Pesticide formulation is highly desirable for effective utilization of pesticide and environmental pollution reduction. Studies of pesticide delivery system such as microcapsules are developing prosperously. In this work, we chose polymeric nanoparticles as a pesticide delivery system and metolachlor was used as a hydrophobic pesticide model to study water-based mPEG–PLGA nanoparticle formulation. Preparation, characterization results showed that the resulting nanoparticles enhanced “water solubility” of hydrophobic metolachlor and contained no organic solvent or surfactant, which represent one of the most important sources of pesticide pollution. After the release study, absorption of Cy5-labeled nanoparticles into rice roots suggested a possible transmitting pathway of this metolachlor formulation and increased utilization of metolachlor. Furthermore, the bioassay test demonstrated that this nanoparticle showed higher effect than non-nano forms under relatively low concentrations on Oryza sativa, Digitaria sanguinalis. In addition, a simple cytotoxicity test involving metolachlor and metolachlor-loaded nanoparticles was performed, indicating toxicity reduction of the latter to the preosteoblast cell line. All of these results showed that those polymeric nanoparticles could serve as a pesticide carrier with lower environmental impact, comparable effect, and effective delivery.Keywords: absorption; formulation; metolachlor; mPEG−PLGA; nanopesticides;

Silica, as a controlled release material, has been applied widely in many fields owing to its high thermal and mechanical stability, corrosion resistance, biocompatibility and low cost. We herein synthesized pesticide cyhalothrin/SiO2 microcapsules and cyhalothrin/silica–N-isopropyl acrylamide (NIPAM)–bis-acrylamide (MBA) microcapsules. A silica shell was formed through the hydrolysis and polycondensation of tetraethyl orthosilicate under alkaline conditions, and then the single-shelled silica microcapsules were modified by triethoxyvinylsilane and cross-linked with NIPAM and MBA through free radical polymerization. The microcapsules were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis, and their release kinetics and biological activity were also detected. The single- and double-shelled microcapsules had excellent loading abilities for cyhalothrin (about 50.0% and 25.0%, respectively). The release curves showed that the double-shelled microcapsules allowed better controlled release, probably through a combination of diffusion and erosion. The microcapsules showed longer persistence than that of cyhalothrin emulsifiable concentrate. This study provides a novel material for fabricating pesticides with controlled release.

Porous microspheres with different sizes were prepared through solvent evaporation method with ethylcellulose as a matrix material and abamectin as a core material. The abamectin-loaded microspheres were characterized through scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The chemical structure of the microspheres was determined through FTIR. DLS analysis showed that the diameter of the microspheres range from 10 to 100 μm. SEM analysis revealed that the inner structure of the microspheres is characterized by a porous network. TGA revealed that the microspheres are thermally stable below 125 °C. The controlled release of abamectin from the microspheres into water and soil was also investigated. Abamectin was released from microspheres into water through diffusion. The release of abamectin into soil was mainly caused by erosion, a result that was verified through SEM.

In this work, a novel thermo and pH responsive magnetic hydrogel nanosphere poly(N-isopropylacrylamide-co-acrylic acid)/Fe3O4 (poly(NIPAAm-co-AA)/Fe3O4) has been successfully prepared. The magnetic hydrogel nanospheres with thermo and pH-sensitivity were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared-spectrometer (FT-IR), UV–vis absorption spectroscopy, and vibrating sample magnetometer (VSM). The magnetic hydrogel nanospheres exhibited uniform sphere structures and superparamagnetic property. Finally, the drug loading capacities and the releasing behavior of the magnetic hydrogel nanospheres were investigated with doxorubicin hydrochloride (DOX) as an anticancer drug model. The resulting magnetic hydrogel nanospheres exhibited high encapsulation efficiency (95%) to DOX under an appropriate condition. In vitro release experiments revealed that release was faster at pH 5.3 (37 °C) than at pH 7.4 (25 °C) or pH 7.4 (37 °C). The DOX-loaded magnetic hydrogel nanospheres also showed enhanced anticancer effect compared with the free drug in vitro. These presented results suggested that the magnetic hydrogel nanospheres have a potential as tumor targeting drug carrier.Graphical abstractHighlights► Novel thermoresponsive and pH-sensitivity polymer magnetic hydrogel nanospheres (poly (NIPAAm-co-AA)/Fe3O4) were prepared. ► The resulting magnetic hydrogel nanospheres exhibited high encapsulation efficiency to doxorubicin hydrochloride (DOX). ► In vitro release experiments revealed that the release of DOX-loaded magnetic hydrogel nanospheres was faster at pH 5.3 (37 oC) than at pH 7.4 (25 oC) or pH 7.4 (37 oC). ► DOX-loaded magnetic hydrogel nanospheres showed enhanced anti-tumor effect compared with the free drug in vitro.

Emulsifiers for pesticide microemulsions contain a part of volatile organic compounds (VOCs), and ionic liquids (ILs) are becoming potential substitutes. In order to apply ILs in pesticide microemulsions, the study of interaction between ILs and surfactants is necessary. Therefore, the surface properties and aggregation of anionic surfactant sodium dodecyl sulfate (SDS) in ILs, including N-hexyl-N-methylmorpholinyl bromide ([C6mm][Br]), N-hexyl-N-methylpiperidyl bromide ([C6mp][Br]), N-hexyl-N-methylpyrrolidyl bromide ([C6mpyr][Br]), N-octyl-N-methylpyrrolidyl bromide ([C8mpyr][Br]), N-dodecyl-N-methylpyrrolidyl bromide ([C12mpyr][Br]) and N-hexadecyl-N-methylpyrrolidyl bromide ([C16mpyr][Br]), were investigated in terms of surface tension, conductivity, dynamic light scattering (DLS), viscosity, fluorescence, pseudo-ternary phase diagram and 1H NMR measurements. Generally in agreement, the methods afforded the evaluation of various micellar parameters such as critical micelle concentration (CMC), degree of counterion ionization (α), the maximum surface excess concentration (Γmax), the minimum area per surfactant headgroup (Amin) as well as some thermodynamic parameters, including standard free energy of micellization (ΔG0m), standard enthalpy of micellization (ΔH0m) and standard entropy of micellization (ΔS0m). The results indicated a hydrophobic effect as the primary force of a spontaneous, exothermic, entropy driven micellization process. 1H NMR technique was applied to reveal the solubilization site and interaction of ILs in aqueous SDS micellar solutions. Fluorescence, DLS and viscosity measurements revealed considerable micellar morphologies and various phase behaviors. Furthermore, the 10% difenoconazole microemulsion was successfully prepared and showed good stability and spreadability in mixtures which indicated ILs' potential application in pesticide formulation.