Design and Evaluation of a Multicomponent Herbal Nanogel for Mosquito Repellency: An Integrated In Silico Experimental Approach Against Aedes aegypti and Anopheles stephensi.

Abstract

This study describes the development and characterization of a hydroxypropyl methylcellulose (HPMC)-based nanogel. The nanogel coencapsulates thymol, carvacrol, and cinnamaldehyde to enhance mosquito repellency. These phytochemicals were selected for their potential complementary and multimodal neurotoxic and olfactory-disrupting effects. The nanogel was synthesized by spontaneous emulsification, followed by polymeric gelation. Its physicochemical properties were assessed with dynamic light scattering (DLS), zeta potential, rheological measurements, and stability tests. The nanogel showed an optimal size (177 ± 6 nm; PDI: 0.17 ± 0.02; SPAN: 0.96), robust colloidal stability, and pseudoplastic flow behavior. This is consistent with the Carreau-Yasuda model. Repellency assays showed complete protection for 410 ± 45 min against Anopheles stephensi and 210 ± 30 min against Aedes aegypti. Specifically, the nanogel was statistically superior to 40% DEET against Anopheles stephensi, while providing comparable (noninferior) protection against Aedes aegypti. Molecular docking showed strong binding affinities of thymol and carvacrol to mosquito odorant-binding proteins providing mechanistic support for the potential complementary activity of the multicomponent formulation. The formulation maintained physical and rheological stability for 6 months. There was no phase separation or syneresis. These findings show this nanogel's promise as an effective natural mosquito repellent.