A Near-Infrared and Temperature-Responsive Pesticide Release Platform through Core-Shell Polydopamine@PNIPAm Nanocomposites

Amine-Polyether-Epoxide Nanoplatform-Driven Seed Germination, Plant Growth, and Nutrient Uptake for Sustainable Agriculture

Polymeric systems can facilitate the diffusion of micronutrients through seeds, offering an innovative and sustainable way to improve plant health and increase food production. In the present work, a polymeric nanogel based on polyether-POE-diamine and bisepoxide was synthesized and in-depth characterized, encompassing its morphological characteristics (by Transmission Electron Microscopy, TEM), the size distribution, and surface charge of the particles (by dynamic light scattering, DLS and zeta potential, ζ). The formation of the polymeric network was assessed using Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR), confirming the opening of the epoxide ring and the formation of amine and glycol groups. The effects of seed priming with the nanogel (well-defined spherical particles, with sizes around 120 nm, named POE-gel) on the early growth stage of cucumber plants (Cucumis sativus) exhibited a discernible ameliorative impact on root and shoot lengths, with average improvements of 33% and 90%, respectively, compared to the control group after 12 days. Extensive investigation using germination assays and micro X-ray fluorescence (μ-XRF) analysis indicated potential applications of the POE-gel as a carrier for micronutrients (such as Fe3+). The seeds treated with the iron-loaded POE-gel presented a substantial positive effect on root length, exhibiting a 3-fold increase in size compared with the control-Fe treatment at the same concentration. The loaded POE-gel effectively penetrated through the seed compartments, providing an even distribution of iron ions and facilitating the uptake of nutrients (K, Mn, and Zn) by the seeds. Toxicological assays using zebrafish (Danio rerio), seeds, and leaves revealed notable safety of the iron-loaded and unloaded POE-gel for agricultural purposes. Employing water as the only solvent in the synthesis, as well as eliminating the use of a catalyst, makes this class of polymeric particles suitable for sustainable agricultural applications. The findings of this work contribute to the development of sustainable agriculture, presenting an innovative approach to enhancing plant development and nutrient uptake through the application of polymeric nanogels as a seed priming technology.

Stimuli-responsive carrageenan-based biomaterials for biomedical applications

Carrageenan-based biomaterials have attracted considerable attention in recent years due to their unique biological properties, including their biodegradability, compatibility, and lack of adverse effects. These biomaterials exhibit a variety of beneficial properties, such as antiviral, antitumor, and immunomodulatory effects, which set them apart from other polysaccharides. Stimuli-responsive carrageenan-based biomaterials have attracted particular attention due to their unique properties, such as reducing systemic toxicity and controlling drug release. In this review, a comprehensive investigation of stimuli-responsive carrageenan-based biomaterials was conducted under the influence of various stimuli such as pH, electric field, magnetic field, temperature, light, and ions. These structures exhibited good stimulus-responsive properties and involved corresponding physical and chemical changes, such as changes in swelling ratio and gelling power among others. The biomedical application of carrageenan-based stimuli-responsive biomaterials in the field of tissue engineering, anticancer, antibacterial, and food monitoring has been investigated, showing the great potential of these structures. Although there are promising developments in the design and use of stimuli-responsive carrageenan-based biomaterials, further research is advisable to further investigate their potential applications, particularly in animal models. Extensive studies are needed to investigate the benefits and limitations of these materials to ensure their safety and effective use in biomedical applications.

Copper Ion-Chelated and Polydopamine-Modified Hydroxypropyl Methylcellulose Nanoparticles with Multiple Responses for Intelligent Pesticide Release and Improved Foliar Deposition

Intelligent controlled-release nanopesticides have been a crucial tactic in advanced precision agriculture during the past few years, which can improve pesticide utilization and reduce environmental pollution. Herein, a novel hydroxypropyl methylcellulose-based nanopesticide carrier (PCH) with pH-/enzyme-/near-infrared multiple responses was constructed by the initial cross-linking with dimethyl diallyl ammonium chloride and the subsequent copper ion chelation and polydopamine coating. Avermectin (Av) was further loaded to create the intelligent pesticide release system (APCH) by antisolvent precipitation. The release of APCH increases under near-infrared light (NIR) conditions, with an accumulative release that is 3.26 times higher than that without NIR. The contact angles of APCH on cabbage leaves are 33 and 29% lower than those of water and technical Av (Av-tech), respectively, verifying that APCH has a good wettability property. Simultaneously, APCH displays better insecticidal activity than Av formulations because of its outstanding ultraviolet (UV) light stability of Av. The degradation rate of Av in APCH is less than 2% in 50 h under UV light, which is considerably lower than that of Av-tech (∼60%). The biosafety assessments manifest that the PCH carrier has remarkable biological safety on the growth of nontarget organisms in a certain range. Overall, the APCH system is bio-friendly with multiple-response release behaviors, excellent UV light stability, and foliar deposition performance, which can offer a new strategy for sustainable agricultural development.

