology of the sample was observed by tin foil dispensing is the optimal preparation conditions for SDNs.Scanning electron microscopy showed that the SDNs were spherical.The average particle size of the SDNs was 270±3.2 nm and the Zeta potential was-22.1±0.3 mV.The SDNs were tested by infrared spectroscopy,contact angle and X-ray diffraction.The stimuli responsiveness of the particle size indicated that the SDNs had some stimuli responsiveness to glutathione and papain.Secondly,the drug-loaded nanoparticles SDNs@PTX were prepared.The optimal dosage of paclitaxel was determined by observing the morphology to be 15%.At this time,the drug-loaded nanoparticles were spherical.The average particle size of SDNs@PTX was 315.9±2.6 nm.The zeta potential is-24.8±2.4 mV.It was proved by infrared spectroscopy,contact angle and X-ray diffraction that the drug could be successfully coated by nanoparticles through hydrophobic interaction.The encapsulation efficiency and drug loading of the nanoparticles by paclitaxel were 35%and 4.56%,respectively.In vitro drug release experiments showed that SDNs@PTX had multiple stimuli-responsive release to pH,glutathione and papain.Under acidic conditions or with increasing amounts of glutathione and papain,the release of loaded drugs increased.Finally,the growth inhibition of human colon cancer cell line HT-29by SDNs@PTX was preliminarily evaluated by cell phagocytosis,cytotoxicity assay and cell morphology observation.The results showed that the IC₅₀ value of SDNs@PTX to HT-29 cell line was 0.159?g./mL,with the increase of time,the phagocytosis of SDNs@PTX by tumor cells gradually increased,and its anti-tumor effect also gradually increased.