Silver nanoparticles(Ag NPs)are an effective antibacterial agent,but their application in food packaging is limited due to their easy agglomeration and oxidation.In this study,antibacterial microcapsules were fabricat...Silver nanoparticles(Ag NPs)are an effective antibacterial agent,but their application in food packaging is limited due to their easy agglomeration and oxidation.In this study,antibacterial microcapsules were fabricated using Ginkgo biloba essential oil(GBEO)as core material and chitosan and type B gelatin biopolymer as capsule mate-rials.These antibacterial microcapsules were then modified with green-synthesized Ag NPs,blended into the bio-polymer polylactic acid(PLA),and finally formed as films.Physicochemical properties and antibacterial activity against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were evaluated.Results showed that the prepared antibacterial PLA films exhibited excellent antibacterial activity against foodborne pathogens.Its TVC exceeded the limit value of 7 log CFU/g at 7 days compared with the 5 days of pure PLA films.Therefore,these films can extend the shelf life of grass carp fillets by 2–3 days under refrigeration.展开更多
In this study, lambda-cyhalothrin(LC) loaded polyurea microcapsules(MCs) with different particle sizes were fabricated.All of the MCs showed varying degrees of physical collapse, which was more obvious among those wit...In this study, lambda-cyhalothrin(LC) loaded polyurea microcapsules(MCs) with different particle sizes were fabricated.All of the MCs showed varying degrees of physical collapse, which was more obvious among those with smaller particle sizes. MCs with particle sizes of 1.38 μm(MC-S), 5.13 μm(MC-M) and 10.05 μm(MC-L) had shell thicknesses of 39.6,50.3 and 150.1 nm, respectively. MCs with smaller particles tended to have significantly faster release profiles, and the MC-S group had much higher bioactivity against Agrotis ipsilon and better foliar affinity on the peanut leaves(indicated by rainfastness) than MC-M and MC-L. All of the MCs exhibited light-enhanced release profiles and had much slower degradation compared with the emulsifiable concentrate(EC) group, among which MC-L had the slowest degradation.To generate MCs with both favorable quick efficacy and long-lasting efficacy, binary mixtures of MC-S, MC-M and MC-L were produced by mixing them in pairs at ratios of 2:1, 1:1 and 1:2. The mixture of MC-S:MC-L at 1:2 showed the best comprehensive efficacy in the peanut foliar spray scenario among the nine tested combinations, and its effective duration was three times longer than that of EC. Overall, the precise combination of MCs with different particle sizes can regulate the efficacy of pesticide control and serve as a strategy for the better utilization of pesticides.展开更多
Immobilization biocatalysis is a potential technology to improve the activity and stability of biocatalysts in nonaqueous systems for efficient industrial production.Alginate-chitosan(AC)microcapsules were prepared as...Immobilization biocatalysis is a potential technology to improve the activity and stability of biocatalysts in nonaqueous systems for efficient industrial production.Alginate-chitosan(AC)microcapsules were prepared as immobilization carriers by emulsifi cation-internal gelation and complexation reaction,and their contribution on facilitating the growth and metabolism of yeast cells were testifi ed successfully in culture medium-solvent biphasic systems.The cell growth in AC microcapsules is superior to that in alginate beads,and the cells in both immobilization carriers maintain much higher activity than free cells,which demonstrates AC microcapsules can confer yeast cells the ability to resist the adverse effect of solvent.Moreover,the performance of AC microcapsules in biphasic systems could be improved by adjusting the formation of outer polyelectrolyte complex(PEC)membrane to promote the cell growth and metabolic ability under the balance of resisting solvent toxicity and permitting substrate diffusion.Therefore,these findings are quite valuable for applying AC microcapsules as novel immobilization carriers to realize the biotransformation of value-added products in aqueous-solvent biphasic systems.展开更多
The self-healing microcapsules can be buried in the coating to improve the anticorrosive ability.In this paper,self-healing microcapsules of polyurea(PU)/melamine resin(MF)double shell were prepared by in-situ polymer...The self-healing microcapsules can be buried in the coating to improve the anticorrosive ability.In this paper,self-healing microcapsules of polyurea(PU)/melamine resin(MF)double shell were prepared by in-situ polymerization and interfacial polymerization with isocyanate as the core material.Scanning electron microscope was used to observe the microcapsule morphology.The structures of microcapsules prepared with different chain extenders were characterized by Fourier transform infrared spectroscopy.The micromanipulation system was used to loading–holding,loading–unloading and loading to rupture individual microcapsules,so as to explore the mechanical properties of microcapsules.The Young’s modulus corresponding to microcapsules was calculated by mathematical model fitting.The self-healing properties of microcapsule coating were characterized by optical microscope.The experimental results showed that the microcapsule shell prepared under optimized conditions had a complete morphology and good mechanical properties.The microcapsule was in the elastic deformation stage under small deformation,and the plastic deformation stage under large deformation.The Young’s modulus range of microcapsules was 9.29–14.51 MPa,and the corresponding Young’s modulus could be prepared by adjusting the process.The surface crack of the coating containing microcapsule could heal itself after48 h in a humid environment.展开更多
