Maltoheptaose-functionalized cellulose nanocrystals for curcumin delivery and light-responsive antibacterial activity

The utilization of natural polysaccharides for the development of nanostructured systems aligns with the principles of green chemistry and environmental sustainability. This study reports the synthesis of novel polysaccharide-based nanocarriers comprising cellulose nanocrystal (CNCs) covalently conjugated with maltoheptaose (MH), serving as an efficient carrier for curcumin (CUR). Curcumin is a natural antibacterial agent and photosensitizer for bacterial photodynamic therapy; however, its practical application is limited by its low solubility, instability, as well as its low bioavailability. Cellulose nanocrystals were extracted from cotton linter, aminated and functionalized with MH via a reductive amination reaction to construct a CNC-based carrier for curcumin delivery. The prepared nanocarrier exhibited an entrapment efficiency of 90% and loading capacity of 6.8%. The in vitro release studies demonstrated pH and light sensitive release behavior with approximately 89% cumulative release at pH 5.4 under light irradiation after 24 h. Antibacterial activity evaluation under blue light irradiation revealed a 20-33% increase in inhibition zone diameters compared to dark conditions, confirming the enhanced antibacterial activity under light irradiation. The findings suggest that the MH-functionalize CNC (CNC-MH) provides an effective platform for curcumin loading and light-responsive antibacterial delivery.