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.
The
use of nanomaterials and nanotechnology to construct a smart
pesticide delivery system with target-oriented and controlled-release
functions is important to increase the effective utilization rate
and minimize environmental residue pollution. A temperature-dependent
delivery system can modulate the release of pesticide with temperature
to improve the efficacy and precision targeting. A series of poly(N-isopropylacrylamide) (PNIPAM)-based nanogels with high
deformability and tunable structure were successfully constructed
for smart pesticide delivery and effective pest control. A lambda-cyhalothrin
(LC)-loaded Pickering emulsion (LC@TNPE) with a stable gel-like network
structure was further formed by the temperature-dependent nanogel
to encapsule the pesticide. The foliar wettability, photostability,
and controlled-release property of LC@TNPE were effectively enhanced
compared to the commercial formulation because of the encapsulation
and stabilization of nanogel. The release rate of LC positively correlated
with temperature changes and thereby adapted to the trend of pest
population increase at higher temperature. The LC@TNPE displayed improved
control efficacy on multiple target pests including Plutella
xylostella, Aphis gossypii, and Pieris rapae compared with the commercial suspension concentrate
and microcapsule suspension, and it showed marked efficacy to control Pieris rapae for an extended duration even at a 40% reduced
dosage. Furthermore, the safety was evaluated systematically on cells in vitro and with a nontarget organism. Studies confirmed
that the system was relatively safe for HepG2 cells and aquatic organism
zebrafish. This research provides an insight into creating an efficient
and environmentally friendly pesticide nanoformulation for sustainable
agriculture production.
In this study, pyraclostrobin nanocapsules were prepared by in situ polymerization with urea–formaldehyde resin as a wall material. The effects of different emulsifiers, emulsifier concentrations, and solvents on the physicochemical properties of pyraclostrobin nanocapsules were investigated. SolvessoÔ 100 was selected as the solvent, and Emulsifier 600# was used as the emulsifier, which accounted for 5% of the aqueous phase system, to prepare pyraclostrobin nanocapsules with excellent physical and chemical properties. The particle size, ζ potential, and morphology of the nanocapsules were characterized by a particle size analyzer and transmission electron microscope. The nanocapsules were analyzed by Fourier-transform infrared spectroscopy, and the loading content and sustained release properties of the nanocapsules were measured. The results show that the size of the prepared nanocapsules was 261.87 nm, and the polydispersity index (PDI) was 0.12, presenting a uniform spherical appearance. The loading content of the pyraclostrobin nanocapsules was 14.3%, and their cumulative release rate was 70.99% at 250 h, providing better efficacy and sustainability compared with the common commercial formulation.
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