Development of an Eco-Friendly Nanogel Incorporating Pectis brevipedunculata Essential Oil as a Larvicidal Agent Against Aedes aegypti

Abstract

Background/objectives: Arboviruses, transmitted by mosquitoes like Aedes aegypti, pose significant public health challenges globally, particularly in tropical regions. The rapid spread and adaptation of viruses such as Dengue, Zika, and Chikungunya have emphasized the need for innovative control methods. Essential oils from plants, such as Pectis brevipedunculata (Gardner) Sch.Bip. (Pb), have emerged as potential alternatives to conventional insecticides.

Methods: In this work, we developed an eco-friendly nanogel using a low-energy, solvent-free method, incorporating the copolymer F127 and Carbopol 974p, enriched with a high concentration of essential oil from Pb (EOPb). The resulting nanogel displayed excellent physical stability, maintained under varying temperature conditions. Characterization techniques, including FTIR and DLS, confirmed the stable incorporation of EOPb within the nanogel matrix.

Results: The in vitro assays against Aedes aegypti larvae revealed that at 500 μg/mL, the mortality rates were 96.0% ± 7.0 after 24 h and 100.0% ± 0.0 after 48 h. The positive control group treated with temefos, achieved 100% mortality at both time points, validating the experimental conditions and providing a benchmark for assessing the efficacy of the nGF2002Pb nanogel.

Conclusions: These results indicate that nGF2002Pb demonstrates a pronounced concentration-dependent larvicidal effect against Aedes aegypti, offering an innovative and sustainable approach to arbovirus vector control.

Keywords: Aedes aegypti; Pectis brevipedunculata essential oil; thermoresponsive nanogel.

Figure 1

Experimental sequence for the extraction procedure of EOPb involved air drying of the plant material, trituration, and hydrodistillation under controlled conditions. The essential oil yield was 0.81%, and the collected oil was stored appropriately for subsequent analysis.

Figure 2

Schematic illustration of the experimental sequence for the preparation of the nGF2002Pb. Green chemistry procedures are presented in the experimental steps.

Figure 3

Photos of nanogel formulations prepared in different compositions % (w/w) of F127, 974p, H₂O, and EOPb according to Table 4. (A) GF1-GF4 show stable formulations; (B) GF5 to GF8 exhibit phase separation; (C) GF9 and GF10 show phase separation, and GF11 exhibits stability in the form of a nanoemulsion. (D) Thermoresponsive behavior was shown for the GF4 formulation.

Figure 4

FTIR spectra: (A) EOPb and (B) nGF2002Pb and DLS analysis of the nGF2002Pb: (C) Particle size distribution under high dilution conditions, showing a D_H of 30.18 nm and PDI of 0.54, and (D) $\zeta$ potential of −1.6 mV.

Figure 5

Lethal concentrations LC₅₀ and LC₉₀ for Aedes aegypti larvae. After 24 h of treatment with nGF2002Pb nanogel, the LC₅₀ was 199.5 ± 5.6 $\mathsf{\mu }$g/mL and the LC₉₀ was 392.0 ± 16.6 $\mathsf{\mu }$g/mL, with an R² of 0.9992. After 48 h of treatment, the LC₅₀ decreased to 184.5 ± 8.2 $\mathsf{\mu }$g/mL and the LC₉₀ to 253.4 ± 7.6 $\mathsf{\mu }$g/mL, with an R² of 0.9989.