Synthesis and Insecticidal Activity of Enzyme-Triggered Functionalized Hollow Mesoporous Silica for Controlled Release

Nano-pesticide delivery system based on UiO-66 with pH sensitivity for precise control of Spodoptera frugiperda

BACKGROUND

Metal-organic frameworks have the advantages of easy synthesis, high loading capacity and good biocompatibility, making them essential materials for constructing pesticide nano-delivery systems. In this study, a pH-responsive nano-controlled-release formulation Chl@UiO-66 was prepared using UiO-66 as the nano-scale carrier for adsorbing chlorantraniliprole (Chl).

RESULTS

The appearance, pesticide loading, release behaviour, insecticidal activity, long-term control efficacy and safety of Chl@UiO-66 for non-target organisms were extensively evaluated. The results showed that the prepared Chl@UiO-66 was a regular octahedron with a uniform particle size of 230 nm and pesticide loading of 15.62%. The release of pesticides under alkaline conditions was superior to that under acidic and neutral conditions, which showed pH-responsive performance. Chl@UiO-66 had an excellent ability to protect pesticides from ultraviolet degradation. Compared with chlorantraniliprole suspension concentrate, Chl@UiO-66 had a better control effect against Spodoptera frugiperda and long-term control efficacy. The prepared nano-controlled-release formulation had low toxicity to zebrafish, earthworms and human BEAS-2B cells.

CONCLUSION

Chl@UiO-66 is a new pesticide formulation with high efficacy and low toxicity that provides a smart controlled-release solution. © 2024 Society of Chemical Industry.

Bio-friendly multi-stimuli responsive α-CD polymer-gated mesoporous carbon nanoherbicides for enhanced paraquat delivery

INTRODUCTION

Weeds seriously affect crop yield in global agricultural production. Paraquat (PQ), as one of low cost and highly effective herbicide, is forbidden or severely restricted in production and sales owing to its lethal toxicity to humans. Creating an efficient and bio-friendly PQ formulation is crucial to facilitate the open use of PQ in world's agriculture.

OBJECTIVES

This study aims to construct one intelligent and bio-friendly mesoporous carbon nanoparticles (MCN) nanoherbicides coated with α-CD polymer (CDP) gatekeepers.

METHODS

MCN was prepared through the low-concentration hydrothermal way, calcined and carbonized. PEG stalks were immobilized on MCN surface by amidation reaction. The PQ was trapped in the MCN pores via physical diffusion adsorption and the robust π-π effects between electron-deficient PQ and electron-rich MCN. CDP gatekeepers were fastened via host-guest effects between the chamber of α-CD units and PEG stalks.

RESULTS

The PQ-loaded MCN-PEG@CDP nanoherbicides integrated with multi-stimuli responses to amylase, elevated temperature under sunlight, and competitors at leaf interface to control the PQ release for efficient weed control, while appeared low PQ leakage under the simulated human gastric or intestinal conditions, low cytotoxicity to human normal cells in vitro, and high mouse survival rate in vivo. Even through the nanoherbicides inevitably contact with water or intake by beneficial insects, they appear good biosafety on zebrafish (D. rerio) and honeybees (Apis mellifera L.).

CONCLUSION

The as-prepared nanoherbicides have high herbicidal efficacy and low risks to non-target species, and could promote the open use of PQ in agriculture.

Cellulase-responsive hydroxypropyl cellulose-anchored hollow mesoporous silica carriers for pesticide delivery

In this study, a cellulase-responsive controlled-release formulation (FPR-HMS-HPC) was developed by grafting hydroxypropyl cellulose (HPC) onto fipronil (FPR) loaded hollow mesoporous silica (HMS) nanoparticles via ester linkage. The FPR-HMS-HPC formulation was characterized using scanning and transmission electron microscopies, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results indicated that FPR-HMS-HPC exhibited a high loading capacity of 10.0 % (w/w) and demonstrated favorable responsiveness to cellulase enzyme. Moreover, its insecticidal efficacy against Reticulitermes flaviceps surpassed that of an equivalent dose of FPR. Toxicology studies showed that the mortality and hatching rates of zebrafish exposed to FPR-HMS-HPC nanoparticles were reduced by >6.5 and 8.0 times, respectively. Thus, HPC-anchored HMS nanoparticles as insecticide delivery systems present a sustainable method for pest control significantly reducing harm to non-target organisms and the environment.

Redox/pH Dual-Responsive Fluorescent Nanoparticles for Intelligent Pesticide Release and Visualization in Gray Mold Disease Synergistic Control

An intelligent delivery nanoformulation could enhance the utilization efficacy, uptake, and translocation of pesticides in plants. Herein, a redox/pH-triggered and fluorescent smart delivery nanoformulation was designed and constructed by using hollow mesoporous organosilica nanoparticles (HMONs) and ZnO quantum dots as the nanocarrier and capping agent, respectively. Boscalid was further loaded to generate Boscalid@HMONs@ZnO with a loading rate of 9.8% for controlling Botrytis cinerea (B. cinerea). The quantity of boscalid released by Boscalid@HMONs@ZnO in a glutathione environment or at pH 3.0 was 1.3-fold and 1.9-fold higher than that in a neutral condition. Boscalid@HMONs@ZnO has 1.7-fold the toxicity index of boscalid technical against B. cinerea in antifungal experiments. Pot experiments revealed that the efficacy of Boscalid@HMONs@ZnO was significantly enhanced more than 1.27-fold compared to commercially available water-dispersible granules of boscalid. Due to the fluorescence properties of Boscalid@HMONs@ZnO, pesticide transport's real-time monitoring of pesticide translocation in tomato plants could be observed by confocal laser scanning microscopy. Fluorescence images revealed that HMONs@ZnO had been effectively transported via treated leaves or roots in tomato plants. This research showed the successful application of HMONs@ZnO as a nanocarrier for controlling disease and offered an effective avenue to explore the real-time tracking of pesticide translocation in plants.

Layer-by-layer assembled decomposable nanocapsules for light-responsive release of pesticide imidacloprid on Aphis craccivora Koch

BACKGROUND

Conventional pesticide formulations are often inefficient because of low biological uptake after spraying. Controlled release nanopesticides can release pesticides precisely in response to specific stimuli, thereby killing pests and pathogens using the least effective concentration. This study aims to develop nanocapsule-based photo-decomposable nanopesticides for efficient pesticide control.

RESULTS

The target nanopesticides were successfully fabricated using layer-by-layer assembly of the negative azobenzene-grafted hyaluronic acid (azo-HA) and positive polydimethyldiallylammonium chloride (polyDADMAC), confirmed by UV-visible, dynamic light scattering, Zeta potential and transmission electron microscopy measurements. The particle size and Zeta potential of the fabricated nanocapsules were 220 nm and +46.1 mV, respectively, and the nanocapsules were found to remain stable for up to 30 days. The optimized drug loading and encapsulation ratio of imidacloprid (IMI) in IMI/azo-HA@polyDADMAC were 21.5% and 91.3%, respectively. Cumulative release of IMI from the nanopesticides increased from ~50% to ~95% upon UV light irradiation (365 nm). The half lethal concentration (LC50) value of the nanopesticides toward Aphis craccivora Koch decreased from 2.22 to 0.55 mg L-1 upon UV light irradiation.

