Composite Microcapsules Research Articles

Synthesis and performance evaluation of polymer-ceramic composite microcapsules as reservoir protectant for natural gas hydrate drilling.

Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules. As an additive to the drilling fluid, the BDTPM can minimize drilling fluid intrusion by plugging the reservoir during drilling and afterwards maximize permeability recovery by degrading the material. The particle size distribution was in the range of 1-130μm. The optimal mass ratio between modified ceramic particles, ethyl cellulose and epoxy resin was found to be 4:2:1. The plugging rate was 100% when ethyl cellulose and epoxy resin were mixed to coat the ceramic particles to form BDTPM, and the plugging performance was the best. At a temperature close to the typical hydrate reservoir environment (5°C), 0.02 wt% low-temperature complex enzyme can degrade BDTPM, and the permeability recovery rate is 64.66%. The efficient reservoir protectant developed in this work could play an important role in the successful drilling of natural gas hydrate reservoirs.

Thermal and cyclic performance of aluminum alloy composite phase change microcapsules for high-temperature thermal energy storage

Al alloys are suitable for high-temperature applications such as solar thermal power generation and industrial heat utilization. However, addressing the challenges of high-temperature corrosion and material failure in Al alloys is of paramount importance. In practical industrial applications, there is a need to develop encapsulation techniques applicable to a wider range of Al alloy types and phase change temperature ranges, exploring the universality of the technology and the diversity of application scenarios. In this study, a dual encapsulation was conducted on binary and ternary Al alloys (including Al-Ni, Al-Mg, Al-Si-Mg, and Al-Mg-Zn). Aiming at thermal energy storage, four composite phase change microcapsules (CPCM) were successfully prepared and subjected to material characterization, thermal performance analysis, and thermal cyclic tests in air environments. After 2000 thermal cycles, no cracks were observed on the surface of the four CPCMs, and the microstructure remained intact. The components of the CPCMs maintained good chemical compatibility. Among the four types of CPCMs, the Al-Si-Mg CPCMs exhibited the best thermal cyclic stability, with a latent heat reduction rate of 19.5 % after 2000 cycles. The experimental results indicated that the dual encapsulation strategy was effective for various types of Al alloy PCMs, thereby expanding the application of Al alloys in high-temperature thermal storage. Furthermore, Al alloys with more regular morphology and lower active metal content exhibited better thermal performance and cyclic capability, making them more suitable candidates for high-temperature thermal storage applications.

Crack/Cl− - triggered design and tensile self-healing mechanism of epoxy coatings on offshore steel bars

The double-walled microcapsules triggered under the crack/Cl− condition were prepared by using isocyanate and 1,6-diaminohexane respectively as the internal and external core material, and polyurea as the wall material. During the synthesis process, lead sulfate was added to the wall material to trap chloride ions. The morphology and dispersion of the microcapsules embedded in the epoxy composite were characterized, using the scanning electron microscope (SEM) and super depth of field microscope. Self-healing coatings containing 0.0 wt%, 3.0 wt%, 5.0 wt%, and 8.0 wt% of composite double-walled microcapsules were subjected to tensile tests. The digital speckle correlation method (DSCM) and pull-out test were applied to analyze the mechanical properties and crack-triggering principle of the coating. The toughening effect and self-healing behavior of the epoxy resin with varying dosages of microcapsules were studied. The self-healing efficiency and mechanism of the composite coating were obtained during the process of stretching, crack expansion, and micro-capsule triggering.

