Preparation And Properties Of Intelligent Environment-responsive Polysaccharide Hydrogel

Due to the continuous development of modern medical technology,traditional drug delivery systems(such as oral agents,injections,etc.)cannot meet clinical needs due to the low drug utilization rate and the need for frequent dosing to produce negative effects such as toxic side effects on normal parts.Therefore,the drug carrier that can deliver the drug to the lesion site for drug release has become a research hotspot,and intelligent environment-responsive hydrogels have emerged as the times require.The drug-loaded smart hydrogel can change the phase volume according to the change of pH,temperature,etc.in the environment to achieve the purpose of controlling drug release.As a drug carrier,smart hydrogel not only avoids the damage to the healthy parts of the drug,but also has a slow-release effect,which can improve the drug utilization rate and has a good application prospect.In this paper,three kinds of smart hydrogels were prepared,which were pH-sensitive responsive hydrogel,temperature-sensitive responsive hydrogel and temperature-sensitive in situ gel.Main researches:(1)Preparation of pH-sensitive hydrogel: mixing polyvinyl alcohol(PVA)with carboxymethyl chitosan(CMCS)solution to form a three-dimensional physical network cross-linking structure through hydrogen bonding,hydrogel formation The mechanism is that the amino group of carboxymethyl chitosan and the aldehyde group of oxidized sodium alginate(OAlg)are crosslinked by Schiff-base to form a gel.(2)Preparation of temperaturesensitive hydrogel: Mixing Pluronic-F127(Plu-F127)with carboxymethyl chitosan(CMCS)solution to form a three-dimensional physical network interpenetrating structure,and the formation mechanism of hydrogel is also Schiff-base reaction.(3)Preparation of temperaturesensitive in situ gel: Pluronic-F127 powder was added to the carboxymethyl chitosan solution to dissolve to form a uniform solution.The gelation mechanism is that the molecular chain of the Pluronic-127 is in a contracted state at a low temperature.After the temperature rises,the molecular chain is stretched to form a micelle into a gel.The effects of(1)the concentration and molecular weight of polyvinyl alcohol on gel swelling properties,mechanical properties and pH sensitivity were investigated.(2)The effect of the concentration of Pluronic-F127 on gel swelling performance,mechanical properties,temperature sensitivity and the like.(3)Effect of the concentration of carboxymethyl chitosan on gel time,temperature,viscoelasticity,and dissolution rate of the gel.The drug was loaded with optimal parameters to evaluate drug release performance,antimicrobial performance and biompatibility.The results showed that:(1)The pH-sensitive performance of 2% PVA-105 was the best,and it had obvious pH response in drug release.(2)The temperature-sensitive gel with8% Plu-F127 has the best comprehensive performance and obvious temperature response in drug release.(3)The temperature-sensitive in situ gel with 0.8% CMCS has the best comprehensive performance,and the coagulation and drug release rate has a linear relationship with the dissolution rate.(4)All three drug carriers have a certain drug sustained-release function,and the hydrogel has obvious antibacterial properties against Staphylcus aureus and Escherichia coli after drug loading.