High-throughput microfluidic production of carbon capture microcapsules:fundamentals,applications,and perspectives

In the last three decades,carbon dioxide(CO_(2)) emissions have shown a significant increase from various sources.To address this pressing issue,the importance of reducing CO_(2) emissions has grown,leading to increased attention toward carbon capture,utilization,and storage strategies.Among these strategies,monodisperse microcapsules,produced by using droplet microfluidics,have emerged as promising tools for carbon capture,offering a potential solution to mitigate CO_(2) emissions.However,the limited yield of microcapsules due to the inherent low flow rate in droplet microfluidics remains a challenge.In this comprehensive review,the high-throughput production of carbon capture microcapsules using droplet microfluidics is focused on.Specifically,the detailed insights into microfluidic chip fabrication technologies,the microfluidic generation of emulsion droplets,along with the associated hydrodynamic considerations,and the generation of carbon capture microcapsules through droplet microfluidics are provided.This review highlights the substantial potential of droplet microfluidics as a promising technique for large-scale carbon capture microcapsule production,which could play a significant role in achieving carbon neutralization and emission reduction goals.

Antibacterial Chitosan-Gelatin Microcapsules Modified with Green-Synthesized Silver Nanoparticles for Food Packaging

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.

Photosensitivity and a precise combination of size-dependent lambda-cyhalothrin microcapsules synergistically generate better insecticidal efficacy

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.

Performance and Application of Double-layered Microcapsule Corrosion Inhibitors

Double-layered microcapsule corrosion inhibitors were developed by sodium monofluorophosphate as the core material,polymethyl methacrylate as the inner wall material,and polyvinyl alcohol as the outer wall material combining the solvent evaporation method and spray drying method.The protection by the outer capsule wall was used to prolong the service life of the corrosion inhibitor.The dispersion,encapsulation,thermal stability of microcapsules,and the degradation rate of capsule wall in concrete pore solution were analyzed by ultra-deep field microscopy,scanning electron microscopy,thermal analyzer,and sodium ion release rate analysis.The microcapsules were incorporated into mortar samples containing steel reinforcement,and the effects of double-layered microcapsule corrosion inhibitors on the performance of the cement matrix and the actual corrosion-inhibiting effect were analyzed.The experimental results show that the double-layered microcapsules have a moderate particle size and uniform distribution,and the capsules were completely wrapped.The microcapsules as a whole have good thermal stability below 230 ℃.The monolayer membrane structure microcapsules completely broke within 1 day in the simulated concrete pore solution,and the double-layer membrane structure prolonged the service life of the microcapsules to 80 days in the simulated concrete pore solution before the core material was completely released.The mortar samples containing steel reinforcement incorporated with the double-layered microcapsule corrosion inhibitors still maintained a higher corrosion potential than the monolayer microcapsule corrosion inhibitors control group at 60 days.The incorporation of double-layered microcapsules into the cement matrix has no significant adverse effect on the setting time and early strength.

Research Progress of Aromatic Bed Curtains for Aiding Sleep Based on Lavender Microcapsule Technique

In this paper, the preparation technique of lavender essential oil microcapsules and the construction method of aromatic textiles were expounded, and the research status of bed curtains and lavender microcapsules at home and abroad was analyzed and studied from the perspective of application in textiles. The application of lavender essential oil to bed curtains through the microcapsule technique was put forward to allow lavender essential oil to play its role of helping sleep in bed curtains. This paper expounded the material selection and preparation technique of lavender microcapsule agents, and put forward the preparation method of microcapsules with mixed solutions of pure Chinese medicine extracts and natural essences as core material and high-viscosity epoxy resin as wall materials. The post-processing techniques and the spray ironing method for clothing were studied and developed, and these techniques and methods were applied to bed curtains, and good results were obtained.

RP-HPLC determination of lycopene in microcapsules

Aim A RP- HPLC method for determination of lycopene in microcapsules was established. Methods The HPLC assay was performed on an Alltima Cls （4.6 mm × 250 mm, 5μm） column with a mixture of methanol-THF-water （66：30：4, V/V/V） as mobile phase at a flow rate of 1.5 mL·min^-1 and the UV detection wavelength was 472 nm. Results The linear range of lycopene was 3.6-18 μg·mL^-1, r = 0.999 8, the average recovery was from 99.81% to 101.06% with RSD less than 1.83%. The RSD of intra-day and interday precision were less than 3.34%. Conclusion The method is simple, accurate and suitable for the determination of lycopene in microcapsules.

