Microcapsule Suspension Research Articles

Identification and potential application of key insecticidal metabolites in Tilia amurensis, a low-preference host of Hyphantria cunea

Developing effective insecticidal strategies is an important means of reducing the spread and host plant damage by Hyphantria cunea. In this study, key metabolites with insecticidal activity against H. cunea were screened by targeted metabolomics in Tilia amurensis, a low-preference host plant. Subsequently, the potential of key metabolites that could be used as botanical pesticides was evaluated. The results showed that coumarin was the key insecticidal metabolite of T. amurensis and had a significant insecticidal effect and weight inhibition effect on H. cunea larvae. Coumarin treatment significantly decreased the larval nutrient content and the gene expression of rate-limiting enzymes in the glycolytic pathway and tricarboxylic acid cycle. A significantly enhanced detoxification enzyme activity (CarE and GST), antioxidant oxidase activity (SOD and CAT), non-enzymatic antioxidant levels (GSH), and total antioxidant capacity were observed in coumarin-treated larvae. Coumarin treatment resulted in a significant increase in the expression levels of detoxification enzyme genes (CarE1, CarE2, CarE3, GST2, and GST3) and antioxidant oxidase genes (SOD1, CAT1, and CAT2) in H. cunea larvae. Coumarin treatment significantly increased the levels of MDA and H2O2 in larvae but did not cause pathological changes in the ultrastructure of the larval midgut. Coumarin solution sprayed directly or as a microcapsule suspension formulation with coumarin as the active ingredient had significant insecticidal activity against the H. cunea larvae. Overall, coumarin, a key anti-insect metabolite identified from T. amurensis, can significantly inhibit the growth and survival of H. cunea larvae and has the potential to be developed as a botanical pesticide.

Study on the mechanism of nitrapyrin microcapsule suspension effectively improving nitrification inhibition rate in black soil

Nitrification inhibitors (NIs) have been widely applied to inhibit nitrification and reduce N2O emissions in agriculture. However, there are still some shortcomings, e.g. short effective periods, large applying amounts, low effectiveness, easy deactivation and different effect. Thus, a nitrapyrin microcapsule suspension (CPCS) was used as a new experimental material to elaborate its effects on nitrogen transformation and microbial response mechanisms in black soil by cultivation experiments with six treatments of no fertilization (CK), urea, urea+ 0.2 % CPES, urea+ 0.1 % CPCS, urea+ 0.2 % CPCS, and urea+ 0.3 % CPCS. The content of ammonium, nitrate nitrogen, functional microbial activity, degradation rate and adsorption characteristics of CPCS in the soil at different incubating times were determine. Compared with the nitrapyrin emulsifiable concentrate (CPEC) treatment, the degradation rate of CPCS decreased by 21.54 %, the half-life increased by 10.2 days, and the adsorption rate of nitrapyrin on black soil decreased more than 6-fold. CPCS effectively inhibited the transformation of ammonium nitrogen to nitrate nitrogen within more than 42 days. CPCS had a negative effect on amoA gene abundance and a positive effect on nrfA gene abundance. The research results provide a basic theoretical support for the application of CPCS on black soil.

Microencapsulation of moringa oil in bio-polymer by simple solvent evaporation technique

