No abstract

In 1997, a research programme was initiated to assess the ability of nanospheres (NS) to improve the biodelivery of a new insecticide to plants. Stable polymeric NS, with a size near 135 nm and an encapsulation rate in the range of 3.5%, have been obtained using a nanoprecipitation method with Eudragit S100 polymer. Biological studies have been performed on cotton plants infested with aphid, to estimate the direct contact efficacy of NS formulations on the insects and the systemicity of the encapsulated active ingredient and its level of penetration through the plant, compared to a classical suspension used as a reference. Results indicate that NS formulations are not so good as the reference in terms of speed of action and sustained release. Nevertheless, NS formulation performed better than the reference to enhance the systemicity of the AI and improve its penetration through the plant. It is concluded that the NS do not provide a controlled release of AI but, due to their small size, they enhance the penetration in the plant compared to the classical suspension.

In 1997, a research program was initiated in the laboratories to assess the ability of nanosperes (NS) to improve the biodelivery of new active ingredients (AI) to plants. The goal was to obtain stable poly (epsilon-caprolactone) NS (PeC-NS) with the smallest size and the largest amount of encapsulated AI, using a nanoprecipitation method. The smallest particles obtained were in the range of 200-250 nm. The highest encapsulation is obtained with Montanox 80 as surfactant and is between 5-10% (expressed in per cent weight relative to the total weight of polymer), which corresponds to an encapsulation yield of 95%. There is no desorption of the AI with time. In contrast, the dilution of the NS suspension in water is followed by a large removal of the AI in the aqueous phase. This suggests that NS are complex dynamic systems in equilibrium with the external medium and disturbances of this system lead to a loss of AI.