Title: In situ incorporation of silver nanoparticles within gelatin hydrogels through tyrosinase-mediated reaction for enhanced antimicrobial activity
Phuong Le Thi1, Kyung Min Park2, Yunki Lee1, Joo Young Son1, and Ki Dong Park1*
Ph. D. candidate
1Department of Molecular Science and Technology, Ajou University, Suwon 443-749, Republic of Korea
2Division of Bioengineering, Incheon National University, Incheon 406-772, Republic of Korea
(*)
Abstract
In recent years, the interest in antimicrobial hydrogels with impregnated antibacterial agents has significantly increased to combat the infection during their biomedical applications, including wound dressing, tissue engineering, surface coating of medical devices. Among these reagents, it is well known that silver nanoparticles (Ag NPs) have a great antibacterial activity against both gram-negative and gram-positive bacteria, including highly multi-resistant strains against use of antibiotic drugs. However, the entrapment of Ag NPs within hydrogel matrix often remain toxic problems due to the use of chemical reductants (e.g., commonly sodium borohydride), burst leaching and unwanted agglomeration of Ag NPs in the absence of surfactant or stabilizers. Recently, mussel-inspired approacheshave been utilized to preparehydrogel network formation with Ag NPs in a solution of AgNO3. The catechol side chains of DOPA, an amino acid residue of mussel-secreted protein, readily react with Ag(I) and induces formation of stable metal nanoparticle cores surrounded by polymerized shell of cross-linked catechol polymervia catechol oxidation. In this study, we report a simple approach to generate an injectable and antimicrobial gelatin hydrogel by in situ incorporating of Ag NPs during hydrogel formation.The hydrogel was formed rapidly by conjugation of phenol moieties via HRP-catalyzed cross-linking. Simultaneously, redox coupling between catechols and Ag(I) ions leads to formation of Ag NPs entrapped in hydrogel network. The Ag NPs generated within hydrogel matriceswere mostly round-shaped with average size of 20 nm and kept sustained release (from 6 to 14% for first 10days) to ensure appropriate level for biocompatibility as well as antibacterial activity. In the antibacterial test, hydrogels exhibited killing effect for both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria, depending on amount of Ag NPsreleased from hydrogel. After 24 h and 48 h incubated in hydrogel extracted media, fibroblast viability was not significantly affected, indicating the biocompatibility of composite hydrogels. We strongly believe that this injectable hydrogel with intrinsic antibacterial properties have a potential for biomedical applications, where advantageous antibacterial activities are required to reduce the infection rates.
Acknowledgement:This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science, ICT & Future Planning (NRF-2015M3A9E2028577)