Release Of Imidacloprid Research Articles

Maleic anhydride-functionalized cellulose nanocrystal-stabilized high internal phase Pickering emulsion for pesticide delivery

The salt-responsiveness of Pickering emulsions has significantly influenced their applications due to the large amount of salt on the surface of plant leaves. The present study provided a maleic anhydride-functionalized cellulose nanocrystal-stabilized high internal phase Pickering emulsion (MACNCs-HIPPEs) that was stable to high-concentration salt and used for pesticide delivery. The stability of MACNCs-HIPPEs was investigated by adjusting the oil-phase volume fraction (φ), the MACNCs concentration, NaCl dosages, and the rheological properties. The high internal phase Pickering emulsion was obtained at φ of 0.8 and MACNCs concentration of 2wt% and showed excellent salt stability (NaCl, 1200 mM) and significant storage stability (60 days). The sustained release of imidacloprid (IMI) from imidacloprid-loaded MACNCs-HIPPEs (IMI@MACNCs-HIPPEs) showed a positive correlation to the temperature (15°C, 25°C, 35°C), indicating clear thermo-responsiveness of the prepared pesticide formulation. The test of spread and retention of IMI@MACNCs-HIPPEs on the leaf surface showed a significant advantage compared with the commercial IMI water dispersible granules (CG). All the advantages mentioned above showed the excellent potential of the MACNCs-HIPPEs in delivering lipophilic pesticides.

Silver Nanoparticle-Decorated Carbon Fiber Microelectrode for Imidacloprid Insecticide Analysis

The electrocatalytic activity of silver towards imidacloprid reduction was demonstrated at both macro- and nano-scales. Coupled with the advantages of microscopic electrodes, this has led to the development of a highly-sensitive and selective electrochemical sensor for imidacloprid detection. This sensor utilizes silver nanoparticle-decorated carbon fiber microelectrodes (AgNPs/CF) fabricated through a single-step electrodeposition. Employing AgNPs/CF, the linear range, sensitivity, and limit of detection (3SB/m) were determined to be 0.0–0.40 mM, 2.98 × 10−8 ± 0.10 × 10−8 A mM−1, and 60.4 nM, respectively. The sensor was successfully applied to detect imidacloprid directly in various water samples without the need for sample preparation, demonstrating ca. 100% recoveries. Moreover, the sensor was applied to analyze imidacloprid release from contaminated soil samples, revealing Langmuir characteristics of the desorption process.

A pesticide sustained‐release microcapsule from cellulose nanocrystal stabilized Pickering emulsion template

AbstractEfficient utilization of pesticides has presented various advantages in the ecological environment, food safety, and agricultural sustainability. Pesticide microcapsule could significantly improve the pesticide utilization ratio, and thus, we prepared a sustained‐release microcapsule from cellulose nanocrystal (CNCs) stabilized Pickering emulsion template. The NaCl was added to overcome the strong electrostatic repulsion among CNCs for forming a stable oil‐in‐water (O/W) CNCs‐based Pickering emulsion template, followed by crosslinking with hexamethylene diisocyanate on the interface. UV–vis and zeta‐potential were used to characterize the as‐prepared Pickering emulsion, and the stability and emulsion fraction were calculated. Results indicated that NaCl contributed to the stability of Pickering emulsion, even at a low concentration. The obtained CNCs‐based microcapsule was characterized by FT‐IR, XRD, SEM, TG‐DTG, and three‐phase contact angles. The microcapsule presented an encapsulation efficiency of 96.76% and sustained release of the imidacloprid for more than 82 h. Results indicated the potential for loading and sustained release of imidacloprid, which is beneficial to the environment, food, and agriculture.

Construction of a novel fluorescent nanocarrier with double hollow shells for pH-controlled release of imidacloprid and its distribution and transport in bok choy

Nanotechnology has been widely used in the field of pesticides. Integration of nano-pesticides and carbon dot fluorescence can fully utilize the potential for high admission of pesticides on leaves and convenience observation of its distribution and transport in the tissues. In the present study, a fluorescent mesoporous nanosilica with double hollow shells for loading imidacloprid (Im@FL-MSNs) was designed and synthesized. The physical and chemical properties of the imidacloprid nanocarriers were characterized by transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and N2 adsorption/desorption. When the mass ratio of FL MSNs to imidacloprid is 6:5, Im@FL-MSNs exhibits good fluorescence properties, high loading efficiency (∼30%), great slow-release performance as well as pH controllability. Besides, Im@FL-MSNs can improve the ability of imidacloprid to adhere on the leaf surface of bok choy (Initial contact angled is greater than 80°）. Importantly, Im@FL-MSNs did not reduce the biological activity of imidacloprid (LC50 (95% CI) = 1.43 mg/L). It was able to visually study the absorption and distribution of imidacloprid in bok choy plants, and provide theoretical and technical guidance for pesticide reduction.

