Microencapsulation of citronella oil by electrospray to increase repellency time against mosquitoes

FRANCISCO PARDINI; MARIA HORMAIZTEGUI; EVANGELINA MUTTIS ; MELINA BRIVIDORO; MARÍA VICTORIA MICIELI

Rosario

Workshop; 7ma edición de la reunión internacional de Ciencias Farmacéuticas; 2023

Universidad Nacional de Rosario

Introduction:The use of natural oils as insect repellents has several advantages over synthetic repellents. However, the protection time is short due to its high volatility. Therefore, its application must be optimized to achieve a more lasting and effective effect. In this sense, encapsulation of essential oils in low-cost and biodegradable polymers emerges as an alternative strategy. Electrospray (EP), as an encapsulation method, is a versatile, effective, simple technique and is therefore suitable for incorporating natural oils into polymeric matrices. This work then proposes the preparation of microcapsules (MC) of Poly--Caprolactone (PCL) with citronella oil (C) using the EP method, to evaluate the percentage of repellency against mosquitoes over time.Experimental: By applying a certain voltage (10 kV), homogeneous polymer/oil solutions were electrosprayed to obtain polymer/oil microcapsules. The flow of the polymer solution (0.5 mL/h) was regulated with an injection pump and the particles were collected on a metal collector. The process was evaluated by means of microscopy (optical, SEM) and infrared spectroscopy. The encapsulation efficiency (EE) was calculated by HPLC for each proportion tested using equation 1.EE =(Mt-Me)/Mt x100 Eq. 1Where Mt and Me are the theoretical and experimental oil masses respectively.The repellency tests were carried out in the CEPAVE insectary with Aedes aegypti mosquitoes. An ethanol/water lotion with the CM was applied to one arm, on a delimited surface of 75 cm2 (5 x 15). The repellency percentage (R%) was calculated using equation 2:R (%) = [(C – T)/C]x100 Eq. 2where C and T are the number of mosquitoes that rest on or bite the control arm and the treated arm respectively.Results: Through microscopy, the formation of PCL capsules with citronella (PCL/C) was observed in the three proportions tested (1/1, 2/1 and 3/1). The presence of the oil was confirmed with FTIR tests of the capsules where the appearance of bands belonging to the oil was observed. EE calculations showed that the highest efficiency was obtained in PCL-C 3/1 capsules with a value greater than 80%. The repellency tests showed an increase in the protection time of the solution with the microcapsules compared to the control, with satisfactory repellency values.Conclusions: Citronella oil was successfully encapsulated in PCL capsules by electrospray. By using a lotion containing the capsules with citronella, the protection time against mosquitoes was increased. Microencapsulation of citronella oil by EP is a potentially viable alternative as a long-lasting natural repellent.