Pesticides are the basis for defending against major biological disasters and important for ensuring national food security. Biocompatible, biodegradable, intelligent, and responsive materials are currently an emerging area of interest in the field of efficient, safe, and green pesticide formulation. Using nanotechnology to design and prepare targeted pesticides with environmentally responsive controlled release via compound and chemical modifications has also shown great potential in creating novel formulations. In this review, special attention has been paid to intelligent pesticides with precise controlled release modes that can respond to micro-ecological environment changes such as light-sensitivity, thermo-sensitivity, humidity sensitivity, soil pH, and enzyme activity. Moreover, establishing intelligent and controlled pesticide release technologies using nanomaterials are reported. These technologies could increase pesticide-loading, improve the dispersibility and stability of active ingredients, and promote target ability.

Nanomaterials (NMs) have received considerable attention in the field of agrochemicals due to their special properties, such as small particle size, surface structure, solubility and chemical composition. The application of NMs and nanotechnology in agrochemicals dramatically overcomes the defects of conventional agrochemicals, including low bioavailability, easy photolysis, and organic solvent pollution, etc. In this review, we describe advances in the application of NMs in chemical pesticides and fertilizers, which are the two earliest and most researched areas of NMs in agrochemicals. Besides, this article concerns with the new applications of NMs in other agrochemicals, such as bio-pesticides, nucleic acid pesticides, plant growth regulators (PGRs), and pheromone. We also discuss challenges and the industrialization trend of NMs in the field of agrochemicals. Constructing nano-agrochemical delivery system via NMs and nanotechnology facilitates the improvement of the stability and dispersion of active ingredients, promotes the precise delivery of agrochemicals, reduces residual pollution and decreases labor cost in different application scenarios, which is potential to maintain the sustainability of agricultural systems and improve food security by increasing the efficacy of agricultural inputs. Graphical Abstract

Pesticides are commonly used in modern agriculture and are important for global food security. However, postapplication losses due to degradation, photolysis, evaporation, leaching, surface runoff, and other processes may substantially reduce their efficacy. Controlled-release formulations can achieve the permeation-regulated transfer of an active ingredient from a reservoir to a target surface. Thus, they can maintain an active ingredient at a predetermined concentration for a specified period. This can reduce degradation and dissipation and other losses and has the potential to improve efficacy. Recent developments in controlled-release technology have adapted the concepts of intelligence and precision from the pharmaceutical industry. In this review, we present recent advances in the development of controlled-release formulations and discuss details of the preparation methods, material improvements, and application technologies.

Water contamination by ammonium ions presents huge risks to the ecosystems. This work evaluated the potential of biochar as an alternative adsorbent to remove ammonium from aqueous solutions. Nine types of biochars were converted from three types of agricultural residuals at three pyrolysis temperatures. Batch sorption experiment showed that all the biochars effectively removed ammonium ions from water. The biochars produced at low pyrolysis temperatures, however, showed higher sorption of ammonium. The low-temperature biochars showed relatively fast sorption kinetics of ammonium, which reached equilibrium around 10 h. Sorption isotherms showed that the low-temperature biochars had high sorption capacities to the ammonium, and the Langmuir maximum capacities were all higher than 200 mg/g. Batch sorption experiments also showed the sorption of ammonium onto the biochar was affected by pH and temperature, but not by ionic strength. The biochar showed good sorption ability to ammonium in aqueous solutions under all of the tested conditions. Findings from this work indicated that biochar could be used as an alternative adsorbent for the treatment of ammonium in water.

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Pesticide slow-release formulations provide a way to increase the efficiency of active components by reducing the amount of pesticide that needs to be applied. Slow-release formulations also increase the stability and prolong the control effect of photosensitive pesticides. Surfactants are an indispensable part of pesticide formulations, and the choice of surfactant can strongly affect formulation performance. In this study, emamectin-benzoate (EMB) slow-release microspheres were prepared by the microemulsion polymerization method. We explored the effect of different surfactants on the particle size and dispersity of EMB in slow-release microspheres. The results indicated that the samples had uniform spherical shapes with an average diameter of 320.5 ±5.24 nm and good dispersity in the optimal formulation with the polymeric stabilizer polyvinyl alcohol (PVA) and composite non-ionic surfactant polyoxyethylene castor oil (EL-40). The optimal EMB pesticide slow-release microspheres had excellent anti-photolysis performance, stability, controlled release properties, and good leaf distribution. These results demonstrated that EMB slow-release microspheres are an attractive candidate for improving pesticide efficacy and prolonging the control effect of EMB in the environment.

Pesticides are being used in agriculture to control pests for better yield and production. However, due to evaporation, rain waste-out, photodegradation, hydrolysis and other factors, most pesticides are lost before they reach their targets.1) Extensive quantities of pesticides are used to compensate for the losses that lead to serious environmental pollution and human toxicity.1,2) An e ective way to solve these problems is nanotechnology. e increase in the surface to volume ratio and surface energy of nanopesticides facilitates the penetration and attachment of an e ective agent on the surface of plant. As a result, the e cacy could be signi cantly increased by the application of nanopesticides. 3,4) In some cases, controlled release technology can integrate into the advantages of nanopesticides. 5)erefore, it is believed that the production of nanopesticides will result in the use of smaller amount and fewer applications.3) Nanopesticides are environmentally friendly and provide new opportunities and wide application prospects for pesticide research. 3)Recently, the use of silica nanoparticles in pesticides has been attracting progressively more attention. 6,7) ey have been shown to be biocompatible and has potential as drug delivery vehicles for medical and veterinary treatments. Hollow and mesoporous silica nanoparticles have also been developed as carriers. [8][9][10] Experiments have demonstrated that they are e ective in the protection against UV degradation and controlled release dependently on the pore diameter and shell thickness. 8,9) However, the cost and industrialization of the carrier is usually the main impediment to the application of a nanopesticide. erefore, to accelerate the application of nanopesticides, inexpensive and commercialized carriers are required, and related studies are important.In research, s) both hydrophilic and hydrophobic silica nanoparticles have been reported to provide insecticide activity on their own. Dispersible silica nanoparticles have been inexpensively commercialized for years. ese nanoparticles were modi ed with an organic surfactant that made them dispersible into organic solvent, 11) enhancing the ability of a carrier to load a hydrophobic drug because the enormous surface-to-volume ratio will not be wasted by aggregation. In this paper, an e ective chlorfenapyr nanoformulation was prepared based on the above carrier.In a typical drug-loading process, 0.5 g of silica nanoparticles and 2.0 g of chlorfenapyr are added to acetone. e mixture is then stirred continuously by a magnetic follower at room temperature. A white turbid suspension appears, and the process continues for 30 min to ensure maximum drug loading. e white turbid suspension is centrifuged and washed with ethanol.e nal product is a white powder that has been dried in air at 40°C for 24 hr and ground in a ceramic pestle and mortar.The morphology and size of chlorfenapyr-loaded silica nanoparticles were measured with a JEM 2100 transmission electron microscopy (TEM) instrument. As shown in Fig. 1, the...

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