CONCLUSION

The trans to cis transformation of the azo group in HA decomposed IMI/azo-HA@polyDADMAC nanopesticides upon UV irradiation, thus facilitating the release of IMI, resulting in a decrease in the concentration of pesticides required for efficient pesticide control. Our work demonstrated the great potential of light-responsive nanocapsules as a controlled release nanocarrier for efficient and eco-friendly pesticide control in sustainable agriculture. © 2024 Society of Chemical Industry.

Fabrication and application of carrier-free and carrier-based nanopesticides in pest management

Pesticides are widely used for pest control to promote sustained and stable growth of agricultural production. However, indiscriminate pesticide usage poses a great threat to environmental and human health. In recent years, nanotechnology has shown the ability to increase the performance of conventional pesticides and has great potential for improving adhesion to crop foliage, solubility, stability, targeted delivery, and so forth. This review discusses two types of nanopesticides, namely, carrier-free nanopesticides and carrier-based nanopesticides, that can precisely release necessary and sufficient amounts of active ingredients. At first, the basic characterization and preparation methods of these two distinct types of nanopesticides are briefly summarized. Subsequently, current applications and future perspectives on scientific examples and strategies for promoting the usage efficacy and reducing the environmental risks of these nanopesticides were also described. Overall, nanopesticides can promote higher crop yields and lay the foundation for sustainable agriculture and global food security.

Biomass-Based, Dual Enzyme-Responsive Nanopesticides: Eco-friendly and Efficient Control of Pine Wood Nematode Disease

Pine wood nematode (PWN) disease is a globally devastating forest disease caused by infestation with PWN, Bursaphelenchus xylophilus, which mainly occurs through the vector insect Japanese pine sawyer (JPS), Monochamus alternatus. PWN disease is notoriously difficult to manage effectively and is known as the "cancer of pine trees." In this study, dual enzyme-responsive nanopesticides (AVM@EC@Pectin) were prepared using nanocoating avermectin (AVM) after modification with natural polymers. The proposed treatment can respond to the cell wall-degrading enzymes secreted by PWNs and vector insects during pine tree infestation to intelligently release pesticides to cut off the transmission and infestation pathways and realize the integrated control of PWN disease. The LC50 value of AVM@EC@Pectin was 11.19 mg/L for PWN and 26.31 mg/L for JPS. The insecticidal activity of AVM@EC@Pectin was higher than that of the commercial emulsifiable concentrate (AVM-EC), and the photostability, adhesion, and target penetration were improved. The half-life (t1/2) of AVM@EC@Pectin was 133.7 min, which is approximately twice that of AVM-EC (68.2 min). Sprayed and injected applications showed that nanopesticides had superior bidirectional transportation, with five-times higher AVM contents detected in the roots relative to those of AVM-EC when sprayed at the top. The safety experiment showed that the proposed treatment had lower toxicity and higher safety for nontarget organisms in the application environment and human cells. This study presents a green, safe, and effective strategy for the integrated management of PWN disease.

Recent Advances in Stimulus-Responsive Nanocarriers for Pesticide Delivery

In an effort to make pesticide use safer, more efficient, and sustainable, micro-/nanocarriers are increasingly being utilized in agriculture to deliver pesticide-active agents, thereby reducing quantities and improving effectiveness. In the use of nanopesticides, the choice to further design and prepare pesticide stimulus-responsive nanocarriers based on changes in the plant growth environment (light, temperature, pH, enzymes, etc.) has received more and more attention from researchers. Based on this, this paper examines recent advancements in nanomaterials for the design of stimulus-responsive micro-/nanocarriers. It delves into the intricacies of preparation methods, material enhancements, in vivo/ex vivo controlled release, and application techniques for controlled release formulations. The aim is to provide a crucial reference for harnessing nanotechnology to pursue reduced pesticide use and increased efficiency.

Pesticide Nanoformulations Based on Sunlight-Activated Controlled Release of Abamectin

A controlled release system that enables the sunlight-triggered release of a model agrochemical, abamectin (abm), is presented. The release system consists of polydopamine functionalized halloysite nanotubes (HNT-PDA) utilized as photothermal nanocarriers to encapsulate 25 wt % abm and 37 wt % lauric acid (LA), a phase change material, that acts as a heat-activable gatekeeper stopping or facilitating the abm release. When exposed to sunlight for 20 min at 1 and 3 sun light density, the temperature of the photothermal nanocarriers reaches 51 and 122 °C, respectively, which triggers the melting of LA and the consequent release of abm from the nanocarriers. Abm was shown to be released gradually over a period of 10 days when nanohybrids were exposed to sunlight for 6 h per day and to remain stable and kill Myzus persicae (Sulzer) (Hemiptera: Aphididae), green peach aphids, at a mortality rate of over 70% for at least 10 days. Aqueous dispersions of the LA/abm@HNT-PDA nanohybrids were studied in terms of their potential as aqueous sprayable pesticide nanoformulations and presented over 30% suspensibility, 36 mg/cm2 foliar retention, strong rainwater resistance, and a 50% mortality rate for M. persicae at a concentration of 9 mg/mL. The proposed sunlight-activated controlled release system based on photothermal, LA-functionalized HNT-PDA nanocarriers holds great potential as controlled release pesticide nanoformulations.

Construction and biological effects of a redox-enzyme dual-responsive lufenuron nano-controlled release formulation

BACKGROUND

Pesticide formulations based on nanotechnology can effectively improve the efficiency of pesticide utilization and reduce pesticide residues in the environment. In this study, mesoporous silica nanoparticles containing disulfide bonds were synthesized by the sol-gel method, carboxylated and adsorbed with lufenuron, and grafted with cellulose to obtain a lufenuron-loaded nano-controlled release formulation (Luf@MSNs-ss-cellulose).

RESULTS

The structure and properties of Luf@MSNs-ss-cellulose were characterized. The results showed that Luf@MSNs-ss-cellulose exhibits a regular spherical shape with 12.41% pesticide loading. The highest cumulative release rate (73.46%) of this pesticide-loaded nanoparticle was observed at 7 days in the environment of glutathione and cellulase, which shows redox-enzyme dual-responsive performance. As a result of cellulose grafting, Luf@MSNs-ss-cellulose had a small contact angle and high adhesion work on corn leaves, indicating good wetting and adhesion properties. After 14 days of spraying with 20 mg L-1 formulations in the long-term control efficacy experiment, the mortality of Luf@MSNs-ss-cellulose against Ostrinia furnacalis larvae (56.67%) was significantly higher than that of commercial Luf@EW (36.67%). Luf@MSNs-ss-cellulose is safer for earthworms and L02 cells.

CONCLUSION

The nano-controlled release formulation obtained in this study achieved intelligent pesticide delivery in time and space under the environmental stimulation of glutathione and cellulase, providing an effective method for the development of novel pesticide delivery systems. © 2023 Society of Chemical Industry.

Encapsulated nanopesticides application in plant protection: Quo vadis?

