Effect of size and charge of sílica nanoparticles on human lice (Pediculus humanus capitis)

SANTO ORIHUELA, PABLO LUIS; PICOLLO, MARÍA INÉS; DESIMONE, MARTÍN FEDERICO; VASSENA, CLAUDIA VIVIANA

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

Society of Environmental Toxicology and Chemistry (SETAC) Latin America

In the last decade, the development of products at nanometric scale in fields of science as health, energy, catalysis, agriculture and environment has increased significantly. The progress in the ability to synthesize nanoparticles (NPs) with homogeneous size, charge and structure has conducted to employ these particles as insecticides. Nowadays it has been described the use of nanostructured alumina in controlling pest species of stored food and silver NPs as larvae mosquito insecticide. Moreover, toxicity studies with silica nanoparticles (SiNPs) on mosquitoes, (vectors of Malaria, Dengue and Chickungunya) demonstrated its effectiveness as potential insecticide for chemical control. The advantage of SiNPs is the possibility to synthesize particles with different sizes and charges and these variables determine their insecticidal capacity, stability and environmental safety. The mode of action of the SiNPs is by drying cuticle (physical absorption) and also likely by chitin-silica interactions. Herein, we evaluate the toxicity of SiNPs with different size and charges on human lice, Pediculus humanus capitis (De Geer). Solid silica nanoparticles were obtained by Stöber method. Particles from 60 to 300 nanometers with positive and negative charge were obtained. Adult lice were collected from heads of children (6-12 years old) and then transported to the laboratory where they were maintained at 18°C and 97% RH. Groups of standardized lice were placed on Petri dishes and exposed to 20 μl of different size and charge SiNPs solutions. The exposition was held for 2 minutes. The values of mortality were calculated to compare the toxicity of different charges and sizes of SiNPs on P. humanus capitis. ANOVA showed a higher toxic effect by exposing the insects to negative SiNPs [Mortality = (SiNPs -60: 72.90 ± 0.06 and SiNPs -300: 66.00 ± 0.13) % vs. (SiNPs + 60: 6.30 ± 0.09 and SiNPs +300 nm: 24.3 ± 0.22) %. These results suggested insecticidal capacity of SiNPs in this specie as previously described in other species and showed a higher susceptibility of P. humanus capitis to negative SiNPs in relation to positive nanoparticles. These data contribute to further understand the potential toxicological effect that would be associated to nanoparticles and how they can be modify in order to meet the requirements of each desired application, for example as insecticide in this study.