Hybrid silica–sodium lignosulfonate nanoparticles for the controlled release of azadirachtin

Abstract

This study explores the preparation and characterization of hybrid silica/sodium lignosulfonate nanoparticles using a simple method designed for the controlled release of azadirachtin, a bioinsecticide derived from the neem tree. Bioinsecticides like azadirachtin are highly effective, but prone to rapid photolytic degradation, which significantly limits their efficacy and longevity in agricultural applications. By combining the robust physical and chemical stability of silica with the biodegradability, UV-absorbing, and antioxidant properties of lignin, a renewable, sustainable, and cost-effective natural polymer, this innovative hybrid nanoparticle system addresses key challenges in bioinsecticide encapsulation, protection, and sustained release. The hybrid nanoparticles exhibited distinct nanocluster formation with well-defined spherical morphologies, while increasing lignin content was found to improve nanoparticle recovery and biopolymer incorporation. Specifically, lignin incorporation at 12.5, 25, and 50 mg resulted in respective lignin contents of 13.81%, 15.71%, and 21.75% within the nanoparticles. The results of this study include an optimized azadirachtin encapsulation efficiency of 37.4% and a controlled release profile extending over 48 h, demonstrating sustained release properties well suited for agricultural applications. Furthermore, environmental toxicity assessments using Vibrio Fischeri confirmed that the formulation poses minimal risk to non-target organisms, highlighting its potential as a highly safe, effective, and eco-friendly pest management solution.

Graphical abstract