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Synthesis and characterization of hydrophilically modified Tecoflex® polyurethane catheters for drug delivery

Abstract:

Hydrophilic surface modification of Tecoflex® polyurethane (PU) catheters was performed by grafting poly(1-Vinylimidazole) (PVim) and poly(N-isopropylacrylamide) (PNIPAAm) using the grafting-radiation method. The first graft was achieved by the pre-irradiation oxidative technique and the second one by the simultaneous one. Grafting yields were adjusted by varying factors such as monomer concentration, absorbed dose, and reaction time. All this to improve the hydrophilicity of the medical device and endow it with the functional groups able to host an anti-inflammatory agent to prevent the undesirable side-effects related to a polymeric implant. Grafted catheters were well characterized by several methods such as Infrared Spectroscopy (IR-ATR), Nuclear Magnetic Resonance 13C (13C-NMR), X-ray Diffraction (XDR), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Modified catheters proved to have a good affinity to water after the grafting process; they presented responsiveness to pH and temperature changes; exhibiting a critical pH of 6 and a Lower Critical Solution Temperature (LCST) of 28 °C. Furthermore, the stimuli-sensitive catheters were able to load sodium diclofenac which released it for a prolonged time in serum saline 0.9 % at different pH and temperature.