Novel eco-friendly nanodiamonds@chitosan hybrid microcapsules via facile electrospraying for self-healing and anticorrosion coating

Nanodiamonds were immobilized into chitosan biopolymer to fabricate hybrid microcapsules via electrospraying technique. Previously optimized electrospraying parameters for the formulation of chitosan microcapsules were adjusted to accommodate the immobilized nanodiamonds and maintain a suitable capsule size for the novel hybrid. The yield and entrapment efficiency of the composite microcapsules, including capsule strength were analyzed. The chemical structure, elemental composition, crystalline phases, size distribution, surface morphology, and thermal stability of microcapsules were assessed by Fourier transform infrared (FTIR) spectroscopy, energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), respectively. The results demonstrated a 39 % reduction in the size of composite microcapsules and sphericity improvement after the adjustment. There was a general observation of good yield and immobilization efficiency with the maximum at 96.2 % and 93.8 % for yield and entrapment efficiency, respectively. Characterized composite microcapsules showed desirable morphology, good thermal stability and enhanced mechanical strength, and overall successful fabrication of the hybrid microcapsules. The hybrid microcapsules were subsequently loaded in epoxy resin and coated on a steel substrate to assess their self-healing and anticorrosion abilities. Cross-scratched coating samples were monitored visually for healing efficiency and further analyzed with EIS and potentiodynamic polarization. The self-healing coating showed efficient self-healing and anticorrosion capabilities with a healing efficiency of 97.3 % and a protection efficiency of 99.4 %, confirming the unique feature of the hybrid chitosan-nanodiamonds microparticles for self-healing and anticorrosion purposes.

Protective Effects of Laminaria japonica Polysaccharide Composite Microcapsules on the Survival of Lactobacillus plantarum during Simulated Gastrointestinal Digestion and Heat Treatment.

To improve probiotics' survivability during gastrointestinal digestion and heat treatment, Lactobacillus plantarum was microencapsulated by spray-drying using Laminaria japonica polysaccharide/sodium caseinate/gelatin (LJP/SC/GE) composites. Thermogravimetry and differential scanning calorimetry results revealed that the denaturation of LJP/SC/GE microcapsules requires higher thermal energy than that of SC/GE microcapsules, and the addition of LJP may improve thermal stability. Zeta potential measurements indicated that, at low pH of the gastric fluid, the negatively charged LJP attracted the positively charged SC/GE, helping to maintain an intact microstructure without disintegration. The encapsulation efficiency of L. plantarum-loaded LJP/SC/GE microcapsules reached about 93.4%, and the survival rate was 46.9% in simulated gastric fluid (SGF) for 2 h and 96.0% in simulated intestinal fluid (SIF) for 2 h. In vitro release experiments showed that the LJP/SC/GE microcapsules could protect the viability of L. plantarum in SGF and release probiotics slowly in SIF. The cell survival of LJP/SC/GE microcapsules was significantly improved during the heat treatment compared to SC/GE microcapsules and free cells. LJP/SC/GE microcapsules can increase the survival of L. plantarum by maintaining the lactate dehydrogenase and Na+-K+-ATPase activity. Overall, this study demonstrates the great potential of LJP/SC/GE microcapsules to protect and deliver probiotics in food and pharmaceutical systems.

Pancreatic stellate cells support human pancreatic β-cell viability in vitro and enhance survival of immunoisolated human islets exposed to cytokines

Pancreatic islet transplantation is proposed as a cure for type 1 diabetes mellitus (T1D). Despite its success in optimal regulation of glucose levels, limitations in longevity of islet grafts still require innovative solutions. Inflammatory stress post-transplantation and loss of extracellular matrix attribute to the limited β-cell survival. Pancreatic stellate cells (PSCs), identified as pancreatic-specific stromal cells, have the potential to play a crucial role in preserving islet survival. Our study aimed to determine the effects of PSCs co-cultured with human CM β-cells and human islets under inflammatory stress induced by a cytokine cocktail of IFN-γ, TNF-α and IL-1β. Transwell culture inserts were utilized to assess the paracrine impact of PSCs on β-cells, alongside co-cultures enabling direct interaction between PSCs and human islets. We found that co-culturing PSCs with human CM β-cells and human cadaveric islets had rescuing effects on cytokine-induced stress. Effects were different under normoglycemic and hyperglycemic conditions. PSCs were associated with upregulation of β-cell mitochondrial activity and suppression of inflammatory gene expression. The rescuing effects exist both in indirect and direct co-culture methods. Furthermore, we tested whether PSCs have rescuing effects on human islets in conventional alginate-based microcapsules and in composite microcapsules composed of alginate-pectin collagen type IV, laminin sequence RGD, Nec-1, and amino acid. PSCs partially prevented cytokine-induced stress in both systems, but beneficial effects were stronger in composite capsules. Our findings show novel effects of PSCs on islet health. Islets and PSCs coculturing or co-transplantation might mitigate the inflammation stress and improve islet transplantation outcomes.