The increased global food insecurity due to the growing population can be addressed with precision and sustainable agricultural practices. To tackle the issues regarding food insecurity, farmers used different agrochemicals that improved plant growth and protection. Among these agrochemicals, synthetic pesticides used for plant protection in the agricultural field have various disadvantages. Conventional applications of synthetic pesticides have drawbacks such as rapid degradation, poor solubility, and non-target effects, as well as increased pesticide runoff that pollutes the environment. Nanotechnology has evolved as a potential solution to increase agricultural productivity through the development of different nanoforms of agrochemicals such as nanopesticides, nano-fabricated fertilizers, nanocapsules, nanospheres, nanogels, nanofibers, nanomicelles, and nano-based growth promoters. Encapsulation of these pesticides inside the nanomaterials has provided good biocompatibility over conventional application by inhibiting the early degradation of active ingredients (AI), increasing the uptake and adhesion of pesticides, improving the stability, solubility, and permeability of the pesticides, and decreasing the environmental impacts due to the pesticide runoff. In this review, different nanoforms of encapsulated pesticides and their smart delivery systems; nanocarriers in RNA interference (RNAi) based pesticides; environmental fate, practical implications, management of nanopesticides; and future perspectives are discussed.

Redox/Near-Infrared Dual-Responsive Hollow Mesoporous Organosilica Nanoparticles for Pesticide Smart Delivery

Extremely inefficient utilization of pesticides has prompted a study of low-cost, sustainable, and smart application systems. Herein, as a promising pesticide nanocarrier, hollow mesoporous organosilica nanoparticles (HMONs) were first synthesized by using inexpensive CaCO3 nanoparticles as the hollow templates. A redox/near-infrared light dual-triggered pesticide release system was further achieved via loading avermectin (AVM) into the HMONs and coating a layer of polydopamine (PDA). The as-prepared AVM@HMONs@PDA displays a favorable pesticide load capability (24.8 wt %), outstanding photothermal performance, and high adhesion to leaves. In addition, with glutathione (GSH), the AVM cumulative release from AVM@HMONs@PDA was 3.5 times higher than that without GSH. Under ultraviolet light irradiation, the half-life of AVM@HMONs@PDA was prolonged by 17.0-fold compared to that of the AVM technical. At day 21 after treatment in the insecticidal activity, the median lethal concentrations (LC50) values displayed that the toxicity of AVM@HMONs@PDA for Panonychus citri (McGregor) was enhanced 4.0-fold compared with the commercial emulsifiable concentrate. In the field trial, at day 28 after spraying, AVM@HMONs@PDA was significantly more control effective than AVM-EC in controlling the P. citri (McGregor), even at a 50% reduced dosage. Moreover, HMONs@PDA was safe for crops. This research presents a novel preparation approach for HMONs, and it also offers a promising nanoplatform for the precise release of pesticides.

Smart, degradable, and eco-friendly carboxymethyl cellulose-CaII hydrogel-like networks gated MIL-101(FeIII) nanoherbicides for paraquat delivery

Nanopesticides have been selected as one of the top 10 chemical innovations for enhancing the efficacy and safety of agrochemicals. Herein, smart, degradable, and eco-friendly metal-organic framework MIL-101(FeIII) nanoherbicides coated with carboxymethyl cellulose-CaII (CMC-CaII) cross-linking hydrogel-like networks are synthesized via a simple strategy. The coating of the CMC-CaII hydrogel-like gatekeepers is oriented by the coordination unsaturated FeIII clusters on the surfaces of the MIL-101(FeIII) nanocarriers to form a dense film network to prevent paraquat (PQ) leakage. Based on the stimuli factors (acid/basic pH, GSH, phosphates, and EDTA) of physiological and natural environments of target plants, the nanoherbicides are combined with five stimuli-responsive properties to attain the various controlled release of packaged PQ by the disassembly of the gatekeepers and/or the degradation of the MOF skeleton structure. More importantly, based on the stimuli-responsive controlled release mechanisms, the eco-friendly nanocarriers are ultimately degraded against bioaccumulation in plants or soil. The coating of natural CMC could promote the spreading of PQ owing to improvement of wettability for aqueous droplets of nanoherbicides on hydrophobic foliage. The PQ trapped in nanocarriers can effectively prevent PQ degradation, which showed that cumulative degradation rate is ca. 2.6 times lower than that of technical PQ under UV irradiation. The prepared nanoherbicides loaded with PQ show good control efficacy against weeds by controlling the release of PQ; good safety on seed germination (germination rate 97.32-99.67 %), seedling emergence (emergence rate 95.53-99.67 %), and are beneficial for the growth of wheat seedling (increase rate of plant height 1.89-6.97 % and 0.54-5.67 % after 7 and 15 days of seedling emergence, respectively) in the greenhouse; good biosafety for honeybees (Apis mellifera L.), which shows that lethal rates were 2.04 and 2.55 times lower than technical PQ for incubation 24 and 48 h, respectively. The nanoherbicides have potential applications in the field for PQ green agriculture.

Chitosan-Delivered Chlorantraniliprole for Pest Control: Preparation Optimization, Deposition Behavior, and Application Potential

Chitosan has emerged as a promising biopolymer carrier for the sustained release of pesticides owing to its good biocompatibility, biodegradability, and bioactivity. In this work, a controlled-release formulation of insecticide chlorantraniliprole was fabricated through coprecipitation-based synchronous encapsulation with chitosan, where the optimum preparation conditions, storage stability, deposition behavior, and application potential were investigated. Preparation of optimization data from response surface methodology showed high correlation coefficient (R2) of 0.9875 and adjusted coefficient (Radj2) of 0.9715. The resulting formulation displayed good loading content of 28.39%, high encapsulation efficiency of 75.71%, and good storage stability. Compared with the commercial suspension concentrate, the formulation exhibited better wettability and retention behaviors on plant leaves. Excitingly, effective control against one species of mealybug genus Paraputo Laing (outside the killing spectrum) on the Hippeastrum reticulatum plant was successfully achieved by spraying the controlled-release formulation at different time intervals. This work indicates the good potential of the developed formulation in expanding the application scope of chlorantraniliprole, which shows a new strategy for sustainable pest management.

Coprecipitation-based synchronous chlorantraniliprole encapsulation with chitosan: carrier-pesticide interactions and release behavior

BACKGROUND

Controlled-release pesticide formulations have emerged as a promising approach towards sustainable pest control. Herein, an environment-friendly formulation of insecticide chlorantraniliprole (CAP) was fabricated through a simple approach of coprecipitation-based synchronous encapsulation by chitosan (CTS), with carrier-pesticide interaction mechanism and release behavior investigated.

RESULTS

The resulting CAP/CTS controlled-release formulation (CCF) showed a good loading content of 28.1% and a high encapsulation efficiency of 75.6%. Instrument determination in combination with molecular dynamics (MD) simulations displayed that the primary interactions between CAP and CTS were physical adsorption and complicated hydrogen (H)-bonds, which formed dominantly between NH in amides [or nitrogen (N) in ring structures] of CAP and hydroxyl (or amino) groups of CTS, as well as oxygen (O) in CAP with hydrogen in CTS or H2 O molecules. The in vitro release tests exhibited obvious pH/temperature sensitivity, with release dynamics following the first-order or Ritger-Peppas model. As the temperature increased, the CAP release process of the Ritger-Peppas model changed from Case-II to anomalous transport, and ultimately to a Fickian diffusion mechanism. The control effect against Plutella xylostella larvae also was evaluated by toxicity tests, where comparable efficacy of CCF to the commercial suspension concentrate was obtained.