Environmental cleaning is an important aspect of bacteria control.Ethyl cellulose microcapsules containing potassium monopersulfate(PMCM)were prepared by emulsified solvent diffusion method.The chemical structure and ...Environmental cleaning is an important aspect of bacteria control.Ethyl cellulose microcapsules containing potassium monopersulfate(PMCM)were prepared by emulsified solvent diffusion method.The chemical structure and microstructure of the obtained PMCM was characterized by methods of Fourier transform infrared spectroscopy(FT-IR),optical microscopy,scanning electron microscopy and X-ACT energy dispersive X-ray spectroscopy.The SEM micrographs of the PMCM containing 21.6%of C,46.8%of O,10.7%of S and 19.4%of K was relatively smooth.Thermal stability,sustained release performance,and antimicrobial activity of PMCM were investigated.The results showed that the drug loading and encapsulation efficiency of PMCM were 30.3%and 42.6%respectively.Potassium monopersulfate was fully released after 8 h,following a Fickian diffusion mechanism.Results showed that the microcapsules prepared with a high concentration of potassium monopersulfate solution showed a good antimicrobial effect.The microcapsule wall of the resulting PMCM increased with increasing ethyl cellulose content and had high thermal stability from the data of 69%residue rate.The excellent thermal stability and high sustained release performance of PMCM showed high application value.展开更多
Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tigh...Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tight crosslinking of microcapsules wall.Microcapsules of neroline were characterized for their chemical composition and structure of the polyurethane shell by FTIR spectroscopy,thermogravimetric analysis,optical and electron microscopy,light scattering and electrophoresis measurements.Core content and encapsulation yield were 15%and 60%,respectively.Spherical microcapsules of mean diameter 29μm were slightly cationic with an isoelectric point of 6.3.Neroline-loaded microcapsules were fixed on cotton fabric using an impregnation technique.The functionalized fabric showed improved resistance to washing cycles in comparison with previously reported diol-based microcapsules.Such microcapsules display great potential for the long-lasting release of fragrance in the framework of cosmetotextile.展开更多
The aim of this study was to characterize tinctures and microcapsules loaded with an ethanol extract of red propolis through chemical, physicochemical and microbiological assays in order to establish quality control t...The aim of this study was to characterize tinctures and microcapsules loaded with an ethanol extract of red propolis through chemical, physicochemical and microbiological assays in order to establish quality control tools for nutraceutical preparations of red propolis. The markers(isoflavonoids, chalcones, pterocarpans,flavones, phenolic acids, terpenes and guttiferones) present in the tinctures A and B were identified and confirmed using LC/ESI/FTMS/Orbitrap. Four compositions(A, B, C and D) were prepared to contain B tincture of the red propolis with some pharmaceutical excipients and submitted to two drying processes, i. e.spray-drying and freeze-drying to obtain microcapsules loaded with the red propolis extract. The tinctures and microcapsules of the red propolis were submitted to the total flavonoid content and antioxidant activity tests.The antibacterial activity and minimum inhibitory concentration(MIC) were tested using Staphylococcus aureus ATCC 25293 and Pseudomonas aeruginosa ATCC 27853 strains. The tinctures and microcapsules presented high flavonoid quantities from 20.50 to 40.79 mg/100 mg of the microcapsules. The antioxidant activity and IC50 were determined for the tinctures A and B(IC50: 6.95 μg/m L and 7.48 μg/m L), the spray-dried microcapsules(IC50: 8.89–15.63 μg/m L) and the freeze-dried microcapsules(IC50: 11.83–23.36 μg/m L). The tinctures and microcapsules were proved to be bioactive against gram-positive and gram-negative bacteria with inhibition halos superior to 10 mm at concentration of 200 μg/m L and MIC values of 135.87–271.74 μg/m L using gram-positive strain and 271.74–543.48 μg/m L using gram-negative strain. The tinctures and microcapsules of the red propolis have a potential application for nutraceutical products.展开更多
Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The ...Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption(DVS),with the results fitted to three kinds of adsorption kinetics models.In addition,the specific surface area(SSA)was also calculated based on BET theory;and the thermal performance was investigated by laser flash analysis(LFA).Experimental results show a change of 103%in mass of the microcapsule sample under 90%relative humidity(RH)at 30℃after water vapor sorption.The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism,followed by the pseudo-first-order adsorption process.In comparison with most conventional pavement materials,it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower.The unique properties of the formulated SiO_(2)-LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.展开更多
Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix ma...Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.展开更多
We have tried to prepare the microcapsules containing water droplets stabilized with solid powder by utilizing the (W/O)/W emulsion. The water droplets as core material were stabilized in the monomer droplets with tit...We have tried to prepare the microcapsules containing water droplets stabilized with solid powder by utilizing the (W/O)/W emulsion. The water droplets as core material were stabilized in the monomer droplets with titanium dioxide (TiO2) as a particulate surfactant. Before adding the TiO2 powder into the monomer phase, the powder was modified with triethoxyvinylsilane to adjust the degree of hydrophobicity and to promote adhesion on the interface between the inner water phase and the monomer phase in the (W/O) emulsion. It was investigated how the degree of hydrophobicity of the TiO2 powder affected the stability of water droplets in the (W/O) emulsion and the (W/O) droplets in the (W/O)/W emulsion. Moreover, the microcapsule diameters were measured before and after the expansion operation where the water droplets microencapsulated were applied as a blowing agent. The expansion ratio was increased with increase in the stability of the water droplets and the amount of water microencapsulated.展开更多
