Sericins of mulberry and non-mulberry silkworms for eco-friendly synthesis of silver nanoparticles.

Green synthesis of silver nanoparticles (AgNPs) has received many interests as a simple, cost-effective, and environmentally friendly method. This study reported the use of sericins extracted from non-mulberry (Samia cynthia ricini) and mulberry (Bombyx mori) silkworms for green syntheses of AgNPs. Both sericins possessed the reducing activity, which the reducing activity of S. c. ricini sericin was significantly higher than that of B. mori sericin. The formation of AgNPs facilitated by S. c. ricini sericin was greater than B. mori sericin as determined by the intensity of the surfacing plasmon resonance peak of silver at 412 nm. The synthesized AgNPs using both sericins were spherical and uniform in size with the average diameter of ∼13 nm. The silver component and the crystalline structure was determined by energy-dispersive X-ray and X-ray diffraction analyses. The synthesized AgNPs exhibited the antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, suggesting their potential application as an effective antibacterial agent.