CONCLUSION

The innovative, easy-to-prepare CCF can be used as a formulation with obvious pH/temperature sensitivity and good efficacy on target pests. This work contributes to the development of efficient and safe pesticide delivery systems, especially using the natural polymer materials as carriers. © 2023 Society of Chemical Industry.

Recent advances in stimuli-response mechanisms of nano-enabled controlled-release fertilizers and pesticides

Nanotechnology-enabled fertilizers and pesticides, especially those capable of releasing plant nutrients or pesticide active ingredients (AIs) in a controlled manner, can effectively enhance crop nutrition and protection while minimizing the environmental impacts of agricultural activities. Herein, we review the fundamentals and recent advances in nanofertilizers and nanopesticides with controlled-release properties, enabled by nanocarriers responsive to environmental and biological stimuli, including pH change, temperature, light, redox conditions, and the presence of enzymes. For pH-responsive nanocarriers, pH change can induce structural changes or degradation of the nanocarriers or cleave the bonding between nutrients/pesticide AIs and the nanocarriers. Similarly, temperature response typically involves structural changes in nanocarriers, and higher temperatures can accelerate the release by diffusion promoting or bond breaking. Photothermal materials enable responses to infrared light, and photolabile moieties (e.g., o-nitrobenzyl and azobenzene) are required for achieving ultraviolet light responses. Redox-responsive nanocarriers contain disulfide bonds or ferric iron, whereas enzyme-responsive nanocarriers typically contain the enzyme's substrate as a building block. For fabricating nanofertilizers, pH-responsive nanocarriers have been well explored, but only a few studies have reported temperature- and enzyme-responsive nanocarriers. In comparison, there have been more reports on nanopesticides, which are responsive to a range of stimuli, including many with dual- or triple-responsiveness. Nano-enabled controlled-release fertilizers and pesticides show tremendous potential for enhancing the utilization efficiency of nutrients and pesticide AIs. However, to expand their practical applications, future research should focus on optimizing their performance under realistic conditions, lowering costs, and addressing regulatory and public concerns over environmental and safety risks.

Multifunctional Metal-Organic Framework (MOF)-Based Nanoplatforms for Crop Protection and Growth Promotion

Phytopathogen, pest, weed, and nutrient deficiency cause severe losses to global crop yields every year. As the core engine, agrochemicals drive the continuous development of modern agriculture to meet the demand for agricultural productivity and increase the environmental burden due to inefficient use. With new advances in nanotechnology, introducing nanomaterials into agriculture to realize agrochemical accurate and targeted delivery has brought new opportunities to support the sustainable development of green agriculture. Metal-Organic frameworks (MOFs), which weave metal ions/clusters and organic ligands into porous frameworks, have exhibited significant advantages in constructing biotic/abiotic stimuli-responsive nanoplatforms for controlled agrochemical delivery. This review emphasizes the recent developments of MOF-based nanoplatforms for crop protection, including phytopathogen, pest, and weed control, and crop growth promotion, including fertilizer/plant hormone delivery. Finally, forward-looking perspectives and challenges on MOF-based nanoplatforms for future applications in crop protection and growth promotion are also discussed.

Engineered silica nanomaterials in pesticide delivery: Challenges and perspectives

Over the past decade, nanopesticide has been developed rapidly for exploring effective and safe alternatives to conventional pesticides with significant drawbacks and risks. Many nanotechnologies, including pesticide nanoemulsions, polymer-based nanopesticides, and metal/metal oxide nanoparticle-based pesticides have emerged and are extensively reviewed. Engineered silica nanomaterials (ESNs) have also shown promising potential as carriers in nanopesticides for modern agriculture. However, there are limited reviews specifically on ESN-based nanopesticides. Herein, we provide a comprehensive review on the recent progress of ESN-based nanopesticide technologies. An introduction of synthetic technology, formation mechanism, and surface engineering technology is firstly presented. Then, the advantages of ESN-based pesticide formulation and their structure-function-relationship are illustrated in detail. Finally, our perspectives on challenges and future research in ESN-based nanopesticide development are discussed.

pH-responsive λ-cyhalothrin nanopesticides for effective pest control and reduced toxicity to Harmonia axyridis

In this study, pH-responsive LC@O-CMCS/PU nanoparticles were prepared by encapsulating λ-cyhalothrin (LC) with O-carboxymethyl chitosan (O-CMCS) to form LC/O-CMCS and then covering it with polyurethane (PU). Characterization and performance test results demonstrate that LC@O-CMCS/PU had good alkaline release properties and pesticide loading performance. Compared to commercial formulations containing large amounts of emulsifiers (e.g., emulsifiable concentrate, EC), LC@O-CMCS/PU showed better leaf-surface adhesion. On the dried pesticide-applied surfaces, the acute contact toxicity of LC@O-CMCS/PU to Harmonia axyridis (H. axyridis) was nearly 20 times lower than that of LC EC. Due to the slow-releasing property of LC@O-CMCS/PU, only 16.38 % of LC was released at 48 h in dew and effectively reduced the toxicity of dew. On the pesticide-applied leaves with dew, exposure to the LC (EC) caused 86.66 % mortality of H. axyridis larvae significantly higher than the LC@O-CMCS/PU, which was only 16.66 % lethality. Additionally, quantitative analysis demonstrated 11.33 mg/kg of λ-cyhalothrin in the dew on LC@O-CMCS/PU lower than LC (EC) with 4.54 mg/kg. In summary, LC@O-CMCS/PU effectively improves the safety of λ-cyhalothrin to H. axyridis and has great potential to be used in pest control combining natural enemies and chemical pesticides.

Preparation and Properties of Photoresponsive Pendimethalin@Silica-cinnamamide/γ-CD Microspheres for Pesticide Controlled Release

Photocontrolled pesticide delivery systems have broad prospects for application in agriculture. Here, a novel photoresponsive herbicide delivery system was fabricated by functionalizing silica microsphere surfaces with cinnamamide and encapsulating the silica-cinnamamide with γ-cyclodextrin (γ-CD) to form a double-layered microsphere shell loaded with pendimethalin (pendimethalin@silica-cinnamamide/γ-CD). The microspheres showed remarkable loading capacity for pendimethalin (approximately 30.25% w/w) and displayed excellent photoresponsiveness and controlled release. The cumulative drug release rate exceeded 80% over 72 h under UV or sunlight irradiation. The herbicidal activity of the microspheres against Echinochloa crusgalli (L.) Beauv. was almost the same as that of pendimethalin under UV or sunlight. A bioactivity survey confirmed that the pendimethalin@silica-cinnamamide/γ-CD microspheres exhibited longer duration weed control than commercial pendimethalin. Allium cepa chromosomal aberration assays demonstrated that the microspheres showed lower genotoxicity than pendimethalin. These advantages indicate that pendimethalin@silica-cinnamamide/γ-CD microspheres constitute an environmentally friendly herbicidal formulation.