Regenerated cellulose-stabilized pickering emulsion for sustained release of Imidacloprid

Regenerated cellulose-stabilized pickering emulsion for sustained release of Imidacloprid

New Formulation to Accelerate the Degradation of Pesticide Residues: Composite Nanoparticles of Imidacloprid and 24-Epibrassinolide.

Pest control effectiveness and residues of pesticides are contradictory concerns in agriculture and environmental conservation. On the premise of not affecting the insecticidal effect, the pesticide residues in the later stage should be degraded as fast as possible. In the present study, composite nanoparticles in a double-layer structure, consisting of imidacloprid (IMI) in the outer layer and plant hormone 24-epibrassinolide (24-EBL) in the inner layer, were prepared by the W/O/W solvent evaporation method using Eudragit RL/RS and polyhydroxyalkanoate as wall materials. The release of IMI in the outer layer was faster and reached the maximum within 24 h, while the release of 24-EBL in the inner layer was slower and reached the maximum within 96 h. The contact angle of the composite nanoparticles was half that of the 5% IMI emulsifiable concentrate (EC), and the deposition of composite nanoparticles on rice was twice that of 5% IMI EC, which increased the pesticide utilization efficiency. Compared with the common pesticide, 5% IMI EC, the insecticidal effect of the composite nanoparticles was stronger than that of planthoppers, with a much lower final residue amount on rice after 21 days. The composite nanoparticles prepared in this study to achieve sustained release of pesticides and, meanwhile, accelerate the degradation of pesticide residues have a strong application potential in agriculture for controlling pests and promoting crop growth.

Application of the photothermal-responsive gelatin-based microspheres for controlled release of imidacloprid by helix-coil structural transition mechanism

Intelligent controlled release systems (ICRS) are recognized as a feasible and economical way for the highly efficient utilization of agrochemicals. In this work, we developed an intelligent photothermal-responsively controlled-release pesticide particle (IYGCP) based on imidacloprid (IMI, a model pesticide), yeast biochar (YB, adsorbent and photothermal material), gelatin (GE, temperature-responsive polymer), and Ca-alginate (CA, microsphere matrix). Therein, YB with high adsorption property and photothermal conversion capacity was used as a carrier of IMI to avoid the loss of active ingredients, and as an agent to endow the IYGCP platform with unique photothermal-responsive performance. After IMI loading, IMI/YB was scattered and anchored in CA/GE semi-interpenetrating hydrogels by the chelation of sodium alginate and Ca2+. Upon irradiation under simulated sunlight, YB with satisfactory photothermal conversion efficiency can effectively transfer solar energy into thermal energy, induing a free helix-coil structural transition of the un-crossed GE polymers, thereby resulting in changes in microstructure of hydrogel spheres and further enabling a controlled release of IMI encapsulated in the IYGCP. Besides, the composite displayed high control efficacy on corn borers. Consequently, this photothermal-responsive gelatin-based microsphere shows a bright prospect for controlling the release and loss of pesticides.

Intelligent response release of imidacloprid from a tailored star‐shaped polymer targeting the temperature‐dependent reproduction of cotton aphids

AbstractIntelligent response carriers have been developed and widely used in agriculture to improve pesticide utilization. However, there are few tailored response carriers that are targeting the cotton aphid pest. Based on the temperature‐dependent growth and reproduction of cotton aphids, we constructed a tailored temperature‐responsive star‐shaped polymer to achieve on‐demand controlled release of imidacloprid (IMI) to more effectively kill cotton aphids. In this work, a series of star‐shaped polymers based on β‐cyclodextrin (β‐CD), 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA), and tert‐butyl acrylate (tBA) were synthesized via atom transfer radical polymerization (ATRP). Next, β‐CD‐PMEO2MA (β‐CD‐P0) micelles were developed having different controlled release rates of IMI at different temperatures (14, 21, or 27°C) following the cotton aphid growth and reproduction cycle. At 21°C, the micelle underwent a phase transition from a solution state to a turbidity state. By inducing this structural change, release of IMI was increased to adapt to the reproduction of the cotton aphid population which is highest at 21–27°C. In vitro release experiments showed that 48% of IMI was released from β‐CD‐P0 after the phase transition temperature (PTT). An aqueous solution of the β‐CD‐P0 polymer micelle was stable at 4°C for at least 28 days. Therefore, this intelligent response release model has enormous potential as a novel carrier for various pesticides.