Density Matching for Microencapsulation of Field Responsive Suspensions of Non-Brownian Microparticles.

When forming composite microcapsules through the emulsification of a dispersed phase laden with microparticles, one will find that the microparticles become irreversibly embedded in the resulting microcapsule membrane. This phenomenon, known as Pickering stabilization, is detrimental when the end function of the microcapsules relies on the mobility of encapsulated microparticles within the capsule core. In this work, a robust microencapsulation route using density matching of non-Brownian microparticles in a binary solvent is shown to easily and effectively encapsulate particles, with >90% of particles retaining mobility within the microcapsules, without the necessity for prior chemical/physical modifications to the microparticles. This is proposed as a generalized method to be used for all manner of particle chemistries, shapes, and sizes.

Preparation and performance enhancement of MXene/Na2HPO4·12H2O@SiO2 phase change microcapsule

Currently, the leakage problem of phase change materials can be solved by the microencapsulation technology. Inorganic hydrated salt materials have the advantages of high latent heat density, high thermal conductivity and low cost. How to construct inorganic hydrated salt microcapsules with excellent heat storage capacity and photothermal conversion performance maintains a challenge. In this work, the MXene/Na2HPO4·12H2O@SiO2 (MXene/MPCMs) composite phase change microcapsules were designed and prepared. The Na2HPO4·12H2O was directly used as phase change material and TEOS was used as raw material to generate SiO2 wall material. The MXene played a key and important role in simultaneously enhancing their photothermal conversion efficiency while maintaining available latent heat. The prepared composite microcapsules (MPCM-1) showed more obvious heat storage and release characteristics, and the latent heat reached 169.62 J/g. Besides, when the hydrated salt was encapsulated in silica shell, the supercooling degree of hydrated salt was reduced from 14.2 °C to 10.1 °C. With the increase of MXene content, the maximum surface temperature of microcapsules significantly increased. Based on the results of surface temperature distribution, the photothermal conversion ability and heat transfer rate of microcapsules were effectively improved, which was mainly attributed to the remarkable light absorption conversion ability of MXene. When the MXene was added, the MXene/MPCMs still showed excellent heat storage properties (∼ 156.64 J/g). At the same time, the MXene/MPCMs showed good chemical compatibility, crystallization characteristics and thermal stability. Considering available performance enhancement, the prepared microcapsules show good application prospect in solar energy utilization.

An Effective Method to Prepare Curcumin-Loaded Soy Protein Isolate Nanoparticles Co-Stabilized by Carrageenan and Fucoidan.

In this study, a novel and simple strategy is proposed based on 3D network formed by easily blending polysaccharide carrageenan (Car) and fucoidan (Fuc) without a crosslinker. The Fuc/Car dual coating effectively assists the self-assembly of soy protein-isolated (SPI)/curcumin (Cur, C) composite microcapsules (SPI/C) and achieves an excellent curcumin encapsulation efficiency (EE) up to 95.28% with a 4.16% loading capacity (LC) under optimal conditions. The resulting nanocomposites achieved a satisfying redispersibility in aqueous solution and enhanced the water solubility with a lower size dispersity index (PDI) of 0.12 and a larger zeta potential of -29.67 mV. The Fuc/Car double-layer network not only dramatically improved its thermal stability and photostability, but also provided controlled release and enhanced antioxidant activity in in vitro conditions. The underlying mechanism of the self-assembly of the curcumin-loaded nanoparticles was also addressed. The results proved the feasibility of the encapsulation of unstable hydrophobic bioactive substances (curcumin) with the dual anionic polysaccharide Fuc/Car co-stabilized SPI nanoparticles. This study paves the way for an alternative way of developing novel curcumin delivery systems and will have broad prospects in the pharmaceutical industries.

