Fabrication Of Poly（Acrylic Acid） Hydrogel And Study On The Orally Hypoglycemic Effect Of Insulin-loaded Hydrogels

BackgroundInsulin is clinically used in the treatment of type I diabetes.Different methods of insulin administration have their advantages and disadvantages.The adverse reactions,e.g.:hypoglycemia and fat atrophy caused by conventional high frequency subcutaneous injection,are also very common.The main purpose of this study is to develop a safe,effective and convenient approach to administrate insulin.The three-dimensional network structure of hydrogel not only provides enough space for loading drugs,but also plays a controlled release role by swelling.Because of its excellent properties,the hydrogels have become an important component of biomaterials and widely used in drug delivery.It is an urgent problem to explore a kind of composite hydrogel which is convenient for administration,high in insulin utilization and lasting in efficacy.Compared with subcutaneous injection,oral administration of insulin shows manmy disadvantages,for example,convenient to use,good compliance,and stable blood glucose,etc.ObjectiveThe hydrogels with high swelling rates were prepared and used as an insulin delivery system to study the hypoglycemic effect of oral administration on type I diabetes.MethodsPolyacrylic acid hydrogel was prepared by free radical polymerization.The structure of hydrogel was characterized by Fourier transform infrared spectroscopy（FTIR）.Thermodynamic properties of hydrogels were studied by thermogravimetric analyzer（TGA）.The swelling behavior of hydrogels were studied in phosphate buffer solution（PBS,p H7.4）.The internalmorphology of the cargo-free hydrogel was observed by scanning electron microscope（SEM）.Insulin（INS）,as a model drug,was encapsulated into the hydrogels to study the hypoglycemic effect of oralhydrogel and its physiological and pathological effects.ResultsFirstly,according to the highest swelling rate,the optimum formula of the cargo-free hydrogels were obtained.The successful preparation of composite hydrogel was confirmed by FTIR spectra.TGA curve showed that the cargo-free hydrogel had high thermal stability.SEM image illustrated that there are many micropores inside thehydrogel,which could encapsulate lots of guest molecules（such as: INS）.Animal experiments showed that THe INS-loadedhydrogels displayed excellent hypoglycemic effects.Studies on the in vivo biosecurity of the cargo-free hydrogels found that the cargo-free hydrogels did not induce serious damages on the blood and main orgains of the treated rats.ConclusionThe high bio-security of the hydrogel gave them a potential application in the treatment of type I diabetes by oral administration.