Stimuli-responsive Ca-alginate-based photothermal system with enhanced foliar adhesion for controlled pesticide release

For minimizing volatilization and leaching of pesticides, and enhancing their residence time on crop surfaces, we synthesized and characterized a novel intelligent pesticide delivery system. Therein, imidacloprid (IMI) was adsorbed by polydopamine modified kaolin (PK) with high adsorption property through hydrogen bonds. Ca-alginate was used as a structural matrix of the system and a protective shell to hinder the pesticide burst release from PK, and endowed the system with unique pH-sensitive property for IMI release. The amino silicone oil (ASO) coating could bind with the waxy layer of crop leaves by the theory of “similarity-intermiscibility”, which increased the adhesion of composite on crop leaves. Moreover, by the excellent light-sensitive property of detonation nanodiamond (DND) and temperature-responsive performance of poly(N-isopropylacrylamide) (PNIPAm), the release of IMI from the functional system could be adjusted by sunlight. Besides, the composite displayed high control efficacy. This novel composite can promote the targeting ability and utilization efficiency of pesticides, thus having a huge potential application prospect in agriculture.

Alternating Magnetic Field-Responsive Nanoplatforms for Controlled Imidacloprid Release and Sustainable Pest Control

Alternating Magnetic Field-Responsive Nanoplatforms for Controlled Imidacloprid Release and Sustainable Pest Control

PH-responsive eco-friendly chitosan modified cenosphere/alginate composite hydrogel beads as carrier for controlled release of Imidacloprid towards sustainable pest control

Efficacious pesticide formulations having prolonged activity with minimal environmental risks is imperative for sustainable agriculture. Control release formulation is a prudent approach towards efficient pesticide utilization with reduced environmental implications. This work embodies an innovative easy-to-prepare pesticide formulation using chitosan (Cht)-alginate (Alg)-cenosphere (Cn) composite hydrogel beads for the sustained release of imidacloprid (IMI) with added advantage of UV safeguarding of pesticide, direct on-field application and upscalability. The IMI@Cht-Alg-Cn beads showed high encapsulation efficiency of around 80%, owing to their hollow structure and porous crosslinked network. Around 80% release of pesticide over a period of 72 hr substantiates a slower release profile under different pH conditions mimicking different soil types. Excitingly, leaching study reveal a two fold slow pesticide loss of 12 % compared to a commercial formulation. Subsequent validations in a model plant system (Vigna unguiculata) signify on-field universal applicability of the efficacious formulation. A long-term safety assessment study involving a human skin cell line (HaCaT), a plant model (Vigna radiata), soil-dwelling bacteria (E. coli and B. subtilis) and a non-targeted aquatic model organism (Daphnia magna) advocates a safe-by-design approach of the hydrogel beads. A 100% efficacy against Aphis crassivora (cowpea aphid) over 48 hrs compared to commercial formulation and technical grade of IMI suggest its suitability for on field application. This work merits sustainable pesticide use by providing application-based proofs and qualifies as a potential pesticide formulation for sustainable pest management.

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

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

The effect of swellable carboxymethyl cellulose coating on the physicochemical stability and release profile of a zinc hydroxide nitrate–sodium dodecylsulphate–imidacloprid

The environmental pollution that results from the excessive usage of pesticides has been threatening the communities for decades. In this study, carboxymethyl cellulose (CMC) is proposed as a coating agent to encapsulate zinc hydroxide nitrate–sodium dodecylsulphate–imidacloprid (ZHN–SDS–IC) for the implementation of controlled release formulation (CRF) in pesticide. The physicochemical properties of the ZHN–SDS–IC–CMC were characterised so that their crystallinity, thermal behaviour and surface morphology could be examined. The findings from the release study revealed the potential for CMC to prolong the release of imidacloprid (IC). A strong hygroscopic and adequate swelling characteristic enabled the CMC to develop an external gel layer on the surface of the ZHN–SDS–IC–CMC that acted as an additional barrier and slowed the release of the intercalated IC. The ZHN–SDS–IC–CMC that was synthesised can contribute to overcoming the environmental issues due to excessive usage of pesticides and can create a better future for the community.

Novel fabrication of a yeast biochar-based photothermal-responsive platform for controlled imidacloprid release.

