Dual-Drug Delivery via the Self-Assembled Conjugates of Choline-Functionalized Graft Copolymers

Graft copolymers based on a choline ionic liquid (IL), [2-(methacryloyloxy)ethyl]-trimethylammonium chloride (TMAMA), were obtained by atom transfer radical polymerization. The presence of chloride counterions in the trimethylammonium groups promoted anion exchange to introduce fusidate anions (FUS, 32-55 mol.%) as the pharmaceutical anions. Both the choline-based IL copolymers and their ionic drug-carrier conjugates (FUS systems as the first type, 26-208 nm) formed micellar structures (CMC = 0.011-0.025 mg/mL). The amphiphilic systems were advantageous for the encapsulation of rifampicin (RIF, 40-67 mol.%), a well-known antibiotic, resulting in single-drug (RIF systems as the second type, 40-95 nm) and dual-drug systems (FUS/RIF as the third type, 31-65 nm). The obtained systems released significant amounts of drugs (FUS > RIF), which could be adjusted by the content of ionic units and the length of the copolymer side chains. The dual-drug systems released 31-55% FUS (4.3-5.6 mu g/mL) and 19-31% RIF (3.3-4.0 mu g/mL), and these results were slightly lower than those for the single-drug systems, reaching 45-81% for FUS (3.8-8.2 mu g/mL) and 20-37% for RIF (3.4-4.0 mu g/mL). The designed polymer systems show potential as co-delivery systems for combined therapy against drug-resistant strains using two drugs in one formula instead of the separate delivery of two drugs.