Moringa oil (MO) contains various bioactive components and pharmacology. It is attractive to use as a raw ingredient in various products. However, there are limitations on its direct utilization, especially MO's instability and hastening the active ingredient's degradation from external environmental factors, including temperature, humidity, oxidation, light, and heat. To solve these problems, in this work, microencapsulation of MO using different biopolymers as cellulose acetate butyrate (CAB), ethyl cellulose (EC), and poly(L-lactic acid) (PLLA) were carried out by a simple solvent evaporation technique. The prepared polymer microcapsule suspensions were highly colloidal stable for all types of biopolymers and ratios. The spherical biopolymer capsules were formed to a micrometer size after solvent evaporation under all conditions. However, when the microcapsules were dried, aggregation was found with the polymer microcapsules at a ratio of PLLA to MO of 50:50 for all three types of polymers, possibly due to the low amount of polymer to completely encapsulate all of MO. When polymer contents increased to 70%, the dried spherical polymer microcapsules were smoothly produced. Using 70% polymers, the PLLA microcapsule surface was smoother than the polymer microcapsules prepared by CAB and EC which exhibited the dent or hole on the outer surface. Micrometer size, spherical polymer capsules with a core-shell morphology were fabricated. Due to the higher hydrophilicity of the polymer than the MO, the polymer moves outward, forming a strong shell around the MO. Then, all three biopolymers can be used for the microencapsulation of MO at a suitable polymer to MO ratio. However, using PLLA at a ratio of PLLA to MO of 70:30 presented the highest encapsulation efficiency (74.08%), which may be due to its high molecular weight. Because of the non-toxicity and biodegradability of biopolymers, the fabricated microcapsules would be well applied in cosmetic products.

Preparation of chitosan/sodium tripolyphosphate@nano‐silica sol microcapsule suspensions and their application in soybean cyst nematode control

Fosthiazate is a common insecticide for root-knot nematode control, but it has a short shelf life and is prone to decomposition. In order to improve the stability and prolong the release time, this experiment used the ionic gel method to cross-link chitosan with sodium tripolyphosphate and added nano-silica sol to prepare microcapsules suspensions. The optimal preparation parameters for the preparation of chitosan/sodium [email protected] sol microcapsulated suspensions were optimized by single factor experiments and response surface analysis, and the encapsulation efficiency reached 61.3%. The highest control effect in greenhouse pots can reach 84.1%, and the optimal concentration was 2 g/m2 mixed with soil, which increased stem length, root length and fresh weight by 81.1%, 47.7% and 62.5%. The study showed that the microcapsules of chitosan cross-linked with sodium tripolyphosphate and added with nano-silica sol could significantly prolong the release of Fosthiazate, which also provided a positive effect on soybean cyst nematode control.

Residue levels of emamectin benzoate, imidacloprid and its major metabolites in cabbage from twelve regions in China and dietary risk assessment.

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established to investigate the residues of emamectin benzoate (EB), imidacloprid (IMI) and five IMI metabolites (IMI-olefin, IMI-urea, IMI-guanidine, 5-OH and 6-CNA) in cabbage. The average recoveries of the seven compounds in cabbage were 80%-102%, with relative standard deviations (RSDs) <8.0%. The limit of quantification (LOQ) for each compound was 0.01 mg kg -1 . Standardized residue tests were carried out in 12 areas of China under Good Agricultural Practice (GAP) conditions. A 10% EB-IMI microcapsule suspension was applied once with the high recommended dosage (18 g a.i. ha-1 ) on cabbage. The residues of EB (<0.01 mg kg-1 ), IMI (<0.016 mg kg-1 ) and the sum of IMI and its metabolites (<0.068 mg kg-1 ) in cabbage on the recommended preharvest interval (PHI) (7 d) were lower than the maximum residue limits (MRLs) in China. Based on residual data from fields, toxicology data, and Chinese dietary patterns, dietary risk assessments were conducted. Both the chronic risk quotients (25.2%-73.1%) and acute risk quotients (0.43%-1.57%) of EB and IMI were below 100%, indicating no unacceptable public health risk for different populations. This study provides guidance on the rational application of these insecticides in cabbage.

Numerical simulation of inhibition characteristics of wall temperature rise of phase change microcapsule in liquid-cooled microchannel

Phase change microcapsule suspension is a new type of heat-storage and heat-transfer functional fluid. Owing to the lack of understanding of flow-solid interaction, there exists a difference in research result of the heat transfer performance of suspension fluid. Therefore, the arbitrary Lagrangian-Euler method is used to simulate the flow-solid transfer characteristics of phase-change microcapsules in the liquid-cooled microchannel. Furthermore, the comparison of heat-transfer between particle and phase-change capsules is conducted. The influences of the position, shape, and number of capsules on the inhibition of the wall temperature rise are investigated. The results show that the wall-temperature-rise inhibition mainly occurs in the upstream area of the capsules. The phase change of capsules can reduce the wall temperature rise. On the other hand, the spin movement is faster when the capsule is closer to the wall, and the heat transfer is enhanced. As a result, the inhibitory effect on the wall temperature rise becomes stronger, especially near the heating surface. The circular capsules spin movement is faster and the inhibition performance is better than the ellipse. With the capsules number increasing, the wall temperature inhibition effect also gradually strengthens.

