Preparation Of PH-Responsive Hydrogel Carriers And The Loading Of Resveratrol

Resveratrol(RES)is a natural non-flavonoid polyphenolic compound that exists widely in nature and has various benefits to the human body,but the existence of the double-bond structure makes it very unstable,especially in the human gastrointestinal tract,which results in low bioavailability.Therefore,it is of great significance to develop a delivery system to achieve intestinal-targeted delivery of RES and sustained release to improve its bioavailability.In this study,the effects of the ratio of α-L-guluronic acid(G block)and β-Dmannuronic acid(M block)of the sodium alginate structure and the degree of pectin esterification on the encapsulation and loading efficiency,hardness,and elasticity of the gel carrier,as well as the in vitro release characteristics of RES were discussed.And finally,we chose sodium alginate(M/G = 1:2)and low-ester pectin as raw materials to develop an oral intestinal-specific gel delivery system for encapsulation,transport,and controlled release of RES through ion-crosslinking technology.Combining single factor and response surface experiments,it was determined that the raw material with a concentration of 2.47% and a mass ratio of 1:1 was reacted with a crosslinking agent with a concentration of 4.22% for 24 hours,and 0.40 g/10 m L of RES was added at the same time as the optimal preparation method.The encapsulation and loading efficiency of RES were increased to 92.04 ± 0.32%and 6.41 ± 0.022 mg/g sample,respectively.Scanning electron microscope images show that the gel carrier has a porous structure,which is conducive to the retention of RES.Fourier transform infrared spectroscopy demonstrated the interaction between sodium alginate(M/G = 1:2)and low-ester pectin and the successful coating of RES.Thermogravimetric analysis indicated that the encapsulation of the carrier enhanced the thermal stability of the RES.It was proved by swelling experiments and in vitro simulated gastrointestinal digestion experiments that the carrier had a good p H response,provided good protection for RES in the stomach,and the spherical structure could make the sample pass through the stomach more uniformly.Two hours after oral administration,about 94.71% of the RES can be transported to the small intestine,and finally enter the colon with the prolongation of time.The sustained release time reaches 10 hours totally.At the same time,the gel carrier has great biocompatibility and universal applicability and can encapsulate other health factors,such as curcumin,ascorbic acid,ginsenoside RG3,and EGCG with encapsulation rates of 93.52%,90.33%,81.54%,and 92.27%,respectively.It is also able to load hydrophilic and hydrophobic functional factors simultaneously.The gel carrier not only effectively improves the oral availability of RES but also has broad application prospects.