Curcumin Microcapsule Formulations for Prolong Persistence in the Photodynamic Inactivation of Aedes aegypti Larvae

Background: Viral diseases including dengue, zika, chikungunya, and yellow fever remain a significant public health challenge, primarily due to the increasing resistance of these vectors, the Aedes aegypti mosquito, to conventional control methods. Objectives: Herein, a microencapsulated curcumin formulation was developed and characterized using spray-drying technology, with D-mannitol and starch as encapsulating agents. After microencapsulation, photolarvicidal tablet formulations (Formulated Curcumin Tablets-FCT) were prepared, varying the proportions of starch and pectin: FCT1 (60% starch), FCT2 (35% pectin and 25% starch), and FCT3 (42.5% pectin and 17.5% starch), while maintaining 10% curcumin and 30% D-mannitol in all formulations. The main goal was to enhance the stability and efficacy of curcumin as a photolarvicidal agent. Methods: The formulation was characterized by UV-Vis spectroscopy, confocal microscopy, thermal analysis (TG and DSC), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and photodegradation assays under fluorescent light. Results: The photodynamic inactivation (PDI) of Ae. aegypti larvae was evaluated under white, fluorescent light exposure, and the formulation exhibited a significantly enhanced larvicidal activity compared to free curcumin, with a 57-fold reduction in LC₅₀ (LC_50-24h = 0.27 mg/L). Additionally, the most effective formulation, FCT2, maintained its residual activity for 27 days, reinforcing that curcumin microencapsulation, combined with PDI, can extend vector control. Release studies under different pH conditions confirmed a controlled release mechanism, favoring environmental stability. Conclusions: The results indicate that microencapsulated curcumin has great potential as a sustainable photoinsecticidal agent, offering stability, efficacy, and a promising alternative for managing Ae. aegypti larval populations.