Larvicidal activity of different molecular weights chitosan-plant extract complex against Anopheles stephensi

Molecular weights of chitosan are important to their physical and biological features. The present study aims to compare the larvicidal efficacy of nanoparticles prepared with low (L-CS) and medium molecular weight (M-CS) chitosan, encapsulated with methanolic aerial part extract (MAE) of Artemisia absinthium (chitosan-plant extract complex) against Anopheles stephensi. They were characterised in terms of entrapment efficiency, drug release percentage, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and zeta potential. Out of various concentrations of L-CS- and M-CS-based nanoparticles, MAEL-CSNPs and MAEM-CSNPs, respectively, 10 μg/mL MAEL-CSNPs exhibited higher entrapment efficiency (64.10%). In vitro drug release study showed a controlled and sustained crude drug release from MAEL-CSNPs (86.60%) within three hours, with the best R2 value observed in the Higuchi model (0.97). Spectroscopically characterised MAEL-CSNPs with the lowest LC50 value (2.99 μg/mL) were subjected to toxicity analysis using zebrafish embryos, and the result indicates that, for the encapsulated drug, below 100% mortality at 10 μg/mL concentration and it may act as a potent larvicide without harming non-targeted organisms. Thus, the results showed the capability of MAEL-CSNPs to act as a potent, eco-friendly larvicide against An. stephensi larvae.