Temperature-Dependent Nanogel for Pesticide Smart Delivery with Improved Foliar Dispersion and Bioactivity for Efficient Control of Multiple Pests.

The use of nanomaterials and nanotechnology to construct a smart pesticide delivery system with target-oriented and controlled-release functions is important to increase the effective utilization rate and minimize environmental residue pollution. A temperature-dependent delivery system can modulate the release of pesticide with temperature to improve the efficacy and precision targeting. A series of poly(N-isopropylacrylamide) (PNIPAM)-based nanogels with high deformability and tunable structure were successfully constructed for smart pesticide delivery and effective pest control. A lambda-cyhalothrin (LC)-loaded Pickering emulsion (LC@TNPE) with a stable gel-like network structure was further formed by the temperature-dependent nanogel to encapsule the pesticide. The foliar wettability, photostability, and controlled-release property of LC@TNPE were effectively enhanced compared to the commercial formulation because of the encapsulation and stabilization of nanogel. The release rate of LC positively correlated with temperature changes and thereby adapted to the trend of pest population increase at higher temperature. The LC@TNPE displayed improved control efficacy on multiple target pests including Plutella xylostella, Aphis gossypii, and Pieris rapae compared with the commercial suspension concentrate and microcapsule suspension, and it showed marked efficacy to control Pieris rapae for an extended duration even at a 40% reduced dosage. Furthermore, the safety was evaluated systematically on cells in vitro and with a nontarget organism. Studies confirmed that the system was relatively safe for HepG2 cells and aquatic organism zebrafish. This research provides an insight into creating an efficient and environmentally friendly pesticide nanoformulation for sustainable agriculture production.

Efficacy of Talaromyces flavus microcapsule in controlling cotton important fungal diseases

Purpose: Evaluation of efficacy of Talaromyces flavus microcapsule in controlling cotton important fungal diseases and introducing Talaromyces flavus for using in the cotton fields. Methods: In this research focused on the application and efficiency evaluation of two new formulations of T. flavus microcapsules (TF-Co-G-1: Isolate 1 obtained from the Gorgan cotton farm) in suspension and powder forms, which were compared with the fungicide Talaromin® in farmers' fields. In this research, two cotton farms (Karkandeh and Hashemabad) with a history of infection with VW and DO were selected in two different regions of Golestan province. Each of the fields with an area of 1000 m2 was divided into seven equal parts. In each part, the treatments were applied separately, including microcapsule suspension with soil application, microcapsule suspension as seed impregnation, microcapsule powder with soil application, microcapsule suspension as seed impregnation, Talaromin® fungicide with soil application, Talaromin® as seed impregnation, and a control. The efficiencies of different treatments in terms of controlling the studied diseases and strengthening different growth indicators were evaluated by comparing the means of nine measured traits, including three traits for disease indicators (the percentage healthy seedlings for DO and the incidence rate and severity percentage of VW). To this end, the mixed analysis of variance (ANOVA) was first performed for two regions using the MS TAT C software, and the ANOVA of means was performed for each region separately with the significant effect of treatment × location. Results and conclusion: The results showed that among the studied formulations, powder microcapsules with seed impregnation by 32% and Talaromin® with soil application by 59% were respectively the most effective treatments for a significant increase in the percentage of healthy seedlings and a significant decrease in the severity of VW. Therefore, the obtained results indicate that the technical knowledge to produce T. flavus microcapsule formulations with two forms of suspension and powder can be transferred to manufacturing companies to carry out the commercialization and mass production process. Originality/value: Production of Talaromyces flavus microcapsule.

