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

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.

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.

O-nitrobenzyl Caged Molecule Enables Photo-controlled Release of Thiabendazole

Pesticides are essential in agricultural development. Controlled-release pesticides have attracted great attentions. Base on a principle of spatiotemporal selectivity, we extended the photoremovable protective group (PRPG) into agrochemical agents to achieve controllable release of active ingredients. Herein, we obtained NP-TBZ by covalently linking o-nitrobenzyl (NP) with thiabendazole (TBZ). Compound NP-TBZ can be controlled to release TBZ in dependent to light. The irradiated and unirradiated NP-TBZ showed significant differences on fungicidal activities both in vitro and in vivo. In addition, the irradiated NP-TBZ displayed similar antifungal activities to the directly-used TBZ, indicating a factual applicability in controllable release of TBZ. Furthermore, we explored the action mode and microcosmic variations by SEM analysis, and demonstrated that the irradiated NP-TBZ retained a same action mode with TBZ against mycelia growth.

Enhanced control efficacy of spinosad on corn borer using polylactic acid encapsulated mesoporous silica nanoparticles as a smart delivery system

Asion corn borer (Ostrinia furnacalis (Guenee)) is one of the most important factors affecting the normal growth and yield of corn. However, chemical control methods currently in use cause severe pollution. In the present study, aminated mesoporous silica nanoparticles (MSNs-NH2) and polylactic acid (PLA) were used as the carrier and capping agent respectively to construct an insect gut microenvironment nano-response system that loaded spinosad, a biopesticide used to control O. furnacalis. The resulting spinosad@MSNs-PLA demonstrated high loading capacity (38.6 %) and improved photostability of spinosad. Moreover, this delivery system could intelligently respond to the intestinal microenvironment of the corn borer's gut and achieve the smart release of spinosad. Compared with the conventional pesticide, spinosad@MSNs-PLA exhibited superior efficacy in controlling the O. furnacalis and could uptake and transport in maize plants without adverse effects on their growth. Furthermore, the toxicity of spinosad@MSNs-PLA on zebrafish was reduced by over 50 times. The prepared spinosad@MSNs-PLA has great potential and could be widely applied in agricultural production in the future. This approach could improve the utilization of pesticide and reduce environmental pollution. In addition, MSNs-PLA nano vectors provide new ideas for the control of other borer pests.

Continuous-Flow Nanoprecipitation Method to Synthesize Degradable Hollow Mesoporous Organosilica Nanoparticles for Insecticide Delivery

Degradable mesoporous organosilica nanoparticles (MONPs) are attracting significant attention in the area of designing smart drug carriers mainly due to their excellent stability and multiple functions. However, the efficient, controllable, and large-scale production of MONPs still faces huge challenges. Herein, a novel and facile continuous-flow nanoprecipitation strategy was reported to synthesize hollow MONPs with highly uniform and tailored properties. The synthesized hollow MONPs possessed a large surface area (SBET > 1070.1 m2 g-1), narrow size distribution, large hollow cavity, and thin shell. Interestingly, the incorporation of organic moieties into silica cross-linked networks led to the timely degradation of nanocarriers with the desired responsiveness. Moreover, the applicability of the as-obtained hollow MONPs has been demonstrated in the loading and pH-responsive release of thiamethoxam (THI). The resultant THI-loaded MONPs possessed long-term storage stability at a low temperature and showed release behaviors in response to a basic environment. Benefiting from the shielding property of MONPs, THI-loaded MONPs manifested superior stability against the photolysis as compared to that of the THI technical. This work provides a new consideration for promoting the advancement of nanotechnology in agricultural fields.

Carboxymethyl β-cyclodextrin grafted hollow copper sulfide@mesoporous silica carriers for stimuli-responsive pesticide delivery

