The design of new polymeric systems for antimicrobial drug release focused on medical/surgical procedures is of great interest in the biomedical area due to the high prevalence of bacterial infections in patients with wounds or burns. For this reason, in this work, we present a new design of pH-sensitive hydrogels copolymerized by a graft polymerization method (gamma rays), intended for localized prophylactic release of ciprofloxacin and silver nanoparticles (AgNPs) for potential topical bacterial infections. The synthesized hydrogels were copolymerized from acrylic acid (AAc) and agar. Cross-linked hydrogel film formation depended on monomer concentrations and the degree of radiation used (Cobalt-60). The obtained hydrogel films were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical testing. The swelling of the hydrogels was evidenced by the influence of their pH-sensitiveness. The hydrogel was loaded with antimicrobial agents (AgNPs or ciprofloxacin), and their related activity was evaluated. Finally, the antimicrobial activity of biocidal-loaded hydrogel was tested against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA) on in vitro conditions.

A polymeric pro-drug was produced by means of two-step grafting of N-vinylcaprolactam and 2-methacryloyloxy-benzoic acid (2MBA) onto polypropylene sutures, showing in vitro slow release of salicylic acid (SA). Pre-irradiation grafting method was implemented to functionalize the surface of sutures using gamma rays as starter to induce the polymerization process. 2MBA was grafted on a polymer surface to obtain a polymeric system with ability to release SA in a localized site by hydrolysis of its labile ester bond. Factors such as applied dose, reaction time, temperature reaction, and monomer concentration were analyzed to understand how it affects the grafting process. Functionalized sutures were analyzed by FTIR-ATR, thermogravimetric analysis, and DSC. The release profile study of block copolymer was carried out in a phosphate buffer solution at pH 7.4 and 37°C; the assay was monitored by UV–vis at 296 nm; finally, molecule of released SA was identified by mass spectrometry.

The functionalization of polymeric matrices through graft polymerization offers multiple advantages by introducing new properties through the incorporation of functional chemical groups on the surface. These modifications can change the chemical properties of the matrix, such as hydrophilicity and chemical reactivity, and enable new chemical interactions with other molecules that the matrix alone could not achieve. This expands the applicability of the material in various fields, particularly in medicine, where these functionalized matrices can be employed as drug delivery systems. In this work, poly(N-vinylpyrrolidone) was incorporated through a graft polymerization of N-vinylpyrrolidone on silicone rubber catheters using gamma radiation to promote the polymerization reaction on the matrix. The graft degree of poly(N-vinylpyrrolidone) on the SR matrix was studied based on the absorbed dose and monomer concentration. Additionally, the new materials were characterized using TGA, wettability kinetics, ATR-FTIR, and Raman spectroscopy, as well as a drug loading evaluation.