Smart carrageenan/carboxymethyl cellulose films combined with zein/gellan gum microcapsules encapsulated by composite anthocyanins for chilled beef freshness monitoring

The demand for smart packaging to monitor food spoilage is increasing. In the present study, composite anthocyanin microcapsules (CAM) were prepared by using zein and gellan gum as wall materials and protecting composite anthocyanin (CA). Carrageenan (Car)/sodium carboxymethylcellulose (CMC)-based indicator films (CC) containing CAM microcapsules were developed for monitoring the freshness of beef. The results demonstrated that the composite anthocyanins could be well dispersed in the CC matrix. CAM significantly reduced the effects of light and temperature on the stability of anthocyanins. CAM significantly improved the thermal stability, barrier properties and tensile strength of the films. The infrared spectra showed that the components of the indicator films were structurally similar and well-compatible. Among them, the indicator film CC/CAM-3 had the highest tensile strength (17.76 MPa), the lowest water vapor transmission rate (1.35 × 10−11 g/m·s·Pa) and a tight and neat cross-section. The color of the indicator film changed significantly in the ammonia environment: pink→blue-green→yellow. Applying different concentrations of indicator films to beef freshness monitoring, we found that beef reached sub-freshness and spoilage on days 4 and 7, respectively, and accordingly the indicator film CC/CAM-3 changed from pink to purple and green. To examine its capability as a colorimetric indicator film, we related the change in beef quality to the ΔE value of the indicator film, which proved to be the most sensitive when used to monitor the freshness grade of beef, as demonstrated by the indicator film CC/CAM-3.

Metal-organic framework/polyurea composite microreactors prepared in oil-in-oil emulsions

A new technique was developed to create composite microcapsules consisting of metal–organic framework (MOF) and polyurea. This method employs oil-in-oil (O/O) emulsion as a template for forming these microcapsules. It involves emulsifying a polar solvent containing MOF reagents within a nonpolar phase containing a suitable surfactant and an isocyanate monomer. Subsequently, the addition of the amine monomer initiates two simultaneous processes: the formation of MOF crystals in the core of polar droplets and the interfacial polymerization to create polyurea shell. Optimization of the method involved adjusting various parameters affecting the composite microcapsules' structure and morphology. These parameters include the surfactant’s type and concentration, the emulsion phases’ type and concentration, and quantity of the MOF component.This method was applied to create palladium-based MOF/polyurea microreactors by encapsulating sodium tetrachloropalladate and then reducing the palladium salt with hydrogen to generate reactive palladium species. The produced catalysts were utilized in the selective hydrogenation of terminal alkynes. It was observed that the selectivity of the catalyst is influenced by the quantity of encapsulated MOF, the amount of encapsulated palladium, and the solvent type used for the reaction.

Compound probiotics microcapsules improve milk yield and milk quality of dairy cows by regulating intestinal flora

