Preparation And Loaded Drug Release Characterization Of Soy Protein Isolate/poly (vinyl Alcohol) Composite Films

The films of soy protein isolate (SPI) are one kind of economic, natural andeco-friendly materials, bearing great potential application prospects. However, SPIinherently possesses poor mechanical and water resistance properties so that it is difficult tomeet the application requirements and must, therefore, be appropriately modified. In thispaper the blending method has been attempted to prepare SPI composite films so as toachieve the purpose of the modifying SPI. The exploration based on the compositemembrane characterization has been carried out in order to obtain edible or biodegradableor medicine-controlled-release compatible SPI composite film materials.First of all, SPI was dissolved with a conventional routine method, added by glyceroleas a plasticizer, and then the resultant dope was cast through the solution casting method toform SPI films crosslinked with fumaric acid. FTIR results show that the cross-linkingreaction has occured between the fumaric acid and SPI. The tensile test results show thatafter crosslinked with fumaric acid, the tensile strength of the SPI film has increased butthe film moisture content has not been significantly affected. However, the film watersoluble mater content has reduced to a certain degree.Secondly, SPI was dissolved under acidic conditions and mixed with polyvinylalcohol (PVA) after adding glycerole. Similarly the solution casting method was adoped toprepare the SPI/PVA composite films. FTIR analysis shows that after blended therelatively stronger hydrogen bonding may have formed between the SPI and PVA, thushave greatly improved the tensile strength of the SPI films. The experiment results alsoshow that once the composite films were heat dried at140℃the tensile strength could befurther improved, but the heat treatment will make the SPI films become brittle, and renderthe film elongation decline as well. In this thesis, TGA results have been detailed to analyzethe influence of the glycerol content on the thermal stability of SPI/PVA composite films.Based on TGA results, it can be found that PVA has no obvious effect on the filmthermogravimetric process, and that the P-5-20-0film exbihits the best thermal stabilitywith the thermal decompostion activation energy Eaand pre-exponential factor lnA being157.61kJ/mol and27.00s-1, respectively.Thirdly, a series of the crosslinked SPI/PVA composite films have been fabricatedwith fumaric acid as the crosslinking agent and a vast of test methods like FTIR, the tensileproperties, moisture content, solubility, and light transmittance have been carried out. FTIRspectra reflect that the cross-linking reaction has ocurred. After cross-linked, the compositefilms exhibit higher tensile strength, along with promoted elongation if added with glycerol.The films obtained bear much good transparency with light transmission of up to88.6%. The addition of fumaric acid has less effect on the film moisture content and water solublematter content while the introduction of glycerol can significantly increase the filmmoisture and total soluble matter contents.Finally, we have also prepared SPI composite films loaded with aspirin by in-situmethod, and have experimentally researched the asprin release properties from the filmssynthesized and fitting the tiem-dependent releasing data with cetain mathematical modelsas well. To quantitatively measure the content of aspirin, the influence of SPI must beconsidered and removed. To avoid the interference of SPI, ferric chloride solution was usedto dye aspirin solution, and the absorbance value was then measured with ultraviolet visiblelight spectrophotometer. Using this absorbance value aspirin can be quantitatified. Themethod proposed here is technically feasible and verified to be nice as well. Release dataprofiles show that the drug-loaded SPI composite films can make sustained release time ofaspirin longer for more than24h. Several mathematical models are used to analyze thesustained-release process of aspirin drug, and results indicate that the sustained releaseprocess of aspirin from the film belongs to first-order reaction but the process does notobserve Fick’s law diffusion. Correlation results show that the First-order reaction modeland Hixson-Crowell model are both performing very well and the calculated modelparameters can be used with these two models to accurately predict the release profiles ofaspirin from SPI composite films.