Preparation and in Vitro Evaluation of Polylactic Acid (PLA) or Polylactic-co-Glycolic Acid (PLGA) Microcapsules Loaded with Estradiol

Aim PLA/PLGA was used as biodegradable and biocompatible carriers to achieve sustained release of estradiol (E 2). Methods Microcapsules (MC) were prepared by an emulsification solvent extraction method, and then the properties and in vitro drug release behavior of MC were examined. An analysis of variance (ANOVA) was used to test the statistical significance. Then, multiple comparisons were made with a T method between levels to examine the significance of difference further. For all the results a P value 】0 05 was considered statistically insignificant . Results Under the same conditions, the water adding speed and the particle size had significant effects ( P 【0 01) on the entrapment efficiency of MC; the water adding speed and the concentration of PLA in the oil phase had significant effects ( P 【0 01) on the diameter MC in medium. Release of E 2 from MC was influenced significantly ( P 【0 01) by the water adding speed and the type and molecule weight of the polymers. But the differences between levels of the variates were not all significant. Conclusion E 2 PLA/PLGA MC with various properties can be formed when the formulation and the technology were changed accordingly.

Synthesis and Characterization of Microcapsules with Chlorpyrifos Cores and Polyurea Walls

Microcapsules with chlorpyrifos cores and polyurea walls were synthesized with 2,4-tolylene diisocyanate as an oil-soluble monomer and ethylenediamine as a water-soluble monomer via an interracial polycondensation reaction. The products were characterized by means of Fourier transform infrared spectrometry, ^13C NMR spectrometry and ^31p NMR spectrometry. The morphology, the particle size and the particle size distribution, and the thermal properties were also evaluated. The prepared microcapsules exhibit clear and smooth surfaces and have a mean diameter of 28. 13 μm. These microcapsules also have a good thermal stability for long-term use, and have potential applications in minimizing the toxicity of chlorpyrifos through controlled release.

Research on microcapsules of phase change materials

Microcapsule technology is a kind of technology wrapping the solid or liquid into minute-sized particles within the field of micrometer or millimeter with film forming materials. This thesis introduces microcapsule technology of phase change materials and its main functions and the structural composition, preparation methods and characterization technology of microcapsule of phase change materials. The microcapsule of phase change materials is small in size and its temperature remains unchanged during the process of heat absorption and heat release. It is of great value in research and application prospect due to these characteristics.

Culture of yeast cells immobilized by alginate-chitosan microcapsules in aqueous-organic solvent biphasic system

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.

Synthesis of melamine-formaldehyde microcapsules containing oil-based fragrances via intermediate polyacrylate bridging layers

A general and versatile strategy to prepare melamine-formaldehyde(MF)microcapsules encapsulating oil-based fragrances by combining solvent evaporation and in situ polymerization was proposed in this work.The oil-based fragrance was pre-encapsulated by an inner polyacrylate membrane via solvent evaporation,followed by in situ polymerization of MF precondensates as an outer shell.The polyacrylate membrane is used as an intermediate bridging layer to stabilize the oil-based fragrance,and to provide driving forces for in situ polymerization of MF precondensates through electrostatic attractions between carboxyl groups and ammonium ions.It was demonstrated that MF microcapsules containing clove oil were prepared successfully.The amount and the composition of the intermediate polyacrylate bridging layer were critical.Smooth and sphere-shaped MF-clove oil microcapsules were prepared when the weight ratio of polyacrylate to clove oil was over 60 wt%and the concentration of acrylic acid(AA)increased to 10 wt%in polyacrylate.In addition,MF microcapsules containing sunflower oil and hexyl salicylate were prepared by using this method.The work suggests that this new approach can be potentially used to encapsulate various core materials,tuning the shell properties of microcapsules such as thickness,mechanical strength and release properties.

