Efficacy of nanogels containing carvacrol, cinnamaldehyde, thymol, and a mix compared to a standard repellent against Anopheles stephensi

Mosquito-borne diseases are responsible for about one million death annually worldwide. Especially in endemic regions, using repellents is a practical approach to preventing such diseases. In this study, nanoemulsions containing carvacrol, cinnamaldehyde, thymol, and a mix of them were first prepared. The nanoemulsions were then gellified by adding carboxymethyl cellulose (CMC). Besides, viscosity and successful loading were investigated using viscometry and Attenuated Total Reflection-Fourier Transform InfraRed (ATR-FTIR) analyses. After that, the complete protection time of the nanogels compared to DEET (N, N-diethyl-meta-toluamide) was evaluated against the Anopheles stephensi. The repellent activity of commercial DEET (40% w/v) was 480 ± 30 min; interestingly, nanogel-containing carvacrol (2.4% w/v) showed 470 ± 17 min protection time. Besides, no significant difference was observed between nanogels containing cinnamaldehyde and a mix of them and DEET. The straightforward, repeatable preparation method and no need for advanced devices are some advantages of the developed nanogels. Results suggested that mentioned nanogels, especially carvacrol, could be considered novel natural repellents against A. stephensi and other species of vector mosquitoes. [Display omitted] •Nanogels containing carvacrol, cinnamaldehyde, thymol, and a mix of them are proposed as natural repellents.•Their efficacy with protection times of 470 ± 17, 320 ± 17, 410 ± 34, and 420 ± 30 min against Anopheles stephensi was comparable with DEET 40% (N, N-diethyl-meta-toluamide) as the gold standard repellent.