Fabrication of pH-responsive nanoparticles for high efficiency pyraclostrobin delivery and reducing environmental impact

Multiresponsive Zein Nanospheres for Avermectin B2 Delivery: Enhancing Root-Knot Nematode Control and Safety to Nontarget Organisms

Root-knot nematodes are globally prevalent plant-parasitic pests, distinguished by their widespread distribution, extensive host range, and challenging control measures. Avermectin B2, one of the few effective nematicides available, faces limitations in efficacy and poses environmental concerns due to its eco-unfriendly composition and poor utilization in traditional emulsifiable concentrate (EC) formulations. In this study, we developed core-shell structured Ave B2-BS@Zein@SC nanospheres, incorporating zein as the carrier, sodium caseinate as the stabilizer, and butyl stearate as the temperature "switch". These nanospheres demonstrated multiresponsive characteristics to temperature, pH, and enzymatic conditions, facilitating rapid pesticide release under elevated temperatures, mildly acidic or alkaline conditions, and in the presence of protease. These controlled-release properties effectively responded to both environmental factors during nematode outbreaks and the intestinal conditions of the nematodes, enhancing pesticide targeting and utilization efficiency. The engineered nanospheres improved the mobility and stability of avermectin B2 in soil, enabling more comprehensive control of nematodes across broader and deeper soil layers. Additionally, the penetration capability of Ave B2-BS@Zein@SC into plant roots effectively eliminated nematodes that had already invaded the root system, thereby strengthening crop protection. Crucially, Ave B2-BS@Zein@SC demonstrated enhanced safety for nontarget organisms. This environmentally conscious, and multiresponsive pesticide nanodelivery system presents a promising strategy for sustainable subterranean pest management.

Sustainable pest management using plant secondary metabolites regulated azadirachtin nano-assemblies

Biopesticides have emerged as a global trend to minimize the risks associated with synthetic agrochemicals. However, their stability and efficacies remain challenges for widespread application. Herein, co-assembled nanoparticles (AT NPs or AP NPs) based on azadirachtin (AZA) and tannic acid (TA) or phenylalanine (PA) are constructed in aqueous solution through self-assembly technology. The small particle size, low PDI, high ζ-potential, and related other physicochemical characteristics of nanoparticles can improve wettability, adhesiveness, rain erosion resistance, and photostability compared to the commercial AZA formulation. Importantly, co-assemblies with bidirectional pH-responsive disassembly in acidic or alkaline solutions, allow them to respond to microenvironmental stimuli of targets and enable controlled release of AZA. The nanosystems demonstrated remarkable in vitro and in vivo insecticidal activities against Ostrinia furnacalis and Aphis gossypii. This study illustrates a distinctive perspective for developing eco-friendly nanosystems, highlighting a water-based treatment method for biopesticides with improved physicochemical properties and utilization efficiency.

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.

Design of highly leaf-adhesive and anti-UV herbicide nanoformulation for enhanced herbicidal activity

INTRODUCTION

Conventional pesticide formulations have been widely used to boost agricultural productivity, but their weak foliar adhesion and instability under UV light during spraying lead to low utilization rates and potential environmental and health hazards. To counter these challenges, the development of nanoformulations represents a pivotal strategy. These advanced formulations are designed to enhance the efficacy of active ingredients (AIs) and reduce ecological impacts, thereby addressing the need for sustainable agricultural development.

OBJECTIVES

The study aims to fabricate a highly leaf-adhesive and anti-UV herbicide nanoformulation, designed to enhance the herbicidal activity and utilization rates of AIs.

METHODS

Herein, the herbicide nanoformulations (Called CB@MSNs-TA-Fe) are synthesized by incorporating cyhalofop-butyl into tannic acid-Fe (III) ions-coated functionalized mesoporous silica. The foliar retention performance of the samples was assessed integrating SEM observation and HPLC analysis.

RESULTS

The CB@MSNs-TA-Fe with rough outer surface displays typical core-shell structure featuring an average diameter of about 118 nm. After amino modification, the CB@MSNs-TA-Fe shows enhanced loading rate for CB (14.4 ± 0.2 %) and superior thermal stability. The release rate of CB within CB@MSNs-TA-Fe under acidic conditions is higher compared to that under alkaline and neutral conditions. Upon UV irradiation, the half-life of CB within CB@MSNs-TA-Fe nanoparticles is 12.4 times higher than that of CB technical (CB TC). Enhanced foliar adhesion of CB@MSNs-TA-Fe on hydrophobic leaf surfaces is observed, which can effectively mitigate the risk of wash-off by rainfall. The CB@MSNs-TA-Fe displays enhanced herbicidal efficacies against barnyard grass under UV irradiation or simulated rainwater scouring, compared with CB TC and CB oil dispersion. Furthermore, the TA-Fe-coated MSNs-NH2 nano-carrier (MSNs-TA-Fe) reveals excellent biosafety on rice, zebrafish, and earthworms.

CONCLUSION

The developed TA-Fe-functionalized herbicide nanoformulations, with high foliar adhesion and anti-UV properties, effectively improve the utilization efficiency of AIs, thus offering innovative solutions for the development of efficient pesticide formulations.

pH-Responsive Metal-Organic Framework for Targeted Delivery of Fungicide, Release Behavior, and Sustainable Plant Protection

A smart and environmentally friendly pesticide system was developed that could respond to environmental stimuli while mitigating environmental risks. In this study, thiabendazole (Thi), an effective fungicide, was loaded onto zeolitic imidazolate framework-8 (ZIF-8) using the impregnation method to fabricate a pH-responsive nano hybrid delivery system (Thi@ZIF-8). The results demonstrated that Thi@ZIF-8 had a rhombic dodecahedral morphology and a loading capacity of approximately 25%. Notably, the amount of Thi released from Thi@ZIF-8 at a pH of 5.0 reached 79.54%, which was higher than that at pH 7.0 and 9.0, for 251 h. Such pH-responsive release characteristics of Thi@ZIF-8 were probably related to the pH-dependent structure stability of ZIF-8. The release mechanism of Thi@ZIF-8 conformed to non-Fickian diffusion. Additionally, Thi@ZIF-8 showed a higher control efficacy against B. cinerea compared with Thi alone. Importantly, the ZIF-8 carrier could effectively reduce the leaching loss of Thi in soil and showed no negative effects on the three varieties of tomato seedlings, implying good biocompatibility. This work provides a novel and eco-friendly approach to control B. cinerea effectively that has great potential in modern sustainable agriculture.