Experimental Study of Phase Change Microcapsule Suspensions Applied in BIPV Construction

In this paper, a phase change microcapsule suspension MPCMS25 with a mass fraction of 10% was prepared with TH-ME25 as the phase change microcapsule particles and deionized water as the base fluid. The experimental benches of the Building Integrated Photovoltaic (BIPV) system and BIPV-MPCMS system were set up, and the comparative tests were carried out in Nanjing to study the optimization effect of phase change microcapsule suspension on the thermal and electrical properties of the BIPV system. The results show that MPCMS25 reduces the component temperature of the system by 8.8 °C and the backplane temperature by 11.1 °C. The optimization time of the component operating temperature and the backplane temperature is 9.5 h and 9.75 h, respectively. Delay appearance of peak module operating temperature by 114 min and peak backplane temperature by 125 min. In addition, the suspension can also improve the power conversion efficiency (PCE) of photovoltaic modules by 0~5%. After a simulation study on the energy consumption of a high-speed railway station, it is found that using the BIPV-MPCMS system as the building envelope can achieve an energy saving rate of about 8.5%.

Effects of Different Environment-Friendly Gibberellic Acid Microcapsules on Herbicide Injury of Wheat.

Environmentally friendly microcapsules are becoming more and more widely used due to the increasing demand for environmental safety in pesticides. To compare the impact of differences in wheat herbicide phytotoxicity of different gibberellic acid microcapsule suspensions, two microcapsule suspensions were separately formulated using the phase transfer method and the in situ polymerization method, and the key performance indicators are the size of microcapsules and the degree of encapsulation. Meanwhile, through field trials, the pharmacological and detoxification effects of different types of microcapsule suspensions on the herbicide methyldisulfuron in wheat fields were compared. The microcapsule suspension was prepared by the phase transfer method and the particle sizes D10, D50, and D90 are 0.990, 2.136, and 5.201 μm, respectively; the microcapsule suspension was prepared by the in situ polymerization, the particle sizes D10, D50, and D90 are 4.365, 8.547, and 16.782 μm, respectively. The encapsulation rate of the microcapsules prepared by the phase transfer method and the in situ polymerization method was 86.9% and 91.2%, being higher than 80%, the national standard for capsules. Meanwhile, the release rate conforms to first-order release kinetics in 0–4 days and zero-order release kinetics in 5–28 days. The plot trials' result showed that the detoxification effect of the microcapsules prepared by the in situ polymerization method was significantly better than the detoxification effect of the microcapsules prepared by the phase transfer method and the control agent. The growth index of wheat was higher than that of the untreated check after using the agent.

Experimental study on the preparation and cool storage performance of a phase change micro-capsule cold storage material

In this paper, a cold storage air conditioning system based on a phase change micro-capsule material was constructed. The appropriate micro-encapsulated phase change materials were selected according to the temperature of the generator and evaporator. In addition, phase change materials were encapsulated and mixed with water with good thermal conductivity to form phase change micro-capsule suspensions, which takes into account the latent heat, fluidity and thermal conductivity of the phase change. Three kinds of micro-capsule phase change material suspensions with good stability and mass fractions of 5%, 10% and 15% were prepared. The main thermophysical parameters of the suspensions were obtained by analysis. In addition, the cold storage characteristics of the phase change micro-capsule suspensions in the cold storage tank of the composite system were experimentally studied. The results showed that the best composition ratio of base liquid was 99.1% deionized water, 0.2% SDS, 0.2% xanthan gum, and 0.5% NaCl. At the same cold storage time, compared with the evaporation temperature of −5 °C, when the evaporation temperature was −10 °C, the cooling capacity of the system decreased significantly. The cold storage capacity of phase change cold storage was approximately 1.5 times higher than that of ice cold storage, and the overall performance of phase change cold storage was better than that of ice cold storage. The developed phase change micro-capsule suspension has been considered to have some effect on phase change cold storage.