Fluorescent aptamer-modified mesoporous silica nanoparticles for quantitative acetamiprid detection

Acetamiprid (ACE) is widely used to control aphids, brown planthoppers, and other pests in agricultural production. However, ACE is difficult to degrade in the environment, resulting in excessive residue, which causes acute and chronic toxicity to human beings and non-target organisms. Therefore, the development of a rapid, convenient, and highly sensitive method to quantify ACE is essential. In this study, aminated mesoporous silica nanoparticles (MSNs-NH₂) were synthesized by one-pot method, and 6-carboxyl fluorescein modified aptamers (FAM-Apt) of ACE were adsorbed on the surface of MSNs-NH₂ by electrostatic interaction. Finally, a simple and sensitive fluorescence analysis method for the rapid detection of ACE was established. In the absence of ACE, the negatively charged FAM-Apt was electrostatically bound to the positively charged MSNs-NH₂, followed by centrifugation to precipitate MSNs-NH₂@FAM-Apt, and no fluorescent signal was detected in the supernatant. In the presence of ACE, the specific combination of FAM-Apt with ACE was greater than its electrostatic interaction with MSNs-NH₂, so that FAM-Apt was separated from MSNs-NH₂, and the supernatant had strong fluorescence signal after centrifugation. For ACE detection, the linear concentration range was 50-1100 ng/mL, and the detection limit (LOD) was 30.26 ng/mL. The method exhibited high sensitivity, selectivity and reproducibility, which is suitable for practical sample analysis and provides guidance for rapid detection of pesticide residues.

Enhanced and sustained pesticidal activity of a graphene-based pesticide delivery system against the diamondback moth Plutella xylostella

BACKGROUND

Traditional abamectin (Abm) formulations have several shortcomings, such as low water solubility, burst release behavior, poor photostability, and short persistence periods, which decrease their pesticidal activity and the risks they pose to the environment. Nanomaterial-based pesticide delivery systems (PDSs) provide new strategies for the efficient and safe application of pesticides. Here, we developed Abm-loaded graphene oxide (Abm/GO) as a PDS for the sustained release of Abm, which shows enhanced control efficacy against Plutella xylostella.

RESULTS

The hydrophobic Abm molecule was effectively loaded on GO nanocarrier by a physisorption method, which formed a uniform and stable Abm/GO nanoformulation. GO possesses high adsorption capacity and can effectively load Abm. The Abm/GO nanoformulation shows enhanced water dispersion stability and can remain stable during a 2-year storage period in contrast to the water-insoluble Abm. In addition, the Abm/GO nanoformulation exhibits sustained pesticide release behavior and possesses significantly improved anti-ultraviolet properties. Thus, the Abm/GO nanoformulation shows superior pesticidal activity compared with Abm. Abm/GO showed negligible toxicity to maize seedlings, and its GO nanocarrier can reduce the cytotoxicity of Abm to A549 cells.

CONCLUSION

GO-based PDSs can effectively overcome the disadvantages of traditional pesticides, such as their insolubility, burst release behavior, instability, and short persistence period. GO shows much future promise in agriculture in light of its industrialization potential. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Engineered Nanomaterials for Improving the Nutritional Quality of Agricultural Products: A Review

To ensure food safety, the current agricultural development has put forward requirements for improving nutritional quality and reducing the harmful accumulation of agricultural chemicals. Nano-enabled sustainable agriculture and food security have been increasingly explored as a new research frontier. Nano-fertilizers show the potential to be more efficient than traditional fertilizers, reducing the amount used while ensuring plant uptake, supplying the inorganic nutrients needed by plants, and improving the process by which plants produce organic nutrients. Other agricultural uses of nanotechnology affect crop productivity and nutrient quality in addition to nano-fertilizers. This article will review the research progress of using nanomaterials to improve nutritional quality in recent years and point out the focus of future research.

Biodegradable and Light-Responsive Polymeric Nanoparticles for Environmentally Safe Herbicide Delivery

The low utilization efficiency of pesticides exerts an adverse impact on the environment and human health. Polymer-related controlled-release nanosized pesticide systems provide a promising and efficient way to overcome the problem. In this work, a biodegradable and light-responsive amphiphilic polymer was synthesized via 1,1,3,3-tetramethylguanidine-promoted polyesterification under mild conditions (low temperature, no vacuum, and no inert gas protection). We used this polymer to fabricate a light-triggered controlled-release nanosized pesticide system. The herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was selected as a model drug to show its potential as a controlled-release pesticide system. It was found that the 2,4-D-loaded polymeric nanoparticles were stable without the treatment of UV, while the release rate of 2,4-D from the nanoparticles gradually increased after treatment with UV light. Pot trial showed that the 2,4-D-loaded polymer nanoparticles showed a good herbicidal effect. Finally, toxicity studies suggested that the polymer can reduce toxicity to nontarget organisms.

Construction of Prochloraz-Loaded Hollow Mesoporous Silica Nanoparticles Coated with Metal-Phenolic Networks for Precise Release and Improved Biosafety of Pesticides

Currently, environmental-responsive pesticide delivery systems have become an essential way to improve the effective utilization of pesticides. In this paper, by using hollow mesoporous silica (HMS) as a nanocarrier and TA-Cu metal-phenolic networks as a capping agent, a pH-responsive controlled release nano-formulation loaded with prochloraz (Pro@HMS-TA-Cu) was constructed. The structure and properties of Pro@HMS-TA-Cu were adequately characterised and analysed. The results showed that the loading content of Pro@HMS-TA-Cu nanoparticles was about 17.7% and the Pro@HMS-TA-Cu nanoparticles exhibited significant pH-responsive properties. After a coating of the TA-Cu metal-phenolic network, the contact angle and adhesion work of Pro@HMS-TA-Cu nanoparticles on the surface of oilseed rape leaves after 360 s were 59.6° and 107.2 mJ·m^-2, respectively, indicating that the prepared nanoparticles possessed excellent adhesion. In addition, the Pro@HMS-TA-Cu nanoparticles demonstrated better antifungal activity against Sclerotinia sclerotiorum and lower toxicity to zebrafish compared to prochloraz technical. Hence, the pH-responsive nanoparticles prepared with a TA-Cu metal-phenolic network as a capping agent are highly efficient and environmentally friendly, providing a new approach for the development of new pesticide delivery systems.

A pH- and redox-stimulated responsive hollow mesoporous silica for triggered delivery of fungicides to control downy mildew of Luffa cylindrica

BACKGROUND

Downy mildew, a devastating disease of cucurbitaceous crops caused by Pseudoperonospora cubensis. Although a variety of fungicides are used to control downy mildew, choosing an effective product can be challenging. Environmental stimulus-responsive pesticide delivery systems have great potential to improve the effectiveness of disease and pest control and reduce the impact on environmentally beneficial organisms.

RESULTS

In this work, a disulfide bond (SS)-modified and chitosan oligosaccharide (COS)-capped hollow mesoporous silica (HMS) pesticide delivery system was synthesized using a hard template method for the control of downy mildew in cucurbit crops. The synthesized nanoparticles were loaded with dimethomorph (DMM), denoted as DMM@HMS-SS-COS, and the developmental toxicity of these nanoparticles to zebrafish embryos were evaluated. The results showed that the prepared DMM@HMS-SS-COS exhibited excellent dual response properties to pH and glutathione (GSH), with an encapsulation rate of up to 24.36%. DMM@HMS-SS-COS has good ultraviolet (UV) radiation stability and adhesion properties. Compared with dimethomorph suspension concentrate (SC), DMM@HMS-SS-COS was more effective against downy mildew for up to 21 days. Toxicity tests showed that DMM@HMS-SS-COS significantly reduced the effect of DMM on the hatching rate and survival rate of zebrafish embryos.