Preparation of pH-Responsive Kas@ZnO Quantum Dots for Synergistic Control of Rice Blast and Enhanced Disease Resistance in Rice

The construction of controlled-release formulations improves the sustained-release performance and utilization efficiency of pesticides, which are important aspects in plant protection and environmental chemistry. The current study employs kasugamycin (Kas), which is widely used to control Magnaporthe oryzae, conjugated with carboxyl-functionalized ZnO quantum dots via amide linkages to yield a pH-responsive pesticide delivery system (Kas@ZnO). Physicochemical characterizations indicated the successful preparation of the Kas@ZnO nanoparticles. In vitro drug release assessments indicated that Kas@ZnO exhibited a loading capacity of 21.05% and could effect the controlled release of Kas in an acidic environment, which is beneficial given the unique acidic microenvironment of M. oryzae. Bioactivity assays demonstrated that Kas@ZnO could simultaneously inhibit mycelial growth and spore germination. Additionally, bioactivity tests showed that the control efficacy of Kas@ZnO against rice blast reached 67.43% after 14 days of in vivo spray inoculation, which was higher than that obtained with Kas (55.50%), suggesting improved beneficial effects of Kas@ZnO application over a prolonged duration. Moreover, Kas@ZnO enhanced the activity of defense-related enzymes in rice and upregulated the expression of defense-related genes, such as OsPR2, OsPR3, OsPR5, OsWRKY45, OsLYP6, and OsNAC4. Ultimately, the biosafety assessments revealed that Kas@ZnO did not exert any harmful effects on rice and demonstrated slight toxicity toward zebrafish. These findings indicate that Kas@ZnO can function as a pH-sensitive pesticide delivery system, allowing for targeted release of the pesticide within plant tissues. This technology demonstrates significant potential for eco-friendly plant disease management.

Recent advances and applications of stimuli-responsive nanomaterials for water treatment: A comprehensive review

The development of stimuli-responsive nanomaterials holds immense promise for enhancing the efficiency and effectiveness of water treatment processes. These smart materials exhibit a remarkable ability to respond to specific external stimuli, such as light, pH, or magnetic fields, and trigger the controlled release of encapsulated pollutants. By precisely regulating the release kinetics, these nanomaterials can effectively target and eliminate contaminants without compromising the integrity of the water system. This review article provides a comprehensive overview of the advancements in light-activated and pH-sensitive nanomaterials for controlled pollutant release in water treatment. It delves into the fundamental principles underlying these materials' stimuli-responsive behaviour, exploring the design strategies and applications in various water treatment scenarios. In particular, the article indicates how integrating stimuli-responsive nanomaterials into existing water treatment technologies can significantly enhance their performance, leading to more sustainable and cost-effective solutions. The synergy between these advanced materials and traditional treatment methods could pave the way for innovative approaches to water purification, offering enhanced selectivity and efficiency. Furthermore, the review highlights the critical challenges and future directions in this rapidly evolving field, emphasizing the need for further research and development to fully realize the potential of these materials in addressing the pressing challenges of water purification.

Metal-Organic Frameworks for Sustainable Crop Disease Management: Current Applications, Mechanistic Insights, and Future Challenges

Efficient management of crop diseases and yield enhancement are essential for addressing the increasing food demands due to global population growth. Metal-organic frameworks (MOFs), which have rapidly evolved throughout the 21st century, are notable for their vast surface area, porosity, and adaptability, establishing them as highly effective vehicles for controlled drug delivery. This review methodically categorizes common MOFs employed in crop disease management and details their effectiveness against various pathogens. Additionally, by critically evaluating existing research, it outlines strategic approaches for the design of drug-delivery MOFs and explains the mechanisms through which MOFs enhance disease resistance. Finally, this paper identifies the current challenges in MOF research for crop disease management and suggests directions for future research. Through this in-depth review, the paper seeks to enrich the understanding of MOFs applications in crop disease management and offers valuable insights for researchers and practitioners.

Carboxymethyl cellulose-coated iron-doped hollow silica carriers with erythrocyte-like structure for improved foliar adhesion and responsive pesticide delivery

The development of nanopestcide carriers with high foliage adhesion remains a challenging task. Erythrocytes are double concave disc structure with thinner center and thicker rim and erythrocyte-like carriers would present enhanced foliar affinity. In this study, we fabricated novel rough-surfaced erythrocyte-like carriers for pesticide delivery. Firstly, erythrocyte-like silica (ES) nanoparticles were prepared by sol-gel method. Subsequently, the ES nanoparticles were further hydrothermal treated to obtain rough-surfaced iron-doped hollow ES (Fe-EHS) nanocarriers. The Fe-EHS nanocarriers could increase contact area and form a topological effect between the pesticide carriers and the micro/nanostructures on plant foliage, effectively enhancing the retention and rain fastness on foliage. Fe-EHS nanocarriers presented a loading capacity of 38.1 % for imidacloprid (IMI). After loading IMI, carboxymethyl cellulose (CMC) was encapsulated to generate nanopesticide delivery system (IMI@Fe-EHS-CMC). The obtained IMI@Fe-EHS-CMC exhibited good foliar adhesion, biosafety, and excellent UV shielding. Additionally, the IMI@Fe-EHS-CMC system possessed pH/cellulase responsive release behavior and could be bidirectionally transported through vascular bundles in tobacco plants. Furthermore, the IMI@Fe-EHS-CMC system showed potent insecticidal activity. This work offers valuable insights for enhancing the effective utilization of pesticides.

