Gas-modulating microcapsules for spatiotemporal control of hypoxia.

Oxygen is a vital molecule involved in regulating development, homeostasis, and disease. The oxygen levels in tissue vary from 1 to 14% with deviations from homeostasis impacting regulation of various physiological processes. In this work, we developed an approach to encapsulate enzymes at high loading capacity, which precisely controls the oxygen content in cell culture. Here, a single microcapsule is able to locally perturb the oxygen balance, and varying the concentration and distribution of matrix-embedded microcapsules provides spatiotemporal control. We demonstrate attenuation of hypoxia signaling in populations of stem cells, cancer cells, endothelial cells, cancer spheroids, and intestinal organoids. Varying capsule placement, media formulation, and timing of replenishment yields tunable oxygen gradients, with concurrent spatial growth and morphogenesis in a single well. Capsule containing hydrogel films applied to chick chorioallantoic membranes encourages neovascularization, providing scope for topical treatments or hydrogel wound dressings. This platform can be used in a variety of formats, including deposition in hydrogels, as granular solids for 3D bioprinting, and as injectable biomaterials. Overall, this platform's simplicity and flexibility will prove useful for fundamental studies of oxygen-mediated processes in virtually any in vitro or in vivo format, with scope for inclusion in biomedical materials for treating injury or disease.

Assembly of Metal-Phenolic Networks onto Microbubbles for One-Step Generation of Functional Microcapsules.

The one-step assembly of metal-phenolic networks (MPNs) onto particle templates can enable the facile, rapid, and robust construction of hollow microcapsules. However, the required template removal step may affect the refilling of functional species in the hollow interior space or the in situ encapsulation of guest molecules during the formation of the shells. Herein, a simple strategy for the one-step generation of functional MPNs microcapsules is proposed. This method uses bovine serum albumin microbubbles (BSA MBs) as soft templates and carriers, enabling the efficient pre-encapsulation of guest species by leveraging the coordination assembly of tannic acid (TA) and FeIII ions. The addition of TA and FeIII induces a change in the protein conformation of BSA MBs and produces semipermeable capsule shells, which allow gas to escape from the MBs without template removal. The MBs-templated strategy can produce highly biocompatible capsules with controllable structure and size, and it is applicable to produce other MPNs systems like BSA-TA-CuII and BSA-TA-NiII . Finally, those MBs-templated MPNs capsules can be further functionalized or modified for the loading of magnetic nanoparticles and the pre-encapsulation of model molecules through covalence or physical adsorption, exhibiting great promise in biomedical applications.

A Room-Temperature Self-Healing Liquid Metal-Infilled Microcapsule Driven by Coaxial Flow Focusing for High-Performance Lithium-Ion Battery Anode.

Liquid metals have attracted a lot of attention as self-healing materials in many fields. However, their applications in secondary batteries are challenged by electrode failure and side reactions due to the drastic volume changes during the "liquid-solid-liquid" transition. Herein, a simple encapsulated, mass-producible method is developed to prepare room-temperature liquid metal-infilled microcapsules (LMMs) with highly conductive carbon shells as anodes for lithium-ion batteries. Due to the reasonably designed voids in the microcapsule, the liquid metal particles (LMPs) can expand freely without damaging the electrode structure. The LMMs-based anodes exhibit superior capacity of rete-performance and ultra-long cycling stability remaining 413 mAh g-1 after 5000 cycles at 5.0 A g-1. Ex situ X-ray powder diffraction (XRD) patterns and electrochemical impedance spectroscopy (EIS) reveal that the LMMs anode displays a stable alloying/de-alloying mechanism. DFT calculations validate the electronic structure and stability of the room-temperature LMMs system. These findings will bring some new opportunities to develop high-performance battery systems.

Designing Tough Hydrogel Shells for Glucose Sensing.