For improving the utilization efficiency of pesticides, we developed a novel pesticide delivery particle (YINCP@EC) with a core–shell structure based on yeast biochar, imidacloprid (IMI), ammonium bicarbonate (NH4HCO3), calcium alginate (CA), and ethyl cellulose (EC). Therein, yeast biochar, IMI and NH4HCO3 were absorbed in the network-structured of CA to obtain YINCP through hydrogen bonds. The resulting composite was granulated using an ion gelation technique and then coated with EC to form YINCP@EC. In this platform, yeast biochar serving as a photothermal agent can efficiently convert sunlight energy into thermal energy, thereby triggering NH4HCO3 decomposition into CO2 and NH3 that can break through the EC coating and facilitate IMI release. In addition, the influence of yeast biochar content, pH, and coexisting ions was systematically studied to evaluate the release behavior of IMI from YINCP@EC. Moreover, the hydrophobic EC shell endowed YINCP@EC with high stability in aqueous solution for at least 60 days. Consequently, this novel composite with simple preparation, low cost and remarkable photothermal-responsive properties has a huge application potential in agriculture.

Near infrared light-driven release of pesticide with magnetic collectability using gel-based nanocomposite

A near infrared light (NIRL)-driven release imidacloprid (NDRI) with magnetic collectability property was constructed using agarose hydrogel (AG), CuS-polydopamine (CP), zeolitic imidazolate framework-8 (ZIF-8), imidacloprid (IM), and ferriferrous oxide (Fe3O4). Therein, ZIF-8 with a large specific surface area was used to efficiently load IM molecules. CP, as a photothermal agent, could soften AG and enlarge the pores in hydrogel spheres under NIRL, resulting in the release of IM. After release, Fe3O4 was beneficial to conveniently collect the remaining NDRI from water. Additionally, the AG hydrogel with a porous structure acted as a good carrier for NDRI. Importantly, NDRI possessed an outstanding controlled-release property and could be reutilized at least for four times. Consequently, this technology may provide a potential approach to control release of IM, improve utilization efficiency, and decline pesticide usage and contamination to environment.

Structure Regulation of Bentonite-Alginate Nanocomposites for Controlled Release of Imidacloprid.

To reveal the structure and release properties of bentonite-alginate nanocomposites, bentonite of different amounts was incorporated into alginate by the sol–gel route. The structure of the composites was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis and related to the swelling property of the matrix and the release of imidacloprid. Bentonite was subject to exfoliation into nanoplatelets and combined into the polymeric network within alginate hydrogel, exhibiting profound effects on the structure features and release properties of the composites. Bentonite was of good compatibility with alginate due to the hydrogen bonding and the electrostatic attraction between them. The polymer chains were found to intercalate into the interlayer gallery of the clay. The high specific area of the nanoplatelets of bentonite benefited the intimate contact with alginate and reduced the permeability of the composites. However, in the composites with clay content of more than 10%, the polymer was insufficient to accommodate the silicate sheets completely. The aggregation of the platelets destroyed the structure integrity of the composites, facilitating the diffusion of the pesticide. The release of imidacloprid was greatly retarded by incorporating into bentonite-alginate composites and dominated by Fickian diffusion depending on the permeability of the matrix. The time taken for 50% of the active ingredient to be released, T50, first increased and then decreased with increasing clay content in the composites, reaching a maximum around a weight percentage of 10%, at which the T50 value for imidacloprid release was about 2.5 times that for the release from pure alginate formulation.

Synthesis and Characterization of Chitosan-PVA hydrogels for pesticide release

ABSTRACTChitosan (Ch)-Polyvinyl (alcohol) (PVA) hydrogels cross-linked with sodium tripolyphosphate were synthetized to obtain a polymer matrix encapsulating an insecticide (active ingredient: imidacloprid). Imidacloprid release tests were performed separately with moist and lyophilized hydrogel beads with a diameter of 3.47 and 3.30 mm respectively. The concentration of the insecticide released in the medium was determined by UV-Visible spectroscopy, reaching equilibrium for wet hydrogels at 72h at a concentration of 330 mg L-1 and 281 mg L-1 in 48h for lyophilized hydrogels, comparing it with a maximum load of 330.18 mg L-1of imidacloprid contained in the hydrogels. The characterization of hydrogels was performed by Fourier transform infrarred spectroscopy (FTIR) to determine the functional groups. The morphology of the polymer matrix of the hydrogels was carried out in a scanning electron microscope (SEM). The size distribution and diameter of bead samples were observed through a stereomicroscope. The percentage of humidity of the hydrogels was determined obtaining 94.8% once the imidacloprid was released. the pore size of the samples was determined by the Brunauer-Emmet-Teller (BET) technique. The techniques used indicated that controlled release of imidacloprid could be more efficient with wet hydrogels in relation to the maximum load of imidacloprid contained, for protection of crops is necessary for a long time because of insecticide disponible in the soil.