Carrier-free self-assembled nanoparticles based on prochloraz and fenhexamid for reducing toxicity to aquatic organism

Nanoformulations of pesticides are an effective way to increase utilization efficiency and alleviate the adverse impacts on the environments caused by conventional pesticide formulations. However, the complex preparation process, high cost, and potential environmental risk of nanocarriers severely restricted practical applications of carrier-based pesticide nanoformulations in agriculture. Herein, carrier-free self-assembled nanoparticles (FHA-PRO NPs) based on fenhexamid (FHA) and prochloraz (PRO) were developed by a facile co-assembly strategy to improve utilization efficiency and reduce toxicity to aquatic organism of pesticides. The results showed that noncovalent interactions between negatively charged FHA and positively charged PRO led to core-shell structured nanoparticles arranged in an orderly manner dispersing in aqueous solution with a diameter of 256 nm. The prepared FHA-PRO NPs showed a typical pH-responsive release profile and exhibited excellent physicochemical properties including low surface tension and high max retention. The photostability of FHA-PRO NPs was improved 2.4 times compared with free PRO. The FHA-PRO NPs displayed superior fungicidal activity against Sclerotinia sclerotiorum and Botrytis cinerea and longer duration against Sclerotinia sclerotiorum on potted rapeseed plants. Additionally, the FHA-PRO NPs reduced the acute toxicity of PRO to zebrafish significantly. Therefore, this work provided a promising strategy to develop nanoformulations of pesticides with stimuli-responsive controlled release characteristics for precise pesticide delivery.

A dew-responsive pectin-based herbicide for enhanced photodynamic inactivation

5-aminolevulinic acid (5-ALA) has been fully demonstrated as a biodegradable, without resistance, and pollution-free pesticide. However, the lack of targeting and the poor adhesion result in a low utilization rate, limiting its practical application. Herein, a dew-responsive polymer pro-pesticide Pec-hyd-ALA was successfully synthesized by grafting 5-ALA onto the pectin (PEC) backbone via acid-sensitive acylhydrazone bonds. When the pro-pesticide is exposed to acid dew on plant surfaces at night, 5-ALA is released and subsequently converted to photosensitize (Protoporphyrin IX, PpIX)in plant cells, leading to its accumulation and promoting photodynamic inactivation (PDI). An inverted fluorescence microscope has verified the accumulation of tetrapyrrole in plant cells. In addition, the highly bio-adhesive PEC backbone effectively improved the wetting and retention of 5-ALA on leaves. The pot experiment also demonstrated the system's control effect on barnyard grass. This work provides a promising approach to improving the herbicidal efficacy of 5-ALA.

Mesoporous silica nanospheres-mediated insecticide and antibiotics co-delivery system for synergizing insecticidal toxicity and reducing environmental risk of insecticide

Mesoporous silica nanoparticles (MSNs) are efficient carriers of drugs, and are promising in developing novel pesticide formulations. The cotton aphids Aphis gossypii Glover is a world devastating insect pest. It has evolved high level resistance to various insecticides thus resulted in the application of higher doses of insecticides, which raised environmental risk. In this study, the MSNs based pesticide/antibiotic delivery system was constructed for co-delivery of ampicillin (Amp) and imidacloprid (IMI). The IMI@Amp@MSNs complexes have improved toxicity against cotton aphids, and reduced acute toxicity to zebrafish. From the 16S rDNA sequencing results, Amp@MSNs, prepared by loading ampicillin to the mesoporous of MSNs, greatly disturbed the gut community of cotton aphids. Then, the relative expression of at least 25 cytochrome P450 genes of A. gossypii was significantly suppressed, including CYP6CY19 and CYP6CY22, which were found to be associated with imidacloprid resistance by RNAi. The bioassay results indicated that the synergy ratio of ampicillin to imidacloprid was 1.6, while Amp@MSNs improved the toxicity of imidacloprid by 2.4-fold. In addition, IMI@Amp@MSNs significantly improved the penetration of imidacloprid, and contributed to the amount of imidacloprid delivered to A. gossypii increased 1.4-fold. Thus, through inhibiting the relative expression of cytochrome P450 genes and improving penetration of imidacloprid, the toxicity of IMI@Amp@MSNs was 6.0-fold higher than that of imidacloprid. The greenhouse experiments further demonstrated the enhanced insecticidal activity of IMI@Amp@MSNs to A. gossypii. Meanwhile, the LC50 of IMI@Amp@MSNs to zebrafish was 3.9-fold higher than that of IMI, and the EC50 for malformation was 2.8-fold higher than IMI, respectively, which indicated that the IMI@Amp@MSNs complexes significantly reduced the environmental risk of imidacloprid. These findings encouraged the development of pesticide/antibiotic co-delivery nanoparticles, which would benefit pesticide reduction and environmental safety.

