The biocompatibility of sulfobetaine engineered poly (ethylene terephthalate) by surface entrapment technique

Sulfobetaine-modified poly(ethylene terephthalate) (PET) systems were created by physically entrapping the zwitterionic species on the PET surface. The presence of the sulfobetiane molecules on these surfaces were verified by ATR-FTIR and SEM-EDAX analysis, while wettability of the films was investigated by water contact angle measurements. The blood compatibility of the modified films was evaluated by platelet adhesion in human platelet-rich plasma (PRP). The adhesion and inflammatory response of Mouse RAW 264.7 macrophage cells were studied. The surface induced cellular inflammatory response was determined by quantifying the expression levels of proinflammatory cytokines namely TNF-alpha and IL-1beta by measuring their mRNA profiles in the cells using real time polymerase chain reaction normalized to the housekeeping gene GAPDH. L-929 fibroblast cells were used to assess the propensity of the materials to support the fibroblast cell adhesion. A lower platelet adhesion and activation were observed on the sulfobetaine-modified PET film incubated in PRP after 2h when compared to control. The modified film reduced cellular adhesion events ( p<0.05) with respect to the base material, which could be linked to the reduced protein adsorption observed on this surface. The cellular inflammatory response was suppressed on sulfobetaine-modified substrate. Expression levels of pro-inflammmatory cytokines (TNF-alpha and IL-1beta) was found to be upregulated on bare PET, while it was significantly lower on modified PET ( p<0.001). Thus the sulfobetaine entrapment process can be applied on PET in order to achieve low biointeractions and reduced inflammatory host response for various biomedical and biotechnological applications.