Synthesis and evaluation of thiazolium-functionalized biobased copolymers with antioxidant and antimicrobial bioactive properties

Herein, we report the synthesis of a series of copolymers based on methacrylic and itaconate monomers functionalized with triazolium and thiazolium groups and the evaluation of their bioactive properties and cytotoxicity. The copolymers were obtained from biobased monomers, one an itaconate derivative with alkyne groups (PrI) and the other one a methacrylic monomer enzymatically synthesized from vinyl methacrylate and a thiazole derived from vitamin B1 (MTA). Throughout a combination of radical polymerization, click chemistry and alkylation reaction, five copolymers were obtained by varying the positive charge density and the distribution of the charge along the structure. The copolymers exhibit high zeta potential values between +39 and + 76 mV, even the copolymers with low charge density due to the aggregation of the chains in aqueous solutions and the rearrangement of the charges at the surface. The neutrally charged copolymers, before incorporating the positive charges, presented moderate antioxidant activity that slightly increases by the augment of the number of thiazole units. Nevertheless, clear enhancement of the scavenging capacity was observed when the positive charge was incorporated by alkylation reaction. These positive charges also provide excellent antibacterial activity against Gram-positive and Gram-negative bacteria, in particular the copolymer having hydrophobic alkyne groups, with MIC values between 62 and 8 μg/mL. Also, the copolymers exhibited relatively low human cell toxicity, yielding high selectivity, which made these polymers highly desirable for effectively preventing bacterial infections. • New biobased copolymers with antimicrobial and antioxidant properties were synthesized. • Surface charge and hydrophobic/hydrophilic balance strongly influence the copolymers bioactive properties • Incorporation of thiazolium groups derived from vitamin B1 into provides worthy antibacterial activity • The copolymers exhibited low human cell toxicity, yielding high selectivity indexes. • Antioxidant properties increases with the number of thiazolium groups in the copolymer