Injectable, self-healing and degradable dynamic hydrogels with tunable mechanical properties and stability by thermal-induced micellization

Dynamic hydrogels possessing injectable, degradable and self-healing abilities have attracted considerable attention in the biomedical field in recent years, but it is difficult to tune the mechanical properties and stability of conventional dynamic hydrogels. In this work, we synthesized ABA-triblock copolymers via RAFT polymerization, where the A block consisted of thermo-sensitive poly(N-isopropylacrylamide-co-diacetone acrylamide) and the B block was hydrophilic poly(acrylamide). Subsequently, dynamic hydrogels were obtained based on the acylhydrazone bonds between the triblock copolymers and adipic acid dihydrazide (ADH). The obtained hydrogels exhibited injectable and self-healable abilities. In response to the thermal-induced micellization of their temperature-responsive blocks, the mechanical strength of the hydrogels not only increased, but also they exhibited high stability even at pH 2.0. Moreover, the hydrogel in the stable state could be degraded by the fracture of its trithiocarbonate groups. In addition, the hydrogels exhibited good cytocompatibility and controlled release behavior for doxorubicin (DOX). Considering these attractive tunable properties, these dynamic hydrogels show various potential applications in the biomedical field, such as drug carriers and cell or tissue engineering scaffolds.

In situ generation of copper(Ⅱ)/diethyldithiocarbamate complex through tannic acid/copper(Ⅱ) network coated hollow mesoporous silica for enhanced cancer chemodynamic therapy

The Cu2+ complex formed by the coordination of disulfiram (DSF) metabolite diethyldithiocarbamate (DTC), Cu(DTC)2, can effectively inhibit tumor growth. However, insufficient Cu2+ levels in the tumor microenvironment can impact tumor-suppressive effects of DTC. In this study, we proposed a Cu2+ and DSF tumor microenvironment-targeted delivery system. This system utilizes hollow mesoporous silica (HMSN) as a carrier, after loading with DSF, encases it using a complex of tannic acid (TA) and Cu2+ on the outer layer. In the slightly acidic tumor microenvironment, TA/Cu undergoes hydrolysis, releasing Cu2+ and DSF, which further form Cu(DTC)2 to inhibit tumor growth. Additionally, Cu2+ can engage in a Fenton-like reaction with H2O2 in the tumor microenvironment to form OH, therefore, chemodynamic therapy (CDT) and Cu(DTC)2 are used in combination for tumor therapy. In vivo tumor treatment results demonstrated that AHD@TA/Cu could accumulate at the tumor site, achieving a tumor inhibition rate of up to 77.6 %. This study offers a novel approach, circumventing the use of traditional chemotherapy drugs, and provides valuable insights into the development of in situ tumor drug therapies.

Efficient Control of Rhizoctonia solani Using Environmentally Friendly pH-Responsive Tannic Acid-Rosin Nano-Microcapsules

A nanomicrocapsule system was constructed through the polymerization of tannic acid (TA) and emulsifier OP-10 (OP-10), followed by the chelation of iron ions, to develop a safe and effective method for controlling Rhizoctonia solani in agriculture. The encapsulated active component is a rosin-based triazole derivative (RTD) previously synthesized by our research group (RTD@OP10-TA-Fe). The encapsulation efficiency of the nanomicrocapsules is 82.39%, with an effective compound loading capacity of 96.49%. Through the encapsulation of the RTD via nanomicrocapsules, we improved its water solubility, optimized its stability, and increased its adhesion to the leaf surface. Under acidic conditions (pH = 5.0), the release rate of nanomicrocapsules at 96 h is 96.31 ± 0.8%, which is 2.04 times higher than the release rate under normal conditions (pH = 7.0). Additionally, the results of in vitro and in vivo antifungal assays indicate that compared with the original compound, the nanomicrocapsules exhibit superior antifungal activity (EC50 values of RTD and RTD@OP10-TA-Fe are 1.237 and 0.860 mg/L, respectively). The results of field efficacy trials indicate that compared with RTD, RTD@OP10-TA-Fe exhibits a more prolonged period of effectiveness. Even after 3 weeks, the antifungal rate of RTD@OP10-TA-Fe remains at 40%, whereas RTD, owing to degradation, shows an antifungal rate of 11.11% during the same period. Furthermore, safety assessment results indicate that compared with the control, RTD@OP10-TA-Fe has almost no impact on the growth of rice seedlings and exhibits low toxicity to zebrafish. This study provides valuable insights into controlling R. solani and enhancing the compound performance.

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.

Near-infrared-responsive CuS@Cu-MOF nanocomposite with high foliar retention and extended persistence for controlling strawberry anthracnose

Strawberry anthracnose (Colletotrichum gloeosporioides) exhibits a high pathogenicity, capable of directly infecting leaves through natural openings, resulting in devastating impacts on strawberries. Here, nanocomposite (CuS@Cu-MOF) was prepared with a high photothermal conversion efficiency of 35.3% and a strong response to near-infrared light (NIR) by locally growing CuS nanoparticles on the surface of a copper-based metal-organic framework (Cu-MOF) through in situ sulfurization. The porosity of Cu-MOF facilitated efficient encapsulation of the pesticide difenoconazole within CuS@Cu-MOF (DIF/CuS@Cu-MOF), achieving a loading potential of 19.18 ± 1.07%. Under NIR light irradiation, DIF/CuS@Cu-MOF showed an explosive release of DIF, which was 2.7 times higher than that under dark conditions. DIF/CuS@Cu-MOF exhibited a 43.9% increase in efficacy against C. gloeosporioides compared to difenoconazole microemulsion (DIF ME), demonstrating prolonged effectiveness. The EC50 values for DIF and DIF/CuS@Cu-MOF were 0.219 and 0.189 μg/mL, respectively. Confocal laser scanning microscopy demonstrated that the fluorescently labeled CuS@Cu-MOF acted as a penetrative carrier for the uptake of hyphae. Furthermore, DIF/CuS@Cu-MOF exhibited more substantial resistance to rainwater wash-off than DIF ME, with retention levels on the surfaces of cucumber leaves (hydrophilicity) and peanut leaves (hydrophobicity) increasing by 36.5-fold and 9.4-fold, respectively. These findings underscore the potential of nanocomposite to enhance pesticide utilization efficiency and leaf retention.

