Development of expanded polytetrafluoroethylene cardiovascular graft platform based on immobilization of poly lactic-co-glycolic acid nanoparticles using a wet chemical modification technique.

Expanded polytetrafluoroethylene ePTFE grafts are mostly employed to replace damaged blood vessels and to restore normal blood flow. However, the dilemma of early thrombosis, inflammation, and development of biofilms after implantation limit ePTFE long-term patency and restrict the patient's life quality. In this study, poly lactic-co-glycolic acid (PLGA) nanoparticles were covalently immobilized on ePTFE surface for local therapeutic purposes. First, the ePTFE surface was primarily oxidized by H2O2/H2SO4 solution to create hydroxyl groups. Consequently, free amino groups were introduced onto ePTFE surface by an aminolyzation reaction of the activated hydroxyl groups using 3-aminopropyl triethoxysilane. The produced amino groups were further used as anchor sites for covalent immobilization of previously prepared PLGA nanoparticles. The functional groups originated on ePTFE surface were confirmed by FTIR analysis. Furthermore, the scanning electron microscopy visualization evidenced a homogeneous distribution pattern of the immobilized PLGA nanoparticles on the surface. The immobilized PLGA nanoparticles showed stability on ePTFE surface under blood flow mimetic conditions. Additionally, light microscopy observation confirmed the biocompatibility of mouse L929 fibroblasts on the nano-coated ePTFE graft. The cellular adhesion and growth did not reveal remarkable cytotoxicity in the tested modified ePTFE grafts.

Covalent immobilization of lysozyme onto woven and knitted crimped polyethylene terephthalate grafts to minimize the adhesion of broad spectrum pathogens.

Graft-associated infections entirely determine the short-term patency of polyethylene terephthalate PET cardiovascular graft. We attempted to enzymatically inhibit the initial bacterial adhesion to PET grafts using lysozyme. Lysozyme was covalently immobilized onto woven and knitted forms of crimped PET grafts by the end-point method. Our figures of merit revealed lysozyme immobilization yield of 15.7 µg/cm(2), as determined by the Bradford assay. The activity of immobilized lysozyme on woven and knitted PET manifested 58.4% and 55.87% using Micrococcus lysodeikticus cells, respectively. Noteworthy, the adhesion of vein catheter-isolated Staphylococcus epidermidis decreased by 6- to 8-folds and of Staphylococcus aureus by 11- to 12-folds, while the Gram-negative Escherichia coli showed only a decrease by 3- to 4-folds. The anti-adhesion efficiency was specific for bacterial cells and no significant effect was observed on adhesion and growth of L929 cells. In conclusion, immobilization of lysozyme onto PET grafts can inhibit the graft-associated infection.

Multifunctional network-structured film coating for woven and knitted polyethylene terephthalate against cardiovascular graft-associated infections.

Multifunctional network-structured polymeric coat for woven and knitted forms of crimped polyethylene terephthalate PET graft was developed to limit graft-associated infections. A newly synthesized antibacterial sulfadimethoxine polyhexylene adipate-b-methoxy polyethylene oxide (SD-PHA-b-MPEO) di-block copolymer was employed. Our figures of merit revealed that the formed coat showed a porous topographic architecture which manifested paramount properties, mostly bacterial anti-adhesion efficiency and biocompatibility with host cells. Compared to untreated grafts, the coat presented marked reduction of adhered Gram-positive Staphylococcus epidermidis previously isolated from a patient's vein catheter by 2.6 and 2.3 folds for woven and knitted grafts, respectively. Similarly, bacterial anti-adhesion effect was observed for Staphylococcus aureus by 2.3 and 2.4 folds, and by 2.9 and 2.7 folds for Gram-negative Escherichia coli for woven and knitted grafts, respectively. Additionally, adhesion and growth characteristics of L929 cells on the modified grafts revealed no significant effect on the biocompatibility. In conclusion, coating of PET with (SD-PHA-b-MPEO) is a versatile approach offers the desired bacterial anti-adhesion effect and host biocompatibility.