It was tried to microencapsulate erythritol as a phase change material with the interfacial polycondensation reaction method by using the (W/O) emulsion and to characterize the microcapsules prepared. In the experimen...It was tried to microencapsulate erythritol as a phase change material with the interfacial polycondensation reaction method by using the (W/O) emulsion and to characterize the microcapsules prepared. In the experiment, toluene diisocyanate, diphenyl methane diisocyanate and hexamethylenediisocyanate were used to form the polyurethane shell and the effects of them on the heat storage density and the microencapsulation efficiency were investigated. Furthermore, the effect of supercooling prevention agent on the phase change behavior of erythritol was investigated. The microcapsules prepared with toluendiisocyanate monomer showed the highest heat storage density and the higher microencapsulation efficiency. Considerable supercooling phenomenon in the microcapsule was observed and prevented to a certain degree by addition of potassium dihydrogen phosphate and calcium sulfate as the supercooling prevention agent.展开更多
It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water solubl...It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water soluble solid powder, sodium hydrogen carbonate was adopted in order to generate carbon dioxide gas and as a thermosensitive shell material, olefin resin with the melting point of ca. 40°C was used. In the experiment, the concentration of olefin resin in the shell material solution was mainly changed together with the concentrations of the oil soluble surfactant species and the α-tocopherol as a modifier of shell. Addition of α-tocopherol into the shell material solution could prevent the core from breaking away during the microencapsulation process and result in the higher microencapsulation efficiency, because the dispersion stability of solid powder in the shell material solution could be increased due to the increase in affinity between the shell material solution and solid powder. Also, the microencapsulation efficiency increased with the concentration of olefin resin, became maximum at 50 wt% and then, decreased. The microcapsules were found to begin melting at 36°C and to generate carbon dioxide gas.展开更多
Poly(urea-formaldehyde)(PUF)microcapsules were prepared by in-situ polymerization with four different pro-cesses in this paper.The chemical composition,surface morphology,particle size distribution,and thermal sta-bil...Poly(urea-formaldehyde)(PUF)microcapsules were prepared by in-situ polymerization with four different pro-cesses in this paper.The chemical composition,surface morphology,particle size distribution,and thermal sta-bility were characterized by FTIR,SEM,particle size analyzer,and TGA,respectively.The results demonstrated that the agglomeration of the PUF microcapsules was related to the agglomeration of the emulsion particles caused by the changes of emulsion interface during the shell polymerization.Due to the slow deposition of the shell material,the PUF microcapsules with the core-shell structure prepared by the process with ammonium chloride as the last additive showed good dispersibility with an average diameter of 6.36μm,high core content of 71.3 wt%,and high yield of 61.3 wt%.The PUF microcapsules had good thermal stability below 216?C.The PUF microcapsules could be uniformly dispersed in the epoxy coating in a single form.The epoxy coating with 2 wt%PUF microcapsules showed good self-healing property,and the service life of the coating was about doubled.展开更多
Microcapsules consisting of human serum albumin, magnetite and a prototype drug (5-fluroouracil) are obtained from emulsion by heat-stabilization. The most probable diametre of the magnet-sensitive microcapsules is 0....Microcapsules consisting of human serum albumin, magnetite and a prototype drug (5-fluroouracil) are obtained from emulsion by heat-stabilization. The most probable diametre of the magnet-sensitive microcapsules is 0.15 pm. The microcapsules satisfy the requirement of the magnetic carrier of drugs for the use of injection from the view points of size and shape. Flowing in an aqueous suspension, the microcapsules can be retained easily by the control of a magnetic field. The drug can be released gradually from the microcapsules when they are in physiological saline. The microcapsules prepared at the stabilization temperature of 200C have the least variable of permeation property. A structure model of the microcapsules has been proposed.展开更多
In the present study,microcapsules with disperse dye solutions and a direct dye solution ascore materials were prepared by the complex coaeervation method and the interfacialpolycondensation method respectively.Experi...In the present study,microcapsules with disperse dye solutions and a direct dye solution ascore materials were prepared by the complex coaeervation method and the interfacialpolycondensation method respectively.Experiments and theoretical analysis showed that there wasan exponential relationship between the diffusion time and the release rate of the core material intothe surrounding medium.A concise equation to calculate the permeability constant was derivedand verified by the experimental results.By means of duplex focus on the inner and outer diametersof a microcapsule,the average wall thickness of microcapsules was measured.展开更多
