An antimicrobial film by embedding in situ synthesized silver nanoparticles in soy protein isolate

Abstract An antimicrobial silver nanoparticles (AgNPs) embedded soy protein isolation (SPI) film was prepared by an easy and efficient blending method. AgNPs were in situ synthesized from SPI/AgNO 3 solution, taking the advantage of the reducibility of tyrosine residue in SPI. The whole reaction process was carried out by exposure to the white light at ambient temperature, so such a synthesis method of AgNPs is highly energy-efficient and eco-friendly. The TEM and UV–vis spectroscopy observations indicated that the AgNPs were homogeneously distributed without obvious aggregation. The SPI/AgNPs films were prepared by blending in situ synthesized AgNPs in SPI solution and additional pristine SPI solution, which showed an effective antimicrobial activity against both Gram-positive and Gram-negative bacteria. In the film preparation process, SPI acts as the reducing agent of AgNO 3 , the stabilizing agent of AgNPs, and the matrix of SPI/AgNPs film simultaneously, avoiding using any other chemicals. Such a green route of the preparation ensures SPI/AgNPs film may have the great potential for the application in food industry and biomedical fields.