Conventional hydrogel microcapsules often suffer from inadequate mechanical stability, hindering their use. Here, water-cored double-network (DN) hydrogel shells are designed, formed by polyacrylamide and calcium alginate networks using triple-emulsion templates. These DN hydrogel shells offer robust mechanical stability, optical transparency, and a precisely-defined cut-off threshold. The feasibility of this platform is demonstrated through the development of a fluorometric glucose sensor. Glucose oxidase is enclosed within the water core, while a pH-responsive fluorescent dye is incorporated into the DN shells. Glucose diffuses into the core through the DN shells, where the glucose oxidase converts glucose into gluconic acid, leading to pH reduction and a subsequent decrease in fluorescence intensity of DN shells. Additionally, the pH-sensitive colorant dissolved in the medium enables visual pH assessment. Thus, glucose levels can be determined using both fluorometric and colorimetric methods. Notably, the DN shells exhibit exceptional stability, enduring intense mechanical stress and cycles of drying and rehydration without leakage. Moreover, the DN shells act as effective barriers, safeguarding glucose oxidase against proteolysis by large disruptive proteins, like pancreatin. This versatile DN shell platform extends beyond glucose oxidase encapsulation, serving as a foundation for various capsule sensors utilizing enzymes and heterogeneous catalysts.

NIR Light-Fuse Drug-Free Photothermal Armor-Piercing Microcapsule for Femoral Vein Thrombosis Therapy.

Acute thrombosis and its complications are leading global causes of disability and death. Existing thrombolytic drugs, such as alteplase and urokinase (UK), carry a significant bleeding risk during clinical treatments. Thus, the development of a novel thrombolysis strategy is of utmost urgency. Based on the previous work, the hollow structure of microcapsules (MC) is fabricated. Subsequently, armor-piercing MC, known as Fucoidan/S-Nitrosoglutathione/Melanin@MC (FGM@MC) is obtained, using a layer-by-layer (LBL) self-assembly method. Utilizing near-infrared (NIR) light as a trigger, the FGM@MC demonstrated photothermal thrombolysis at the site of thrombus due to its stable and outstanding photothermal properties. Simultaneously, photothermal stimulation leads to the release of a significant amount of nitric oxide from the FGM@MC, resulting in cavitation effects for mechanical thrombolysis. In vivo experiments confirmed the stable release of nitric oxide under NIR light irradiation. Treatment of femoral vein thrombosis in rats revealed that the thrombolytic effectiveness of FGM@MC+NIR (53.71%) is comparable to that of UK (59.70%). Notably, FGM@MC does not interfere with the coagulation function of rats and exhibits a favorable safety profile. In conclusion, this study demonstrates that the drug-free armor-piercing microcapsule has significant potential in the treatment of thrombosis, offering a safe and effective alternative to traditional thrombolytic therapies.

Nanoparticle-Empowered Core-Shell Microcapsules: From Architecture Design to Fabrication and Functions.

Compartmentalization is a powerful concept to integrate multiscale components with diverse functionalities into miniature architectures. Inspired by evolution-optimized cell compartments, synthetic core-shell capsules enable storage of actives and on-demand delivery of programmed functions, driving scientific progress across various fields including adaptive materials, sustainable electronics, soft robotics, and precision medicine. To simultaneously maximize structural stability and environmental sensitivity, which are the two most critical characteristics dictating performance, diverse nanoparticles are incorporated into microcapsules with a dense shell and a liquid core. Recent studies have revealed that these nano-additives not only enhance the intrinsic properties of capsules including mechanical robustness, optical behaviors, and thermal conductivity, but also empower dynamic features such as triggered release, deformable structures, and fueled mobility. In this review, the physicochemical principles that govern nanoparticle assembly during microencapsulation are examined in detail and the architecture-controlled functionalities are outlined. Through the analysis of how each primary method implants nanoparticles into microcapsules, their distinct spatial organizations within the core-shell structures are highlighted. Following a detailed discussion of the specialized functions enabled by specific nanoparticles, the vision of the required fundamental insights and experimental studies for this class of microcarriers to fulfill its potential are sketched.

Eucalyptol-loaded microcapsules combined with Cynanchum komarovii extracts provide long-term and low-risk management of Chinese wolfberry (Lycium barbarum L.).