Development of Ca-alginate-chitosan microcapsules for encapsulation and controlled release of imidacloprid to control dengue outbreaks

Abstract Ca-alginate-chitosan based microcapsules were prepared and used for the controlled release of imidacloprid larvacide against Aedes aegypti larvae. Imidacloprid encapsulation was evidenced through HPLC and FTIR analysis. Imidacloprid loading varied from 2.79% to 6.85% with encapsulation efficiency of up to 39.16%. TGA and DSC studies revealed good thermal stability and compatibility between the polymers and imidacloprid. X-ray diffractometry (XRD) results indicated a molecular level dispersion of imidacloprid in the polymer matrix. The in vitro release profiles of imidacloprid could be controlled by modifying the formulation, pH, or temperature. The imidacloprid release kinetics fit the Korsmeyer–Peppas model and follows the anomalous transport profile. The mechanism of imidacloprid release was proposed. In vivo release studies demonstrated that a dose of 6.11 mg/L is sufficient to destroy Aedes aegypti larvae. It was predicted that 50% and 100% larvae mortality are achieved for 369 and 141 days respectively.

Preparation of poly(propylene carbonate-co-ε-caprolactone) and their applications in drug delivery

ABSTRACTAn aliphatic poly(propylene carbonate-co-ε-caprolactone) (PPCCL) was synthesized by terpolymerization of CO2, propylene oxide, and epsi;-caprolactone (CL) using SalenCoIII(2,4-dinitrophenoxy) (Salen = N,N-bis(3,5-di-tert-butylsalicylidene)-ethylenediimine) (1)/1,10-phenanthroline monohydrate catalyst system. The obtained terpolymers were characterized by IR and 1H NMR to determine its structure. The reactivity ratios of CO2 and CL ( = 6.54 and rCL = 0.22) were evaluated by Fineman–Ross methodology. The reaction conditions were optimized according to the factors affecting the terpolymerization. The results indicated that the polymer yield is high to 7.15 g using 0.1 mmol complex 1 for 10 h. Using the PPCCL as the carrier, PPCCL microcapsule was prepared through solvent volatilization. The stirring speed had a significant effect on morphology and particle size of PPCCL microcapsules. The composition of terpolymer had little effect on morphology and particle size of PPCCL microcapsules. However, the rate of imidacloprid release from the microcapsules was accelerated with the amount of polyester component in terpolymer increasing.

Effects of organobentonites on imidacloprid release from alginate-based formulation

To provide effective delay in release, organobentonites with different loading levels of dodecyltrimethylammonium chloride (DTMA) and hexadecyltrimethylammonium chloride (HTMA) were used as modifying agents in the alginate-based controlled release formulation (CRF) containing imidacloprid. The structure of organobentonites was characterized by FTIR and XRD, and adsorption toward imidacloprid was investigated. The results were utilized to reveal the effects of organobentonites on the release of imidacloprid as well as its mechanism, and to evaluate the potential use of organobentonites to modulate the release of imidacloprid. The results showed that organobentonites could reduce the release of imidacloprid from alginate-based granules, different from the natural bentonite that accelerated the release of imidacloprid. The time taken for 50% of the active ingredient to be released, T50, for CRF incorporating organobentonites with DTMA at loading level of 50, 75, 100 and 125% of the clay's cation exchange capacity was 2.12, 1.59, 1.55 and 1.38 times of the value for the formulation without modifying agent, respectively. The values for those incorporating organobentonites with HTMA at the same loading level were 2.61, 2.20, 1.89 and 1.88 times. It was suggested that imidacloprid released via an anomalous transport kinetics predominated by Fickian diffusion and was influenced by the addition of bentonite and organobentonites due to the change of matrix permeability and the interaction with organobentonites. The enhancement of matrix permeability and imidacloprid release resulting from the addition of natural bentonite might be attributed to the lamellar structure and swellability of bentonite in water. In contrast, the matrix permeability and imidacloprid release decreased when organobentonites were used as modifier agents, as a consequence of the hydrophobicity of organobentonite. The results also suggested the feasibility of regulating imidacloprid release via controlling the structure of the organobentonites. An increase in loading level of quaternary ammonium ions could result in an enhancement of the release, while the extension of the alkyl chain slowed down the release of imidacloprid.