| Silver nanoparticles (AgNPs) as one kind of antimicrobial agent have attracted a great deal of interests in biomedical applications. Till now, various AgNPs-based medical products, as antibacterial coatings on the wound dressing, have been proven to be effective in preventing bacterial infections. Hence, improvements in the development of novel AgNPs-containing products are highly sought-after. In particular, there is an urgent need for the exploitation of AgNPs technology in the development of functional biomaterials, aiming at combining the prominent antibacterial properties of the AgNPs with the peculiar performance of the biomaterials.In the report, through the process including reduction reaction, gelation, dehydration in gradient and vacuum drying, the AgNPs are generated, stabilized and dispersed within the composite. More important, the release of AgNPs is regulated by the ion exchange between the Na+in the body fluid and the Ca2+in the composite. The ion exchange is like a switch, in which the link between Ca2+and guluronic residues is a lock, while the Na+is a key being able to open the lock and release AgNPs. The amount and the releasing rate of AgNPs are controlled by the body fluid and the loadings of AgNPs within composites. The antimicrobial activity and biocompatibility of the composite were characterized with E.coli and S. aureus growth inhibition and mouse M3T3-E1pre-osteoblast cells, respectively. With regard to this kind of AgNPs, the concentration of1.1ppm is the critical point determining the fate of cells. Therefore, through controlling the releasing process of AgNPs, the retention of antimicrobial activity and absence of cytotoxicity can be synchronously achieved. The feature of ion-exchange responsive controlled release permitting management of antimicrobial activity without impairment of wound healing, makes this composite a very promising material for antimicrobial wound dressing applications. |
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