Realizing eco-friendly, long-term, and low-risk aphid control on Lycium barbarum (medicinal cash crop) using a Cynanchum komarovii extracts and eucalyptus oil-loaded microcapsules (EOMCs) formulation compositions is viable. In this study, the aim is to optimize the composition of Cynanchum komarovii extracts and EOMCs formulation for effective control of aphids, the release of EOMCs was controlled by changing the cross-linking degree of the shell to match the aphid control characteristics of Cynanchum komarovii extracts. Four types of polyamines were used as cross-linking agents for the preparation of EOMCs by interfacial polymerization. The bioactivity, wettability, and field application efficacy of Cynanchum komarovii extracts and different EOMCs formulation compositions were evaluated. These EOMCs exhibited an encapsulation efficiency exceeding 85 %. The control efficiency of the formulation compositions of microcapsules with a moderate release rate and Cynanchum komarovii extracts on aphids remained at 62.86 %, while the control efficiency of the combination of microcapsules with the fastest and slowest rates with Cynanchum komarovii extracts was only 48.62 % and 57.11 %, respectively. The formulation compositions of Cynanchum komarovii extracts with all four types of EOMCs were found to be safe for Chinese wolfberry plants. Overall, by selecting appropriate polyamines during fabrication, the release rate can be effectively controlled to achieve sustainable and low-risk aphid control in Lycium barbarum through compounding with selected microcapsules.

Polyelectrolyte Microcapsules: An Extended Release System for the Antiarrhythmic Complex of Allapinin with Glycyrrhizic Acid Salt.

Allapinin has antiarrhythmic activity and can be used to prevent and treat various supraventricular and ventricular arrhythmias. Nevertheless, it is highly toxic and has a number of side effects associated with non-specific accumulation in various tissues. The complex of this substance with the monoammonium salt of glycyrrhizic acid (Al:MASGA) has less toxicity and improved antiarrhythmic activity. However, the encapsulation of Al:MASGA in polyelectrolyte microcapsules (PMC) for prolonged release will reduce the residual adverse effects of this drug. In this work, the possibility of encapsulating the allapinin-MASGA complex in polyelectrolyte microcapsules based on polyallylamine and polystyrene sulfonate was investigated. The encapsulation methods of the allapinin-MASGA in polyelectrolyte microcapsules by adsorption and coprecipitation were compared. It was found that the coprecipitation method did not result in the encapsulation of Al:MASGA. The sorption method facilitated the encapsulation of up to 80% of the original substance content in solution in PMC. The release of the encapsulated substance was further investigated, and it was shown that the release of the encapsulated Al:MASGA was independent of the substance content in the capsules, but at pH 5, a two-fold decrease in the rate of drug release was observed.

Polyethersulfone Polymer for Biomedical Applications and Biotechnology.

Polymers stand out as promising materials extensively employed in biomedicine and biotechnology. Their versatile applications owe much to the field of tissue engineering, which seamlessly integrates materials engineering with medical science. In medicine, biomaterials serve as prototypes for organ development and as implants or scaffolds to facilitate body regeneration. With the growing demand for innovative solutions, synthetic and hybrid polymer materials, such as polyethersulfone, are gaining traction. This article offers a concise characterization of polyethersulfone followed by an exploration of its diverse applications in medical and biotechnological realms. It concludes by summarizing the significant roles of polyethersulfone in advancing both medicine and biotechnology, as outlined in the accompanying table.

Synthesis and characterisation of microcapsules for self-healing dental resin composites.

AIM: The purpose of this study was to i) synthesise TEGDMA-DHEPT microcapsules in a laboratory setting; ii) characterise the resultant microcapsules for quality measures. MATERIALS & METHODS: Microcapsules were prepared by in situ polymerization of PUF shells. Microcapsules characterisation include size analysis, optical and SEM microscopy to measure the diameter and analyse the morphology of PUF microcapsules. FT-IR spectrometer evaluated microcapsules and benzyl peroxide catalyst polymerization independently. RESULT: Average diameter of TEGDMA-DHEPT microcapsules was 120 ± 45 µm (n: 100). SEM imaging of the capsular shell revealed a smooth outer surface with deposits of PUF nanoparticles that facilitate resin matrix retention to the microcapsules upon composite fracture. FT-IR spectra showed that microcapsules crushed with BPO catalyst had degree of conversion reached to 60.3%. CONCLUSION: TEGDMA-DHEPT microcapsules were synthesised according to the selected parameters. The synthesised microcapsules have a self-healing potential when embedded into dental resin composite as will be demonstrated in our future work.