High deposition and precise stimulus-response release performance of lignin-coated dendritic mesoporous organosilica nanoparticles for efficient pesticide utilization

The inefficient and improper use of conventional pesticides has prompted the development of targeted and cost-effective pesticide delivery systems, which aim to optimize the efficient utilization of pesticides while minimizing environmental pollution in surrounding areas. In this paper, a dual-stimuli-responsive pesticide slow-release nanopesticide system (NES@DMONs@LGN) was designed in this study, utilizing mesoporous silica (DMONs) as a nanocarrier and lignin (LGN) as a capping agent to encapsulate the pesticide molecules within DMONs. This system enables intelligent release of pesticide molecules while preventing environmental pollution caused by leakage. Additionally, NES@DMONs@LGN exhibit excellent specific loading efficiency. The abundant hydrophilic functional groups in the lignin layer on the surface of NES@DMONs@LGN can establish hydrogen bonds with advanced fatty acids and fatty alcohols present in the waxy epidermis of plants, thereby significantly enhancing carrier wettability and adhesion. Typically, phytophagous lepidopteran pests have an alkaline midgut and possess lignin-degrading enzymes. The NES@DMONs@LGN developed in this study are capable of rapid release under high temperature and alkaline conditions. Therefore, the precise release of pesticide molecules in the target pests can be achieved, thus increasing the actual utilization rate of pesticides. The experimental results demonstrated that NES@DMONs@LGN effectively prevented photodegradation of the active ingredient after 48 h of UV irradiation, resulting in a 3.7-fold improvement in photostability and providing robust UV protection. By encapsulating pesticide molecules with nanocarriers, the release of pesticides in non-targeted environments can be prevented, thereby significantly reducing toxicity to zebrafish. Thus, this study provides a promising solution for sustainable greening of agriculture.

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.

A multidimensional optimization strategy of pyraclostrobin-loaded microcapsules to improve the selectivity between toxicological risk in zebrafish and efficacy in controlling rice blast

Developing microcapsules (MCs) delivery systems can effectively mitigate toxicological risk of highly active/toxic pesticides; whereas the controlled release functions also limiting their practical effectiveness. Therefore, designing a precise regulating strategy to balance the toxicity and bioactivity of MCs is urgently needed. Here, we prepared a series of pyraclostrobin-loaded MCs with different wall materials, particle sizes, core density and shell compactness using interfacial polymerization. The results showed that the MCs released more slowly in water with increasing particle sizes and capsule compactness, and they sunk more quickly with the increasing particle sizes and core density. Additionally, MCs with slower release speed was always accompanied with lower acute toxicity levels to zebrafish. When the release dynamics slowed down to the threshold dose on demand for disease control, facilitating settlement of MCs can further reduce toxicity within spatial and temporal dimensions. The poor accumulation of MCs with larger particle sizes or dense shell in gills was closely related to their efficient detoxification. Importantly, seven of the MCs samples possessed superior selectivity between bio-performance in controlling rice blast and toxicological hazard to fish compared to commercial formulations. The results provide a comprehensive guidance for developing an efficient and safe pesticide delivery system.

Fabrication of ROS-responsive nanoparticles by modifying the interior pore-wall of mesoporous silica for smart delivery of azoxystrobin

The suboptimal efficiency in pesticide utilization may elevate residues, posing safety risks to human food and non-target organisms. To address this challenge, delivery systems, such as pathogen infection stimuli-responsive carriers, can be employed to augment the efficiency of fungicide utilization. The bursting of reactive oxygen species (ROS) is a common defense response of host plants to pathogenic infections. In this study, ROS-responsive mesoporous silica nanoparticles (MSN) modified with phenyl sulfide (PHS) as azoxystrobin (AZOX) carrier (MSN-PHS-AZOX) were fabricated. Results demonstrated that MSN-PHS-AZOX exhibited fungicide release kinetics dependent on ROS. In vitro inhibition experiments confirmed the fungicidal effect of MSN-PHS-AZOX on Botrytis cinerea, relying on external ROS. In vivo leaf experiments showcased the superior persistence of MSN-PHS-AZOX in compared to AZOX SC. Furthermore, MSN-PHS-AZOX exhibits favorable biosafety and lower toxicity to aquatic zebrafish compared to AZOX SC, with no adverse impact on cucumber leaf growth. These findings suggest the potential application of this ROS-responsive nano fungicide in managing plant disease in agricultural fields.

Sodium alginate-carboxymethyl chitosan hydrogels loaded with difenoconazole for pH-responsive release to control wheat crown rot

Increasing concern about environmental pollution has driven the development of controlled release formulations for agrochemicals. Due to the advantages of degradability and responsiveness to environmental stimuli, polysaccharide-based hydrogel is an ideal carrier for agrochemicals controlled release. In this study, a method-easy polysaccharide hydrogel for controlled release of difenoconazole (DZ) was prepared with sodium alginate (SA) and carboxymethyl chitosan (CMCS). Due to its three-dimensional crosslinked mesh structure, the prepared hydrogels (CSDZ) showed an agrochemical load capacity of 9.03 % and an encapsulation efficiency of 68.64 %. The release rate is faster in alkaline solution, followed by neutral solution, and slowest in an acid environment, which is consistent with the swelling behavior. Furthermore, leaching studies showed that CSDZ hydrogels have excellent protective properties for encapsulated agrochemicals. Compared with technical DZ, the results of in vitro and pot antifungal testing showed that CSDZ had a better control effect against wheat crown rot (Fusarium pseudograminearum). Safety assessment studies indicated that CSDZ hydrogels exhibit good biocompatibility on nontargeted organisms (Daphnia magna, zebrafish and Eisenia fetida) and wheat. This study aims to provide a potentially promising approach for the preparation and application of biocompatible polysaccharide-based hydrogels for agrochemical-controlled release in sustainable disease management.

