Effect of Surface Modification by Ammonia Plasma on Vascular Graft: PET Film and PET Scaffold

Nowadays, poly (ethylene terephthalate) (PET) textiles, either knitted or woven, are largely used as substitutes for replacement of medium and large calibre (10-40 mm) arteries. Unfortunately, these substitutes do not perform well when they are used to replace small diameter arteries due to thrombogenicity and compliance mismatch issues. Surface treatments were often used as the first step to solve thrombogenicity issues. For example, low pressure ammonia plasma processes can provide modification of the top ≈ 10 - 50 Å of polymer surface without affecting bulk properties of materials. This work compared ammonia plasma surface modifications of PET film (flat surface) and PET scaffolds (porous surface). Plasma treatments lead to a higher amount of nitrogen as well as amino groups on scaffolds compared to films. N/C maximum was reached for PET film and scaffold after plasma treatments of 5 s and 100 s, respectively. Highest amine concentration on films and scaffolds were obtained at short treatment time, specifically 1 s. In addition, high resolution spectra of C 1s confirmed that amino groups were mainly grafted on aromatic rings. Nodule formation was observed after plasma treatment with atomic force microscopy. Their size and shape increased with longer treatment time.