Porous Microspheres Research Articles

Magnetic open porous microspheres via high internal phase emulsion templating as efficient Pb adsorption material

Emulsion templating enables the synthesis of hierarchically porous polymers. By adding another phase to this process and therefore, creating a multiple emulsion templating method, it is possible to synthesise hierarchically porous microspheres. In this study water-in-oil-in-water double emulsion templating was used to prepare porous microspheres by utilising thiol-ene click chemistry. For this trimethylolpropane tris(3-mercaptopropionate) and trimethylolpropane triacrylate were used. To the monomer phase magnetic nanoparticles were added to synthesise polyHIPE microspheres with magnetic properties. The higher magnetic nanoparticles (MNPs) content also affected the morphology and microsphere size. With increasing MNPs content the bead diameter decreased, while the diameter of the primary pores of the cross-section increased. However, while the MNPs influenced the morphology, the chemical composition was not influenced. The microspheres were used for the removal of Pb2+. From a 2.9 mg/L solution up to 97.0% of Pb was removed after 24 h.

Selective adsorption of tetracycline and copper(II) on ion-imprinted porous alginate microspheres: performance and potential mechanisms.

A novel epichlorohydrin and thiourea grafted porous alginate adsorbent (UA-Ca/IIP) was synthesized using ion-imprinting and direct templating to remove copper ions (Cu(II)) and tetracycline (TC) in aqueous solution. UA-Ca/IIP demonstrated great selectivity for Cu(II) and TC among different coexisting anions (CO32-, PO43- and SO42-), cations (Ca2+, Mg2+ and NH4+), and antibiotics (oxytetracycline and sulfamethoxazole). The adsorption of TC and Cu(II) by UA-Ca/IIP was significantly affected by the pH of the solution, and the quantity of TC and Cu(II) adsorbed reached a maximum at pH 5. A pseudo-second-order model better fitted the kinetic data; the Langmuir model predicted the maximum adsorption quantities 3.527 mmol TC g-1 and 4.478 mmol Cu(II) g-1 at 298 K. Thermodynamic studies indicated that the TC and Cu(II) adsorption was more rapid at a higher temperature. Antagonistic and synergistic adsorption experiments showed that the adsorption capacity of TC would increase significantly with the increase of Cu(II) concentration. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that along with the influence of pH, electrostatic interaction and complexation were the main mechanisms of TC and Cu(II) adsorption. Regeneration experiments revealed that TC and Cu(II) were removed efficiently and that UA-Ca/IIP was recyclable over the long term. These results show that the modified porous alginate microsphere is a green and recyclable adsorbent, which has good selectivity and high adsorption performance for the removal of TC and Cu(II).

A Detailed Review on Porous Microspheres: Methods of Preparation, Characterization, and its Applications

Porous microspheres are a new kind of carrier with high porosity, uniform porous structure, and pore size with narrow distribution. They are having inter-connective pores present externally and internally which leads to very low mass density and greater specific surface area, making them have excellent adsorption properties. Because of this uniqueness over non-porous microspheres, they are having extensive pharmaceutical applications. Porous microspheres are formulated by several methods, which involve the use of porogens or templating agents for the formation of pores, self-forming pores by particle matrices without any pore-forming agents, and chemical synthesis. These microspheres are very promising in varied fields of medicine such as enhancing of dissolution of poorly soluble drugs, developing novel drug delivery systems, and improving the functional properties of drug-loaded particles. The main factor governing their applications depends on the pore structure and porosity. Therefore, this review aims at emphasizing the principles underlying the development and evaluation of porous microspheres as a controlled and targeted drug delivery system and becomes an informative reference that can be beneficial for several interested research scholars.

Functional Polymeric Micromaterials Based on Aggregation‐Induced Emission Luminogens

AbstractAggregate materials have attracted tremendous attention because of their modified or totally different properties compared with their molecular counterparts. Among various mesoscopic aggregate materials, polymeric micromaterials possess the advantages of diverse structures and flexible manufacturing, enabling them to serve as excellent carriers for aggregation‐induced emission luminogens (AIEgens) and good platforms for the research of aggregate science. In recent years, polymeric micromaterials constructed from AIEgens have witnessed rapid development and show great application potential in various fields, such as environmental sensing, multicolor displaying, and energy conversion. This review summarizes the recent progress on the design, preparation, structure, and applications of AIEgen‐based polymeric micromaterials. According to the structure features, AIEgen‐based polymeric micromaterials are divided into three categories, including microsphere, microfiber, and other‐shaped microparticles. The most representative examples in each category are highlighted by focusing on their subdivision structures such as solid microsphere, porous microsphere, microcapsule, microfiber doped‐ or coated with AIEgens, and core–shell microfiber. Finally, the challenges and prospects in this research field are also discussed. It is hoped that this review can provide readers with an overall view on the development of AIEgen‐based polymeric micromaterials and boost their further research.

