Studies On Preparation And Properties Of Silk Fibroin Based Antibacterial Films

In this study, silk fibroin (SF) based antibacterial films were casted by using pearlpowder (PP) and nano silver (NS) as antibacterial agents, in addition, glycerol was selectedas a plasticizer. In order to investigate the effects of additives on the structure andperformance of the flms, SF/PP blend films, SF/Calcium carbonate (CC) blend films,SF/NS blend films and SF based bi-layered antibacterial films were prepared. The surfaceof the films was observed by SEM. The structure of the flms was investigated by X-raydiffraction and Infrared spectroscopy. The mass loss percentages of the films wereexamined by weighing method and the dissolution rates of SF in films were measured byultraviolet spectroscopy. The mechanical properties of the films were examined by Instron5967mechanical instrument. The antibacterial properties of films were evaluatedaccording to GB/T20944.3-2008textile-evaluation for antibacterial activity. Theexperimental results show that,The structure of blend films are affected markedly by the addition of glycerol.Glycerol played a role in inducing SF to transform from random coil to silkI and silkII. Thestructure of SF in the films without glycerol was mainly random coil. The effect ofglycerol on the structure of blend films was directly related to the additives and its quantityin films. When the amount of PP added was10%and amount of glycerol added was lessthan or equal to20%, the structure of SF/PP blend films was mainly silkI, a small amountof silkII was also contained. When the amount of glycerol added was more than20%, thestructure of SF/PP blend films was mainly silkI. When the amount of PP added was20%and amount of glycerol added was between20%and35%, the structure of SF/PP blendfilms was mainly silkI. The addition of glycerol has no significant effect on the structure ofSF/NS blend films. The dissolution rates of SF in blend films: The addition of glycerol has significanteffect on the dissolution rates of SF in films, the dissolution rates of SF in the films withoutglycerol were very large, under the experimental condition in this paper, when glycerolwas added in the films, the dissolution rates of SF in the films containing PP or CC or NSwere quite small, were all less than0.6%.Mechanical property of the blend films: Plastication effect of glycerol on the filmswas significant. When the amount of PP added was10%and amount of glycerol added was20%, SF/PP blend films has the better mechanical properties. When amount of PP addedwas20%and amount of glycerol added was30%, SF/PP blend films has the bettermechanical properties. When the amount of NS added was between0%and0.6%, theelongation at break of films containing different amount of NS has no significantdifference. The tensile strength of films containing NS was less than the films without NS.When the amount of NS added was0.6%and amount of glycerol added was15%, SF/NSblend films has the better mechanical properties.Mechanical property of the bi-layered films: When the amount of NS added in theunderlayer was0.6%and PP was added in the upper layer of bi-layered films, theelongation at break dropped significantly with the increase of amount of PP, there was nosignificant difference among the tensile strength of the films.The antibacterial property of blend films: Antibacterial rates of SF/PP blend films toStaphylococcus aureus increases with increasing PP amount. SF/PP blend films hasantibacterial activity when the PP amount added reached15%. The amount of PP has noobvious effect on the antibacterial property of SF/PP blend films to Escherichia coli,antibacterial rates were all less than70%. SF/CC blend films containing15%CC has noantibacterial activity to Staphylococcus aureus and Escherichia coli. Antibacterial rates ofSF/NS blend films to Staphylococcus aureus and Escherichia coli increase with increasingNS amount, the minimum amount of NS is0.1%and the maximum amount is0.5%in theantibacterial SF/NS blend films.The antibacterial property of bi-layered films: When the amount of NS added in underlayer was0.6%and amount of PP added in the upper layer was between10%and20%, antibacterial rates of bi-layered films to Staphylococcus aureus and Escherichia coliwere all more than70%, and antibacterial rates of bi-layered films to Staphylococcusaureus were greater than Escherichia coli.