A novel biodegradable and biocompatible multilayer hollow microcapsules,modified by folate-conjugated polyethyleneimine(PEI),as targeted and sustained release carriers of doxorubicin(DOX),were successfully synthesized...A novel biodegradable and biocompatible multilayer hollow microcapsules,modified by folate-conjugated polyethyleneimine(PEI),as targeted and sustained release carriers of doxorubicin(DOX),were successfully synthesized using the sequential layer-by-layer electrostatic assembly technique from the sacrificial microtemplates(CaCOj/CMC,spherical,1.7 μm) with chitosan(CS) and sodium carboxymethyl cellulose(CMC) as the polycation and polyanion polyelectrolyte.Scanning electron microscope(SEM) observation showed that the diameter of the seven assembly multilayer microparticles was about 2.0 μm with relatively regular sphere.After the microparticle cores was removed by complexation with ethylene diamine tetraacetic acid(EDTA) for calcium ions,the range of 200- 300 nm wall thickness of microcapsules was built,and it made the forming microcapsules to be stable.Thermogravimetric analysis confirms the deposition and modification total amount of polymer on the microtemplates is about33.5%.The assembly microparticles were modified by introducing PEI,and the grafting rate of folate could reach 20.0%.It was 4times that of traditional method.The high grafting rate helped to improve targeting action of microcapsules.The deposition of DOX was prominent and the encapsulation efficiency was 96.9%,and the plateaued release of loaded drug reached 78%in pH 7.4 buffer solution,and then in pH 5.7 showed significantly a slow release.展开更多
Traditional preparation of magnetic microcapsules involves cumbersome processes and often results in irregular-shaped products. Due to the stable laminar flow of reaction solution and the moderate reaction conditions,...Traditional preparation of magnetic microcapsules involves cumbersome processes and often results in irregular-shaped products. Due to the stable laminar flow of reaction solution and the moderate reaction conditions, the T-shaped microchannel (T-MC) reactor is supposed to yield microcapsules with regular shape. In this paper, magnetic particles of ferroferric oxide modified by oleic acid (OA-Fe3O4) and dispersed in tetrachloroethylene were used as core material. Polymethyl methacrylate (PMMA) was used as shell material. Magnetic microcapsules were prepared by using a T-MC reactor. Factors that influenced the encapsulated reaction were investigated in details, which included the velocity ratio of aqueous phase to oil phase, the length and the inner diameter of the microchannel. The morphology, composition, and magnetic responsiveness of the magnetic microcapsules were analyzed and characterized by SEM, FTIR, XRD, TGA, and vibrating sample magnetometer (VSM). The results confirmed that magnetic microcapsules prepared by T-MC reactor were regular in shape.展开更多
Phase change material microcapsules (MicroPCMs) with nano composite structures (NC-MicroPCMs) were fabricated to meet higher demand of thermal stability and hold core better. Degree of crystallinity (DOC) of the NC-Mi...Phase change material microcapsules (MicroPCMs) with nano composite structures (NC-MicroPCMs) were fabricated to meet higher demand of thermal stability and hold core better. Degree of crystallinity (DOC) of the NC-MicroPCMs was evaluated by the differential scanning calorimeter (DSC). The effectiveness of some processing variables, in terms of formaldehyde and melamine molar ratio F/M, weight ratio of core and shell material C/S, and the dosage of silver nano particles D(%), were analyzed statistically. It was found that: (1) DOC was dependent on these processing variables; (2) doping silver nano particles was beneficial to the formation of shell crystallite structure; and (3) higher F/M was helpful in getting a higher DOC for both NC-MicroPCMs and MicroPCMs. Also, DOC was found to be associated with thermal stability and the two features were confirmed, which showed a closely positive correlation.展开更多
The aim of this work was to develop a functional biodegradable nonwoven with antimicrobial microcapsules maintaining the stability and biodegradability of the nonwoven for use in agriculture applications. The nonwoven...The aim of this work was to develop a functional biodegradable nonwoven with antimicrobial microcapsules maintaining the stability and biodegradability of the nonwoven for use in agriculture applications. The nonwoven was obtained using hemp fibers by Wetlaid technology. Microcapsules were prepared by co-extrusion/gelling method with alginate as shell and oregano oil as core material. The microcapsules were developed to protect and control release of oregano oil. Microcapsules were incorporated on the nonwoven by coating method using a natural polymer as a graft material. After incorporating micro-capsules, the nonwoven was subjected to several tests in order to determinate the microcapsules fixation and their functionality. The nonwovens were characterized for their antimicrobial activity against different kinds of bacteria and fungi. Nonwoven loaded with microcapsules was found to show good antimicrobial activity in comparison with nonwoven that was not loaded with microcapsules.展开更多
It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to o...It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to obtain the higher content. As the shell material of the first microcapsules prepared by the spray drying method, palmitic acid with the melting point of 60°C was adopted in order to prevent grape polyphenol from dissolution into water. As the shell material of the second microcapsules prepared by the layer-by-layer method, chitosan was used to coat the first microcapsules and to give the microcapsules alcohol resistance. In the experiment, the spray drying conditions such as the inlet temperature and the spraying pressure, the oil soluble surfactant species and the chitosan concentration were changed. The mean diameters of microcapsules could be controlled in the range from 5 μm to 35 μm by changing the spraying pressure and the inlet temperature. The yield of microcapsules and the microencapsulation efficiency over 50% could be obtained under the conditions of P = 1.0 kgf/cm2 and Tin = 100°C. Furthermore, the microencapsulation efficiency could be increased by adding the oil soluble surfactant with the larger HLB value. Coating with chitosan could considerably increase alcohol resistance.展开更多
基金supported by the National Key R&D Program of China(Grant No.2020YFD0900905).
