Sustained release of Zn from zinc sulfide nanoparticles (ZnS NPs) amplified the bioaccessibility of Zn in soil: Adsorption dynamics and dissolution kinetics.

Controlled-release micronutrient supplementation to provide better bioavailable zinc (Zn) under alkaline soil conditions is a concept of commercial pertinence for sustainable agriculture. High pH stable nano-scaled ZnS is the material under study in the present investigation where the adsorption dynamics and dissolution kinetics of sono-chemically synthesized zinc sulfide nanoparticles (ZnS NPs) were evaluated in comparison to ZnSO4 in Lufa 2.2 soil for supplementation of Zn. The mechanism of adsorption of ZnS NPs and ZnSO4 onto Lufa 2.2 soil was well explained by fitting into the Freundlich adsorption model and pseudo-second order equation. ZnS NPs reflected the stronger ability to get adsorbed on the Lufa 2.2 soil as compared to metal ions, due to higher surface reactivity of NPs and higher Kf value (0.557) than ZnSO4 (0.463). Time relevant enhancement in extractability of Zn from ZnS NPs amended soil and diminution in extractability of Zn from ZnSO4 spiked soil was observed in bioavailability studies. The increased labile pool of Zn from ZnS NPs amended soil over time was due to their slow dissolution in soil and could be adjusted to consider as "sustained released ZnS NPs". Dissolution of ZnS nanoparticles (NPs) in Lufa 2.2 soil adhered to the first-order extraction model, exhibiting extended half-lives of 27.72 days (low dose) and 28.87 days (high dose). This supported prolonged stability, increased reactivity, and reduced ecological risk compared to conventional Zn salt fertilizers, promoting enhanced crop productivity.

First report on larvicidal potential of zinc sulfide aqua nanoparticles against Aedes aegypti (Linnaeus).

BACKGROUND & OBJECTIVES: Mosquitoes are considered to be the deadliest arthropod-vectors, which cause millions of human deaths globally. Presently, nanotechnology in the field of insect pest management is being explored. The current study deals with the synthesis of zinc sulfide nanoparticles (ZnS NPs) in aqueous medium and their larvicidal efficacy against Ae. aegypti. METHODS: Aqueous zinc sulfide nanoparticles were synthesized by mixing equal quantities of zinc acetate and zinc sulfide solutions by using sonochemical irradiation method. The synthesized NPs were characterized by Transmission Electron Microscopy (TEM). Larvicidal activity was performed according to WHO protocol and toxicity values were calculated by log-probit technique using POLO software. The morphological alterations between treated and control larvae were observed and compared. RESULTS: TEM studies revealed the average particle size of synthesized nanoparticles to be 19.65 ± 1.08 nm with distorted spherical shape. The mosquito-larvicidal efficacy of ZnS NPs against Ae. aegypti showed maximum lethal effects with the LC50 and LC90 values of 4.49 and 15.58 ppm respectively. The morphological analysis of the mosquito larvae treated with ZnS NPs revealed shrunken and darkened body. INTERPRETATION & CONCLUSION: This study suggests that synthesized zinc sulfide aqua nanoparticles have good potential larvicidal properties making them best candidate for Aedes aegypti control.