Modification of indwelling PVC catheters by ionizing radiation with temperature- and pH-responsive polymers for antibiotic delivery

Gamma rays were evaluated as energy source to generate reactive points onto polyvinyl chloride (PVC) catheters, allowing the grafting of stimuli-responsive vinyl monomers that may endow the catheters with the ability to load and release vancomycin. Dual temperature-and pH-responsiveness was achieved in PVC catheters in a two-step route using the "grafting from" method. First N-isopropyl acrylamide (NIPAAm) was grafted onto the pre irradiated PVC catheter, and then 4-vinyl pyridine (4VP) was grafted onto the PVC-g-NIPAAm catheter. The effects of reaction conditions, such as solvent, monomer concentration, and radiation dose, were studied. Grafted catheters were characterized by infrared spectroscopy (FTIR-ATR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurement, scanning electron microscopy (SEM), and swelling tests. Binary grafted catheters exhibited affinity for vancomycin, and the vancomycin-loaded catheters sustained the release under simulated physiological conditions of temperature and pH. Vancomycin-loaded catheters inhibited Staphylococcus aureus growth in a highly contaminated in vitro environment. It is to forecast that these modified catheters may be employed to prevent nosocomial infections or applied as antimicrobial therapy.