Stimuli-responsive controlled release systems have received extensive attention to improve the pesticide bioavailability and minimize environmental pollution. Herein, a multiple stimuli-responsive IMI@HCuS@mSiO₂ @ -ss-CβCD delivery system was constructed using modified carboxymethyl β-cyclodextrin (CβCD-ss-COOH) as sealing materials, hollow copper sulfide nanoparticles with amino-functionalized mesoporous silica shell (HCuS@mSiO₂-NH₂) as carriers and imidacloprid (IMI) as the model drug. The cavity structure of HCuS@mSiO₂-NH₂ would provide a large space for pesticide loading. The results revealed that HCuS@mSiO₂-ss-CβCD was approximately 230 nm in size and the loading efficiency for IMI was 25.7%, and exhibited better biosafety on bacteria and seed. HCuS carriers were also served as photothermal agent and possessed high photothermal conversion effect (η = 38.4%). IMI@HCuS@mSiO₂ @ -ss-CβCD displayed excellent foliage adhesion and multiple stimuli-responsive release properties to pH, α-amylase, GSH, and NIR. The photostability of IMI embedded in CuS@mSiO₂ @ -ss-CβCD was approximately 10 times that of IMI solution. This work provides an efficient nanoplatform for realizing pesticide delivery.

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.

Dual photo-controlled release system for fipronil and dinotefuran

Development of controlled release system promises a huge impact on the pesticide delivery, which has raised attentions in improving efficacy of pesticides. Herein, the emerging photoremovable protecting group (PRPG), used in spatiotemporal delivery of drug by light, was introduced into agriculture. We obtained three TNB-insecticides and two of them exhibited excellent photophysicochemical properties. Our dual photo-controlled release system displayed more than sixfold insecticidal activity differences upon irradiation with UV light or sunlight. The dual release of DIN-TNB-DIN showed synergistic effect on mosquito larvae and armyworm larvae. Distribution of the fluorescence in body of dead/alive wigglers clearly illustrated the action mode, and visually demonstrated the precise and spatiotemporal delivery of insecticides in the living mosquito larvae. The new developed dual photo-controlled release system might widen the diversity in pesticide delivery, promoting the development in improving pesticide efficacy.

Advances in stimuli-responsive systems for pesticides delivery: Recent efforts and future outlook

Effective pest management for enhanced crop output is one of the primary goals of establishing sustainable agricultural practices in the world. Pesticides are critical in preventing biological disasters, ensuring crop productivity, and fostering sustainable agricultural production growth. Studies showed that crops are unable to properly utilize pesticides because of several limiting factors, such as leaching and bioconversion, thereby damaging ecosystems and human health. In recent years, stimuli-responsive systems for pesticides delivery (SRSP) by nanotechnology demonstrated excellent promise in enhancing the effectiveness and safety of pesticides. SRSP are being developed with the goal of delivering precise amounts of active substances in response to biological needs and environmental factors. An in-depth analysis of carrier materials, design fundamentals, and classification of SRSP were provided. The adhesion of SRSP to crop tissue, absorption, translocation in and within plants, mobility in the soil, and toxicity were also discussed. The problems and shortcomings that need be resolved to accelerate the actual deployment of SRSP were highlighted in this review.

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.

Pectin functionalized metal-organic frameworks as dual-stimuli-responsive carriers to improve the pesticide targeting and reduce environmental risks

Encapsulation of active ingredients into intelligent response controlled release carriers has been recognized as a promising approach to enhance the utilization efficiency and reduce the environmental risks of pesticides. In this work, an intelligent redox and pectinase dual stimuli-responsive pesticide delivery system was constructed by bonding pectin with metal-organic frameworks (FeMOF nanoparticles) which were loaded with pyraclostrobin (PYR@FeMOF-pectin nanoparticles). The successful fabrication of PYR@FeMOF-pectin nanoparticles was proved by a series of physicochemical characterizations. The results indicated that the loading capacity of PYR@FeMOF-pectin nanoparticles for pyraclostrobin was approximately 20.6%. The pectin covered on the surface of PYR@FeMOF nanoparticles could protect pyraclostrobin from photolysis and improve their spreadability on rice blades effectively. Different biological stimuli associated with Magnaporthe oryzae could trigger the release of pyraclostrobin from the pesticide-loaded core-shell nanoparticles, resulting in the death of pathogens. The bioactivity survey determined that PYR@FeMOF-pectin nanoparticles had a superior fungicidal activity and a longer duration against Magnaporthe oryzae than pyraclostrobin suspension concentrate. In addition, the FeMOF-pectin nanocarriers showed no obvious phytotoxicity and could enhance the shoot length and root length of rice plants. More importantly, PYR@FeMOF-pectin nanoparticles had an 8-fold reduction in acute toxicity to zebrafish than that of pyraclostrobin suspension concentrate. Therefore, the dual-responsive FeMOF-pectin nanocarriers have great potential for realizing site-specific pesticide delivery and promoting plant growth.