Spherical Assembly of Halloysite Clay Nanotubes as a General Reservoir of Hydrophobic Pesticides for pH-Responsive Management of Pests and Weeds

The development of smart systems for pesticidal delivery presents a significant advancement in enhancing the utilization efficiency of pesticides and mitigating environmental risks. Here an acid-responsive pesticidal delivery system using microspheres formed by the self-assembly of halloysite clay nanotubes (HNTs) is proposed. Insecticide avermectin (AVM) and herbicide prometryn (PMT) are used as two models of hydrophobic pesticide and encapsulated within the porous microspheres, followed by a coating of tannic acid/iron (TA/FeIII) complex films to generate two controlled-release pesticides, named as HCEAT and HCEPT, resulting in the loading capacity of AVM and PMT being 113.3 and 120.3 mg g-1, respectively. Both HCEAT and HCEPT exhibit responsiveness to weak acid, achieving 24 h-release ratios of 85.8% and 80.5% at a pH of 5.5. The experiment and simulation results indicate that the coordination interaction between EDTA2- and Ca2+ facilitates the spherical aggregation of HNTs. Furthermore, these novel pesticide formulations demonstrate better resistance against ultraviolet (UV) irradiation, higher foliar affinity, and less leaching effect, with negligible impact of the carrier material on plants and terrestrial organisms. This work presents a promising approach toward the development of efficient and eco-friendly pesticide formulations, greatly contributing to the sustainable advancement of agriculture.

Cationic Amphiphilic Comb-Shaped Polymer Emulsifier for Fabricating Avermectin Nanoemulsion with Exceptional Leaf Behaviors and Multidimensional Controlled Release

The development of intelligent multifunctional nanopesticides featuring enhanced foliage affinity and hierarchical target release is increasingly pivotal in modern agriculture. In this study, a novel cationic amphiphilic comb-shaped polymer, termed PEI-TA, was prepared via a one-step Michael addition between low-molecular-weight biodegradable polyethylenimine (PEI) and tetradecyl acrylate (TA), followed by neutralization with acetic acid. Using the emulsifier PEI-TA, a positively charged avermectin (AVM) nanoemulsion was prepared via a phase inversion emulsification process. Under optimal formulation, the obtained AVM nanoemulsion (defined as AVM@PEI-TA) demonstrated exceptional properties, including small size (as low as 67.6 nm), high encapsulation efficiency (up to 87.96%), and high stability toward shearing, storage, dilution, and UV irradiation. The emulsifier endowed AVM@PEI-TA with a pronounced thixotropy, so that the droplets exhibited no splash and bounce when they were sprayed on the cabbage leaf. Owing to the electrostatic attraction between the emulsifier and the leaf, AVM@PEI-TA showed improved leaf adhesion, better deposition, and higher washing resistance in contrast to both its negatively charged counterpart and AVM emulsifiable concentrate (AVM-EC). Compared to the large-sized particles, the small-sized particles of the AVM nanoemulsion more effectively traveled long distances through the vascular system of veins after entering the leaf apoplast. Moreover, the nanoparticles lost stability when exposed to multidimensional stimuli, including pH, temperature, esterase, and ursolic acid individually or simultaneously, thereby promoting the release of AVM. The release mechanisms were discussed for understanding the important role of the emulsifier in nanopesticides.

Nanomaterials and Nanotechnology in Agricultural Pesticide Delivery: A Review

Pesticides play a crucial role in ensuring food production and food security. Conventional pesticide formulations can not meet the current needs of social and economic development, and they also can not meet the requirements of green agriculture. Therefore, there is an urgent need to develop efficient, stable, safe, and environmentally friendly pesticide formulations to gradually replace old formulations which have high pollution and low efficacy. The rise of nanotechnology provides new possibilities for innovation in pesticide formulations. Through reasonable design and construction of an environmentally friendly pesticide delivery system (PDS) based on multifunctional nanocarriers, the drawbacks of conventional pesticides can be effectively solved, realizing a water-based, nanosized, targeted, efficient, and safe pesticide system. In the past five years, researchers in chemistry, materials science, botany, entomology, plant protection, and other fields are paying close attention to the research of nanomaterials based PDSs and nanopesticide formulations and have made certain research achievements. These explorations provide useful references for promoting the innovation of nanopesticides and developing a new generation of green and environmentally friendly pesticide formulations. This Perspective summarizes the recent advances of nanomaterials in PDSs and nanopesticide innovation, aiming to provide useful guidance for carrier selection, surface engineering, controlled release conditions, and application in agriculture.

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.

Photothermal controlled-release microcapsule pesticide delivery systems constructed with sodium lignosulfonate and transition metal ions: construction, efficacy and on-demand pesticide delivery

BACKGROUND

Widespread application of controlled-release pesticide delivery systems is a feasible and effective method to improve the utilization efficiency of pesticides. However, owing to the high cost and complicated preparation technologies of controlled-release pesticide delivery systems, their applications in agricultural production have been seriously hindered.

RESULTS

This study aimed to construct inexpensive photothermally controlled-release pesticide delivery systems using chitosan (CS) and sodium lignosulfonate (LS) as the wall materials, and a coordination assembly strategy of LS with transition metal ions to encapsulate a model pesticide, avermectin (AVM). The resulting complex or nanoparticle photothermal layers in these systems effectively achieved photothermal conversions, and replaced the use of common photothermal agents. In the prepared pesticide-delivery systems, two systems had remarkable photothermal conversion performance and photothermal stabilities with a photothermal conversion efficiency (η) of 24.03% and 28.82%, respectively, under 808 nm, 2 W near-infrared irradiation. The slow-release and ultraviolet-shielding performance of these two systems were markedly enhanced compared with other formulations. The insecticidal activities of these two systems against Plutella xylostella under irradiation with light-emitting diode (LED)-simulated sunlight were also enhanced by 5.20- and 5.06-fold, respectively, compared with that without irradiation of LED-simulated sunlight.

CONCLUSION

Because of their convenient preparations, inexpensive and renewable raw materials, and excellent photothermally controlled-release performance, these on-demand pesticide delivery systems might have significant potential in improving the utilization efficiency of pesticides in modern agriculture. © 2024 Society of Chemical Industry.