Preparation and Characterization of Microcapsules for Self-healing Materials

The urea-formaldehyde（UF） capsules filled with a healing agent, a mixture of epoxy resins（epoxy 711 and E-51） as core material, were produced by means of one step in-situ polymerization. The characteristics of these microcapsules were studied via scanning electron microscopy（SEM）, particle size analysis, FTIR and DSC/TGA. The results show that the dispersed and integrated microcapsules of 5 μm in shell thickness were synthesized successfully. The capsules were produced with diameters ranging from 10 to 250 μm via controlling agitation rate. Young＇s modulus of the capsule was a little lower than those of the epoxy resins, but the microcapsules having such a shell thickness were robust enough to survive handling during manufacturing self-healing composites. When damage occurred in the epoxy matrix, the crack could rupture the microcapsule to make the repairing agent release.

Numerical Analysis on Thermal Function of Clothing with PCM Microcapsules

To study the influences of phase change material(PCM)microcapsules in clothing on human thermal responses,a mathematical model is developed.The improved Stolwijk’s model is used to simulate human thermo-regulatory process,and the coupled heat and moisture transfer including the moisture sorption/desorption of fibers and effects of phase transition temperature range on the phase change processes of the PCM is considered in clothing model.Meanwhile,the theoretical predictions are validated by experimental data.Then,the interactions between human body thermal responses and the heat and moisture transfer in clothing are discussed by comparing the prediction results with PCMs and without PCMs.Also the effects of fiber hygroscopicity on clothing and human thermal responses are compared.The conclusion shows that the clothing with PCMs microcapsules can delay the human temperature variations and decrease the sweat accumulation rate on the skin surface and heat loss during changing of ambient conditions,and fiber hygroscopicity reduces the effect of PCM microcapsules on delaying garment temperature variations very significantly.

Biomass Microcapsules with Stem Cell Encapsulation for Bone Repair

Bone defects caused by trauma,tumor,or osteoarthritis remain challenging due to the lack of effective treatments in clinic.Stem cell transplantation has emerged as an alternative approach for bone repair and attracted widespread attention owing to its excellent biological activities and therapy effect.The attempts to develop this therapeutic approach focus on the generation of effective cell delivery vehicles,since the shortcomings of direct injection of stem cells into target tissues.Here,we developed a novel core-shell microcapsule with a stem cell-laden core and a biomass shell by using all-aqueous phase microfluidic electrospray technology.The designed core-shell microcapsules showed a high cell viability during the culture procedure.In addition,the animal experiments exhibited that stem cell-laden core-shell microcapsules have good biocompatibility and therapeutic effect for bone defects.This study indicated that the core-shell biomass microcapsules generated by microfluidic electrospray have promising potential in tissue engineering and regenerative medicine.

Diffusion Characteristics in Microcapsules

An equation of diffusion for microcapsules（hollow sphere）was developed,employing the mathematicalmodel for the diffusion characteristics of solid sphere.In the proposed equation,a combination diffusion coeffi-cient was introduced as a substitute for the diffusion coefficient in the solid sphere mathematical model and ex-pressed as a function of the diffusion coefficient inside solution of hollow sphere,as well as in the polymer mem-brane.With this modified model,the diffusion coefficients of glucose in NaCS（sodium cellulose sulfate）-PDADMAC（Poly-diallyl-dimethyl-ammonium chloride）membrane and in Ca-alginate gel membrane were deter-mined.The diffusion coefficient in NaCS-PDADMAC membrane was found to be 2.12×10-11m2·s-1and thatin Ca-alginate membrane 2.62×10-10m2·s-1.

Measurement and Influence Factors of the Flowability of Microcapsules with High-content β-Carotene

The flowability of five kinds of microencapsulation powders,with differentβ-carotene contents and by two alternative particle-forming technologies i.e.spray-drying and starch-catching beadlet technology,was meas- ured.The actual flow properties of the five powders were compared based on bin-flow test,and three flow indexes (Hausner ratio,repose angle and flow index)were measured.It was found that the repose angle is the most suitable index to reflect the flowability of these powders for the particle properties would not be altered due to compaction or tapping during the measuring process.Particle size and particle size distribution play most important roles in the flowability of these granular materials,which was also influenced by other factors like shape,surface texture,sur- face roughness,etc.Microcapsules with wall material of gelatin and a layer of modified starch absorbed on the sur- face showed excellent flowabilities and good mechanical properties,and they are favorable for tabletting to supply β-carotene.