Encapsulation of bioinsecticide oil in phenol-urea-formaldehyde terpolymer

Novel microcapsules were developed by in situ polymerization of phenol-urea-formaldehyde (PUF) terpolymer and employed for the first time for the encapsulation of neem oil bioinsecticide. Neem oil’s rapid degradation in open environment does not permit its use in crops fields. Therefore, microencapsulation seems to be better method to protect it, make it effective and user-friendly. The prepared PUF microcapsules were analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, optical microscopy and particle size analyzer. The controlled release properties of prepared microcapsules were studied by using loss on drying method and by ultraviolet spectrometry. The release kinetics and stability of prepared microcapsules were studied under different pH and temperature conditions. In conclusion, spherical microcapsules with mean particle size 29.8 μm and good thermal stability have been developed. They could release core more at alkaline pH (26%) than acidic (9%) and neutral (18%). Microcapsules follow first order release kinetics and are operational at or below 45 °C. We propose here further that an environment friendly microcapsule suspension formulation of neem oil is possible for application in agriculture which is not explored yet by using terpolymer.

Evaluation of hydromechanical and functional properties of diversion-type microcapsule-suspension bioreactor for bioartificial liver.

To evaluate the performance of a diversion-type microcapsulesuspension fluidized bed bioreactor and a choanoid fluidized bed bioreactor as bioartificial liver support systems. We evaluated the performance between the modified fluidized bed bioreactor based on diversion-type microcapsule suspension (DMFBB) and choanoid fluidized bed bioreactor (CFBB). The fluidization performance, fluidized height, bed expansion, and the mechanical stability and strength of microcapsule were determined. The viability, synthetic, metabolism, and apoptosis of microcapsulated HepLi5 cells were evaluated. Finally, samples were collected for measurement of alanine aminotransferase, total bilirubin, direct bilirubin, and albumin concentrations. Uniform fluidization was established in both DMFBB and CFBB. The bed expansion, shear force, retention rate, swelling rate, and breakage rate of microcapsules differed significantly between two bioreactors over 3 days. The viability of microencapsulated HepLi5 cells and the activities of cytochrome P450 1A2 and 3A4 increased on each day in DMFBB compared to the control. The albumin and urea concentrations in the DMFBB displayed obvious improvements compared to the control. Caspase3/7 activities in the DMFBB decreased compared to those in the CFBB. At 24 h, the alanine aminotransferase concentration in the DMFBB declined significantly compared to the control. The total and direct bilirubin concentrations within plasma perfusion were decreased and albumin was increased in the DMFBB at 24 h than in the CFBB. The DMFBB shows a promising alternative bioreactor for use in bioartificial liver support systems for application of clinical practice.

Preparation and performance of chlorfenapyr microcapsules with a degradable polylactide-based polyurethane wall material.

To improve the utilization rate of chlorfenapyr and make the wall material of chlorfenapyr microcapsules easily degradable, polylactide diol, toluene diisocyanate and 1,4-butanediol were used to prepare a chlorfenapyr microcapsule suspension by interfacial polymerization. The product was characterized by the methods of optical microscopy, scanning electron microscopy and Fourier-transform infrared spectroscopy. The results indicated that the microcapsule particles were spherical, with an encapsulation efficiency of 84.20%. The diluted product had good wetting and spreading abilities on cabbage leaves. Compared with other commercial formulations, the slow-release effect of the microcapsule suspension was more obvious and the release mechanisms conform to Fickian diffusion, with the release rate controllable by adjusting the external pH conditions. Furthermore, the wall material of the microcapsules showed good degradation performance in a phosphate-buffered solution. Microencapsulation by this method significantly increased the validity period of chlorfenapyr and the wall material was also degraded easily.