Smart and Sustainable Crop Protection: Design and Evaluation of a Novel α-Amylase-Responsive Nanopesticide for Effective Pest Control

In this study, an α-amylase-responsive controlled-release formulation was developed by capping polydopamine onto β-cyclodextrin-modified abamectin-loaded hollow mesoporous silica nanoparticles. The prepared Aba@HMS@CD@PDA were subjected to characterization using various analytical techniques. The findings revealed that Aba@HMS@CD@PDA, featuring a loading rate of 18.8 wt %, displayed noteworthy release behavior of abamectin in the presence of α-amylase. In comparison to abamectin EC, Aba@HMS@CD@PDA displayed a significantly foliar affinity and improved rainfastness on lotus leaves. The results of field trail demonstrated a significantly higher control efficacy against Spodoptera litura Fabricius compared to abamectin EC at all concentrations after 7, 14, and 21 days of spaying, showcasing the remarkable persistence of Aba@HMS@CD@PDA. These results underscore the potential of Aba@HMS@CD@PDA as a novel and persistently effective strategy for sustainable on-demand crop protection. The application of nanopesticides can enhance the effectiveness and efficiency of pesticide utilization, contributing to more sustainable agricultural practices.

Recent Advances in Stimulus-Responsive Nanocarriers for Pesticide Delivery

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

Pesticide Nanoformulations Based on Sunlight-Activated Controlled Release of Abamectin

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

Fabrication of Eco-Friendly Hydrolyzed Ethylene-Maleic Anhydride Copolymer-Avermectin Nanoemulsion with High Stability, Adhesion Property, pH, and Temperature-Responsive Releasing Behaviors

In this study, novel amphiphilic polymer emulsifiers for avermectin (Avm) were synthesized facilely via the hydrolysis of ethylene-maleic anhydride copolymer (EMA) with different agents, and their structures were confirmed by various techniques. Then, water-based Avm-nanoemulsions were fabricated with the emulsifiers via phase inversion emulsification process, and superior emulsifier was selected via the emulsification effects. Using the superior emulsifier, an optimal Avm-nanoemulsion (defined as Avm@HEMA) with satisfying particle size of 156.8 ± 4.9 nm, encapsulation efficiency (EE) of 69.72 ± 4.01% and drug loading capacity (DLC) of 54.93 ± 1.12% was constructed based on response surface methodology (RSM). Owing to the emulsifier, the Avm@HEMA showed a series of advantages, including high stability, ultraviolet resistance, low surface tension, good spreading and high affinity to different leaves. Additionally, compared to pure Avm and Avm-emulsifiable concentrate (Avm-EC), Avm@HEMA displayed a controlled releasing feature. The encapsulated Avm was released quite slowly at normal conditions (pH 7.0, 25 °C or 15 °C) but could be released at an accelerated rate in weak acid (pH 5.5) or weak alkali (pH 8.5) media or at high temperature (40 °C). The drug releasing profiles of Avm@HEMA fit the Korsmeyer-Peppas model quite well at pH 7.0 and 25 °C (controlled by Fickian diffusion) and at pH 7.0 and 10 °C (controlled by non-Fickian diffusion), while it fits the logistic model under other conditions (pH 5.5 and 25 °C, pH 8.5 and 25 °C, pH 7.0 and 40 °C).

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.

Functional polymeric molecules for performing autonomous synthesis of particles with core-shell structures and customizable shapes

Self-organization by the directed migration of components within a system is an important process in many applications, such as the unidirectional migration of motor proteins for transporting items to specific sites in a cell. This manuscript describes a class of functional polymeric molecules that have a set of instructions written by specific chemical moieties. These instructions allow the functional polymeric molecules to be used for autonomous synthesis of particles: particles with both functional core-shell structure and customizable shapes are fabricated for the first time. The functional polymeric molecules direct the large-scale migration of the liquid molecules to specific sites for forming the required customized structure of the particle, thus overcoming previous challenges of fabricating this class of particles. This first synthesis of this class of particles enables the development of novel applications: the concept of shape specificity for targeting sites. Both the basic structural properties (core-shell structure and customizable shape) are used in the specific applications of targeted drug delivery and imaging. The secure physical fit due to the complementary shapes enables the particles to remain locked in position for the targeting. Polymeric molecules are first shown to be highly capable of being encoded with instructions for autonomous synthesis of structured materials.

Ecofriendly polysaccharide-based alginate/pluronic F127 semi-IPN hydrogel with magnetic collectability for precise release of pesticides and sustained pest control

Controlled-release systems are crucial for efficient pesticide utilization and environmental protection in agricultural production. The utilization of polysaccharide-based materials derived from biopolymers as carriers for controlling pesticide release holds significant potential. In this work, a reversible near infrared-responsive polysaccharide-based hydrogel (RNPH) was fabricated by employing a semi-interpenetrating polymer network (alginate-FeIII/pluronic F127) as a carrier to encapsulate Fe3O4@polydopamine (FP) and emamectin benzoate (EB)-loaded hollow mesoporous silica. The incorporation of FP into the RNPH introduced a photothermal effect, enabling the precise release of EB through reversible shrinkage of the hydrogel upon NIR irradiation. Additionally, the presence of magnetic Fe3O4 in the system facilitated the rapid removal of remaining RNPH from the environment using a magnet, reducing EB residue. Importantly, RNPH exhibited exceptional controlled-release performance and could be reused for at least 4 cycles. Furthermore, the anti-photolysis ability of EB protected by RNPH was enhanced by 4.8 times compared to EB alone. Moreover, RNPH significantly improved the adhesion of EB to foliar surfaces, thereby reducing the loss of EB while ensuring crop safety. Therefore, the polysaccharide-based hydrogel holds promise as a versatile carrier for the precise release of EB, offering valuable applications in enhancing pesticide bioavailability and promoting environmental safety.

