Encapsulation of essential oil to prepare environment friendly nanobio-fungicide against Fusarium oxysporum f.sp. lycopersici: An experimental and molecular dynamics approach

This study aims to develop a nano-biofungicide comprising of volatile essential oil molecules to enhance its efficacy in the field of agriculture through easily scalable green synthesis technique. It was prepared through one pot hot melt ultrasonication technique with easy water dispersability and long term stability. The effective surface-active agent concentration which controls the size and stability of nano bio-fungicide was studied. The small particle size (158 nm) and narrow particle distribution (0.36) were obtained for the nano bio-fungicide at 20 mg of lecithin and 100 mg of surfactant concentration. The physico-chemical analysis revealed that, nano bio-fungicides were amorphous sphere-shaped nanoparticles with low melting point. The greater molecular level affinity of essential oil towards lipids and their interfacial interaction towards essential oil to achieve stabilised dispersion in aqueous environment were deciphered through molecular dynamics simulation. The unique preferential binding of eugenol, bornanone and cinnamaldehyde with the hydrocarbon chain of glycerol monostearate and phospholipid enhanced their biological stability in aqueous environment by preventing its autoxidation. It was further confirmed through accelarated ageing studies. The major components of essential oil like alpha-terpineol, linalool, thymol and cinamaldehyde had an encapsulation efficiency of 29 %, 65 %, 21 % and 50 % respectively. Subsequently, all these bioactives of essential oil follows Higuchi model of release kinetics. Besides, the essential oil loaded nanostructured lipid carrier had significantly higher mycelial growth inhibition than pure essential oil at the same concentration. Thus, our results suggest that essential oil compactly packed at the intramolecular spaces of lipids and surfactants were having enhanced bio-efficacy with long term storage potential. Hence, the present nano-biofungicide could be a good alternative to the harsh pesticidal chemicals with easy and simple large scale production protocol for the eco-friendly management of wilt disease caused by Fuarium oxysporum.