Substitution of microalgae with microcapsule diet for two bivalve species, manila clam Ruditapes philippinarum and razor clam Sinonovacula constricta

In this study, a microcapsule diet was produced by spray-drying. Then, the filtration rate (FR) and ingestion rate (IR) of manila clam Ruditapes philippinarum were determined in relation to feeding on the microcapsule and microalgal Chaetoceros muelleri diets. Finally, two feeding experiments were conducted to evaluate the effects of increasing substitution of C. muelleri by the microcapsule on the survival rates, growth performances, biochemical compositions, and specific activities of digestive enzymes of two clams, R. philippinarum and razor clam Sinonovacula constricta. In experiment 1, the replacement of C. muelleri with the microcapsule was evaluated at three substitution levels (0%, 50%, and 100%) with R. philippinarum. In experiment 2, the replacement was evaluated at five substitution levels (0%, 25%, 50%, 75%, and 100%) with S. constricta. Results showed that the FR and IR of R. philippinarum in the microcapsule suspension were (4.07 ± 0.19) mL clam−1 min−1 and (6.36 ± 0.19) × 104 microcapsules clam−1 min−1, respectively. In experiment 1 and 2, no significant difference in survival rate of R. philippinarum or S. constricta was observed between different groups. The partial replacement of C. muelleri (25–50%) by the microcapsule diet did not significantly reduce the growth rates of these clams, while higher replacement (50–100%) did. The high-level microcapsule diet led to higher carbohydrate content when compared with high-level C. muelleri diet. In experiment 1, no significant difference in specific activity of amylase or lipase of R. philippinarum was observed between the 50% and 0% microcapsule groups. Meanwhile, no significant difference in specific activity of protease or lipase of S. constricta was observed between the 50% and 0% microcapsule groups in experiment 2. Our result suggested that the microcapsule was effective as a partial replacement of C. muelleri at up to 25–50% of dry weight of C. muelleri in clams.

Preparation of microcapsule suspension of herbicide oxyfluorfen polyurea and its effects on phytotoxicity on rice crop

Herbicides based formulations are conventionally used as wettable powder or as Emulsifiable concentrate. The Emulsifiable Concentrates (EC) are prepared by mixing the active content with solvents and surfactants. However, these formulations have undesirable phytotoxic effects due to hazardous solvent and are unsafe to operators during application. Thus, capsule suspension (CS) formulation is considered as an alternative to EC formulations. In this study, we report the preparation of CS formulation of herbicide oxyfluorfen by polymerizing Methylene diphenyldiisocyanate (MDI) and Ethylenediamine (EDA). Water suspensions of the oxyfluorfen microcapsules were prepared by adding anionic, nonionic, polymeric surfactants and formulation auxiliaries. The study also aimed to determine the effect of surfactant on the stability of the microcapsule suspension. It was found that the nature of surfactant influenced the properties of the formulation. The synthesized microcapsules were characterized by Scanning electron microscope (SEM), Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The microcapsule suspensions were applied on rice crop to establish the safety and its future use instead of oxyfluorfen EC.

Simple production of cellulose nanofibril microcapsules and the rheology of their suspensions.

Microcapsules are commonly used in applications ranging from therapeutics to personal care products due to their ability to deliver encapsulated species through their porous shells. Here, we demonstrate a simple and scalable approach to fabricate microcapsules with porous shells by interfacial complexation of cellulose nanofibrils and oleylamine, and investigate the rheological properties of suspensions of the resulting microcapsules. The suspensions of neat capsules are viscous liquids whose viscosity increases with volume fraction according to a modified Kreiger-Dougherty relation with a maximum packing fraction of 0.74 and an intrinsic viscosity of 4.1. When polyacrylic acid (PAA) is added to the internal phase of the microcapsules, however, the suspensions become elastic and display yield stresses with power-law dependencies on capsule volume fraction and PAA concentration. The elasticity appears to originate from associative microcapsule interactions induced by PAA that is contained within and incorporated into the microcapsule shell. These results demonstrate that it is possible to tune the rheological properties of microcapsule suspensions by changing only the composition of the internal phase, thereby providing a novel method to tailor complex fluid rheology.

Polylactic Acid-Graphene Oxide-based Materials for Loading and Sustained Release of Poorly Soluble Pesticides.

