Amphiphilic star copolymers composed of curcumin core for bacterial inactivation

Polymeric materials with antimicrobial properties hold the potential to be the next generation of therapeutics. This work reports the preparation of amphiphilic and star-like copolymers through arm-first and reversible addition–fragmentation chain transfer polymerization. The copolymers composed of poly(dimethylamine ethyl methacrylate) (PDMAEMA) as the arms and poly(curcumin dimethacrylate) (PCDMA) as the crosslinked core presented a well-controlled amphiphilic structure with low dispersity values (Ð = 1.15). Varying the [CDMA]:[PDMAEMA] molar ratios (4, 6 and 8) led to a significant increase in the molar mass (153, 688 and 1550 kDa), particle size (33, 90 and 105 nm) and the average number of PDMAEMA arms anchored to the curcumin-based core (12, 52 and 125 arms), as determined by dynamic and static light scattering. The antimicrobial activity of cationic PDMAEMA₄₀-co-PCDMA_core was tested against Escherichia coli in the absence of light and under white light to investigate the photodynamic activity of the copolymers. The results demonstrated a concentration dependence but no additional effect under light irradiation. SEM imaging and live/dead assays revealed extensive membrane damage, evidencing a membrane-disruption mechanism. HeLa viability assays demonstrated that at 1 mg mL⁻¹, 80 ± 10% of the cells demonstrated metabolic activity after 24 h. © 2023 Society of Industrial Chemistry.