Exploring Bacterial Interactions of Expanded-PTFE in the Presence of PVP-coated Silver Nanoparticles, Peptides p753 and p359 in 2D and 3D models

M. Finkle, P.M. Navarro, K. Vig
University of Nevada-Las Vegas,
United States

Keywords: vascular tissue, HEK 293, KatA, RecA, RecN, MurE, antibacterial peptides, antibacterial, silver nanoparticles, tissue engineering, low temperature plasma, PTFE, e-PTFE, cardiovascular disease

Summary:

Tissue engineering is recognized as an avenue to improve treatment for various diseases. Expanded-PTFE (e-PTFE) has gained popularity as a tissue scaffold to develop vascular graft for generating blood vessels in cardiac surgeries. However, grafts with antimicrobial properties for efficient functioning are desired. In this study, grafts were prepared using Silver PVP-coated nanoparticles and peptides p359 and p753 and were assessed for antibacterial activity against Escherichia coli in 2D/3D models. The 2D models were carried out by determining MIC of these compounds through the broth dilution method in 96 well plates. MTT assay was done using HEK 293 cells to determine toxicity of these compounds to cells. The MIC of E. coli to Ag PVP was 150 µg/mL and 12.5 µg/mL for P359/P753. The Kirby disk diffusion assay and plate counts supported inhibition. MTT assay showed these compounds were non-toxic to cells up to 100 µg/mL for Ag PVP NPs, and 50 µg/mL for P753 and P359 each. In PTFE 3D model, PTFE was further treated with Low temperature plasma (LTP) to generate cell-friendly functional groups for enhanced cell attachment. PTFE scaffolds were incubated with these compounds overnight and seeded with 20,000 cells the following day on both untreated and LTP treated PTFE. After 24 hours, the cells were infected with Bacteria at MOI 1:10 and inhibition was investigated using microscopy, plate counts and live/dead assay. We observed efficient bacterial inhibition in 3D system without cell death and complemented these findings with SEM. When E. coli is treated in the presence of Ag PVP NPs, P753 and P359, a down-regulation of gene expression was observed within E. coli genes KatA, MurE, RecN, and RecA. These results exhibit that these compounds are antibacterial agents that are viable to use in vascular grafts.