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Penetration of nanocarriers into red pepper leaf was evaluated with the aim of identifying a novel way to enhance the efficacy of applied pesticides on the field. In addition, the effect of surface charge of the nanocarriers on penetration was also studied. Particularly, corn oil-nanoemulsions (NE) and chitosan coated NE (CH-NE) were successfully prepared with a high encapsulation efficiency, a high payload, a very small size, a small polydispersity index, and a high zeta potential. However, after being coated with chitosan, the zeta potential of NE changed from a negative charge to a positive charge. Penetration experiments were also carried out using a Franz diffusion cell followed by visualization using confocal laser scanning microscopy. The images of the vertical sections illustrated that penetration of nanocarriers (NE and CH-NE) into the red pepper leaf occurred very quickly. Nanocarriers fully penetrated the whole leaf after 60 min. Moreover, multi-depth images that paralleled the leaf surface (horizontal visualization) together with removal of plant-autofluorescent emissions and three-dimensional graphs describing the penetration of NE and CH-NE demonstrated that the negatively charged nanocarriers (NE) had a higher penetration rate compared to that of the positively charged nanocarriers (CH-NE). [ABSTRACT FROM AUTHOR]

BACKGROUND: In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient. RESULTS: Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin. CONCLUSION: CH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]