Preparation And Properties Of Curcumin-loaded Polyacrylamide Hydrogels

Hydrogels are three-dimensional networks composed of hydrophilic macromolecules which have many virtues such as liquid absorption,biocompatibility,flexibility,and ductility.As a substitute for traditional dressings such as absorbent cotton gauze and non-woven fabrics,it can provide a good healing environment for wounds while bringing a comfortable experience for patients.Therefore,hydrogels are ideal dressings with great application prospects.In recent years,with the development of science and technology,intelligent dressings have become an important fulcrum leading the reform and upgrading of the dressing industry.“Wound monitoring”and“controlled drug delivery”are two important innovation directions of the current intelligent hydrogel dressings.Here,polyacrylamide（PAM）hydrogels were used as carriers to load functional monomer curcumin to prepare p H-responsive hydrogels and stress-stimulus-responsive hydrogels,respectively.The explorations in the two aspects of"wound monitoring"and"controlled drug delivery"would provide some experiences for the intelligent research of hydrogel dressings.The specific research contents are as follows:In the second chapter,the hydrophobic monomer curcumin was dissolved in polypropylene glycol（PPG）to form a stable emulsion with an aqueous solution of acrylamide monomers（AM）,and then the AM monomers were polymerized in situ to prepare polyacrylamide hydrogels with a low curcumin-loading.The structures of the curcumin-loaded polyacrylamide hydrogels were characterized,and the effects of molecular weight of PPG on the properties of the hydrogels were investigated.The research results showed that the PPG2000 hydrogels showed better comprehensive performances than PPG600 hydrogels.The highest tensile strength was 178 k Pa,the adhesion strength reached up to 29 k Pa,the swelling rate was between 2100～2600%,and the water vapor transmission rate（WVTR）was1500～2500 g/m~2/day,which was suitable for wound dressings.The curcumin-loaded polyacrylamide hydrogel also exhibited good antibacterial capability,biocompatibility,and low hemolysis rate,which could be used as a dressing to promote wound healing of the mice.In addition,benefiting from of the p H sensitivity and fluorescence properties of curcumin,combined with smartphone photography and RGB analysis,precise monitoring of the p H changes of the hydrogel could be achieved under natural light and UV light sources.In the third chapter,modified F127（named as F127DA）was prepared by connecting a double bond to the end of polyether F127,and then F127 and F127DA were used to embed curcumin to prepare polyacrylamide hydrogels with a high curcumin-loading,respectively.The effects of F127 and F127DA on the properties of the hydrogels were explored,mainly focusing on the release of curcumin from the hydrogels under different stress stimuli.The results showed that the curcumin-loaded polyacrylamide with F127DA had good mechanical properties with a breaking strength of 159 k Pa,a maximum elongation at break of 384%,and a maximum adhesive strength of 36 k Pa.The release rate of curcumin increased with the increase of strain,and the effect of compression was more obvious than that of stretching.The release amount of curcumin under pulse stimulation was higher than that under static stimulation,and the cumulative release amount increased in step shape.Compared to chemical or biological triggers,application of mechanical force provided a relatively predictable control in direction and an adjustable magnitude management toward precision release of therapeutics.It was convenient for the patients themselves to regulate the release dosage and timing of the drug.