DOI: https://doi.org/10.55373/mjchem.v26i1.16

Keywords: Chitosan nanoparticles; optimization; Azadirachta excelsa

Abstract

Chemical based pesticides are widely used worldwide. However, there are potential health and environmental effects arising from the use of this type of pesticide. To overcome these problems, people are turning to natural approaches to address this issue. Azadirachta excelsa (A. excelsa) is a plant that can be found in Malaysia and its extract has the potential to be utilized as a biopesticide. However, the shortcomings of the use of biopesticides compared to conventional pesticides include slower rate of control, lower efficacy, shorter persistence, and greater susceptibility to changes in environmental conditions. To address some of these issues, A. excelsa extract was encapsulated in chitosan nanoparticles. The encapsulation of A. excelsa extract into chitosan nanoparticles was optimized using Central Composite Design (CCD) of Response Surface Methodology. The independent variables selected include chitosan’s concentration, chitosan:Tripolyphosphate (TPP) ratio and time of sonication; and the responses studied include size, Polydispersity Index (PDI), zeta potential, encapsulation efficiency and drug loading. The responses were predicted using second order polynomial model. The optimum condition for the preparation of A. excelsa extract loaded chitosan nanoparticles was 1.0 mg/mL of chitosan’s concentration, chitosan:TPP ratio of 4:1 and time of sonication of 3 minutes. The size, PDI, zeta potential, encapsulation efficiency and drug loading at optimum condition were 201.8 nm, 0.390, 86.6 mV, 89.8% and 4.9%, respectively. Transmission electron microscopy (TEM) images of chitosan nanoparticles revealed particles with smooth spherical shape. The study showed that interaction among chitosan’s concentration, chitosan:TPP ratio and time of sonication can significantly change the physical characteristics of chitosan nanoparticles, and this provide an avenue for the formulators to engineer chitosan nanoparticles according to needs.