CONCLUSIONS

This work not only demonstrates that DMM@HMS-SS-COS could be used as a nanodelivery system for intelligent control of downy mildew but also emphasizes the necessity of increasing the acute toxicity of nanoformulations to non-target organisms in environmental risk assessment. © 2022 Society of Chemical Industry.

Chitosan-based organic/inorganic composite engineered for UV light-controlled smart pH-responsive pesticide through in situ photo-induced generation of acid

BACKGROUND

Confined by the volatile property, pesticides are overused and lost significantly during and after spraying, weakening the ecological microbalance among different species of lives. Acid-responsive pesticide is a type of smartly engineered pesticides that contribute to the improvement of utilization efficiency of pesticidal active ingredients in acid-controlled manner, whilst the implementation of acidic solutions may disturb the balance of microenvironment surrounding targeted plants or cause secondary pollution, underscoring the input of acid in a more precise strategy.

RESULTS

Chitosan was chemically modified with a photoacid generator (2-nitrobenzaldehyde) serving as a light-maneuvered acid self-supplier, based on which a smart pesticide was formulated by the integration of attapulgite and organophosphate insecticide chlorpyrifos. Under the irradiation of UV light (365 nm), the modified chitosan would undergo a photolytic reaction to generate an acid and pristine chitosan, which seized the labile protons and facilitated the release of chlorpyrifos based on its inherent pH-responsive flexibility. According to the pesticide release performance, the release rate of chlorpyrifos under UV light (27.2 mW/cm² ) reached 78%, significantly higher than those under sunlight (22%, 4.2 mW/cm² ) and in the dark (20%) within the same time, consistent with the pH reduction to 5.3 under UV light and no obvious pH change for the two other situations, exhibiting an attractive UV light-controlled, acid-propelled release behavior.

CONCLUSION

Compared to direct acid spray approach, the proposed in situ photo-induced generation of acid locally on the spots of applied pesticide circumvents the problem of acid contamination to nontargets, demonstrating higher efficiency and biocompatibility for the controlled delivery of acid-responsive pesticides and pest management. © 2022 Society of Chemical Industry.

β-Glucan-Functionalized Mesoporous Silica Nanoparticles for Smart Control of Fungicide Release and Translocation in Plants

In this work, an enzyme-responsive nanovehicle for improving captan (CAP) contact fungicide bioactivity and translocation in plant tissues was synthesized (CAP-MSNs-β-glucan) by attaching β-glucan to the outer surface of mesoporous silica nanoparticles. CAP-MSNs-β-glucan properties were tested by FTIR, ζ-potential, DLS, XRD, TGA, FE-SEM, and HR-TEM. Cargo protection ability of CAP-MSNs-β-glucan from photolysis and hydrolysis was examined in comparison to CAP commercial formulation (CAP-CF). CAP-MSNs-β-glucan distribution in plant tissues, bioactivity against Fusarium graminearum, and biotoxicity toward zebrafish (Danio rerio) were tested and compared with that of CAP-CF. CAP-MSNs-β-glucan results showed good loading efficacy reaching 18.39% and enzymatic-release dependency up to 83.8% of the total cargo after 20 days of β-glucan unsealing. CAP-MSNs-β-glucan showed significant release protection under pH changes. MSNs-β-glucan showed excellent CAP protection from UV. CAP-MSNs-β-glucan showed better distribution in corn tissues and 1.28 more inhibiting potency to Fusarium graminearum than CAP-CF. CAP-MSNs-β-glucan showed 1.88 times lower toxicity than CAP-CF to zebrafish after 96 h of treatment. We recommend using such formulations to overcome shortcomings of contact fungicides and achieve better and sustainable farming.

Nano-enabled pesticides for sustainable agriculture and global food security

Achieving sustainable agricultural productivity and global food security are two of the biggest challenges of the new millennium. Addressing these challenges requires innovative technologies that can uplift global food production, while minimizing collateral environmental damage and preserving the resilience of agroecosystems against a rapidly changing climate. Nanomaterials with the ability to encapsulate and deliver pesticidal active ingredients (AIs) in a responsive (for example, controlled, targeted and synchronized) manner offer new opportunities to increase pesticidal efficacy and efficiency when compared with conventional pesticides. Here, we provide a comprehensive analysis of the key properties of nanopesticides in controlling agricultural pests for crop enhancement compared with their non-nanoscale analogues. Our analysis shows that when compared with non-nanoscale pesticides, the overall efficacy of nanopesticides against target organisms is 31.5% higher, including an 18.9% increased efficacy in field trials. Notably, the toxicity of nanopesticides toward non-target organisms is 43.1% lower, highlighting a decrease in collateral damage to the environment. The premature loss of AIs prior to reaching target organisms is reduced by 41.4%, paired with a 22.1% lower leaching potential of AIs in soils. Nanopesticides also render other benefits, including enhanced foliar adhesion, improved crop yield and quality, and a responsive nanoscale delivery platform of AIs to mitigate various pressing biotic and abiotic stresses (for example, heat, drought and salinity). Nonetheless, the uncertainties associated with the adverse effects of some nanopesticides are not well-understood, requiring further investigations. Overall, our findings show that nanopesticides are potentially more efficient, sustainable and resilient with lower adverse environmental impacts than their conventional analogues. These benefits, if harnessed appropriately, can promote higher crop yields and thus contribute towards sustainable agriculture and global food security.

Recent development in functional nanomaterials for sustainable and smart agricultural chemical technologies

New advances in nanotechnology are driving a wave of technology revolution impacting a broad range of areas in agricultural production. The current work reviews nanopesticides, nano-fabricated fertilizers, and nano activity-based growth promoters reported in the last several years, focusing on mechanisms revealed for preparation and functioning. It appears to us that with many fundamental concepts have been demonstrated over last two decades, new advances in this area continue to expand mainly in three directions, i.e., efficiency improvement, material sustainability and environment-specific stimulation functionalities. It is also evident that environmental and health concerns associated with nano agrochemicals are the primary motivation and focus for most recent work. Challenges and perspectives for future development of nano agrochemicals are also discussed.

Porous Silica Biofiber: A Reusable, Sustainable Fertilizer Reservoir

Nitrogen fertilizers, namely urea, are prone to leaching that causes inefficiency in crop production and environmental pollution; hence porous particles were explored for slow release. Nevertheless, discrete particles add cost; therefore, jute cellulose has been tested as twine to tether silica together for reusability. On the other hand, silica serves as an exoskeleton to give pore memory property to cellulose, which otherwise is susceptible to loss of porosity during irrigation. The composite shows ∼70% more absorption capacity in the fifth cycle than the fiber without silica coating. The urea release kinetics shows only <1/3 and 3/4 of urea release from the jute-silica composite compared to naked porous silica and cellulose, respectively. The slow and sustained release of fertilizer from the composite results in a continuous increase in the chlorophyll content in rice crops.

