Preparation And Performance Research Of Intelligent F127-based Composite Hydrogels

Hydrogels have excellent water absorption and retention capabilities,and are widelyused in the fields of biomedicine,smart materials,and environmental protection,especially as anticancer drug delivery systems.Hydrogels can be prepared by physical and chemical methods.Among them,physical hydrogels are favored by researchers due to their simple,environmentally friendly preparation process,and unique properties of reversible,self-healing.This thesis aims to prepare non-traditional chemically cross-linked hydrogels with low-cost,renewable materials,and simple methods to achieve sustained and controlled release of loaded drugs.Cyclodextrin(CD),lysine,graphene oxide(GO)and tannic acid(TA)were selected and cross-linked with commercial Pluronic^?F127 through physical interactions and dynamic chemical bonds.Designed and prepared four intelligent F127-based composite hydrogels.The gelation mechanism,gelation properties,rheological properties,and internal morphology of F127-based hydrogels were systematically studied,and the anticancer drug 5-fluorouracil(5-FU)was loaded to study the drug release properties.The main contents are as follows:(1)A series of F127–?-CD hydrogels were prepared by mixing F127 with natural polysaccharide?-CD.The end of F127 could pass through the inner cavity of?-CD to form inclusion complexes,and further self-assembled into microcrystalline regions.The cross-linking points of F127–?-CD system were micelles and microcrystalline regions.F127–?-CD hydrogel had a temperature-dependent sol–gel transition behavior and an adjustable critical gel temperature(CGT)near physiological temperature.The higher cross-linking density and the hydrophobic inner cavity of?-CD reduced the cumulative release of F127–?-CD hydrogels to the loaded 5-FU.Among them,F127–?-CD hydrogel with F127 content of 2.0%had the most obvious release effect.(2)F127 was modified with oligolysine to synthesize the pentablock copolymer FL.FL-2,FL-5,and FL-8 with different oligolysine polymerization degrees were obtained,by changing the composition ratio.FL hydrogels had temperature-dependent micelle transition and gel transition behavior,and had dual responsiveness of temperature and p H.The introduction of lysine increased CGT of the hydrogel,endowed the hydrogel p H responsiveness,and provided chemical sites for subsequent reactions.FL-2hydrogel had low cytotoxicity and cell encapsulation ability.FL-2 hydrogel showed a linear release pattern for the loaded drug within 12 hours,and the cumulative release percentage finally reached 89.5%.(3)A series of FLGO hydrogels were prepared by adding GO to the synthetic FL-5.FL-5 micelles were adsorbed to the surface of GO through electrostatic interactions and hydrogen bonds,and GO acted as a cross-linking agent in FLGO hydrogels.With the increase of GO content,the CGT of FLGO hydrogel decreased,the glass transition temperature decreased,and the stability increased.The cross-linking effect of GO and its hydrophobic basal plane made FLGO hydrogels have a low release rate.The ionization of the hydroxyl groups on the edge of GO and the protonation of the amino groups on FL-5 made FLGO hydrogel have a p H-adjusted release rate,which could be released quickly in an acidic environment.(4)Part of the phenolic hydroxyl groups on plant-derived polyphenol TA were modified into aldehyde groups,and then mixed with synthetic FL-5 to prepare two groups of FLa T hydrogels.The Schiff base was introduced into the hydrogel system on the basis of physical interaction.The amino groups on FL-5,and the phenolic hydroxyl groups and aldehyde groups of the modified TA formed hydrogen bonds and Schiff base bonds respectively.FLa T hydrogels had injectability,self-healing,temperature and p H dual responsiveness.FLa T-2 hydrogel containing more Schiff base bond had faster gelation speed,enhanced mechanical properties and self-healing ability.FLa T hydrogel exhibited linear release pattern of loaded drugs within 6 days,and a p H-adjusted the release rate,which released quickly under acidic conditions.In this paper,four non-traditional chemical cross-linked intelligent F127-based composite hydrogels were designed and prepared.These F127-based composite hydrogels had the CGT near physiological temperature and enhanced stability,had an effective release effect on loaded drugs,and had the p H-adjusted release rate that met the release requirements of tumor lesions.Therefore,the intelligent F127-based hydrogels had potential applications in biomedicine fields such as drug delivery systems.