Tough and Recyclable Phase-Separated Supramolecular Gels via a Dehydration-Hydration Cycle

Hydrogels are compelling materials for emerging applications including soft robotics and autonomous sensing. Mechanical stability over an extensive range of environmental conditions and considerations of sustainability, both environmentally benign processing and end-of-life use, are enduring challenges. To make progress on these challenges, we designed a dehydration-hydration approach to transform soft and weak hydrogels into tough and recyclable supramolecular phase-separated gels (PSGs) using water as the only solvent. The dehydration-hydration approach led to phase separation and the formation of domains consisting of strong polymer-polymer interactions that are critical for forming PSGs. The phase-separated segments acted as robust, physical cross-links to strengthen PSGs, which exhibited enhanced toughness and stretchability in its fully swollen state. PSGs are not prone to overswelling or severe shrinkage in wet conditions and show environmental tolerance in harsh conditions, e.g., solutions with pH between 1 and 14. Finally, we demonstrate the use of PSGs as strain sensors in air and aqueous environments.

Degradable PDA@PNIPAM-TA Nanocomposites for Temperature- and NIR light-Controlled Pesticide Release

Controlled pesticide delivery systems offer many distinctive advantages over conventional pesticide formulations. In this work, degradable poly(N-isopropylacrylamide) (PNIPAM)-tannic acid (TA) microgels and multifunctional PDA@PNIPAM-TA nanocomposites were prepared in a high-gravity rotating packed bed reactor (RPB) for smart pesticide delivery and release. The as-prepared microgels and nanocomposites showed reversible temperature-dependent swelling/deswelling behavior and irreversible pH-induced degradation. A dynamic contact angle test suggested that the introduction of TA and PDA into the PNIPAM matrix could enhance foliar adhesion and deposition efficiency. The nanocomposites were further used for the encapsulation and delivery of imidacloprid (IMI) to protect it from rapid photolysis and improve its pest-control efficiency. Their thermoresponsive behavior as well as pesticide loading capacity could be tuned by tailoring the PNIPAM-TA shell thickness, which could be varied by the NIPAM amount. The release rate of IMI from the core/shell nanocomposites was positively correlated with environmental temperature and near-infrared (NIR) light, which was adaptive to the positive temperature-dependent toxicity correlation of IMI and the increasing trend of pests under high temperature. The cumulative release of IMI was 23.5% at 25 °C, while it was 81.2% at 40 °C after 24 h of incubation, and the release rate was greatly enhanced under NIR irradiation. The results indicated that the facile control of pesticide release could be realized by regulating environmental conditions. This work also provides an idea for using high-gravity technology to conveniently construct a smart, effective, and environmentally friendly pesticide delivery system for sustainable crop protection.

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

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

Adhesive Composite Microspheres with Dual Antibacterial Strategies for Infected Wound Healing

Skin damage and infection pose a severe challenge to human health. Construction of a novel versatile dressing with good anti-infection and healing-promoting abilities is greatly expected. In this paper, nature-source-based composite microspheres with dual antibacterial mechanisms and bioadhesive features by microfluidics electrospray for infected wound healing is developed. The microspheres enable sustained release of copper ions, which not only show long-term antibacterial properties, but also play important role in wound-healing-related angiogenesis. Additionally, the microspheres are coated with polydopamine via self-polymerization, which renders the microspheres adhesive to the wound surface, and further enhance the antibacterial ability through photothermal energy conversion. Based on the dual antibacterial strategies provided by copper ions and polydopamine as well as the bioadhesive property, the composite microspheres exhibit excellent anti-infection and wound healing performances in a rat wound model. These results, along with the nature-source-based composition and biocompatibility, indicate the great potential of the microspheres in clinical wound repair.

Eco-Efficient Systems Based on Nanocarriers for the Controlled Release of Fertilizers and Pesticides: Toward Smart Agriculture

The excessive application of pesticides and fertilizers has generated losses in biological diversity, environmental pollution, and harmful effects on human health. Under this context, nanotechnology constitutes an innovative tool to alleviate these problems. Notably, applying nanocarriers as controlled release systems (CRSs) for agrochemicals can overcome the limitations of conventional products. A CRS for agrochemicals is an eco-friendly strategy for the ecosystem and human health. Nanopesticides based on synthetic and natural polymers, nanoemulsions, lipid nanoparticles, and nanofibers reduce phytopathogens and plant diseases. Nanoproducts designed with an environmentally responsive, controlled release offer great potential to create formulations that respond to specific environmental stimuli. The formulation of nanofertilizers is focused on enhancing the action of nutrients and growth stimulators, which show an improved nutrient release with site-specific action using nanohydroxyapatite, nanoclays, chitosan nanoparticles, mesoporous silica nanoparticles, and amorphous calcium phosphate. However, despite the noticeable results for nanopesticides and nanofertilizers, research still needs to be improved. Here, we review the relevant antecedents in this topic and discuss limitations and future challenges.

