Silver nanoparticle impregnated poly (ɛ-caprolactone) scaffolds: optimization of antimicrobial and noncytotoxic concentrations.

Use of silver nanoparticles (SNPs) for control of implant-associated infection is a promising strategy, if optimum antimicrobial yet nontoxic dose to mammalian cells is identified. This study was done to determine essential quantity of SNPs, which stimulate antimicrobial activity without cytotoxicity, when immobilized on poly (ɛ-caprolactone) (PCL) scaffold proposed for vascular tissue engineering. During SNP synthesis and scaffold preparation, nanoparticle aggregation was protected using poly (ethylene glycol). Transmission electron microscopy was used to characterize SNP size and to detect its mobilization from scaffold to culture medium. Antimicrobial property of the SNP and its dose response was tested using both Gram-positive and Gram-negative bacteria by zone of inhibition assay. Endothelial cells (ECs), the main cell type required for vascular tissue engineering, were grown on scaffolds to identify the nontoxic dose. After seeding EC on scaffolds, cell attachment, spreading, and viability/survival were detected using specific markers by flow cytometric/fluorescence microscopic analysis. Real-time polymerase chain reaction detected effect of SNPs on mRNA expression of selected EC-specific functional proteins. Results suggest that even devoid of antibiotics in the medium, 0.1% (w/w) SNP on PCL scaffold is antimicrobial while nontoxic to EC at cellular and molecular level once cultured on the SNP-PCL scaffold.