文摘Silver nanoparticles(Ag NPs)are an effective antibacterial agent,but their application in food packaging is limited due to their easy agglomeration and oxidation.In this study,antibacterial microcapsules were fabricated using Ginkgo biloba essential oil(GBEO)as core material and chitosan and type B gelatin biopolymer as capsule mate-rials.These antibacterial microcapsules were then modified with green-synthesized Ag NPs,blended into the bio-polymer polylactic acid(PLA),and finally formed as films.Physicochemical properties and antibacterial activity against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were evaluated.Results showed that the prepared antibacterial PLA films exhibited excellent antibacterial activity against foodborne pathogens.Its TVC exceeded the limit value of 7 log CFU/g at 7 days compared with the 5 days of pure PLA films.Therefore,these films can extend the shelf life of grass carp fillets by 2–3 days under refrigeration.
基金funded by grants from the Modern Agricultural Industry Technology System for Vegetables in Shandong Province, China (SDAIT-05)the National Natural Science Foundation of China (32001953)。
文摘In this study, lambda-cyhalothrin(LC) loaded polyurea microcapsules(MCs) with different particle sizes were fabricated.All of the MCs showed varying degrees of physical collapse, which was more obvious among those with smaller particle sizes. MCs with particle sizes of 1.38 μm(MC-S), 5.13 μm(MC-M) and 10.05 μm(MC-L) had shell thicknesses of 39.6,50.3 and 150.1 nm, respectively. MCs with smaller particles tended to have significantly faster release profiles, and the MC-S group had much higher bioactivity against Agrotis ipsilon and better foliar affinity on the peanut leaves(indicated by rainfastness) than MC-M and MC-L. All of the MCs exhibited light-enhanced release profiles and had much slower degradation compared with the emulsifiable concentrate(EC) group, among which MC-L had the slowest degradation.To generate MCs with both favorable quick efficacy and long-lasting efficacy, binary mixtures of MC-S, MC-M and MC-L were produced by mixing them in pairs at ratios of 2:1, 1:1 and 1:2. The mixture of MC-S:MC-L at 1:2 showed the best comprehensive efficacy in the peanut foliar spray scenario among the nine tested combinations, and its effective duration was three times longer than that of EC. Overall, the precise combination of MCs with different particle sizes can regulate the efficacy of pesticide control and serve as a strategy for the better utilization of pesticides.
基金Supported by the National Natural Science Foundation of China(No.21276033)the Open Foundation of the State Key Laboratory of Bioactive Seaweed Substances(Nos.SKL-BASS1707,SKL-BASS1711)the Liaoning Provincial BaiQianWan Talents Program(No.2017-6)
文摘Immobilization biocatalysis is a potential technology to improve the activity and stability of biocatalysts in nonaqueous systems for efficient industrial production.Alginate-chitosan(AC)microcapsules were prepared as immobilization carriers by emulsifi cation-internal gelation and complexation reaction,and their contribution on facilitating the growth and metabolism of yeast cells were testifi ed successfully in culture medium-solvent biphasic systems.The cell growth in AC microcapsules is superior to that in alginate beads,and the cells in both immobilization carriers maintain much higher activity than free cells,which demonstrates AC microcapsules can confer yeast cells the ability to resist the adverse effect of solvent.Moreover,the performance of AC microcapsules in biphasic systems could be improved by adjusting the formation of outer polyelectrolyte complex(PEC)membrane to promote the cell growth and metabolic ability under the balance of resisting solvent toxicity and permitting substrate diffusion.Therefore,these findings are quite valuable for applying AC microcapsules as novel immobilization carriers to realize the biotransformation of value-added products in aqueous-solvent biphasic systems.
基金Supported by State Key Laboratory of Advanced Power Transmission Technology(GEIRI-SKL-2018-005)Guangzhou Major Industrial Technology Research Plan(201802010022)Guangzhou Science and Technology Project(201710010186)。
文摘The self-healing microcapsules can be buried in the coating to improve the anticorrosive ability.In this paper,self-healing microcapsules of polyurea(PU)/melamine resin(MF)double shell were prepared by in-situ polymerization and interfacial polymerization with isocyanate as the core material.Scanning electron microscope was used to observe the microcapsule morphology.The structures of microcapsules prepared with different chain extenders were characterized by Fourier transform infrared spectroscopy.The micromanipulation system was used to loading–holding,loading–unloading and loading to rupture individual microcapsules,so as to explore the mechanical properties of microcapsules.The Young’s modulus corresponding to microcapsules was calculated by mathematical model fitting.The self-healing properties of microcapsule coating were characterized by optical microscope.The experimental results showed that the microcapsule shell prepared under optimized conditions had a complete morphology and good mechanical properties.The microcapsule was in the elastic deformation stage under small deformation,and the plastic deformation stage under large deformation.The Young’s modulus range of microcapsules was 9.29–14.51 MPa,and the corresponding Young’s modulus could be prepared by adjusting the process.The surface crack of the coating containing microcapsule could heal itself after48 h in a humid environment.