Polydopamine-encapsulated cap-like mesoporous silica based delivery system for responsive pesticide release and high retention

Nanopesticides formulation has been applied in modern agriculture, but the effective deposition of pesticides on plant surfaces is still a critical challenge. Here, we developed a cap-like mesoporous silica (C-mSiO₂) carrier for pesticide delivery. The C-mSiO₂ carriers with surface amino groups present uniform cap-like shape and have an mean diameter of 300 nm and width of 100 nm. This structure would reduce the rolling and bouncing of carriers on plant leaves, leading to improving the foliage deposition and retention. After loading dinotefuran (DIN), polydopamine (PDA) was used to encapsulate the pesticide (DIN@C-mSiO₂@PDA). The C-mSiO₂ carriers exhibit high drug loading efficiency (24.7%) and benign biocompatibility on bacteria and seed. Except for pH/NIR response release, the DIN@C-mSiO₂@PDA exhibited excellent photostability under UV irradiation. Moreover, the insecticidal activity of DIN@C-mSiO₂@PDA was comparable to that of pure DIN and DIN commercial suspension (CS-DIN). This carrier system has the potential for improving the foliage retention and utilization of pesticides.

Instant formation of horizontally ordered nanofibrous hydrogel films and direct investigation of peculiar neuronal cell behaviors atop

BACKGROUND

Hydrogels have been widely used in many research fields owing to optical transparency, good biocompatibility, tunable mechanical properties, etc. Unlike typical hydrogels in the form of an unstructured bulk material, we developed aqueous dispersions of fiber-shaped hydrogel structures with high stability under ambient conditions and their application to various types of transparent soft cell culture interfaces with anisotropic nanoscale topography.

METHOD

Nanofibers based on the polyvinyl alcohol and polyacrylic acid mixture were prepared by electrospinning and hydrogelified to nano-fibrous hydrogels (nFHs) after thermal crosslinking and sulfuric acid treatment. By modifying various material surfaces with positively-charged polymers, negatively-charged superabsorbent nFHs could be selectively patterned by employing micro-contact printing or horizontally aligned by applying shear force with a wired bar coater.

RESULTS

The angular distribution of bar-coated nFHs was dramatically reduced to ± 20° along the applied shear direction unlike the drop-coated nFHs which exhibit random orientations. Next, various types of cells were cultured on top of transparent soft nFHs which showed good viability and attachment while their behaviors could be easily monitored by both upright and inverted optical microscopy. Particularly, neuronal lineage cells such as PC 12 cells and embryonic hippocampal neurons showed highly stretched morphology along the overall fiber orientation with aspect ratios ranging from 1 to 14. Furthermore, the resultant neurite outgrowth and migration behaviors could be effectively controlled by the horizontal orientation and the three-dimensional arrangement of underlying nFHs, respectively.

CONCLUSION

We expect that surface modifications with transparent soft nFHs will be beneficial for various biological/biomedical studies such as fundamental cellular studies, neuronal/stem cell and/or organoid cultures, implantable probe/device coatings, etc.

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.

Synthesis, Antifungal Activity, 3D-QSAR and Controlled Release on Hydrotalcite Study of Longifolene-Derived Diphenyl Ether Carboxylic Acid Compounds

Twenty-two novel longifolene-derived diphenyl ether-carboxylic acid compounds 7a-7v were synthesized from renewable biomass resources longifolene, and their structures were confirmed by FT-IR, ¹H NMR, ¹³C NMR, and HRMS. The preliminary evaluation of in vitro antifungal activity displayed that compound 7b presented inhibition rates of 85.9%, 82.7%, 82.7%, and 81.4% against Alternaria solani, Cercospora arachidicola, Rhizoctonia solani, and Physalospora piricola, respectively, and compound 7l possessed inhibition rates of 80.7%, 80.4%, and 80.3% against R. solani, C. arachidicola, P. piricola, respectively, exhibiting excellent and broad-spectrum antifungal activities. Besides, compounds 7f and 7a showed significant antifungal activities with inhibition rates of 81.2% and 80.7% against A.solani, respectively. Meanwhile, a reasonable and effective 3D-QSAR mode (r² = 0.996, q² = 0.572) has been established by the CoMFA method. Furthermore, the drug-loading complexes 7b/MgAl-LDH were prepared and characterized. Their pH-responsive controlled-release behavior was investigated as well. As a result, complex 7b/MgAl-LDH-2 exhibited excellent controlled-releasing performance in the water/ethanol (10:1, v:v) and under a pH of 5.7.

Development of emamectin benzoate-loaded liposome nano-vesicles with thermo-responsive behavior for intelligent pest control

Pesticides play an important role in agricultural disease and pest control. However, the low utilization efficiency and environmentally unfriendly disadvantages of conventional pesticide formulations cause substantial environmental and ecological damage. Constructing intelligent controlled-release pesticide systems via nanotechnology is a feasible way to overcome these defects. In this research, an emamectin benzoate-loaded liposome nano-vesicle (EB-Lip-NV) with a multicompartment structure and thermo-responsive characteristics was developed to accurately control nocturnal pests and improve insecticidal activity. EB-Lip-NV is an unusual low-temperature rapid-release system based on phase transitions of the liposome membrane. Compared with the conventional water-soluble granule (SG), the EB-Lip-NV exhibited higher control activity on Spodoptera exigua. More importantly, the control efficacy of Spodoptera exigua at 20 °C was around 1.4 times that at 40 °C because of low temperature-induced rapid release. This controlled-release behavior of EB-Lip-NV in response to temperature change could effectively control the population of nocturnal pests. In addition, the toxicity of the EB-Lip-NV towards zebrafish was lower than that of SG by above 50%. This study provides a new strategy for constructing intelligent controlled-release pesticide systems with improving utilization rate and reducing harm to the environment and non-target organisms.

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.

