Lucas George Santos Andrade, Julianna Dos Santos de Sousa, Ellen Cristine Nogueira Nojosa, Ariane Maria da Silva Santos, Melissa Pires Souza, Clenilma Marques Brandão, Carlos Alexandre Holanda, Edson Cavalcanti da Silva Filho, Josy Anteveli Osajima, Leociley Rocha Alencar Menezes, Emmanoel Vilaça Costa, Renato Sonchini Gonçalves
Control of Aedes aegypti larvae is essential to reduce arbovirus transmission; however, increasing insecticide resistance and environmental concerns highlight the urgent need for sustainable alternatives. In this study, a solvent-free thermoresponsive nanogel (NGLp), based on Pluronic F127 and Carbopol 974P, was developed to encapsulate Lippia pedunculosa Hayek essential oil (EOLp), aiming to enhance larvicidal performance through improved dispersion and prolonged availability of bioactive constituents. The essential oil was obtained by hydrodistillation and chemically characterized by GC-MS and NMR, identifying 28 constituents (96.65%), with rotundifolone (62.68%) and limonene (20.74%) as the major compounds. Nanogels were prepared using a low-energy cold method, and the optimized formulation (1% w/w EOLp) exhibited a nanometric Z-average size (239.9 nm; PdI 0.474) and a negative zeta potential (-22.3 ± 3.90 mV), indicating a nanoscale but relatively polydisperse dispersion with moderate electrosteric stabilization. FTIR analysis confirmed the physical incorporation of the essential oil within the nanogel matrix. Larvicidal assays against third-instar A. aegypti larvae demonstrated dose- and time-dependent activity, with 100% mortality achieved at concentrations ≥50 μg mL-1 after 48-72 h. The progressive increase in mortality at intermediate concentrations over time indicates time-dependent larvicidal efficacy, as reflected by the reduction in LC50 and LC90 values from 38.6 and 46.0 μg mL-1 at 24 h to 31.6 and 40.9 μg mL-1 at 48 h, with further improvement at 72 h. Although this temporal profile is compatible with prolonged availability of the encapsulated oil, direct release studies would be required to confirm a sustained-release mechanism. These findings demonstrate that the thermoresponsive nanogel enhances the efficacy of L. pedunculosa essential oil, supporting its potential as a sustainable and eco-compatible nanoplatform for mosquito control.