Guanglong Ding

Preparation and characterization of fomesafen ionic liquids for reducing the risk to the aquatic environment

The excessive application of pesticides increases the pollution potential, which leads to groundwater contamination and spreading of toxic substances in the environment by leaching or in runoff. In this study, new herbicide ionic liquids (HILs) based on fomesafen with multifunctions were prepared to improve the herbicidal activity and reduce the risk to the aquatic organisms. The octanol–water partition coefficient (Kow), surface activity, soil adsorption and herbicidal activity of HILs were tested and a comparative analysis with fomesafen was made. The results show that HILs have low water solubility, excellent Kow, low surface tension, and good adsorption ability, and these properties can be regulated and optimized by selecting different counter cations. The physico-chemical properties of HILs were related to the carbon chain length of the cation. Compared with fomesafen sodium, ionic liquids N-1 showed a higher and faster herbicidal activity because of its good lipophilicity and low surface tension. HILs with lower water solubility and greater adsorption capacity in soil have less risk to algae, snail and other aquatic organisms than fomesafen sodium. The HILs will be a candidate in fomesafen applications in the future.

Preparation and Characterization of Novel Functionalized Prochloraz Microcapsules Using Silica–Alginate–Elements as Controlled Release Carrier Materials

Controlled release formulation of pesticides is an effective approach to achieve the desirable purpose of increasing the utilization of pesticides and reducing the environmental residuals. In this work, a novel functionalized microcapsule using silica cross-linked with alginate, and some beneficial elements to crops, was prepared. The microcapsules were structurally characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The results showed that the microcapsules had a high loading efficiency of prochloraz (about 30% w/w) and could effectively protect prochloraz against degradation under UV irradiation and alkaline conditions, showed sustainable release for at least 60 days, and also likely increased disease resistance due to the element on the surface. Given the advantages of the microcapsules, this delivery system may be extended to other photosensitive or pH-sensitive pesticides in the future.

Determination of malondialdehyde in biological fluids by high-performance liquid chromatography using rhodamine B hydrazide as the derivatization reagent

Malondialdehyde (MDA) is a biomarker for lipid peroxidation, and studies of sensitive and selective analytical methods for it are very important for pathological research. The aim of this work was to develop and validate a novel HPLC method for the quantification of MDA in biological fluids using rhodamine B hydrazide (RBH) as the derivatization reagent. After pretreatment and derivatization in acid medium at 50 °C for 40 min, the RBH-derivatized MDA was separated on a Kromasil C18 column at 25 °C and detected by a fluorescence detector at excitation wavelength of 560 nm and emission wavelength of 580 nm. The results showed linearity in the range of 0.8-1500.0 nM with a detection limit of 0.25 nM (S/N = 3). The recovery of MDA from plasma and urine was 91.50 to 99.20%, with a relative standard deviation range of 1.45 to 3.26%. In comparison to other methods reported for the determination of MDA, the proposed method showed superiority in simplicity, more sensitivity, shorter derivatization time, and less interference. The developed method was applied to quantification of MDA in human biological fluids collected from five volunteers with a concentration range of 24.62-245.00 nM.

Preparation and characterization of enzyme-responsive emamectin benzoate microcapsules based on a copolymer matrix of silica–epichlorohydrin–carboxymethylcellulose

Controlled release formulations of pesticides is highly desirable for maximising the utilization of the pesticide, as well as remarkably reducing environmental pollution. A stimuli-responsive controlled release formulation can intelligently respond to the stimuli produced by pests and trigger the release of the active ingredients to control pests effectively. In this work, a novel enzyme-responsive emamectin benzoate microcapsule was prepared using silica cross-linked with carboxymethylcellulose using epichlorohydrin. The results showed that the obtained microcapsules had a remarkable loading ability for emamectin benzoate (about 35% w/w) and could protect emamectin benzoate against photo- and thermal degradation effectively. The silica–epichlorohydrin–carboxymethylcellulose microcapsules displayed excellent cellulase stimuli-responsive properties and a sustained insecticidal efficacy against Myzus persicae. Allium cepa chromosome aberration assays demonstrated that the microcapsules had less genotoxicity than the technical grade emamectin benzoate (referred to throughout the manuscript as the technical). Given these advantages, the enzyme-responsive emamectin benzoate microcapsules are worth extending as a novel safe strategy for sustainable crop protection.

Development and validation of a high-performance liquid chromatography method for determination of ractopamine residue in pork samples by solid phase extraction and pre-column derivatization.

Ractopamine (RAC) has been approved as a feed additive for swine, cattle or turkey, and is likely to have residue in edible animal products and may pose a potential risk for consumer health. Therefore, it is essential to establish a method to detect the residue of RAC in animal products. This work presents a rapid and sensitive HPLC method for the determination of RAC in pork samples with pre-column derivatization. The RAC derivative was separated on a kromasil C18 column and detected at 284nm with a UV detector. The detection capability (CCβ) was 0.078μgg(-1) and the linearity was established over the concentration range of 0.15-100.0μgg(-1). The overall mean recovery in spike range of 0.2μgg(-1) to 100μgg(-1) was 89.9% with the overall mean relative standard deviation of 4.1%. This method can be used for the quantification of RAC in pork samples and help to establish adequate monitoring of the residue of RAC.

Synthesis, characterization, and application of microbe-triggered controlled-release kasugamycin-pectin conjugate.