Polymer nanoparticles pass the plant interface

As agriculture strives to feed an ever-increasing number of people, it must also adapt to increasing exposure to minute plastic particles. To learn about the accumulation of nanoplastics by plants, we prepared well-defined block copolymer nanoparticles by aqueous dispersion polymerisation. A fluorophore was incorporated via hydrazone formation and uptake into roots and protoplasts of Arabidopsis thaliana was investigated using confocal microscopy. Here we show that uptake is inversely proportional to nanoparticle size. Positively charged particles accumulate around root surfaces and are not taken up by roots or protoplasts, whereas negatively charged nanoparticles accumulate slowly and become prominent over time in the xylem of intact roots. Neutral nanoparticles penetrate rapidly into intact cells at the surfaces of plant roots and into protoplasts, but xylem loading is lower than for negative nanoparticles. These behaviours differ from those of animal cells and our results show that despite the protection of rigid cell walls, plants are accessible to nanoplastics in soil and water.

Preparation and characterization of emamectin benzoate nanocapsules based on the dual role of polydopamine

BACKGROUND

Developing pesticide-controlled release formulations with foliage adhesion has become the focus of current research in the field of crop protection. In this study, an excellent adhesive nanocapsule loaded with emamectin benzoate (Eb@PDA) was prepared via emulsion interfacial polymerization based on the self-polymerization ability and adhesion properties of polydopamine (PDA).

RESULTS

The physicochemical properties of the Eb@PDA were characterized by scanning electron microscopy, transmission electron microscopy, particle size statistics, Fourier transform infrared spectroscopy and X-ray diffraction. The Eb@PDA presented a regular spherical shape, with an average particle size of 163.8 nm. Compared with conventional formulations, it had higher pesticide-loading content (34%) and excellent adhesion onto corn leaf. In addition, Eb@PDA showed sustained-release characteristics, facilitating the release of Eb at low pH and high temperature. Eb@PDA could effectively protect Eb against photodegradation and had a longer effective period for controlling Spodoptera frugiperda and Spodoptera exigua. Furthermore, acute toxicity tests showed that the 50% lethal concentration (LC₅₀ ) was 80.91 and 57.91 mg kg^-1 at 7 and 14 days, respectively, indicating a lower toxicity of the Eb@PDA to earthworms. The cells (L02) treated with Eb@PDA showed a higher cell viability but a lower apoptosis rate (only 5.75%), demonstrating the lower cytotoxicity of the Eb@PDA.

CONCLUSION

The self-prepared Eb@PDA could be used as a formulation with the advantages of slow release, UV shielding, strong leaf adhesion, superior insecticidal properties, sustained effectiveness and biosafety. It will also facilitate the development of an efficient and safe pesticide delivery system. © 2022 Society of Chemical Industry.

Multi-responsive mesoporous polydopamine composite nanorods cooperate with nano-enzyme and photosensitiser for intensive immunotherapy of bladder cancer

Bladder cancer is a common malignancy in the urinary system. Defects of drug molecules in bladder during treatment, such as passive diffusion, rapid clearance of periodic urination, poor adhesion and permeation abilities, lead to low delivery efficiency of conventional drugs and high recurrence rate of disease. In this study, we designed multi-responsive mesoporous polydopamine (PDA) composite nanorods cooperating with nano-enzyme and photosensitiser for intensive immunotherapy of bladder cancer. The strongly adhesive mesoporous PDA with wheat germ agglutinin on nanoparticles could specifically adhere to epithelial glycocalyx and made the nanoparticles aggregate in urinary pathways. Meanwhile, 2,3-dimethylmaleic anhydride could be hydrolysed in acidic conditions of tumour microenvironment, giving it a positive charge (charge reversal), which is more amenable to enter cancer cells. Afterwards, manganese dioxide nanorods could catalyse the reaction of excess H2 O2 in tumour microenvironment to generate active oxygen, so as to change the hypoxic environment in tumour, and achieve a pH-responsive for slow release of PD-L1. After the ICG was irradiated by infrared light, a large amount of singlet oxygen was generated, thereby enhancing the therapeutic effect and reducing toxicity in vivo. Besides, mesoporous PDA with indocyanine green photothermal agent could have a local heat up quickly under the near-infrared light to kill cancer cells, thereby enhancing therapeutic efficacy. Accordingly, this mesoporous PDA composite nanorods shed a light on bladder tumour treatment.

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

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

Stimulus responsive microcapsules and their aromatic applications

Fragrances and essential oils are promising for a wide range of applications due to their pleasant odors and diverse effects. However, direct addition to consumer products has the disadvantages of short retention time and easy deterioration of odor. At the same time, releasing a large amount of odor in a short time may be an unpleasant experience, which severely limits the practical application of aromatic substances. Microencapsulation perfectly solves these problems. Stimuli-responsive microcapsules, which combine environmental stimulation with microencapsulation, can not only effectively prevent the rapid decomposition and evaporation of aroma components, but also realize the "on-off" intelligent release of aroma substances to environmental changes, which have great promise in the field of fragrances. In this review, the application of stimuli-responsive microcapsules in fragrances is highlighted. Firstly, various encapsulation materials used to prepare stimuli-responsive aromatic microcapsules are described, mainly including some natural polymers, synthetic polymers, and inorganic materials. Subsequently, there is a detailed description of the common release mechanisms of stimuli-responsive aromatic microcapsules are described in detail. Finally, the application and future research directions are given for stimuli-responsive aromatic microcapsules in new textiles, food, paper, and leather.