基金support From the Open Fund Project of Key Lab.of Biomass Energy and Material,Jiangsu Province(JSBEM201907)the Ordinary University Young Innovative Talents Project of Guangdong Province(2018KQNCX119).
文摘Environmental cleaning is an important aspect of bacteria control.Ethyl cellulose microcapsules containing potassium monopersulfate(PMCM)were prepared by emulsified solvent diffusion method.The chemical structure and microstructure of the obtained PMCM was characterized by methods of Fourier transform infrared spectroscopy(FT-IR),optical microscopy,scanning electron microscopy and X-ACT energy dispersive X-ray spectroscopy.The SEM micrographs of the PMCM containing 21.6%of C,46.8%of O,10.7%of S and 19.4%of K was relatively smooth.Thermal stability,sustained release performance,and antimicrobial activity of PMCM were investigated.The results showed that the drug loading and encapsulation efficiency of PMCM were 30.3%and 42.6%respectively.Potassium monopersulfate was fully released after 8 h,following a Fickian diffusion mechanism.Results showed that the microcapsules prepared with a high concentration of potassium monopersulfate solution showed a good antimicrobial effect.The microcapsule wall of the resulting PMCM increased with increasing ethyl cellulose content and had high thermal stability from the data of 69%residue rate.The excellent thermal stability and high sustained release performance of PMCM showed high application value.
基金by the“Ministry of Higher Education and Scientific Research”of Tunisia,Laboratory of Advanced Materials and Interfaces(LAMI,LR-11-S-55)。
文摘Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tight crosslinking of microcapsules wall.Microcapsules of neroline were characterized for their chemical composition and structure of the polyurethane shell by FTIR spectroscopy,thermogravimetric analysis,optical and electron microscopy,light scattering and electrophoresis measurements.Core content and encapsulation yield were 15%and 60%,respectively.Spherical microcapsules of mean diameter 29μm were slightly cationic with an isoelectric point of 6.3.Neroline-loaded microcapsules were fixed on cotton fabric using an impregnation technique.The functionalized fabric showed improved resistance to washing cycles in comparison with previously reported diol-based microcapsules.Such microcapsules display great potential for the long-lasting release of fragrance in the framework of cosmetotextile.
基金The authors would like to acknowledge CNPq(The Brazilian National Council for Scientific and Technological Development),CAPES(The Brazilian Coordination for the Personal Improvement of Superior Education)and FAPEAL(Foundation for Sponsoring Research in the State of Alagoas)for the scholarships of the Master's course in Nutrition(PPGNUT)and CNPq and FINEP(The Brazilian Financer for Studies and Projects)for financial support(Grant number 478390/2010-6)according to the financial aid to the researchers 14/2010-Universal/MCT/CNPq and 14/2014-Universal/MCT/CNPq.The authors would also like to thank the Microbiological Quality Control Laboratory for Food analysis of the Nutrition College of the Federal University of Alagoas and to the Beekeepers:JoséMarinho de Lima(in memorian)and JoséIzaias Zacarias dos Santos for their support in collecting raw material and for the red propolis donations.
文摘The aim of this study was to characterize tinctures and microcapsules loaded with an ethanol extract of red propolis through chemical, physicochemical and microbiological assays in order to establish quality control tools for nutraceutical preparations of red propolis. The markers(isoflavonoids, chalcones, pterocarpans,flavones, phenolic acids, terpenes and guttiferones) present in the tinctures A and B were identified and confirmed using LC/ESI/FTMS/Orbitrap. Four compositions(A, B, C and D) were prepared to contain B tincture of the red propolis with some pharmaceutical excipients and submitted to two drying processes, i. e.spray-drying and freeze-drying to obtain microcapsules loaded with the red propolis extract. The tinctures and microcapsules of the red propolis were submitted to the total flavonoid content and antioxidant activity tests.The antibacterial activity and minimum inhibitory concentration(MIC) were tested using Staphylococcus aureus ATCC 25293 and Pseudomonas aeruginosa ATCC 27853 strains. The tinctures and microcapsules presented high flavonoid quantities from 20.50 to 40.79 mg/100 mg of the microcapsules. The antioxidant activity and IC50 were determined for the tinctures A and B(IC50: 6.95 μg/m L and 7.48 μg/m L), the spray-dried microcapsules(IC50: 8.89–15.63 μg/m L) and the freeze-dried microcapsules(IC50: 11.83–23.36 μg/m L). The tinctures and microcapsules were proved to be bioactive against gram-positive and gram-negative bacteria with inhibition halos superior to 10 mm at concentration of 200 μg/m L and MIC values of 135.87–271.74 μg/m L using gram-positive strain and 271.74–543.48 μg/m L using gram-negative strain. The tinctures and microcapsules of the red propolis have a potential application for nutraceutical products.