Facile and High Efficient Fabrication of Hybrid Microcapsules for Urease Encapsulation and Their Use as Biomimetic Reactors

Urease-loaded colloidosome microcapsules with SiO2 nanoparticle shells and gellan gel cores were prepared facilely and highly efficiently by self-assembly of colloidal particles at the liquid-liquid interfaces and subsequently in-situ gelation of gellan gum. The urease-loaded colloidosome microcapsules were used as an enzymatic reactor to produce calcium carbonate precipitates by urease-catalyzed urea hydrolysis in the presence of calcium cations. The CaCO3/SiO2 shells were formed finally around the gellan gel cores. The colloidosome microcapsules used as a biomimetic reactor has been demonstrated for the first time.

Preparation of urea-formaldehyde paraffin microcapsules modified by carboxymethyl cellulose as a potential phase change material

We prepared spherical microcapsules modified by carboxymethyl cellulose（CMC） with urea-formaldehyde（UF） resin as a shell material with a two-step process by in situ polymerization, and characterized the microcosmic features, chemical structure, and thermal performance of the microcapsules by SEM, FTIR, DSC, and TGA. We studied the effects of different experimental parameters of curing p H, the amounts of the emulsifier and emulsion speed. The CMC-UF microcapsules had good heat resistance and stability. The enthalpy of CMC-UF microcapsules reached 50.33 J g-1. Therefore, CMC-UF resin can be used as a potential wall material of phase change materials.

Formulation and evaluation of Albendazole microcapsules for colon delivery using chitosan

Objective:To formulate and evaluate Albendazole microcapsules using chitosan,a natural polymer for colon-specific delivery for better treatment of helminthiasis,filariasis,colorectal cancer,avoiding the side effects.Methods:The Albendazole microcapsules were prepared by the use of different concentrations of sodium alginate,chitosan and hydroxypropyl methylcellulose(HPMC).The polysaccharides chitosan reacted with sodium alginate in the presence of calcium chloride to form microcapsules with a polyelectrolyte complex membrane by electrostatic interactions between the two oppositely charged polymers.The microcapsules were then studied for entrapment efficiency,drug-polymer compatibility and surface morphology. In vitro drug release study in presence and absence of cecal content were also studied.Further, kinetic modellings were employed to find out release mechanisms.Results:Albendazole loaded microspheres showd high entrapment efficiency(72.8%) and the microcapsules were free flowing,non aggregated and spherical,between 600 and 1 000μm in diameter.The surface of microcapsules were found to be porous and wavy.The FT-IR spectrum showed that there is no interaction between the polymer and the drug.The in vitro drug release study found to be affected by change in chitosan,sodium alginate and HPMC concentration.The microcapsules with 2.5% sodium alginate and 0.4% chitosan shown minimum release in gastrointestinal simulated condition but shows maximum drug release at the end of 24th hour in presence of cecal content.The rate of drug release follows Korsmeyer-peppas model that was the drug release is by diffusion and erosion.Conclusions:The study reveals that Albendazole loaded chitosanalginate based microsphere can be used effectively for the colon targeting.

Synthesis and Characterization of Ethylenediamine Tetraacetic Acid Tetrasodium Salt Loaded in Microcapsules with Slow Release Properties

The microcapsules with cores of ethylenediamine tetraacetic acid tetrasodium salt(Na4-EDTA)and walls of polyurea were synthesized via an interfacial polycondensation reaction with 2,4-tolylene diisocyanate as an oil-soluble monomer and diethyl triamine as a water-soluble monomer.Various manufacturing parameters,including the amount of emulsifier,agitation speed,stirring time and ratios of the wall materials to core materials,were altered to optimize process variables during the synthesis of microcapsules,and the effects of these parameters on the characteristics of the microcapsules were examined.The structure,morphology,mean particle size and size distribution were characterized by optical microscope and scanning electron microscopy(SEM),showing that the mean diameter of optimal microspheres was approximately 6μm,and microcapsules were spherical.In vitro release of Na4-EDTA from these microcapsules was performed in distilled water.Under the optimal preparation conditions, the Na4-EDTA release profiles were biphasic with a burst release followed by a gradual release phase.After an initial burst,a continuous Na4-EDTA release was up to 5-7 days.The optimal synthesis conditions for the microcapsules with stable,good morphology and good controlled-release properties were as follows:emulsifier Span-80 10% (by mass),agitation speed 900 r·min1,stirring time 30 min,and the ratio of the wall materials to core materials 0.15.