Self-Assemble Silk Fibroin Microcapsules for Cartilage Regeneration through Gene Delivery and Immune Regulation.

Effective treatments for cartilage defects are currently lacking. Gene delivery using proper delivery systems has shown great potential in cartilage regeneration. However, the inflammatory microenvironment generated by the defected cartilage severely affects the system's delivery efficiency. Therefore, this study reports a silk fibroin microcapsule (SFM) structure based on layer-by-layer self-assembly, in which interleukin-4 (IL-4) is modified on silk by click chemistry and loaded with lysyl oxidase plasmid DNA (LOX pDNA). The silk microcapsules display good biocompatibility and the release rate of genes can be adjusted by controlling the number of self-assembled layers. Moreover, the functionalized SFMs mixed with methacrylated gelatin (GelMA) exhibit good injectability. The IL-4 on the outer layer of the SFM can regulate macrophages to polarize toward the M2 type, thereby promoting cartilage matrix repair and inhibiting inflammation. The LOX pDNA loaded inside can be effectively delivered into cells to promote extracellular matrix generation, significantly promoting cartilage regeneration. The results of this study provide a promising biomaterial for cartilage repair, and this novel silk-based microcapsule delivery system can also provide strategies for the treatment of other diseases.

Promoting ß-cells function by the recapitulation of in vivo microenvironmental differentiation signals.

The study aims to transdifferentiate rat bone marrow-derived mesenchymal stem cells (BM-MSCs) more efficiently into islet-like cells and encapsulate and transplant them with vital properties like stability, proliferation, and metabolic activity enhanced for the treatment of T1DM. Trans-differentiation of BM-MCs into islet-like cells induced by high glucose concentration combined with Nicotinamide, ꞵ-Mercaptoethanol, ꞵ-Cellulin, and IGF-1. Glucose challenge assays and gene expression profiles were used to determine functionality. Microencapsulation was performed using the vibrating nozzle encapsulator droplet method with a 1% alginate concentration. Encapsulated ꞵ-cells were cultured in a fluidized-bed bioreactor with 1850 µL/min fluid flow rates and a superficial velocity of 1.15 cm/min. The procedure was followed by transplanting transdifferentiated cells into the omentum of streptozotocin (STZ)-induced diabetic Wistar rats. Changes in weight, glucose, insulin, and C-peptide levels were monitored for 2 months after transplantation. PDX1, INS, GCG, NKx2.2, NKx6.1, and GLUT2 expression levels revealed the specificity of generated ß-cells with higher viability (about 20%) and glucose sensitivity about twofold more. The encapsulated ß-cells decreased the glucose levels in STZ-induced rats significantly (P < 0.05) 1 week after transplantation. Also, the weight and levels of insulin and C-peptide reached the control group. In contrast to the treated, the sham group displayed a consistent decline in weight and died when loss reached > 20% at day ~ 55. The coated cells secrete significantly higher amounts of insulin in response to glucose concentration changes. Enhanced viability and functionality of ß-cells can be achieved through differentiation and culturing, a promising approach toward insulin therapy alternatives.

Advances in spray-dried probiotic microcapsules for targeted delivery: a review.

Probiotics have gained significant attention owing to their roles in regulating human health. Recently, spray drying has been considered as a promising technique to produce probiotic powders due to its advantages of high efficiency, cost-saving, and good powder properties. However, the severe environmental conditions from drying and digestion can significantly reduce cell viability, resulting in poor bioaccessibility and bioavailability of live cells. Therefore, there is a need to develop effective targeted delivery systems using spray drying to protect bacteria and to maintain their physiological functions in the targeted sites. This review highlights recent studies about spray-dried targeted delivery vehicles for probiotics, focusing on key strategies to protect bacteria when encountering external stresses, the formation mechanism of particles, the targeted release and colonization mechanisms of live cells in particles with different structures. Advances in the targeted delivery of live probiotics via spray-dried vehicles are still in their early stages. To increase the possibilities for industrialization and commercialization, functional improvement of microcapsules in terms of protection, targeted release, and colonization of bacteria, as well as the effect of spray drying on bacterial physiological functions in the host, need to be further investigated.

Nanocoating of lactic acid bacteria: properties, protection mechanisms, and future trends.

