Green Synthesis of Silk Fibroin-Silver Nanoparticle Composites with Effective Antibacterial and Biofilm-Disrupting Properties

Abstract

Natural polymer Bombyx mori silk fibroin is used as a biotemplate to produce silver nanoparticles in situ under light (both incandescent light and sunlight) at room temperature. Silk fibroin provides multiple functions in the whole reaction system, serving as the reducing agent of silver, and the dispersing and stabilizing agent of the resulted silver nanoparticles. As the reaction needs not any other chemicals and only uses light as power source, the synthetic route of silver nanoparticles reported here is rather environment-friendly and energy-saving. The silk fibroin-silver nanoparticle composite prepared by this method can be stably stored in a usual environment (room temperature, exposure to light, and so forth) for at least one month. Such a silk fibroin-silver nanoparticle composite shows an effective antibacterial activity against the methicillin-resistant Staphylococcus aureus (S. aureus) and subsequently inhibits the biofilm formation caused by the same bacterium. Moreover, a maturely formed biofilm created by methicillin-resistant S. aureus can be destroyed by the silk fibroin-silver nanoparticle composite, which meets the demand of clinical application. Therefore, the silk fibroin-silver nanoparticle composite prepared by this clean and facile method is expected to be an effective and economical antimicrobial material in biomedical fields.

Efficacy of silk fibroin&ndash;nano silver against <em>Staphylococcus aureus</em> biofilms in a rabbit model of sinusitis

“…19 Although in vitro and in vivo conditions are not the same, yet the purpose is the same, which is to observe biofilm-disrupting properties of SF-NS after direct contact with the biofilms. Hence, SF-NS solution was used at the concentrations of 153.6 and 384 mg/L (2× MBC and 5× MBC, respectively) as anti-biofilm agents in this study.…”

“…The principles of synthesis of SF-NS and its key characteristics are shown in Figure 1; a more detailed description is available in a previous study. 19 The average size of the silver nanoparticle was 12.0±2.1 nm. …”

“…Earlier, the efficacy of silk fibroin-nano silver (SF-NS) solution in disrupting S. aureus biofilms has been demonstrated in vitro. 19 This study tested the use of topical SF-NS solution in a rabbit model of S. aureus biofilm-associated sinusitis. The stable existence of S. aureus biofilms on the maxillary sinus mucosa was verified after 4 weeks of bacterial inoculation, 20 which gave an opportunity to test this novel therapeutic agent against biofilm under in vivo conditions.…”

“…32 This study used green product SF-NS synthesized by the reaction of silk fibroin and silver nitrate, detailed information on which can be found in our previously published literature. 19 The silk fibroin acted as a soluble template for biomineralization and the tyrosine residues in the silk fibroin backbone were thought to be responsible for the reduction of Ag + into silver nanoparticles in situ. Silk fibroin is a natural nonionic surfactant that enhances the stability of silver nanoparticles in aqueous dispersion.…”

Green Synthesis of Silver Nanoparticles Using Sago (Metroxylon Sagu) via Autoclaving Method

“…Therefore, researches are working and innovating the method and process in manufacturing the devices to be applied in biomedical-related field. Some of the key issues that need to be focused is the utilization of nontoxic chemicals, environmentally benign solvents and renewable materials [1][2] . One of those field is the process of synthesizing nanoparticles to be applied as the antibacterial agent in medical application.…”