In vitro characterization and mosquito (Aedes aegypti) repellent activity of essential-oils-loaded nanoemulsions.
The nanoemulsions composed of citronella oil, hairy basil oil, and vetiver oil with mean droplet sizes ranging from 150 to 220 nm were prepared and investigated both in vitro and in vivo. Larger emulsion droplets (195-220 nm) shifted toward a smaller size (150-160 nm) after high-pressure homogenization and resulted in higher release rate. We proposed that thin films obtained from the nanoemulsions with smaller droplet size would have higher integrity, thus increasing the vaporization of essential oils and subsequently prolonging the mosquito repellant activity. The release rates were fitted with Avrami's equations and n values were in the same range of 0.6 to 1.0, implying that the release of encapsulated limonene was controlled by the diffusion mechanism from the emulsion droplet. By using high-pressure homogenization together with optimum concentrations of 5% (w/w) hairy basil oil, 5% (w/w) vetiver oil (5%), and 10% (w/w) citronella oil could improve physical stability and prolong mosquito protection time to 4.7 h due to the combination of these three essential oils as well as small droplet size of nanoemulsion.
National Nanotechnology Center, National Science and Technology Development Agency, 111 Thailand Science Park, Paholyothin Road., Klong 1, Klong Luang, Pathumthani, 12120, Thailand.
Onanong
O
Nuchuchua
Usawadee
U
Sakulku
Napaporn
N
Uawongyart
Satit
S
Puttipipatkhachorn
Apinan
A
Soottitantawat
Uracha
U
Ruktanonchai
D000330:Aedes; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D049930:Chrysopogon; D004355:Drug Stability; D004655:Emulsions; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007302:Insect Repellents / Q000008:administration & dosage*; D053758:Nanoparticles; D031339:Ocimum; D009822:Oils, Volatile / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D010316:Particle Size; D010938:Plant Oils / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D012995:Solubility
D004655:Emulsions; D007302:Insect Repellents; D009822:Oils, Volatile; D010938:Plant Oils; C076730:citronella oil; C051168:basil oil