AbstractTo address the issues of probiotic activity loss during storage and feeding, as well as the limited efficacy of single probiotics, a solution was devised by embedding a mixture of Bacillus coagulans SN‐8 (SN‐8) and Saccharomyces boulardii SN‐6 (SN‐6) in a gel. The initial step involved screening the probiotic microcapsules' preparation method and wall material. Using sodium alginate and β‐cyclodextrin as composite wall material and chitosan as the outer coating material allowed for an embedding rate of 82.11% in composite probiotic microcapsules prepared by the air atomization method. Next, in vitro, simulated digestion experiments were conducted to determine the number of viable bacteria and the release rate of the microcapsules. The results showed that compared to the free strain, the mixed probiotic microcapsules retained a survival rate of 67.5% after 3 h of simulated gastric juice exposure and 70.56% after 42 days of storage at 4°C. This demonstrated higher survival rates and storage stability. The prepared probiotic microcapsules were then administered to dairy cows. 16S rDNA gene sequencing showed that consumption of the microcapsules reduced the number of harmful bacteria, such as Paeniclostridium, in the intestinal tract of dairy cows while accelerating the growth of beneficial bacteria, such as Bifidobacterium. In particular, this resulted in a significant improvement in the lactation performance of the cows, with a 4.5% increase in milk fat content, a 92.5% increase in milk protein content, and a 3.5% increase in milk urea nitrogen content (6.75 mL/dL). In conclusion, probiotic microcapsules can effectively regulate intestinal flora, improving milk production, and quality in dairy cows.

Preparation and characterization of chitosan/ZnO-Ag composite microcapsules and their applications in solar energy harvesting and electromagnetic interference shielding

Phase change microcapsules are known for their latent heat storage capability. However, the efficient absorption and utilization of solar energy by these microcapsules remains a significant challenge. In this study, we successfully prepared composite phase change microcapsules containing ZnO-Ag nanospheres, chitosan, and paraffin. These microcapsules demonstrated remarkable photothermal conversion efficiency. ZnO was found to effectively absorb ultraviolet light, while the plasmonic resonance of Ag was utilized to absorb and make use of light energy in the visible region. Moreover, due to the synergistic absorption and reflection of electromagnetic waves by ZnO-Ag nanoparticles and graphene, the well-dispersed chitosan/ZnO-Ag composite microcapsules and graphene in the fabric coating demonstrated exceptional electromagnetic shielding performance. In addition, the coated fabric based on composite microcapsules exhibited excellent antibacterial properties, effectively inhibiting the growth of bacteria such as S. aureus and E. coli. This antibacterial performance adds to their potential applications in various fields. These multifunctional phase change microcapsules offer vast potential for the effective utilization of solar energy, serving as efficient photothermal conversion and energy storage materials.

Fabrication of composite polymer microcapsules via the supercritical extraction of Pickering emulsion Method: Insights into emulsification and extraction

Polyphenylene oxide (PPO)/cellulose nanocrystal (CNC)/carbon black (CB) microcapsules were fabricated by the supercritical extraction of Pickering emulsion (SFEPE) method. The effects of Pickering emulsion formulations on the emulsion properties, emulsification kinetics, and CPM properties were investigated. The phase behaviors in the supercritical extraction process were studied, and the mass transfer between the emulsion droplet and supercritical carbon dioxide (SCCO2) was also interpreted. The results indicate that CNC concentration, CB concentration, and NaCl concentration can decrease the droplet size and creaming index of emulsions, while the water–oil ratio can decrease the droplet size but enhance the creaming index. The emulsion formulations of water–oil > 3, CNC concentration > 0.25 mg/mL, CB concentration < 2.5 mg/mL, and NaCl concentration > 2.5 mg/mL are conducive to the emulsion formation and emulsification kinetics. For the supercritical extraction on Pickering emulsions, the operation conditions slightly above the mixture critical point (9 MPa at 313 K, for example) are proved to be conducive to the extraction.

Preparation and characterisation of novel casein-gum Arabic composite microcapsules for targeted in vivo delivery of Lactiplantibacillus plantarum A3.

