Evaluation of penetration of nanocarriers into red pepper leaf using confocal laser scanning microscopy

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).