The controlled and targeted release of pesticides with high water solubility has been a challenge for integrated pest management. In this paper, kasugamycin, an antibiotic broadly used in plant disease control, was covalently conjugated to pectin to form a kasugamycin-pectin conjugate by an amide bond. The conjugate was structurally characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, and thermal gravimetric analysis. The results showed that the conjugate was stable over a wide range of pH and temperatures, as well as under UV irradiation. When incubated with Pseudomonas syringae pv. lachrymans, the conjugate could be activated, releasing the kasugamycin, which made it a promising controlled-release formulation of pesticide.

Developing ionic liquid forms of picloram with reduced negative effects on the aquatic environment

As a widely used herbicide, picloram has been frequently detected in the aquatic environment due to its high leaching potential and low adsorption by soil. To reduce aquatic environmental risk of this herbicide caused by leaching and runoff, five herbicidal ionic liquids (HILs) based on picloram were prepared by pairing isopropylamine, octylamine, octadecylamine, 1-methylimidazole, 4-methylmorpholine respectively. Their physicochemical properties including water solubility, octanol-water partition coefficient, surface activity, leaching, as well as soil adsorption were compared. The results showed that these properties could be adjusted by appropriate selection of counter cations. The HILs with long alkyl chains in cations had low water solubility and leaching characteristics, good surface tension and lipophilicity, as well as high soil adsorption. Compared with currently used picloram in the forms of potassium salts, HIL3 had more excellent herbicidal activity against broadleaf weeds and may offer a lower use dosage. The HILs based on picloram can reduce its negative effects on the aquatic environment and can be used as a desirable alternative to commercial herbicidal formulations of picloram in future.

Ionic liquids based on bromoxynil for reducing adverse impacts on the environment and human health

Many herbicides exhibit some disadvantages such as high water solubility and volatility after application, which lead to potential threats to the aquatic and atmospheric environment and human health. Herbicidal ionic liquids (HILs) can effectively eliminate these intrinsic shortcomings by pairing with appropriate counterions (cation or anion). In this study, new HILs based on bromoxynil with eight typical cations were synthesized to reduce the negative impacts of currently used forms of bromoxynil. All the obtained compounds were investigated for solubility, octanol–water partition coefficient, surface activity, volatilization rate, and herbicidal activity in a greenhouse. The results showed that the HILs with long alkyl chains in the cations had reduced water solubility and volatilization rate, better surface activity and Kow, and substantially improved efficacy against weeds over bromoxynil sodium. Due to their adjustable physicochemical properties and improved herbicidal activity, the HILs could tremendously reduce the adverse impacts of bromoxynil on the environment and human health and may be potential alternatives to currently popular forms of bromoxynil in the future.

Pectin-conjugated silica microcapsules as dual-responsive carriers for increasing the stability and antimicrobial efficacy of kasugamycin

Kasugamycin is an aminoglycoside antibiotic originally isolated from Streptomyces kasugaensis, which has been widely used for the management of plant diseases. However, photo-thermal instability and low efficiency limit its application. Therefore, it is an urgent task to prevent unwanted loss of kasugamycin and ensure maximum bioactivity at target site. In this work, a novel formulation of kasugamycin that responds to different biological stimuli produced by pests was prepared using silica microcapsules crosslinked with pectin via special disulfide bonds. The results demonstrated that the silica-SS-pectin microcapsules had a high loading efficiency (20% w/w) and could effectively enhance the thermal and light stability of kasugamycin. The microcapsules displayed excellent pectinase and glutathione dual-responsive properties and the release kinetics investigated by Riger-Peppas model suggested combination of various release mechanisms. Compared with kasugamycin wettable powder, the microcapsules possessed sustained and improved antimicrobial efficacy against Erwinia carotovora. Thus, the dual-responsive microcapsules potentially have agricultural application as a controlled release system.

Preparation and characterization of indole-3-butyric acid nanospheres for improving its stability and utilization

Indole-3-butyric acid (IBA) is an efficient plant growth regulator for promoting germination and the formation of rooting of various plants. Since it is unstable and presents the low utilization ratio, there is a compelling need to design an environmentally friendly formulation for IBA, which can reduce the loss of degradation and improve its utilization. Nano-sized controlled-release formulations can provide better durability and penetrate through the plant epidermis to efficiently deliver the agrochemicals to the target tissues. In this work, a kind of novel nano controlled-release formulation was prepared by conjugating the IBA and 3-glycidoxypropyltrimethoxysilane (GPTMS) through a covalent cross-linking reaction, and subsequently hydrolyzation and polycondensation with tetraethoxysilane. The resulting nanospheres were characterized by Fourier transform infrared spectroscopy, ultraviolet spectrophotometry, scanning electron microscope, and thermal gravity analysis. The results showed that the obtained nanospheres had a remarkable loading efficiency of IBA (about 43% w/w). The formation of covalent between IBA and GPTMS enabled the nanospheres with a good chemical stability that could protect against photo-degradation effectively. The released rate of the IBA from nanospheres was related to the temperature, pH value. With increased temperature as well as acidity and alkality, the release of the IBA was sped up. The IBA could also be released effectively from IBA-silica nanospheres by esterase, and the sustainable release characteristics of IBA-silica nanospheres were in conformity with the Ritger and Peppas equation. The IBA-silica nanospheres displayed excellent dual stimuli-responsive properties under esterase and weak acid conditions, and could obviously promote the growth of root and bud of pea. Thus, the IBA silica nanospheres prepared by covalent cross-linking reaction have a good potential application as a controlled-release formulation and environmentally-friendly plant growth regulator.