The current procedure of chronic wound care requires continuous monitoring to prevent bacterial infection and facilitate wound healing. However, upon removal, current materials can cause damage to new tissue growth and antibiotic resistant microbes are increasingly prevalent. The need for innovative wound management materials has emerged with the implementation of antimicrobial agents in polymer-based materials. Hydrogels synthesized from natural biopolymers have gained attention due to their biodegradability and biocompatibility. These three-dimensional non-covalent nanocomposites known for their swelling and easy functionalization have become the ideal replacement. This work will focus on the design of alginate-based hydrogel networks containing multifunctional additives (i.e., amino acids) and Ag- or Cu-TiO₂ nanoparticles. Ag⁺ or Cu²⁺ were photochemically deposited onto the surface of TiO₂ ex-situ and integrated into the alginate polymer backbone. The antimicrobial nature of the resulting network was evaluated with a focus on determining the mechanism of bacterial cell death. Kirby Bauer was utilized to understand a possible diffusive mechanism of antimicrobial properties; however, the lack of a zone of inhibition suggested a differing mechanism. The surface-contact mechanism of bacterial cell death, using E. coli as a model, was examined utilizing an epi-fluorescent optical tweezer to measure the kinetics of cell death. Results showed that upon the incorporation of Ag-TiO₂or Cu-TiO₂ nanoparticles, there was an increase in the decay of green signal (live cells) within 1 hour of exposure. Additionally, the wound healing capacity of the nanocomposite was monitored through changes in genomic expression of growth factors (i.e., collagen 5 and TGF-β) and simulated wound closure rates using human dermal fibroblast cells (HDFa). Preliminary results show an increase in the expression of both growth factors and an increased rate of wound closure within 48 hours. To further this work, the order of addition and in-situ photo-deposition of metals onto TiO₂ was also examined.

Ulysses Flores

Appearances