Toxicity effects of pesticides based on zebrafish (Danio rerio) models: Advances and perspectives

Pesticides inevitably enter aquatic environments, posing potential risks to organisms. The common aquatic model organism, zebrafish (Danio rerio), are widely used to evaluate the toxicity of pesticides. In this review, we searched the Web of Science database for articles published between 2012 and 2022, using the keywords "pesticide", "zebrafish", and "toxicity", retrieving 618 publications. Furthermore, we described the main pathways by which pesticides enter aquatic environments and the fate of their residues in these environments. We systematically reviewed the toxicity effects of pesticides on zebrafish, including developmental toxicity, endocrine-disrupting effects, reproductive toxicity, neurotoxicity, immunotoxicity, and genotoxicity. Importantly, we summarized the latest research progress on the toxicity mechanism of pesticides to zebrafish based on omics technologies, including transcriptomics, metabolomics, and microbiomics. Finally, we discussed future research prospects, focusing on the combined exposure of multiple pollutants including pesticides, the risk of multigenerational exposure to pesticides, and the chronic toxicity of aquatic nanopesticides. This review provides essential data support for ecological risk assessments of pesticides in aquatic environments, and has implications for water management in the context of pesticide pollution.

Deposition and water repelling of temperature-responsive nanopesticides on leaves

Pesticides are widely used to increase agricultural productivity, however, weak adhesion and deposition lead to low efficient utilization. Herein, we prepare a nanopesticide formulation (tebuconazole nanopesticides) which is leaf-adhesive, and water-dispersed via a rapid nanoparticle precipitation method, flash nanoprecipitation, using temperature-responsive copolymers poly-(2-(dimethylamino)ethylmethylacrylate)-b-poly(ε-caprolactone) as the carrier. Compared with commercial suspensions, the encapsulation by the polymer improves the deposition of TEB, and the contact angle on foliage is lowered by 40.0°. Due to the small size and strong van der Waals interactions, the anti-washing efficiency of TEB NPs is increased by 37% in contrast to commercial ones. Finally, the acute toxicity of TEB NPs to zebrafish shows a more than 25-fold reduction as compared to commercial formulation indicating good biocompatibility of the nanopesticides. This work is expected to enhance pesticide droplet deposition and adhesion, maximize the use of pesticides, tackling one of the application challenges of pesticides.

A high adhesion co-assembly based on myclobutanil and tannic acid for sustainable plant disease management

BACKGROUND

Pesticides are irreplaceable inputs for protecting crops from pests and improving crop yield and quality. Self-assembly nanotechnology is a promising strategy by which to develop novel nano-formulations for pesticides. Nano-formulations improve the effective utilization of pesticides and reduce risks to the environment because of their eco-friendly preparation, high drug loading, and desirable physicochemical properties. Here, to enhance the utilization efficiency of myclobutanil (MYC) and develop a novel nano-formulation, carrier-free co-assembled nanoparticles (MT NPs) based on MYC and tannic acid (TA) were prepared by noncovalent molecular interactions using a green preparation process without any additives.

RESULTS

The results showed that the prepared spherical nanoparticles had good stability in neutral and acidic aqueous solutions, low surface tension (40.53 mN m-1 ), high rainfastness, and good maximum retention values on plant leaves. Release of active ingredients from MT NPs could be regulated by altering the molar ratio of subassemblies in the co-assembly and the pH of the environment. Antifungal experiments demonstrated that MT NPs had better activities against Alternaria alternata and Fusarium graminearum [half-maximal effective concentration (EC50 ) = 6.40 and 77.08 mg/L] compared with free MYC (EC50  = 11.46 and 124.82 mg/L), TA (EC50  = 251.19 and 503.81 mg/L), and an MYC + TA mixture (EC50  = 9.62 and 136.21 mg/L). These results suggested that MYC and TA incorporated in the co-assembled nanoparticles had a synergistic antifungal activity. The results of a genotoxicity assessment indicated that MT NPs could reduce the genotoxicity of MYC to plant cells.

CONCLUSION

Co-assembled MT NPs with synergistic antifungal activity have outstanding potential for the management of plant diseases. © 2023 Society of Chemical Industry.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

Fabrication of Enzyme-Responsive Prodrug Self-Assembly Based on Fluazinam for Reducing Toxicity to Aquatic Organisms

Prodrug-based nanodrug delivery systems were drug formulations by covalently conjugating drugs with inversely polar groups via a cleavable bond to self-assemble into nanoparticles for efficient drug delivery. To improve the utilization efficiency of fluazinam (FZN), enzyme-responsive prodrugs were prepared by conjugating FZN with different alkyl aliphatic acids through a nucleophilic substitution reaction and subsequently self-assembled into nanoparticles (FZNP NPs) without using any harmful adjuvant. The obtained FZNP NPs exhibited excellent efficacies against Sclerotinia sclerotiorum as a result of improved physicochemical properties, including low surface tension, high retention, and enhanced photostability. The LC50 values of FZNP NPs toward zebrafish were 3-8 times that of FZN, which illustrated that the FZNP NPs reduced the detriments of FZN to the aquatic organisms while retaining good biological activity. Therefore, prodrug self-assembly technology would offer a potential method for improving the utilization efficiency of pesticides and lowering the risks to the ecological environment.