Lactic acid bacteria (LAB) is a type of probiotic that may benefit intestinal health. Recent advances in nanoencapsulation provide an effective strategy to protect them from harsh conditions via surface functionalization coating techniques. Herein, the categories and features of applicable encapsulation methods are compared to highlight the significant role of nanoencapsulation. Commonly used food-grade biopolymers (polysaccharides and protein) and nanomaterials (nanocellulose and starch nanoparticles) are summarized along with their characteristics and advances to demonstrate enhanced combination effects in LAB co-encapsulation. Nanocoating for LAB provides an integrity dense or smooth layer attributed to the cross-linking and assembly of the protectant. The synergism of multiple chemical forces allows for the formation of subtle coatings, including electrostatic attractions, hydrophobic interactions, π-π, and metallic bonds. Multilayer shells have stable physical transition properties that could increase the space between the probiotic cells and the outer environment, thus delaying the microcapsules burst time in the gut. Probiotic delivery stability can be promoted by enhancing the thickness of the encapsulated layer and nanoparticle binding. Maintenance of benefits and minimization of nanotoxicity are desirable, and green synthesized nanoparticles are emerging. Future trends include optimized formulation, especially using biocompatible materials, protein or plant-based materials, and material modification.

Encapsulation of Fragrances in Micro- and Nano-Capsules, Polymeric Micelles, and Polymersomes.

Fragrances are ubiquitously and extensively used in everyday life and several industrial applications, including perfumes, textiles, laundry formulations, hygiene household products, and food products. However, the intrinsic volatility of these small organic molecules leaves them particularly susceptible to fast depletion from a product or from the surface they have been applied to. Encapsulation is a very effective method to limit the loss of fragrance during their use and to sustain their release. This review gives an overview of the different materials and techniques used for the encapsulation of fragrances, scents, and aromas, as well as the methods used to characterize the resulting encapsulation systems, with a particular focus on cyclodextrins, polymer microcapsules, inorganic microcapsules, block copolymer micelles, and polymersomes for fragrance encapsulation, sustained release, and controlled release.

Capsule-based colorimetric temperature monitoring system for customizable cold chain management.

The COVID-19 pandemic and the resulting supply chain disruption have rekindled crucial needs for safe storage and transportation of essential items. Despite recent advances, existing temperature monitoring technologies for cold chain management fall short in reliability, cost, and flexibility toward customized cold chain management for various products with different required temperature. In this work, we report a novel capsule-based colorimetric temperature monitoring system with precise and readily tunable temperature ranges. Triple emulsion drop-based microfluidic technique enables rapid production of monodisperse microcapsules with an interstitial phase-change oil (PCO) layer with precise control over its dimension and composition. Liquid-solid phase transition of the PCO layer below its freezing point triggers the release of the encapsulated payload yielding drastic change in color, allowing user-friendly visual monitoring in a highly sensitive manner. Simple tuning of the PCO layer's compositions can further broaden the temperature range in a precisely controlled manner. The proposed simple scheme can readily be formulated to detect both temperature rise in the frozen environment and freeze detection as well as multiple temperature monitoring. Combined, these results support a significant step forward for the development of customizable colorimetric monitoring of a broad range of temperatures with precision.

Preparation and curing behaviour of microencapsulated curing agents for cold-mixed epoxy asphalt.

This study aimed to improve control over the curing behaviour of cold-mixed epoxy asphalt by using a microencapsulated curing agent (2-PZ@PC). Prepared through solvent evaporation, the 2-PZ@PC microcapsules had 2-phenylimidazole as the core material and polycarbonate as the shell material. The research examined the impact of core-shell mass ratio on microcapsule morphology and composition. Various equations, including the kinetics equation, Kissinger equation, Flynn-Wall-Ozawa, and Crane equations, were employed to assess the sustained release effect of 2-PZ@PC microcapsules on epoxy resin curing behaviour. Fluorescence microscopy and viscosity experiments were used to observe the release state of microcapsules and confirm the retardation phenomenon during construction. Optimal 2-PZ@PC microcapsules displayed a smooth spherical morphology and a maximum encapsulation rate of 32 wt% at a 1:1 core-shell ratio. The microencapsulated curing agent effectively regulated cold-mixed epoxy asphalt's curing behaviour, enhancing retention time control and application reliability.

