Preparation and Characterization of Silk Sericin/Glycerol Films Coated with Silver Nanoparticles for Antibacterial Application

Silk sericin is an inexpensive and readily available natural protein with good reactive activity, biocompatibility and biodegradability for biomaterial application. To develop sericin-based materials for potential antibacterial application, a novel and non-toxic sericin/glycerol (SS/Gly) film was prepared by blending sericin with glycerol. Mechanical properties, water contact angle, moisture absorption rate and water retention ratio of the prepared SS/Gly films were measured. The results indicated that a SS/Gly composite film containing 40% (wt) glycerol exhibited excellent flexibility, moderate tensile strength and good hydrophilicity. Then, silver nanoparticles (AgNPs) were synthesized in situ on the surface of SS/Gly film to endow the film with antimicrobial activity. Scanning electron microscopy revealed that sericin and glycerol had good compatibility, and that AgNPs synthesis was dependent on ultraviolet irradiation time. X-ray photoelectron spectroscopy demonstrated the presence of AgNPs on the surface of SS/Gly film. Inhibition zone and bacterial growth assays suggested that the prepared AgNPs/SS/Gly film had excellent antimicrobial activities against both Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). Inductively coupled plasma atomic absorption spectroscopy showed that the synthesized AgNPs could be easily released from the composite film. The developed AgNPs/SS/Gly film has therefore shown great potential in antibacterial applications, such as wound dressing and skin tissue engineering.