A pectin-based photoactivated bactericide nanosystem for achieving an improved utilization rate, photostability and targeted delivery of hematoporphyrin

Photoactivated pesticides have many advantages, such as high activity, low toxicity, and no drug resistance. However, poor photostability and a low utilization rate limit their practical application. Herein, the photosensitizer hematoporphyrin (HP) was used as a photoactivated pesticide, covalently linked with pectin (PEC) via ester bonds, to prepare an amphiphilic polymer pro-bactericide, and subsequently self-assembled in aqueous solutions to obtain an esterase-triggered nanobactericide delivery system. The fluorescence quenching effect due to the aggregation of HP in nanoparticles (NPs) enabled the inhibition of photodegradation of HP in this system. Esterase stimulation could trigger HP release and increase its photodynamic activity. Antibacterial assays have shown that the NPs had potent antibacterial capacity, almost completely inactivating bacteria after 60 min of exposure to light. The NPs had good adherence to the leaves. Safety assessment indicated that the NPs have no obvious toxic effects on plants. Antibacterial studies on plants have shown that the NPs have excellent antibacterial effects on infected plants. These results provide a new strategy for obtaining a photoactivated bactericide nanosystem with a high utilization rate and good photostability and targeting ability.

Fabrication of a dual pH-responsive and photothermal microcapsule pesticide delivery system for controlled release of pesticides

BACKGROUND

The development of stimulus-responsive and photothermally controlled-release microcapsule pesticide delivery systems is a promising solution to enhance the effective utilization and minimize the excessive use of pesticides in agriculture.

RESULTS

In this study, an AVM@CS@TA-Fe microcapsule pesticide delivery system was developed using avermectin as the model drug, chitosan and tannic acid as the wall materials, and tannic acid-Fe complex layer as the photothermal agent. The optical microscope, scanning electron microscope, transmission electron microscope, and Fourier-transform infrared spectroscope were used to characterize the prepared microcapsule. The slow-release, UV-shielding, photothermal performance, and nematicidal activity of the microcapsule were systematically investigated. The results showed that the system exhibited excellent pH-responsive and photothermal-sensitive performances. In addition, the UV-shielding performance of the delivery system was improved. The photothermal conversion efficiency (η) of the system under the irradiation of near-infrared (NIR) light was determined to be 14.18%. Moreover, the nematicidal activities of the system against pine wood nematode and Aphelenchoides besseyi were greatly increased under the irradiation of light-emitting diode (LED) simulated sunlight.

CONCLUSION

The release of the pesticide-active substances in such a pesticide delivery system could be effectively regulated with the irradiation of NIR light or LED-simulated sunlight. Thus, the developed pesticide delivery system may have broad application prospects in modern agriculture fields. © 2022 Society of Chemical Industry.

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.

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.

Degradable Self-Destructive Redox-Responsive System Based on Mesoporous Organosilica Nano-Vehicles for Smart Delivery of Fungicide

The development of stimuli-responsive controlled release formulations is a potential method of improving pesticide utilization efficiency and alleviating current pesticide-related environmental pollution. In this study, a self-destruction redox-responsive pesticide delivery system using biodegradable disulfide-bond-bridged mesoporous organosilica (DMON) nanoparticles as the porous carriers and coordination complexes of gallic acid (GA) and Fe(III) ions as the capping agents were established for controlling prochloraz (PRO) release. The GA-Fe(III) complexes deposited onto the surface of DMON nanoparticles could effectively improve the light stability of prochloraz. Due to the decomposition of GA-Fe(III) complexes, the nano-vehicles had excellent redox-responsive performance under the reducing environments generated by the fungus. The spreadability of PRO@DMON-GA-Fe(III) nanoparticles on the rice leaves was increased due to the hydrogen bonds between GA and rice leaves. Compared with prochloraz emulsifiable concentrate, PRO@DMON-GA-Fe(III) nanoparticles showed better fungicidal activity against Magnaporthe oryzae with a longer duration under the same concentration of prochloraz. More importantly, DMON-GA-Fe(III) nanocarriers did not observe obvious toxicity to the growth of rice seedlings. Considering non-toxic organic solvents and excellent antifungal activity, redox-responsive pesticide controlled release systems with self-destruction properties have great application prospects in the field of plant disease management.

Encapsulation of Imazalil in HKUST-1 with Versatile Antimicrobial Activity

Based on high surface areas, adjustable porosity and microbicide activity, metal-organic frameworks (MOFs) HKUST-1 are widely used as drug release carriers for their slow degradation characteristics under slightly acidic conditions. In this work, porous HKUST-1 was reacted rapidly by cholinium salt (as the deprotonation agent and template) in an aqueous solution at room temperature. A novel antimicrobial system based on an imazalil encapsulated metal organic framework (imazalil IL-3@HKUST-1) was established. Imazalil IL-3@HKUST-1 could achieve synergism in inhibiting pathogenic fungi and bacteria. Moreover, six days after treatment, the slow and constant release of imazalil from imazalil IL@HKUST-1 exhibited better sustainability and microbicidal activity than imazalil. We believe that the method may provide a new strategy for related plant diseases caused by bacteria or fungi.

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.

An overview of synthesis, characterization, applications and associated adverse effects of bioactive nanoparticles

A particle with a diameter ranging from 1 to 100 nm is considered a nanoparticle (NP). Owing to their small size and high surface area, NPs possess unique physical, chemical and biological properties as compared to their bulkier counterparts. This paper describes various physico-chemical as well as green methods that can be used to synthesize different types of NPs including carbon-based, ceramic, metal, semiconductor, polymeric and lipid-based NPs. These methods can be categorized into either top-down or bottom-up approaches. Electron microscopy, atomic force microscopy, dynamic light scattering, X-ray diffraction, zeta-potential instrument, liquid chromatography-mass spectrometry, fourier transform infrared spectroscopy and thermogravimetric analysis are the techniques discussed in the characterization of NPs. This review provides an insight into the extraordinary properties of NPs that have opened the doors for endless biomedical applications like drug delivery, photo-ablation therapy, biosensors, bio-imaging and hyperthermia. In addition, NPs are also involved in improving crop growth, making protective clothing, cosmetics and energy reserves. This review also specifies adverse health effects associated with NPs such as hepatotoxicity, genotoxicity, neurotoxicity, etc., and inhibitory effects on plant growth and aquatic life. Further, in-vitro toxicity assessment assays for cell proliferation, apoptosis, necrosis and oxidative stress, as well as in-vivo toxicity assessment like biodistribution, clearance, hematological, serological and histological studies, are discussed here. Lastly, the authors have mentioned various measures that can be adopted to minimize the toxicity associated with NPs such as green synthesis, use of stabilizers, gene gun, polymer shell, microneedle capsule, etc.