Photothermal-Controlled Release of IL-4 in IL-4/PDA-Immobilized Black Titanium Dioxide (TiO2) Nanotubes Surface to Enhance Osseointegration: An In Vivo Study

Host immune response has gradually been accepted as a critical factor in achieving successful implant osseointegration. The aim of this study is to create a favorable immune microenvironment by the dominant release of IL-4 during the initial few days after implant insertion to mitigate early inflammatory reactions and facilitate osseointegration. Herein, the B-TNT/PDA/IL-4 substrate was established by immobilizing an interleukin-4 (IL-4)/polydopamine (PDA) coating on a black TiO₂ nanotube (B-TNT) surface, achieving on-demand IL-4 release under near infrared (NIR) irradiation. Gene Ontology (GO) enrichment analyses based on high-throughput DNA microarray data revealed that IL-4 addition inhibited osteoclast differentiation and function. Animal experiment results suggested that the B-TNT/PDA/IL-4+Laser substrate induced the least inflammatory, tartrate-resistant acid phosphatase, inducible nitric oxide synthase and the most CD163 positive cells, compared to the Ti group at 7 days post-implantation. In addition, 28 days post-implantation, micro-computed tomography results showed the highest bone volume/total volume, trabecular thickness, trabecular number and the lowest trabecular separation, while Hematoxylin-eosin and Masson-trichrome staining revealed the largest amount of new bone formation for the B-TNT/PDA/IL-4+Laser group. This study revealed the osteoimmunoregulatory function of the novel B-TNT/PDA/IL-4 surface by photothermal release of IL-4 at an early period post-implantation, thus paving a new way for dental implant surface modification.

Multi-Stimuli-Responsive Janus Hollow Polydopamine Nanotubes

A tubular-shaped Janus nanoparticle based on polydopamine that responds to near-infrared, magnetic, and pH stimuli is reported. The robust tubular polydopamine structure was obtained by optimizing the halloysite template-to-dopamine ratio during synthesis. The inner and outer surfaces of the tube were exposed at different steps of the template-sonication--etching process, enabling the differential surface modification of these surfaces. Poly(ethylene glycol) (PEG) and poly(N-isopropylacrylamide) (PNIPAM) were grafted to the outer and inner surface of the nanotube, respectively. The PEG-coated surface limited aggregation of the nanoparticles at elevated temperatures. The PNIPAM-coated interior enhanced doxorubicin loading and endowed the nanoparticle with temperature-responsive behavior. The deposition of precipitated Fe₃O₄ nanoparticles further modified the nanoparticles. The resulting magnetic Janus nanoparticles responded to pH, temperature, and magnetic fields. Temperature changes could be induced by near-infrared laser, and all three stimuli were found to influence release rates of adsorbed doxorubicin from the nanoparticles. The interaction of the stimuli on release kinetics was elucidated using a linear mixed model; reduced pH and NIR irradiation enhanced release while applying a static magnetic field retarded release. Furthermore, the mechanism was shifted toward Fickian behavior by applying a static magnetic field and low pH conditions. However, NIR irradiation only shifted the behavior toward Fickian behavior at low pH.

Metal-Organic Framework (UiO-66)-Based Temperature-Responsive Pesticide Delivery System for Controlled Release and Enhanced Insecticidal Performance against Spodoptera frugiperda

Spodoptera frugiperda is a global pest that brings about great disasters to crops. Conventional pesticide formulations often suffer from poor water solubility, low stability, burst release, weak leaf adhesion, and low efficiency. To improve the insecticidal activity of pesticides, a stimuli-responsive controlled release pesticide delivery system (PDS) has attracted extensive attention in recent years. This paper reports a temperature-responsive controlled release PDS based on poly(N-isopropyl acrylamide) (PNIPAm)-modified indoxacarb (IDC)-loaded UiO-66-(COOH)₂ (IDC@UiO-66-(COOH)₂-PNIPAm) and studies its insecticidal activities against S. frugiperda. The UiO-66-(COOH)₂ nanocarrier has an excellent pesticide loading performance, and the loading rate for IDC is 78.69%. The as-prepared PDS has good stability, temperature-responsive controllable release performance, and enhanced leaf affinity, so it can effectively improve the utilization rate of IDC. The insecticidal experiment indicates that the PDS has an enhanced control effect against S. frugiperda. In addition, biosafety analysis further verifies that the PDS exhibits no obvious negative effects on the germination of maize seeds and the growth of maize seedlings. In view of this, we believe that this PDS will have a broad application in the field of pesticide formulation innovation, pest management, and sustainable agricultural development.

Facile pathway to construct mesoporous silica nanoparticles loaded with pyraclostrobin: Physicochemical properties, antifungal activity, and biosafety

BACKGROUND

A controlled-release formulation based on mesoporous silica nanoparticles (MSNs) provides an effective way for reducing pesticide use and protecting the ecological environment. In this study, MSNs loaded with pyraclostrobin (PYR@MSNs) were prepared using a one-pot method.

RESULTS

The characteristics of PYR@MSNs were systematically investigated, including morphology, loading content, ultraviolet (UV) resistance, release behavior, control effects against pathogens, and safety to nontarget organisms. The results show that the prepared PYR@MSNs presented characteristics of regular spherical shapes, uniform particle size (200 nm), high drug loading (38.9%), and enhanced UV resistance. Compared with traditional formulation, PYR@MSNs exhibited improved control effects against Fusarium graminearum, an extended control period, and lower toxicity to zebrafish, earthworms and BEAS-2B cells.

CONCLUSIONS

This research will facilitate the development of efficient and safe pesticide delivery systems. The PYR@MSNs has showed its potential as a new controlled-release formulation with increased efficacy and is expected to benefit the sustainable development of agriculture. © 2022 Society of Chemical Industry.