The health benefits of probiotics in the body are predicated on their ability to remain viable in harsh gastrointestinal conditions and complex pathological microenvironments. Casein and gum Arabic (GA), with dual emulsifying and stabilising effects in colloidal systems. Therefore, the objective of this research was to develop a novel microcapsule to encapsulate Lactiplantibacillus plantarum A3 using casein and GA as wall materials to improve the survival of the bacteria during gastrointestinal digestion, storage and lyophilization. The casein and GA composite microcapsules were prepared and characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that the microcapsules had stable morphology, uniform size and spherical shape. The results revealed that the encapsulation of microcapsules significantly improved the survival of L. plantarum A3 in gastrointestinal fluid environment (5.52× 109 cfu/ml) and lyophilization treatment (6.25× 109 cfu/ml). Furthermore, the microencapsulated L. plantarum A3 exhibited an improved ability to regulate intestinal microbiota by effectively increasing the relative abundance of Bacteroidetes, Proteobacteria and Actinobacteria and decreasing the relative abundance of Firmicutes in vivo. The findings of the study will help to design a lactic acid bacteria encapsulation system based on the gastrointestinal environment and provide a basis for the development of probiotic functional products.

Design of gum Arabic/gelatin composite microcapsules and their cosmetic applications in encapsulating tea tree essential oil.

Microencapsulation has been widely used to protect essential oils, facilitating their application in cosmetics. In this study, gelatin, gum arabic and n-butyl cyanoacrylate were used as wall materials, and composite microcapsules of tea tree essential oil (TTO) were prepared using a combination of composite coagulation and in situ polymerization methods. When the ratio of gelatin to gum arabic is 1 : 1, the ratio of TTO to n-butyl cyanoacrylate is 4 : 1, the curing time is 10 h, and the encapsulation efficiency (EE) under these conditions is 73.61%. Morphological observation showed that the composite capsule was a micron-sized spherical particle with an average particle size of 10.51 μm, and Fourier transform infrared spectroscopy (FT-IR) confirmed a complex coagulation reaction between gelatin and gum arabic, and the disappearance of the n-butyl cyanoacrylate peak indicated that the film was formed in a condensation layer. The thermogravimetric analysis (TGA) results showed that the composite capsule greatly improved the thermal stability of TTO. Rheological testing showed that the viscosity and viscoelasticity of the surface composite capsules have been improved. In addition, the composite capsule showed good stability in the osmotic environment and has good sustained-release performance and antioxidant capacity in the average human skin environment.

Stimulus triggered release of actives from composite microcapsules based on sporopollenin from Lycopodium clavatum.

Smart drug delivery systems (SDDSs) are a paradigm shift in drug delivery, particularly in microencapsulation technology where the drug is released in response to an internal and/or external stimulus. In this study, a smart microencapsulation platform was developed using three different types of stimuli triggered release of a model active (rhodamine 6G) from sporopollenin from Lycopodium clavatum. Triggers were based on pH-, thermal- and near infrared light-sensitive polymer composition. Carbopol nanogel and methylcellulose were used as responsive aqueous polymers for pH and thermally triggered release, respectively. Methylcellulose loaded with active and gold nanoparticles was used for photothermal triggered release. The formulations were encapsulated into the empty cores of sporopollenin microcapsules using the compressed tablet technique. The pH triggered release of the active was achieved above pH 7, which was mediated by the swelling of the carbopol nanogel that forced its way out of the elastic trilite scars of the sporopollenin. Results from measuring the active fluorescent intensity and its content over time confirmed the crucial role of carbopol in the pH triggered release. For the thermo-sensitive polymer methylcellulose, it was found that the release of the active from methylcellulose loaded sporopollenin was triggered upon heating the system reaching 90% whereas it levelled out at 40% for methylcellulose-free sporopollenin. The maximum amount of active was released at around 55 °C, where the sol-gel transition of the methylcellulose starts. Photothermally triggered release using near infrared (NIR) laser revealed that the amount of active released from sporopollenin loaded with both gold nanoparticles and methylcellulose was approximately four times higher than that from sporopollenin loaded with methylcellulose/active only, confirming the key role of gold nanoparticles in the release via photothermal heating of the polymer formulation.

