Investigation of the effect of nano- and micro-encapsulation on the concentration of essential oil (Artemisia dracunculus) during larvicidal bioassay as well as durability of larvicidal activity

Background: In recent years, essential oil-based larvicides have been introduced as alternatives to industrial ones. However, an appreciable formulation of essential oil with prolonged larvicidal activity has not yet been introduced.Objectives: Investigating the effect of nano- and micro-encapsulation on the concentration of essential oil during larvicidal bioassay as well as durability of larvicidal activity against Anopheles stephensi (Beech strain).Methods: Essential oil of Artemisia dracunculus (Tarragon: TEO) was encapsulated in chitosan nanoparticles using the ion-gelation technique. Physicochemical properties and duration of larvicidal activity of the prepared nanoformulation were investigated.Results: Encapsulation efficiency of the optimum nanoformulations with a particle size of 168±90 nm was calculated as 39.66% using UV-Vis analysis. Encapsulating TEO in chitosan-TPP nanocapsules was shown to increase its activity: perfect larvicidal activity (100% mortality of larvae) continued for 4 days, compared with 2 days for the non-encapsulated form of TEO. Besides, the duration of larvicidal activity of nanoformulation was significantly longer than its corresponding microformulation with the same concentration of ingredients. Furthermore, the concentration of TEO in the solution tests was also monitored, and it was found that the nanoformulation provides a sustained release of TEO. Moreover, there was a logical relationship between larvicidal activity and concentration of TEO in different hours. For instance, the concentration of non-encapsulated TEO at 72 h was 11 μg mL-1 (close to LC50 of TEO: i.e., 11.36 μg mL-1) and observed larvicidal activity was 47%.Conclusion: The prepared nanoformulation could be introduced as an exciting alternative to synthetic larvicides, due to its easy and fast method of preparation and its green constituents

کلیدواژه ها:

Nanoencapsulation ، Tarragon essential oil ، larvicidal activity ، Anopheles stephensi ، and chitosan nanocapsules