Synthesis and characterization of ionic graft copolymers: Introduction and in vitro release of antibacterial drug by anion exchange

Amphiphilic graft copolymers based on [2-(methacryloyloxy)ethyl]trimethyl- ammonium chloride (TMAMA) were obtained for the delivery of pharmaceutical ionic drugs, such as p-aminosalicylate (PAS) and clavunate (CLV) anions. The side chains were attached by grafting from a multifunctional macroinitiator via atom transfer radical polymerization (ATRP) to get polymers with different grafting degrees and ionic content. The self-assembling ability, confirmed by determining the critical micelle concentration (CMC) through interfacial tension (IFT) with the use of goniometry, was reduced after ion exchange (CMC twice higher than for chloride anions contained copolymers 0.005-0.026 mg/mL). Similarly, the hydrophilicity level (adjusted by the content of ionic fraction) evaluated by the water contact angle (WCA) of the polymer film surfaces was decreased with the increase of trimethylammonium units (68°-44°) and after introduction of pharmaceutical anions. The exchange of Cl- onto PAS- and CLV- in the polymer matrix was yielded at 31%-64% and 79%-100%, respectively. The exchange onto phosphate anions to release the drug was carried out (PAS: 20%-42%, 3.1-8.8 μg/mL; CLV: 25%-73%, 11-31 μg/mL from 1 mg of drug conjugates). Because of the bacteriostatic activity of PAS and the support of the action of the antibiotics by CLV, the designed water-soluble systems could be alternatives for the treatment of bacterial infections, including pneumonia and tuberculosis.