Efficient removal of aqueous Pb(II) ions by magnetic alginate composite microcapsules containing canola straw‐derived biochar as the reinforcing fillers

AbstractWith the rapid development of industry, water pollution caused by lead has caused great harm to human health. In this study, alginate is used as a base and blended with biochar to form calcium alginate hydrogel beads with high mechanical properties through ionic cross‐linking. Besides, the material (BC/MCAC) is prepared by the material (C‐γ‐Fe2O3) as a magnetizing agent and to remove lead. Then, a series of batch experiments and material characterizations are performed to evaluate the adsorption process of the material. The results show that the maximum adsorption capacity of BC/MCAC to Pb(II) is 211.6 mg g−1 at pH = 7. The adsorption process is well described by the Langmuir adsorption isotherm and pseudo‐second‐order kinetic model. This indicates that the lead adsorbed by BC/MCAC is a monolayer chemisorption that occurs on a uniform surface. After three regeneration cycles, BC/MCAC is found to retain 82.37% of the lead adsorption capacity and has good regeneration ability. Lead is removed by BC/MCAC mainly through the complexation of oxygen‐containing functional groups, electrostatic interaction, and ion exchange. BC/MCAC allows for more sustainable use of the wastes and is expected to be a new type of lead adsorbent for industrial wastewater.

Pancreatic cancer cell line in responsive hydrogel microcapsules for drug evaluation

AbstractDrug therapies are the cornerstone of systemic treatment for pancreatic cancer patients. However, the relative outcome of drug evaluation is often hampered by the complex microenvironment of pancreatic cancer due to the lack of reasonable tumor models. Here, we proposed a novel platform that integrated pancreatic adenocarcinoma cells encapsulated into hydrogel microcapsules for three‐dimensional (3D) tumor cultivation and antitumor agent evaluation. These hydrogel microcapsules contain alginate/poly (N‐isopropyl acrylamide) (alginate/PNIPAM) shells and carboxymethyl cellulose cores, which are generated through the microfluidic electrospray technique. The microcapsules have the feature of rapid response to temperature, by which they can regulate the internal pressure environment. Besides, benefiting from good monodispersity, precise size control, and biocompatibility of these microcapsules, these wrapped tumor cells have the capacity for proliferating spontaneously and forming 3D tumor spheroids with good cell viability. We have demonstrated that pancreatic adenocarcinoma cells encapsulated in the composite microcapsules with different PNIPAM concentrations showed different drug sensitivity, which could be ascribed to the influence of external pressures environment. These results indicate that the tumor spheroids coated in these responsive microcapsules have great potential in the analysis of antitumor drug sensitivity.

Performance analysis of paraffin microcapsules and phase change concrete based on microporous cenospheres

Combining concrete and phase change materials has created a novel method for building energy conservation. However, introducing phase change materials into the concrete will cause various impacts on its performance. This study explores a novel approach to enhance thermal energy storage in building materials by incorporating phase change materials (PCMs) into concrete. Microporous cenospheres were extracted from fly ash through a three-step process and used to produce composite PCM microcapsules containing paraffin as the core material. The produced PCM microcapsules were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and phase change cycle analysis. Phase change concrete was then formulated by substituting 0–25 % sand with these microcapsules. Effects of the addition of the PCM microcapsule on both the mechanical and thermal properties of concrete were experimentally examined. While the incorporation of microcapsules significantly improved concrete's thermal properties, it also led to a reduction in compressive strength (up to 19.65 % at 28 days), though still meeting specifications. The introduction of microcapsules notably enhanced the temperature control capabilities of concrete. In spring, the model room made with the phase change concrete exhibited a 2.2 °C lower indoor peak temperature 2 h 40 min later than the one room with the ordinary concrete. During active heating in winter, the phase change concrete demonstrated significantly lower indoor temperature fluctuations, with a maximum reduction of 45.39 %. Furthermore, the study found that the particle size of microcapsules had varying effects on concrete performance, with larger particles improving thermal properties and smaller particles enhancing mechanical properties. Overall, this research highlights the potential of composite phase change microcapsules and phase change concrete based on microporous cenospheres for effective temperature control and energy conservation in building applications.