Application Of Fish Scale Gelatin In Preparation Of Silver Nanomaterials

Fish gelatin can be used as an ideal material for preparation of precious metal nanoparticles and degradable film because of its excellent biodegradation properties,high reactive activities of side chains and excellent film-forming properties.However,there are few studies on the bio-systhesis of precious metal nanomaterials by fish gelatin.At the same time,due to the low content of proline and hydroxyproline in fish gelatin,fish gelatin film has certain defects in mechanical properties and water resistance.And application of fish gelatin film depends on the improvement of its performance.Therefore,in order to make the comprehensive use of fish gelatin,in this study,silver nanoparticles(AgNPs)were prepared by biological reduction using fish scale gelatin,and the antibacterial property and stability of the silver nanoparticles were investigated.Then the gelatin-agar-AgNPs composite films were developed by the solution casting methods.And the properties of the composite films were evaluated.Firstly,AgNPs were synthesized via the reduction of[Ag(NH3)2]+by fish scale gelatin and the shape and size of silver nanoparticles were characterized using techniques,such as UV-vis,XRD,FTIR and TEM.The effect of reaction temperature,alkalinity and fish gelatin dosage on the size and morphology of silver nanoparticles were investigated.The stability and antibacterial properties of silver nanoparticles were tested.The results showed that increasing the reaction temperature and OH-concentration could effectively improve the reduction ability of fish scale gelatin,thereby increase the yield of silver nanoparticles,and obtain silver nanoparticles with smaller particle size and more uniform distribution.However when the concentration of fish gelatin increased,there was little difference in the yield of silver nanoparticles,and the reduction rate decreased,and the stability and morphology of AgNPs were significantly changed.AgNPs have good stability in alkali solution.Dissolution of AgNPs occurs in conjunction with aggregation in acid medium.AgNPs can completely dissolve in Fe(NO3)3 solution and severely agglomerate in MnSO4 and ZnSO4 solution.The anions of NO3-CO32-,CHCOO-and SO42-have a weak influence on AgNPs stability.AgNPs are relatively stable in NaCl solution and seawater,and have good stability below 80℃.Secondly,the antimicrobial properties of AgNPs were evaluated against common food-contaminated microorgansims and the inhibition zone diameter,the minimum inhibitory concentration(MIC)and the antibacterial kinetics were tested.Through a series of experiments,the main antibacterial mechanism was determined.The results showed that AgNPs had good antimicrobial activity against both bacteria and fungi.Ag+released from the surface of silver nanoparticles rather than ROS are responsible for their antibacterial activity.The antibacterial properties of AgNPs were less affected by the ionic strength of the medium,but mainly related to the concentration of fish gelation which act as reducing agent and protective agent.Finally,the gelatin-agar-AgNPs composite films were developed by the solution casting methods.The effect of AgNPs dosage on the mechanical properties,water resistance and antibacterial properties of the composite films were investigated.The migration of AgNPs in different food simulated solutions were determined by ICP-MS.The results showed that AgNPs only filled in the composite film and have no chemical bond with the fish scale gelatin-agar biomatrix.After adding AgNPs,the color of the fish scale gelatin-agar composite film was significantly deepened,the transparency was decreased,the tensile strength was not significantly decreased,the elongation at break was significantly increased,the water vapor permeability of the composite films was significantly decreased,the hydrophobicity was remarkably enhanced,and the thermal stability was increased.The fish scale gelatin-agar-AgNPs composite films has good antibacterial effect on common food-contaminated bacteria such as bacteria,mold and yeast,and the inhibition rate is slower than that of free silver nanoparticles.The order of migration rate of AgNPs from the composite films in different food simulants is:acidic foods>neutral,water-based foods>alcoholic foods>alkaline foods>oily foods.The above results indicate that tilapia fish scale gelatin is an ideal material for preparing AgNPs and new food packaging material.It has broad application prospects in the preparation of silver nanomaterials.