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Design and Preparation of Avermectin Nanopesticide for Control and Prevention of Pine Wilt Disease

Pine wilt disease is a devastating forest disaster caused by Bursaphelenchus xylophilus, which has brought inestimable economic losses to the world's forestry due to lack of effective prevention and control measures. In this paper, a porous structure CuBTC was designed to deliver avermectin (AM) and a control vector insect Japanese pine sawyer (JPS) of B. xylophilus, which can improve the biocompatibility, anti-photolysis and delivery efficacy of AM. The results illustrated the cumulative release of pH-dependent AM@CuBTC was up to 12 days (91.9%), and also effectively avoided photodegradation (pH 9.0, 120 h, retention 69.4%). From the traceable monitoring experiment, the AM@CuBTC easily penetrated the body wall of the JPS larvae and was transmitted to tissue cells though contact and diffusion. Furthermore, AM@CuBTC can effectively enhance the cytotoxicity and utilization of AM, which provides valuable research value for the application of typical plant-derived nerve agents in the prevention and control of forestry pests. AM@CuBTC as an environmentally friendly nanopesticide can efficiently deliver AM to the larval intestines where it is absorbed by the larvae. AM@CuBTC can be transmitted to the epidemic wood and dead wood at a low concentration (10 mg/L).

Swelling and glyphosate-controlled release behavior of multi-responsive alginate-g-P(NIPAm-co-NDEAm)-based hydrogel

Intelligent controlled release systems (ICRS) displayed great achievement in agriculture by enhancing the utilization efficiency of agrochemicals. In this work, an intelligent graft copolymer (Alg-g-P(NIPAm-co-NDEAm)) with alginate (Alg) backbone and thermo-responsive poly(N-isopropyl acrylamide-co-N,N-diethylacrylamide) (P(NIPAm-co-NDEAm)) side chain was constructed as the matrix of ICRS through redox copolymerization, and its thermo-induced responsive property was studied. Then, the copolymer was mixed with a promising photothermal material semi-coke (SC) to form hydrogel beads (Ca-Alg-g-P(NIPAm-co-NDEAm)/SC) by ion crosslinking. The water absorbency of beads under different stimuli (pH, temperature, and light) presented outstanding responsive performance and the swelling mechanism was analyzed through coupling theory. Furthermore, the release of glyphosate (Gly) from Ca-Alg-g-P(NIPAm-co-NDEAm)/SC under environmental stimuli displayed regulatable behaviors. This multi-responsive hydrogel bead shows bright prospect in the sustainable advancement of crop production.

Sustainable nano-pesticide platform based on Pyrethrins II for prevention and control Monochamus alternatus

Background

Pine wilt disease as a devastating forest disaster result from Bursaphelenchus xylophilus that spread by stem-borers Monochamus alternatus feeding on pine leaves, which has brought inestimable economic losses to the world's forestry due to lack of effective prevention and control measures. In this paper, we put forward a proposal for utilizing nanoHKUST-1 to encapusulate the Pyrethrins II that a nerve agent extracted from plant to control M. alternatus, including toxicity mechanism research, traceable biopesticide monitoring, and environment assessment for the first time. The highly biocompatible nanoHKUST-1 can solve the problems of poor water solubility, easy degradation and low control efficiency of Pyrethrins II.

Results

The results illustrated the biopesticide loading efficiency of PthII@HKUST-1 reached 85% and the cumulative release of pH-dependent PthII@HKUST-1 was up to 15 days (90%), and also effectively avoid photodegradation (pH 7.0, retention 60.9%). 50 nm PthII@HKUST-1 made it easily penetrate the body wall of MA larvae and transmit to tissue cells through contact and diffusion. Moreover, PthII@HKUST-1 can effectively enhance the cytotoxicity and utilization of Pyrethrins II, which will provide valuable research value for the application of typical plant-derived nerve agents in the prevention and control of forestry pests. PthII@HKUST-1 as an environmentally friendly nano-pesticide can efficiently deliver Pyrethrins II to the larval intestines and absorbed by the larvae. PthII@HKUST-1 could also be transmitted to the epidemic wood and dead wood at a low concentration (10 mg/L).

Conclusion

Here we speculate that nanoHKUST-1 will bring new opportunity to research biopesticide inhibition mechanism of different agricultural and forestry pests, which will break through the existing research limitations on development, utilization and traceable monitoring of biopesticide, especially for the study of targeting specific proteins.

Graphical Abstract

Electrically Controlled Aquatic Soft Actuators with Desynchronized Actuation and Light-Mediated Reciprocal Locomotion

Soft-bodied aquatic invertebrates can overcome hydrodynamic resistance and display diverse locomotion modes in response to environmental cues. Exploring the dynamics of locomotion from bioinspired aquatic actuators will broaden the perspective of underwater manipulation of artificial systems in fluidic environments. Here, we report a multilayer soft actuator design based on a light-driven hydrogel and a laser-induced graphene (LIG) actuator, minimizing the effect of the time delay by a monolithic hydrogel-based system while maintaining shape-morphing functionality. Moreover, different time scales in the response of actuator materials enable a real-time desynchronization of energy inputs, holding great potential for applications requiring desynchronized stimulation. This hybrid design principle is ultimately demonstrated with a high-performance aquatic soft actuator possessing an underwater walking speed of 0.81 body length per minute at a relatively low power consumption of 3 W. When integrated with an optical sensor, the soft actuator can sense the variation in light intensity and achieve mediated reciprocal motion. Our proposed locomotion mechanism could inspire other multilayer soft actuators to achieve underwater functionalities at the same spatiotemporal scale. The underwater actuation platform could be used to study locomotion kinematics and control mechanisms that mimic the motion of soft-bodied aquatic organisms.