Polymeric nanoencapsulation of insect repellent: Evaluation of its bioefficacy on Culex quinquefasciatus mosquito population and effective impregnation onto cotton fabrics for insect repellent clothing

摘要

Graphical abstract Display Omitted Abstract Diethylphenylacetamide (Bulk-DEPA), an organic insect repellent was subjected to Poly(ethylene glycol) (PEG) polymerization followed by Phase Inversion Temperature (PIT) emulsification method to yield the polymeric nanodroplets of DEPA (Nano-DEPA). The mean hydrodynamic diameter was found to be 149±1.06nm. The efficacy of Bulk-DEPA and Nano-DEPA was comparatively investigated on the Culex quinquefasciatus mosquito population. The larvicidal bioassay was performed on the 1st, 2nd, and 3rd instar larvae of Culex quinquefasciatus and the median lethal indices (LC 50 ) of was found to be 0.055, 0.208, 1.397mg/L and 0.023, 0.144, 0.260mg/L for Bulk-DEPA and Nano-DEPA respectively. The histopathological studies were found to be corroborative with the larvicidal bioassay. The median knockdown indices (KD 50 ) on 2–3day old sucrose fed adult mosquitoes determined by WHO cone bioassay and was found to be 55.168 and 33.277mg/L for Bulk-DEPA and Nano-DEPA. The obtained results indicate the improved efficacy possessed by the Nano-DEPA as comparative to Bulk-DEPA even at lower concentrations. Further, the Nano-DEPA was impregnated onto the alginate cross-linked (ACL) and Plain (PL) cotton fabrics, and the Washing resistance index (WRI) was determined. The obtained results indicate the higher WRI possessed by the ACL cotton fabric than the PL cotton fabric. This was owing to the effective physical entrapment of Nano-DEPA onto the alginate matrices, which was further substantiated by high-resolution scanning electron microscopic (HR-SEM) studies. Overall, the present study has emphasized the benefit of formulating Bulk-DEPA into Nano-DEPA to exert higher efficacy on the mosquito population. In addition, study has provided the methodology for the effective impregnation of Nano-DEPA onto the cotton fabrics for the reliable application in long lasting insect repellent clothing.