Abstract
A one-step method was implemented to graft N-vinylcaprolactam (NVCL) and 4-vinylpyridine (4VP) onto silicone rubber (SR) films using gamma radiation in order to endow the silicone surface with temperature- and pH-responsiveness, and give it the ability to host and release diclofenac in a controlled manner and thus prevent bacterial adhesion. The effects of radiation conditions (e.g., dose and monomers concentration) on the grafting percentage were evaluated, and the modified films were characterized by means of FTIR-ATR, Raman spectroscopy, calorimetry techniques (DSC and TGA) and contact angle measurements. The films responsiveness to stimuli was evaluated by recording the swelling degree of pristine and modified SR in buffer solutions (critical pH point) and as a function of changes in temperature (Upper Critical Solution Temperature, UCST). The graft copolymers of SR-g-(NVCL-co-4VP) showed good cytocompatibility against fibroblast cells for prolonged times, could host diclofenac and release it in a sustained manner for up to 24 h, and exhibited bacteriostatic activity when challenged against Escherichia coli.
Highlights
The combination of medical devices with drugs, namely the preparation of drug-eluting medical devices, is receiving a great deal of attention as it can provide relevant therapeutic synergisms.[1,2] Implantable medical devices mainly exert the therapeutic function through a physical mechanism of support or replacement of an affected tissue
To the best of our knowledge, NVCL and 4VP have not been grafted together before and, attention was paid to the effects of monomers concentration and absorbed dose on the graft percent
At high doses more C–H bonds are broken and higher number of reactive sites is created on the silicone rubber (SR), meaning that more N-vinylcaprolactam and 4-vinylpyridine monomers can react
Summary
The combination of medical devices with drugs, namely the preparation of drug-eluting medical devices, is receiving a great deal of attention as it can provide relevant therapeutic synergisms.[1,2] Implantable medical devices mainly exert the therapeutic function through a physical mechanism of support or replacement of an affected tissue. The device can act as a suitable platform for the release of a variety of other drugs for a prolonged time in a specific site, enhancing the therapeutic performance compared to a systemic administration.[4,5] the efficacy and the safety of the treatment, as well as its cost-effectiveness, are improved
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