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.

Hydrogen sulphide alleviates Fusarium Head Blight in wheat seedlings

Hydrogen sulphide (H₂S), a crucial gas signal molecule, has been reported to be involved in various processes related to development and adversity responses in plants. However, the effects and regulatory mechanism of H₂S in controlling Fusarium head blight (FHB) in wheat have not been clarified. In this study, we first reported that H₂S released by low concentrations of sodium hydrosulphide (NaHS) could significantly alleviate the FHB symptoms caused by Fusarium graminearum (F. graminearum) in wheat. We also used coleoptile inoculation to investigate the related physiological and molecular mechanism. The results revealed that FHB resistance was strongly enhanced by the H₂S released by NaHS, and 0.3 mM was confirmed as the optimal concentration. H₂S treatment dramatically reduced the levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) while enhancing the activities of antioxidant enzymes. Meanwhile, the relative expressions levels of defence-related genes, including PR1.1, PR2, PR3, and PR4, were all dramatically upregulated. Our results also showed that H₂S was toxic to F. graminearum by inhibiting mycelial growth and spore germination. Taken together, the findings demonstrated the potential value of H₂S in mitigating the adverse effects induced by F. graminearum and advanced the current knowledge regarding the molecular mechanisms in wheat.

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.

A pH Dual-Responsive Multifunctional Nanoparticle Based on Mesoporous Silica with Metal-Polymethacrylic Acid Gatekeeper for Improving Plant Protection and Nutrition

Integrating pesticides and mineral elements into a multi-functional stimuli-responsive nanocarrier can have a synergistic effect on protecting plants from pesticides and the supply of nutrients. Herein, a pH dual-responsive multifunctional nanosystem regulated by coordination bonding using bimodal mesoporous silica (BMMs) as a carrier and coordination complexes of ferric ion and polymethacrylic acid (PMAA/Fe³⁺) as the gatekeeper was constructed to deliver prochloraz (Pro) for the smart treatment of wilt disease (Pro@BMMs−PMAA/Fe³⁺). The loading capacity of Pro@BMMs−PMAA/Fe³⁺ nanoparticles (Nps) was 24.0% and the “PMMA/Fe³⁺” complexes deposited on the BMMs surface could effectively protect Pro against photodegradation. The nanoparticles possessed an excellent pH dual-responsive release behavior and better inhibition efficacy against Rhizoctonia solani. Fluorescence tracking experiments showed that Nps could be taken up and transported in fungi and plants, implying that non-systemic pesticides could be successfully delivered into target organisms. Furthermore, BMMS−PMAA/Fe³⁺ nanocarriers could effectively promote the growth of crop seedlings and had no obvious toxicological influence on the cell viability and the growth of bacteria. This study provides a novel strategy for enhancing plant protection against diseases and reducing the risk to the environment.

Nanomaterials and nanotechnology for the delivery of agrochemicals: strategies towards sustainable agriculture

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.

Construction of a photothermal controlled-release microcapsule pesticide delivery system

This study aimed to achieve the controlled-release of bioactive ingredients in microcapsule pesticide delivery systems. A photothermal controlled-release microcapsule pesticide delivery system was constructed using chitosan and polydopamine (PDA) as the wall materials to encapsulate avermectin. All the prepared microcapsules were characterized by the methods of optical microscopy, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. The slow-release, UV-shielding, photothermal performance, and the nematicidal activity of the prepared microcapsules were also systematically investigated. The results indicated that the prepared microcapsules had excellent slow-release and UV-shielding performance when further encapsulated with the PDA layer relative to those of the non-PDA-encapsulated products. The photothermal sensitivity of the AVM@CS/CMA/PDA composite microcapsule under the irradiation of near-infrared light (NIR) was dramatically enhanced with the photothermal conversion efficiency (η) of 14.93%. Furthermore, the nematicidal activity of the AVM@CS/CMA/PDA composite microcapsule system was effectively improved on exposure to the irradiation of a light-emitting diode (LED) full-spectrum light. The strategies used in this study for developing the photothermal controlled-release pesticide delivery system might play an important role on improving utilization of pesticides.

A photothermal controlled-release microcapsule pesticide delivery system was constructed using chitosan and polydopamine as the wall materials to encapsulate avermectin, the utilization rate of avermectin was improved.