Thermoresponsive Nanogel Incorporating Duguetia stelechantha Essential Oil: Biological Activity against Leishmania and Aedes aegypti Larvae.

The search for sustainable and effective bioactive compounds from plant sources has intensified due to their potential applications in both healthcare and vector control. In this study, a thermoresponsive nanogel based on Pluronic F127 and Carbopol 974P was developed to incorporate the essential oil of Duguetia stelechantha (EODs; essential oil of D. stelechantha), aiming to improve its physicochemical stability and evaluate its biological activity in a nanostructured delivery system. The optimized formulation containing 1% (w/w) EODs (nGDs) exhibited suitable physicochemical stability and pronounced thermoresponsive behavior, with a reversible sol-gel transition occurring between 19 and 26 °C. Rheological analysis revealed increased viscosity and enhanced structural organization upon oil incorporation, while FTIR and DLS results confirmed the successful encapsulation of EODs and its influence on intermolecular interactions and nanostructural dynamics. Biological assays demonstrated that free EODs exhibited higher immediate leishmanicidal activity against Leishmania amazonensis promastigotes, whereas nGDs showed a time-dependent response, suggesting a possible modulation of essential oil availability within the nanogel matrix. Morphological analysis confirmed significant parasite damage following treatment. Additionally, nGDs exhibited strong larvicidal activity against Aedes aegypti, with LC50 and LC90 values of 97.7 ± 6.4 and 177.7 ± 18.3 μg/mL, respectively. Overall, the developed thermoresponsive nanogel provides a stable platform for incorporating EODs and may contribute to modulating its biological response, although specific release and temperature-dependent biological assays are still required to confirm the functional role of the sol-gel transition. This system represents a promising eco-friendly platform for dual antiparasitic therapy and vector control applications.