A pesticide carrier system can offer advantages to active components, such as improving shelf life, extending the lasting period, and reducing toxicity, all of which could reduce the adverse effects of pesticides on the environment. Graphene oxide (GO) is a promising medical drug carrier material, and its research in the field of pesticides is still in the exploration stage. Herein, in order to load water-insoluble pesticides, a series of polylactic acid-graphene oxides (PLA-GOs) were produced incorporating small amounts (0.1-1 wt %) of GO using acetone-chloroform and N,N-dimethylformamide-dichloromethane, two dual-solvent systems. The prepared PLA-GO carrier materials were characterized by FT-IR, Raman spectroscopy, and differential scanning calorimetry analysis, and their effects on rice growth within 20 days were also evaluated. When the amount of GO added was 0.5% and the solvent system was acetone-chloroform, the amount of pyraclostrobin (Pyr) loaded on PLA-GO (A-0.5%) was very high (39.89%). The PLA-GO pesticide microsphere showed a significantly sustained release of Pyr (up to 30 d). Furthermore, the indoor bioassay results showed that the PLA-GO pesticide microsphere (EC50 = 1.2682) had the best fungicidal activity against Rhizoctonia solani, followed by Pyr technical (EC50 = 2.3137) and commercial Pyr microcapsule suspension (EC50 = 3.4570). In conclusion, it was found that PLA-GOs prepared using the acetone-chloroform system were more suitable as a pesticide carrier, which provided a preliminary basis for GO to realize the coating of water-insoluble pesticides.

Effect of ultrasonic frequency and surfactant addition on microcapsule destruction

In a previous study, we found that cavitation bubbles cause the ultrasonic destruction of microcapsules containing oil in a shell made of melamine resin. The cavitation bubbles can be smaller or larger than the resonance size; smaller bubbles cause Rayleigh contraction, whereas larger bubbles are not involved in the sonochemical reaction. The activity in and around the bubble (e.g., shear stress, shock wave, microjet, sonochemical reaction, and sonoluminescence) varies substantially depending on the bubble size. In this study, we investigated the mechanism of the ultrasonic destruction of microcapsules by examining the correlations between frequency and microcapsule destruction rate and between microcapsule size and cavitation bubble size. We evaluated the bubbles using multibubble sonoluminescence and the bubble size was changed by adding a surfactant to the microcapsule suspension. The microcapsule destruction was frequency dependent. The main cause of microcapsule destruction was identified as mechanical resonance, although the relationship between bubble size and microcapsule size suggested that bubbles smaller than or equal to the microcapsule size may also destroy microcapsules by applying shear stress locally.

Pyraclostrobin loaded lignin-modified nanocapsules: Delivery efficiency enhancement in soil improved control efficacy on tomato Fusarium crown and root rot

Fusarium crown and root rot is among the world's major agricultural diseases caused by Fusarium. oxysporum f. sp. radicis-lycopersici, which always resulted in serious damage to vegetable production worldwide. Pyraclostrobin is a broad-spectrum and highly effective fungicide with strong activity against F. oxysporum f. sp. radicis-lycopersici. However, the limited distribution of pyraclostrobin in the soil compromises its field fungicidal performance due to the difficulty in providing a large protection zone surrounding the growing root system of the plant. Nanotechnology offers a great opportunity to develop new strategies for functionalized pesticide loading systems. In this study, the physicochemical properties of pyraclostrobin in the soil were manipulated by encapsulating the active ingredients in a lignin-modified polymer nanocapsule (NCS) to produce a nanoscale delivery system with excellent soil mobility. These nanocapsules exhibited a stable core-shell structure and rapid release performance. In addition, they also increased the distribution of particles on the surface of target organisms and enhanced the soil mobility of pyraclostrobin, mainly benefitting from the nanocapsule's negatively charged polymer shell and nanoscale size. Pot experiments showed that, compared to treatment with nanosized emulsion in water (NEW) and micron-grade microcapsule suspension (CS) of pyraclostrobin, the NCS provided improved control efficacy on tomato crown and root rot. They also showed lower pesticide residue in the soil than CS treatment.