Preparation and Characterisation of Acid-Base-Change-Sensitive Binary Biopolymer Films with Olive Oil and Ozonated Olive Oil Nano/Microcapsules and Added Hibiscus Extract.

The purpose of this study was to develop and characterise bionanocomposites based on chitosan (CHIT) and alginate (ALG) in two series, which were subsequently functionalised with emulsions based on a combination of water, oil, ozonated oil and hibiscus flower extracts. The structure and morphology of the materials produced were characterised by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and ultraviolet and visible light (UV-Vis) absorption spectroscopy, along with a surface colour analysis and the determination of the mechanical and thermal properties of the resulting composites. Functionalisation did affect the analysed composite parameters. The FTIR spectra indicated that the polysaccharide matrix components were compatible. The SEM images also confirmed the presence of nano/microcapsules in the polysaccharide matrix. The obtained results indicate that the order of adding polysaccharides has a significant impact on the encapsulation capacity. The encapsulation resulted in the improved thermal stability of the composites. The emissions analysis showed that the composites containing nano/microcapsules are characterised by a higher emission intensity and are sensitive to acid or base changes. Significant differences in emission intensity were observed even at low concentrations of acids and bases. A drop in the mechanical properties was observed following functionalisation. The results of this study suggest that these bionanocomposites can be used as active and/or smart packaging materials.

Polyelectrolyte Microcapsules-A Promising Target Delivery System of Amiodarone with the Possibility of Prolonged Release.

Atrial fibrillation is one of the most common cardiac arrhythmias. Pharmacological preparations are used for treatment to control heart rate and rhythm. Amiodarone is one of these highly effective preparations, but, at the same time, it has significant toxicity and nonspecific accumulation in tissues. The drug delivery system based on polyelectrolyte microcapsules is one of the solutions. For this purpose, we compared different encapsulation methods of amiodaron: monoammonium salt of glycyrrhizic acid (Am:MASGA) complex (molar ratio 1:8). The concentration of amiodarone was determined by spectrophotometric methods at 251 nm. It has been shown that the co-precipitation method allows capturing 8% of Am:MASGA by CaCO3 microspherulites, which is not sufficient for the long-acting drug. The adsorption method allows encapsulating more than 30% of Am:MASGA into CaCO3 microspherulites and polyelectrolyte microcapsules CaCO3(PAH/PSS)3, but, at the same time, an insignificant amount of substance is released into the incubation medium. The development of delivery and long-acting drug system based on such methods are not inexpedient. The most appropriate encapsulation method of Am:MASGA is the adsorption method into polyelectrolyte microcapsules with complex interpolyelectrolyte structure (PAH/PSS)3. Such a type of PMC adsorbed about 50% of the initial amount of the substance and 25-30% of Am:MASGA was released into the medium after 115 h of incubation. The adsorption of Am:MASGA by polyelectrolyte microcapsules has electrostatic nature as evidenced by the acceleration of the release by 1.8 times as ionic strength increases.

Sorption of Salts of Various Metals by Polyelectrolyte Microcapsules.

Anthropogenic activity negatively affects the environment by polluting it with the salts of various metals. One of the ways to reduce this influence is to use water purification methods for the salts of various metals. Water purification methods based on nanomaterials are promising. In this regard, we proposed to study polyelectrolyte microcapsules (PMC) as a promising sorption agent for the salts of various metals. It was found that the polystyrene sulfonate-polyallylamine (PSS-PAH) polyelectrolyte complex and polyelectrolyte microcapsules of different compositions are not able to adsorb salts CuSO4, Pb(NO)3, FeCl3, and CuCl2. At the same time, it was found that all types of capsules, except for (PSS/PAH)2/PSS, are capable of sorbing about 420 µg of K3[Fe(CN)6] and about 500 µg of K4[Fe(CN)6] from solution. The adsorption of polyelectrolyte microcapsules has an electrostatic nature which is confirmed by increases in the sorption capacity of PMC of K3[Fe(CN)6] and K4[Fe(CN)6] with decreases in the pH of the solution. Also, It was confirmed that the sorption process of PMC of K3[Fe(CN)6] and K4[Fe(CN)6] is concentration dependent and has the limitation of the number of binding sites.