Efficiency of mesoporous silica/carboxymethyl β-glucan as a fungicide nano-delivery system for improving chlorothalonil bioactivity and reduce biotoxicity

Understanding the lethal effects of pesticides nano formulations on the targeted organisms (pathogens) and the non-targeted organisms (fish, earthworms, etc) is essential in assessing the probable impact of new technologies on agriculture and environment. Here we evaluated the bioactivity and the biotoxicity of new type of fungicide smart-delivery formulation based on conjugating carboxymethylated-β-glucans on the mesoporous silica nanoparticles (MSNs) surface after loading chlorothalonil (CHT) fungicide in the MSNs pores. The obtained formulation has been characterized with FE-SEM, and HR-TEM. The CHT loading efficiency has been measured with TGA. The bioactivity of the obtained formulation (CHT@MSNs-β-glucans) has been tested against four pathogens, fusarium head blight (Fusarium graminearum), sheath rot (Sarocladium oryzae), rice sheath blight (Rhizoctonia solani), and soyabean anthracnose (Colletotrichum truncatum) compared with CHT WP 75% commercial formulation (CHT-WP) and technical CHT. The environmental biotoxicity of CHT@MSNs-β-glucans compared with CHT-WP has been tested toward earthworm (Eisenia fetida) and zebra fish (Danio rerio). The results showed that CHT@MSNs-β-glucans has an excellent bioactivity against the subjected pathogens with better inhabiting effects than CHT-WP. CHT@MSNs-β-glucans toxicity to Eisenia fetida was found 2.25 times lower than CHT-WP toxicity. The LC₅₀ of CHT@MSNs-β-glucans to zebra fish after the first 24h was 2.93 times higher than CHT-WP. After 96h of treatment, the LC₅₀ of CHT@MSNs-β-glucans was 2.66 times higher than CHT-WP. This work highlighted the necessity to increase the mandatory bioassays of nano formulations with the major non-target organisms in the environmental risk assessment of new pesticide formulations.

NCs-Delivered Pesticides: A Promising Candidate in Smart Agriculture

Pesticides have been used extensively in the field of plant protection to maximize crop yields. However, the long-term, unmanaged application of pesticides has posed severe challenges such as pesticide resistance, environmental contamination, risk in human health, soil degradation, and other important global issues. Recently, the combination of nanotechnology with plant protection strategies has offered new perspectives to mitigate these global issues, which has promoted a rapid development of NCs-based pesticides. Unlike certain conventional pesticides that have been applied inefficiently and lacked targeted control, pesticides delivered by nanocarriers (NCs) have optimized formulations, controlled release rate, and minimized or site-specific application. They are receiving increasing attention and are considered as an important part in sustainable and smart agriculture. This review discussed the limitation of traditional pesticides or conventional application mode, focused on the sustainable features of NCs-based pesticides such as improved formulation, enhanced stability under harsh condition, and controlled release/degradation. The perspectives of NCs-based pesticides and their risk assessment were also suggested in this view for a better use of NCs-based pesticides to facilitate sustainable, smart agriculture in the future.

Evaluation of a Spinosad Controlled-Release Formulation Based on Chitosan Carrier: Insecticidal Activity against Plutella xylostella (L.) Larvae and Dissipation Behavior in Soil

Controlled-release pesticide formulations using natural polymers as carriers are highly desirable owing to their good biocompatibility, biodegradability, and improved pesticide utilization. In this study, the application potential of our previously prepared spinosad/chitosan controlled-release suspension (SCCS) was evaluated through both toxicity and dissipation tests. A comparison with the spinosad suspension concentrate and the commercial spinosad emulsion in water showed that the insecticidal activity of SCCS against Plutella xylostella larvae displayed the best quick-acting performance as well as long-term efficacy of more than 20 days. The 48 h LC50 for a 20-day efficacy was calculated to be 29.36 mg/L. The dissipation behavior of spinosad in the spinosad/chitosan microparticles in soil was found to follow the first-order kinetics, with a relatively shorter half-life (2.1 days) than that observed for the unformulated spinosad (3.1 days). This work showed the positive effect of chitosan on spinosad in improving insecticidal activity and reducing environmental risks in soil, which provided useful information on the application potential of pesticide-carrier systems based on natural polymer materials in crop protection and food safety.

Cyclodextrin polymer-valved MoS2-embedded mesoporous silica nanopesticides toward hierarchical targets via multidimensional stimuli of biological and natural environments

Targeted delivery of pesticides towards pests and pathogens can significantly improve the bioavailability and efficacy of pesticides and minimize the impact on the environment. Cyclodextrin polymer (CDP)-valved, benzimidazole functionalized, MoS₂-embedded mesoporous silica (MoS₂@MSN@CDP) nanopesticides were constructed toward hierarchical biological targets of pests, pathogens, and foliage. The splash and bounce of the aqueous droplets containing MoS₂@MSN@CDP nanoparticles in the presence of Aersosol OT on superhydrophobic surfaces were well inhibited available for excellent wetting to prevent pesticides from losing to the environment. The multivalent supramolecular nanovalves between CDP and the functionalized benzimidazole moieties could be activated for the controlled release of pesticides in the cases of low pH and α-amylase. It is the first time to report the foliage-triggered controlled release of pesticides, owing to the competitive binding of epicuticular wax components to CDP. Furthermore, thermogenic MoS₂ cores triggered the controlled release of pesticides under irradiation of near infrared light. The fungicidal efficacies of the stimuli-responsive nanopesticides against pathogenic fungi Rhizoctonia solani and Fusarium graminearum were demonstrated. It is clear that the smart nanopesticides could realize the controlled release of pesticides toward hierarchical biological targets for enhanced pesticide bioavailability and efficacy via the multidimensional stimuli of pH, α-amylase, epicuticular waxes, and sunlight.

The Food-Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri-Food Residues

The most recent strategies available for upcycling agri-food losses and waste (FLW) into functional bioplastics and advanced materials are reviewed and the valorization of food residuals are put in perspective, adding to the water-food-energy nexus. Low value or underutilized biomass, biocolloids, water-soluble biopolymers, polymerizable monomers, and nutrients are introduced as feasible building blocks for biotechnological conversion into bioplastics. The latter are demonstrated for their incorporation in multifunctional packaging, biomedical devices, sensors, actuators, and energy conversion and storage devices, contributing to the valorization efforts within the future circular bioeconomy. Strategies are introduced to effectively synthesize, deconstruct and reassemble or engineer FLW-derived monomeric, polymeric, and colloidal building blocks. Multifunctional bioplastics are introduced considering the structural, chemical, physical as well as the accessibility of FLW precursors. Processing techniques are analyzed within the fields of polymer chemistry and physics. The prospects of FLW streams and biomass surplus, considering their availability, interactions with water and thermal stability, are critically discussed in a near-future scenario that is expected to lead to next-generation bioplastics and advanced materials.