基金financial support of The National Scholarship Foundation of China,China Scholarship Council([2018]3101)。
文摘Novel SiO_(2)-LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope(SEM),particle size analysis,and Fourier transform infrared spectroscopy(FT-IR).The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption(DVS),with the results fitted to three kinds of adsorption kinetics models.In addition,the specific surface area(SSA)was also calculated based on BET theory;and the thermal performance was investigated by laser flash analysis(LFA).Experimental results show a change of 103%in mass of the microcapsule sample under 90%relative humidity(RH)at 30℃after water vapor sorption.The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism,followed by the pseudo-first-order adsorption process.In comparison with most conventional pavement materials,it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower.The unique properties of the formulated SiO_(2)-LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.
文摘Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.
文摘We have tried to prepare the microcapsules containing water droplets stabilized with solid powder by utilizing the (W/O)/W emulsion. The water droplets as core material were stabilized in the monomer droplets with titanium dioxide (TiO2) as a particulate surfactant. Before adding the TiO2 powder into the monomer phase, the powder was modified with triethoxyvinylsilane to adjust the degree of hydrophobicity and to promote adhesion on the interface between the inner water phase and the monomer phase in the (W/O) emulsion. It was investigated how the degree of hydrophobicity of the TiO2 powder affected the stability of water droplets in the (W/O) emulsion and the (W/O) droplets in the (W/O)/W emulsion. Moreover, the microcapsule diameters were measured before and after the expansion operation where the water droplets microencapsulated were applied as a blowing agent. The expansion ratio was increased with increase in the stability of the water droplets and the amount of water microencapsulated.
文摘It was tried to microencapsulate erythritol as a phase change material with the interfacial polycondensation reaction method by using the (W/O) emulsion and to characterize the microcapsules prepared. In the experiment, toluene diisocyanate, diphenyl methane diisocyanate and hexamethylenediisocyanate were used to form the polyurethane shell and the effects of them on the heat storage density and the microencapsulation efficiency were investigated. Furthermore, the effect of supercooling prevention agent on the phase change behavior of erythritol was investigated. The microcapsules prepared with toluendiisocyanate monomer showed the highest heat storage density and the higher microencapsulation efficiency. Considerable supercooling phenomenon in the microcapsule was observed and prevented to a certain degree by addition of potassium dihydrogen phosphate and calcium sulfate as the supercooling prevention agent.
文摘It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water soluble solid powder, sodium hydrogen carbonate was adopted in order to generate carbon dioxide gas and as a thermosensitive shell material, olefin resin with the melting point of ca. 40°C was used. In the experiment, the concentration of olefin resin in the shell material solution was mainly changed together with the concentrations of the oil soluble surfactant species and the α-tocopherol as a modifier of shell. Addition of α-tocopherol into the shell material solution could prevent the core from breaking away during the microencapsulation process and result in the higher microencapsulation efficiency, because the dispersion stability of solid powder in the shell material solution could be increased due to the increase in affinity between the shell material solution and solid powder. Also, the microencapsulation efficiency increased with the concentration of olefin resin, became maximum at 50 wt% and then, decreased. The microcapsules were found to begin melting at 36°C and to generate carbon dioxide gas.
基金This work was supported by the Jiangsu National Synergetic Innovation Center for Advanced Materials and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Poly(urea-formaldehyde)(PUF)microcapsules were prepared by in-situ polymerization with four different pro-cesses in this paper.The chemical composition,surface morphology,particle size distribution,and thermal sta-bility were characterized by FTIR,SEM,particle size analyzer,and TGA,respectively.The results demonstrated that the agglomeration of the PUF microcapsules was related to the agglomeration of the emulsion particles caused by the changes of emulsion interface during the shell polymerization.Due to the slow deposition of the shell material,the PUF microcapsules with the core-shell structure prepared by the process with ammonium chloride as the last additive showed good dispersibility with an average diameter of 6.36μm,high core content of 71.3 wt%,and high yield of 61.3 wt%.The PUF microcapsules had good thermal stability below 216?C.The PUF microcapsules could be uniformly dispersed in the epoxy coating in a single form.The epoxy coating with 2 wt%PUF microcapsules showed good self-healing property,and the service life of the coating was about doubled.
文摘Microcapsules consisting of human serum albumin, magnetite and a prototype drug (5-fluroouracil) are obtained from emulsion by heat-stabilization. The most probable diametre of the magnet-sensitive microcapsules is 0.15 pm. The microcapsules satisfy the requirement of the magnetic carrier of drugs for the use of injection from the view points of size and shape. Flowing in an aqueous suspension, the microcapsules can be retained easily by the control of a magnetic field. The drug can be released gradually from the microcapsules when they are in physiological saline. The microcapsules prepared at the stabilization temperature of 200C have the least variable of permeation property. A structure model of the microcapsules has been proposed.
文摘In the present study,microcapsules with disperse dye solutions and a direct dye solution ascore materials were prepared by the complex coaeervation method and the interfacialpolycondensation method respectively.Experiments and theoretical analysis showed that there wasan exponential relationship between the diffusion time and the release rate of the core material intothe surrounding medium.A concise equation to calculate the permeability constant was derivedand verified by the experimental results.By means of duplex focus on the inner and outer diametersof a microcapsule,the average wall thickness of microcapsules was measured.
