(B-61) Photocatalytic and Photothermal Antimicrobial Mussel-Inspired Nanocomposites for Biomedical Applications

Introduction:: Antibiotic are the main medication used to treat bacterial infections but their misuse is one of the reasons that has led to the development of antibiotic resistance (AR) by various bacterial species, such as the infamous methicillin-resistant Staphylococcus aureus (MRSA). AR may be mitigated by alternative strategies to prevent or treat bacterial infection without the use of antibiotics. A promising antibacterial approach is the use of photo-responsive antimicrobial nanoparticles embedded in hydrogel carriers to form nanocomposites with unique light-responsive properties. In this study, we synthesized core-shell polydopamine-photocatalytic metal oxide nanoparticles (PDA PMO) with photocatalytic and photothermal antibacterial properties triggered by visible or near-infrared (NIR) light. Furthermore, these photo-responsive nanoparticles were combined with mussel-inspired hyaluronic acid hydrogels (HADA) to form antibacterial nanocomposites that were challenged with models of gram negative and gram-positive bacteria under visible or near-infrared light irradiation. When exposed to visible light or NIR light, the nanocomposite inactivated a significant percentage of the bacterial population. These proof-of-concept results confirm the potential of these nanocomposites to contribute to the fight against AR development. Future work is warranted to optimize their composition and to increase their bactericidal efficacy.


Materials and Methods:: PDA PMO nanoparticles were prepared following a previously published oxidative polymerization method [1]. HADA was synthesized via EDC-NHS chemistry, and the HADA PDA PMO nanocomposite (0.78% w/v PDA PMO, 2.5% w/v HADA) was formed via crosslinking and mixing of PDA PMO NPs with hydrogel materials. DLS, PALS, SEM/EDS, TEM, and FTIR were used to characterize the materials. The antimicrobial properties of HADA PDA PMO and its constituents against S. aureus and E. coli under visible light irradiation (6500 K LED light) and near-infrared (NIR) light irradiation (850 nm, 123 mw/cm²) exposure were evaluated by adapting methods from the EPA. The cytocompatibility of HADA PDA PMO was assessed on human dermal fibroblasts (HDF-a).


Results, Conclusions, and Discussions:: PDA PMO nanoparticles with a size of 262 ± 138 nm and a zeta potential of -36.17 mV were obtained. The conjugation of dopamine onto hyaluronic acid was confirmed by FTIR spectra and measured as 13.3 ± 1.4% w/w. Furthermore, HADA and HADA PDA PMO had no adverse effects on HDFa after 72 hours of exposure. Under visible light irradiation, HADA PDA PMO effectively reduced S. aureus and E. coli populations by 92.3% and 94.6%, respectively. In addition, NIR irradiation resulted in 52.8% and 99.2% reduction for E. coli and S. aureus, respectively. Hence, the dual capacity of this material to trigger a photocatalytic effect under visible light, and a photothermal effect under NIR light was confirmed.In conclusion, the HADA PDA PMO nanocomposite showed promising bactericidal photocatalytic and photothermal capacities against S. aureus and E. coli, making it a favorable material to develop treatments for bacterial infections without the use of antibiotics to prevent AR.


Acknowledgements (Optional): : LSG is supported by NIH F31 AI169954 (LS) and previously by NIH T32 HL134613 (LS, KTN). Research has been partially supported by NIH R15 HL156076 (KTN) and R01 HL158204 (KTN).




References (Optional): : [1] W.X. Mao, X.J. Lin, W. Zhang, Z.X. Chi, R.W. Lyu, A.M. Cao, L.J. Wan, Core-shell structured TiO2@polydopamine for highly active visible-light photocatalysis, Chemical Communications (Cambridge, England) 52(44) (2016) 7122-7125.