Redox- and Enzyme-Responsive Macrospheres Gatekept by Polysaccharides for Controlled Release of Agrochemicals

Stimuli-responsive materials afford researchers an opportunity to synthesize controlled-release carriers with various potential applications, especially for reducing the abuse of chemical reagents in farmland soil. To enhance the efficiency of agrochemical utilization, redox- and enzyme-responsive macrospheres were prepared by self-assembling β-cyclodextrin-modified zeolite and ferrocenecarboxylic acid (FcA)-grafted carboxymethyl cellulose (CMC). Scanning electron microscopy and Brunauer-Emmett-Teller analysis revealed that pores of zeolite were sealed by the surface coupling of FcA-modified CMC via the formation of an inclusion complex. Salicylic acid (SA) was loaded as a model agrochemical. The release of SA from macrospheres could be triggered in the presence of hydrogen peroxide (oxidant) and cellulase (enzyme); and the corresponding release percentages, 85.2 and 80.4%, were much higher than those of the control sample without responsive groups in water (12.6%) after 12 h. A release kinetic study showed that cellulase could promote carrier dissolution more effectively than the oxidant. The results demonstrate that the dual-responsive macrospheres are promising as a smart and effective carrier for the controlled release of agrochemicals.

Floating chitosan-alginate microspheres loaded with chlorantraniliprole effectively control Chilo suppressalis (Walker) and Sesamia inferens (Walker) in rice fields

Striped rice stem borer, Chilo suppressalis (Walker) and pink stem borer, Sesamia inferens (Walker) are two important pests, causing substantial yield loss in rice production. Application of conventional synthetic pesticides, such as suspension concentrates and water-dispersible granules, is a primary method for control of the two pests. Due to the flow of water in rice field, spray drift, and soil adsorption, applied such pesticides are often out of the target, resulting in low control efficacy, potential contamination of soil or surface water, and also threat to human health. Thus, there is an urgent need for developing environmentally friendly and highly targeted pesticide formulations to meet the challenges. The present study synthesized chlorantraniliprole loaded chitosan-alginate floating hydrogel microspheres (CCAM) through physical embedding, ionic crosslinking, and incorporation of citronellol as an oil phase. The morphology, particle size, entrapment efficiency, loading capacity, in vitro slow-release kinetics, and floating ability of the CCAM were tested in laboratory conditions. The CCAM and two commercial formulations (suspended and granulated) of chlorantraniliprole were respectively evaluated in two rice fields located in two provinces of China. The CCAM was able to float on the surface of rice field, gather around rice stems, and slowly release chlorantraniliprole, which resulted in significantly higher concentrations of chlorantraniliprole in rice stems and leaves for a prolonged time than suspended and granulated controls. The application of CCAM provided an on-target control of both striped stem borer and pink stem borer. Furthermore, CCAM application had very low residue of chlorantraniliprole in soils. As far as is known, this is the first report of chlorantraniliprole loaded on chitosan-alginate floating hydrogel microspheres for rice stem borer control. Our results indicate that the synthesized CCAM could potentially be used as a controlled-release product for effective control of the two rice pests, while reducing the residual chlorantraniliprole in the soil and avoiding pesticide drift.

Dual stimuli-responsive fungicide carrier based on hollow mesoporous silica/hydroxypropyl cellulose hybrid nanoparticles

The controlled release of pesticides based on nanoparticle platforms has emerged as a new technology for increasing the efficiency of pesticides and for reducing environmental pollution because of their size-dependent and target-modifying properties. In the present study, pH/cellulase dual stimuli-responsive controlled-release formulations (PYR-HMS-HPC) were designed by grafting hydroxypropyl cellulose onto pyraclostrobin-loaded hollow mesoporous silica nanoparticles via an ester linkage. The PYR-HMS-HPC formulations were characterized by Fourier transform infrared spectroscopy, thermogravimetric analyzer, transmission electron microscope and scanning electron microscope. The results demonstrated that PYR-HMS-HPC with a loading capacity of 12.1 wt% showed excellent pyraclostrobin release behaviors in response to acidic environments and the introduction of cellulase, could effectively prevented pyraclostrobin from photolysis. Compared with commercial pyraclostrobin formulations, the PYR-HMS-HPC formulations showed much stronger and statistically significant fungicidal activity against Magnaporthe oryzae from 7 to 21 days. Furthermore, the Allium cepa chromosome aberration assay demonstrated that the PYR-HMS-HPC formulations reduced the genotoxicity of pyraclostrobin. These pH/cellulase dual stimuli-responsive controlled-release formulations are of great interest for sustainable on-demand crop disease protection.

Hollow structures as drug carriers: Recognition, response, and release

Hollow structures have demonstrated great potential in drug delivery owing to their privileged structure, such as high surface-to-volume ratio, low density, large cavities, and hierarchical pores. In this review, we provide a comprehensive overview of hollow structured materials applied in targeting recognition, smart response, and drug release, and we have addressed the possible chemical factors and reactions in these three processes. The advantages of hollow nanostructures are summarized as follows: hollow cavity contributes to large loading capacity; a tailored structure helps controllable drug release; variable compounds adapt to flexible application; surface modification facilitates smart responsive release. Especially, because the multiple physical barriers and chemical interactions can be induced by multishells, hollow multishelled structure is considered as a promising material with unique loading and releasing properties. Finally, we conclude this review with some perspectives on the future research and development of the hollow structures as drug carriers.

Infrared-Light-Responsive Controlled-Release Pesticide Using Hollow Carbon Microspheres@Polyethylene Glycol/α-Cyclodextrin Gel

Controlled release of pesticides by light regulation is one of the most viable strategies recently developed for the highly efficient utilization of agrochemicals. Herein, we report an infrared-light-responsive pesticide delivery system for the controlled release of imidacloprid (IMI) by preparation of functional hollow carbon microspheres (HCMs). After IMI loading and surface functionalization with polyethylene glycol (PEG) and α-cyclodextrin (α-CD), IMI was sequestered in the pesticide system (denoted as HCMs/IMI/PEG/α-CD) as a result of the formation of a PEG/α-CD gel network. Upon the irradiation of infrared light, HCMs with high photothermal conversion efficiency (42.8%) raised the local temperature effectively, leading to the collapse of the gel network and the release of IMI. In comparison to the amount of pesticide release (29%) under sunlight, it could reach 77% driven by infrared light, which was an intriguing improvement. Consequently, HCMs/IMI/PEG/α-CD under infrared light showed significantly higher pest control efficacy on corn borers by 125% than itself alone. This work provides a promising method to intentionally regulate pesticide release and enhance utilization efficiency.

Multiple Roles of Mesoporous Silica in Safe Pesticide Application by Nanotechnology: A Review

Pollution related to pesticides has become a global problem due to their low utilization and non-targeting application, and nanotechnology has shown great potential in promoting sustainable agriculture. Nowadays, mesoporous silica-based nanomaterials have garnered immense attention for improving the efficacy and safety of pesticides due to their distinctive advantages of low toxicity, high thermal and chemical stability, and particularly size tunability and versatile functionality. Based on the introduction of the structure and synthesis of different types of mesoporous silica nanoparticles (MSNs), the multiple roles of mesoporous silica in safe pesticide application using nanotechnology are discussed in this Review: (i) as nanocarrier for sustained/controlled delivery of pesticides, (ii) as adsorbent for enrichment or removal of pesticides in aqueous media, (iii) as support of catalysts for degradation of pesticide contaminants, and (iv) as support of sensors for detection of pesticides. Several scientific issues, strategies, and mechanisms regarding the application of MSNs in the pesticide field are presented, with their future directions discussed in terms of their environmental risk assessment, in-depth mechanism exploration, and cost-benefit consideration for their continuous development. This Review will provide critical information to related researchers and may open up their minds to develop new advances in pesticide application.