基金National Natural Science Foundation of China(No.21472126)
文摘A novel biodegradable and biocompatible multilayer hollow microcapsules,modified by folate-conjugated polyethyleneimine(PEI),as targeted and sustained release carriers of doxorubicin(DOX),were successfully synthesized using the sequential layer-by-layer electrostatic assembly technique from the sacrificial microtemplates(CaCOj/CMC,spherical,1.7 μm) with chitosan(CS) and sodium carboxymethyl cellulose(CMC) as the polycation and polyanion polyelectrolyte.Scanning electron microscope(SEM) observation showed that the diameter of the seven assembly multilayer microparticles was about 2.0 μm with relatively regular sphere.After the microparticle cores was removed by complexation with ethylene diamine tetraacetic acid(EDTA) for calcium ions,the range of 200- 300 nm wall thickness of microcapsules was built,and it made the forming microcapsules to be stable.Thermogravimetric analysis confirms the deposition and modification total amount of polymer on the microtemplates is about33.5%.The assembly microparticles were modified by introducing PEI,and the grafting rate of folate could reach 20.0%.It was 4times that of traditional method.The high grafting rate helped to improve targeting action of microcapsules.The deposition of DOX was prominent and the encapsulation efficiency was 96.9%,and the plateaued release of loaded drug reached 78%in pH 7.4 buffer solution,and then in pH 5.7 showed significantly a slow release.
基金Fundamental Research Funds for the Central Universities,China(No.2011D10543,No.2013D110525)
文摘Traditional preparation of magnetic microcapsules involves cumbersome processes and often results in irregular-shaped products. Due to the stable laminar flow of reaction solution and the moderate reaction conditions, the T-shaped microchannel (T-MC) reactor is supposed to yield microcapsules with regular shape. In this paper, magnetic particles of ferroferric oxide modified by oleic acid (OA-Fe3O4) and dispersed in tetrachloroethylene were used as core material. Polymethyl methacrylate (PMMA) was used as shell material. Magnetic microcapsules were prepared by using a T-MC reactor. Factors that influenced the encapsulated reaction were investigated in details, which included the velocity ratio of aqueous phase to oil phase, the length and the inner diameter of the microchannel. The morphology, composition, and magnetic responsiveness of the magnetic microcapsules were analyzed and characterized by SEM, FTIR, XRD, TGA, and vibrating sample magnetometer (VSM). The results confirmed that magnetic microcapsules prepared by T-MC reactor were regular in shape.
基金Education Commission of Shaanxi Province for Providing Funding Support,China ( No. 2010JS006)
文摘Phase change material microcapsules (MicroPCMs) with nano composite structures (NC-MicroPCMs) were fabricated to meet higher demand of thermal stability and hold core better. Degree of crystallinity (DOC) of the NC-MicroPCMs was evaluated by the differential scanning calorimeter (DSC). The effectiveness of some processing variables, in terms of formaldehyde and melamine molar ratio F/M, weight ratio of core and shell material C/S, and the dosage of silver nano particles D(%), were analyzed statistically. It was found that: (1) DOC was dependent on these processing variables; (2) doping silver nano particles was beneficial to the formation of shell crystallite structure; and (3) higher F/M was helpful in getting a higher DOC for both NC-MicroPCMs and MicroPCMs. Also, DOC was found to be associated with thermal stability and the two features were confirmed, which showed a closely positive correlation.
文摘The aim of this work was to develop a functional biodegradable nonwoven with antimicrobial microcapsules maintaining the stability and biodegradability of the nonwoven for use in agriculture applications. The nonwoven was obtained using hemp fibers by Wetlaid technology. Microcapsules were prepared by co-extrusion/gelling method with alginate as shell and oregano oil as core material. The microcapsules were developed to protect and control release of oregano oil. Microcapsules were incorporated on the nonwoven by coating method using a natural polymer as a graft material. After incorporating micro-capsules, the nonwoven was subjected to several tests in order to determinate the microcapsules fixation and their functionality. The nonwovens were characterized for their antimicrobial activity against different kinds of bacteria and fungi. Nonwoven loaded with microcapsules was found to show good antimicrobial activity in comparison with nonwoven that was not loaded with microcapsules.
文摘It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to obtain the higher content. As the shell material of the first microcapsules prepared by the spray drying method, palmitic acid with the melting point of 60°C was adopted in order to prevent grape polyphenol from dissolution into water. As the shell material of the second microcapsules prepared by the layer-by-layer method, chitosan was used to coat the first microcapsules and to give the microcapsules alcohol resistance. In the experiment, the spray drying conditions such as the inlet temperature and the spraying pressure, the oil soluble surfactant species and the chitosan concentration were changed. The mean diameters of microcapsules could be controlled in the range from 5 μm to 35 μm by changing the spraying pressure and the inlet temperature. The yield of microcapsules and the microencapsulation efficiency over 50% could be obtained under the conditions of P = 1.0 kgf/cm2 and Tin = 100°C. Furthermore, the microencapsulation efficiency could be increased by adding the oil soluble surfactant with the larger HLB value. Coating with chitosan could considerably increase alcohol resistance.
