Madhulika Dixit

Hyaluronic acid from metabolically engineered Lactococcus lactis (HAL) was characterized for its biocompatibility and immobilized on the polyethylene terephthalate (PET) surface. HAL was chemically crosslinked on hydrolyzed PET (hPET) surface to form HAL-coated PET (hPET-HAL). The unmodified and modified PET were characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), contact angle measurement, thermogravimetric analysis (TGA), universal testing machine (UTM) and assessed for their biocompatibility. FT-IR confirmed the successful immobilization of HAL on the hPET surface. HAL coating significantly improved the haemocompatibility compared to hPET and unmodified PET. Endothelial cell attachment was significantly improved on hPET-HAL and hPET surfaces compared to the unmodified PET. Model drugs (aspirin and methylene blue) were loaded into the HAL matrix, and showed complete release at around 18 h. These results confirm that covalent attachment of HAL matrix on PET surfaces is a promising strategy for developing drug-eluting implants with enhanced haemocompatibility and endothelialization.

Surface functionalization of polymers is crucial for improving biocompatibility and haemocompatibility, which correlates to improved performance of medical devices. Here, we have evaluated the effect of four PET surface carboxylation techniques on the antifouling property, haemocompatibility, and endothelialization. Surface carboxylation was achieved by formaldehyde + bromoacetic acid treatment (PET-1[COOH]), methacrylic acid grafting (PET-2[COOH]), NaOH hydrolysis + KMnO4 oxidation (PET-3[COOH]), and oxygen plasma treatment + acrylic acid grafting (PET-4[COOH]). The carboxyl densities on these surfaces were 0.4, 23.2, 31.9, 16.4 nmol/cm2, respectively. XPS and FTIR spectroscopy confirmed the introduction of carboxyl groups. Water contact angle results showed that hydrophilicity increased with an increase in surface carboxyl density. SEM images confirmed that these modifications didn't cause any surface deterioration. AFM studies showed an increase in surface roughness of the carboxylated PET. Tensile testing showed that these modifications did not affect the bulk properties. Compared to control, PET-3[COOH] has a 9-fold reduction in BSA adsorption. Haemocompatibility studies showed significantly reduced %hemolysis and platelet adhesion on the carboxylated PET. Cell culture studies revealed that endothelial cell (EA.hy926) attachment increased with increase in surface carboxyl density. PET-3[COOH] showed the most improved haemocompatibility and endothelial cell attachment. These results clearly show that the method of functionalization has a significant impact on the haemocompatibility and cell attachment.