Development of a new controlled pesticide delivery system based on neem leaf powder

In order to minimize the agro-environmental pollution and health hazards caused by pesticides, in the present study, the neem leaf powder (NLP), a bio-pesticide, has been exploited to develop the pesticide delivery devices. The presence of neem in the formulations along with the pesticide may enhance the potential of these systems due to its inherent pesticidal activity. We have prepared the NLP and alginate based beads by using CaCl(2) as crosslinker. To study the effect of composition of the beads on the release dynamics of fungicide (thiram), beads were prepared by varying the amount of NLP and crosslinker. The beads formed were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), energy dispersion analysis by X-rays (EDAX), thermogravimetric analysis and swelling study. Formulation characteristics such as entrapment efficiency, bead size, percentage equilibrium swelling of the beads and diffusion mechanism for thiram release have been evaluated. Maximum (78.33 +/- 2.89)% swelling has occurred in the beads prepared with 1.5% NLP, 2.5% alginate and 0.1 M crosslinker solution. In most of the formulations the values for the diffusion exponent 'n' have been obtained >1 and hence the release of fungicides occurred through Case II diffusion mechanism. (C) 2010 Elsevier B.V. All rights reserved.