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.

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.

pH and Redox Dual-Responsive Mesoporous Silica Nanoparticle as Nanovehicle for Improving Fungicidal Efficiency

Prochloraz (Pro) controlled-release nanoparticles (NPs) based on bimodal mesoporous silica (BMMs) with redox and pH dual responses were successfully prepared in this study. BMMs was modified by a silane coupling agent containing a disulfide bond, and β-cyclodextrin (β-CD) was grafted on the surface of the NPs through host–guest interaction. Pro was encapsulated into the pores of nanoparticles by physical adsorption. NPs had a spherical structure, and their average diameter was 546.4 ± 3.0 nm as measured by dynamic light scattering. The loading rate of Pro was 28.3%, and it achieved excellent pH/redox dual-responsive release performance under acidic conditions. Foliage adhesion tests on tomato leaves showed that the NPs had good adhesion properties compared to the commercial formulation. Owing to the protection of the nanocarrier, NPs became more stable under ultraviolet light and high temperature, which improves the efficient utilization of Pro. Biological activity tests showed that the NPs exhibited effective antifungal activity, and the benign biosafety of the nanocarrier was also observed through toxicology tests on cell viability and the growth of Escherichiacoli (E. coli). This work provides a promising approach to improving the efficient utilization of pesticides and reducing environmental pollution.

Pyraclostrobin Removal in Pilot-Scale Horizontal Subsurface Flow Constructed Wetlands and in Porous Media Filters

Pyraclostrobin is a fungicide extensively used for the control of various fungal diseases and is frequently detected in environmental samples. Natural systems, such as constructed wetlands (CWs) and gravity filters, are effective and environmentally friendly treatment systems, which can reduce or eliminate pesticides from the environment. The aim of this study was to investigate the capacity of two pilot-scale CWs (porous media: cobbles and fine gravel, planted with Phragmites australis) and six gravity filters (filling material: bauxite, carbonate gravel and zeolite) to remove pyraclostrobin from polluted water originating from spraying equipment rinsing sites. For this, experiments were conducted to test the performance of the above natural systems in removing this fungicide. The results showed that the mean percent pyraclostrobin removal efficiencies for cobbles and fine gravel CW units were 56.7% and 75.2%, respectively, and the mean percent removals for HRTs of 6 and 8 days were 68.7% and 62.8%, respectively. The mean removal efficiencies for the bauxite, carbonate gravel and zeolite filter units were 32.5%, 36.7% and 61.2%, respectively, and the mean percent removals for HRTs 2, 4 and 8 days were 39.9%, 43.4% and 44.1%, respectively. Regarding the feeding strategy, the mean removal values of pyraclostrobin in gravity filter units were 43.44% and 40.80% for continuous and batch feeding, respectively. Thus, these systems can be used in rural areas for the treatment of spraying equipment rinsing water.

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.

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.

Recent Advances on Lignocellulosic-Based Nanopesticides for Agricultural Applications

Controlled release systems of agrochemicals have been developed in recent years. However, the design of intelligent nanocarriers that can be manufactured with renewable and low-cost materials is still a challenge for agricultural applications. Lignocellulosic building blocks (cellulose, lignin, and hemicellulose) are ideal candidates to manufacture ecofriendly nanocarriers given their low-cost, abundancy and sustainability. Complexity and heterogeneity of biopolymers have posed challenges in the development of nanocarriers; however, the current engineering toolbox for biopolymer modification has increased remarkably, which enables better control over their properties and tuned interactions with cargoes and plant tissues. In this mini-review, we explore recent advances on lignocellulosic-based nanocarriers for the controlled release of agrochemicals. We also offer a critical discussion regarding the future challenges of potential bio-based nanocarrier for sustainable agricultural development.

One-Pot Facile Synthesis of Double-Shelled Mesoporous Silica Microcapsules with an Improved Soft-Template Method for Sustainable Pest Management

A controlled release formulation based on silica microcapsules is an ideal selection to improve both the effective utilization and duration of pesticides to decrease ecological damage. Herein, a simple and green method for preparing double-shelled microcapsules was developed using a newly prepared quaternary ammonium ionic liquid (IL) as the functional additive to entrap avermectin (Ave) in mesoporous silica nanospheres (MSNs) and tannic acid-Cu (TA-Cu) complex as the sealing agent to form the core-shell structure (Ave-IL@MSN@TA-Cu). The obtained microcapsules with an average size of 538 nm had pH-responsive release property and good stability in soil. The half-life of microcapsules (34.66 days) was 3 times that of Ave emulsifiable concentrate (EC) (11.55 days) in a test soil, which illustrated that microcapsules could protect Ave from rapid degradation by microorganisms by releasing TA, copper, and quaternary ammonium in the soil. Ave-IL@MSN@TA-Cu microcapsules had better nematicidal activity and antibacterial activity than Ave EC due to the synergistic effect of Ave, IL, and copper incorporated in the microcapsules. Pot experiments showed that the control efficacy of microcapsules was 87.10% against Meloidogyne incognita, which is better than that of Ave EC (41.94%) at the concentration of 1.0 mg/plant by the root-irrigation method after 60 days of treatment owing to the extended duration of Ave in microcapsules. The simple and green method for the preparation of double-shelled microcapsules based on natural quaternary ammonium IL would have tremendous potential for the extensive development of controlled release pesticide formulations.