Reduced graphene oxide wrapped ZnCo layered double hydroxides microsphere as efficient sulfur host in lithium-sulfur batteries

The practical application of lithium-sulfur (Li-S) batteries is impeded by the shuttling of the polysulfide and slow sulfur electrochemical reaction. In this study, a reduced graphene oxide (rGO) wrapped hollow ZnCo layered double hydroxides (ZnCo-LDH) microsphere is fabricated as sulfur host material. The rGO nanosheets offer efficient charge transportation pathways. Meanwhile, the porous rGO and hollow ZnCo-LDH provide sufficient space for sulfur storage and mitigates the volume variation during battery charging and discharging. In addition, ZnCo-LDH exhibits excellent chemical adsorption capacity for polysulfides, and promotes their electrochemical conversion reactions. Benefited from these advantages, the S/ZnCo-LDH@rGO cathode delivers a high rate performance of 796.5 mAh g−1 at 5.0 C, and excellent stability performance with a capacity decay of 0.036 % per cycle after 500 cycles at 1.0 C. This study shows that the porous microsphere design of rGO wrapped layered double hydroxides has excellent application prospects as efficient sulfur host for Li-S batteries.

Synthesis and Characterization of Carbon Microbeads.

We report a microfluidic-based droplet generation platform for synthesizing micron-sized porous carbon microspheres. The setup employs carbon materials such as graphite, carbon nanotubes, graphene, fullerenes, and carbon black as starting materials. Custom composition, structure, and function are achieved through combinations of carbon materials, cross-linkers, and additives along with variations in process parameters. Carbon materials can be assembled into spheres with a mean diameter of units to hundreds of μm with relatively tight size distribution (<25% RSD). Pore structure and size (tens to hundreds of angstrom) can be modulated by incorporating porogen/coporogen dilutants during synthesis. The microbeads have excellent mechanical stability with an elastic modulus of hundreds of MPa. They can sustain high dynamic fluid flow pressures of up to 9000 psi. This work lays the foundation for synthesizing novel tailorable and customizable carbon microbeads. It opens avenues for applying these novel materials for composite and additive manufacturing, energy, life science, and biomedical applications.

Lightweight and self‐healing thermally expandable microsphere/silver composites with segregated conductive network for high‐efficiency electromagnetic interference shielding

AbstractPolymer‐based electromagnetic interference (EMI) shielding materials with lightweight, self‐healing and high shielding performance show a wide application in electronics, medicine, national defense, aerospace and other fields. However, the conflict between a good conductive network structure and obtaining low density and excellent self‐healing property brings about tremendous challenges for fabricating these polymer‐based materials. Herein, a lightweight and self‐healing thermally expandable microsphere / silver (TEM/Ag) EMI shielding composites were prepared through a thermal foaming process. Due to the segregated Ag conductive network and expanded porous microsphere structure, the TEM/Ag composites possessed low density (0.095 g/cm3) and super‐high EMI specific shielding effectiveness (2816.3 dB cm2/g). In addition, benefiting from this unique structure, the composites exhibited excellent EMI shielding durability that can withstand ultrasonic washing 6 h (100 W), ethanol (99.5% purity), strong acid (pH 2.0), strong base (pH 12.0), NaCl solution soaking and long‐term air exposure (180 days). Furthermore, the inherent long‐chain entanglement imparts the composites a self‐healing feature, and 86% of the EMI shielding effectiveness can be maintained after self‐healing procedure.

3D Carbon Microspheres with a Maze-Like Structure and Large Mesopore Tunnels Built From Rapid Aerosol-Confined Coherent Salt/Surfactant Templating.

Hierarchically porous carbons with tailor-made properties are essential for applications wherein rich active sites and fast mass transfer are required. Herein, a rapid aerosol-confined salt/surfactant templating approach is proposed for synthesizing hierarchically porous carbon microspheres (HPCMs) with a maze-like structure and large mesopore tunnels for high-performance tri-phase catalytic ozonation. The confined assembly in drying microdroplets is crucial for coherent salt (NaCl) and surfactant (F127) dual templating without macroscopic phase separation. The HPCMs possess tunable sizes, a maze-like structure with highly open macropores (0.3-30µm) templated from NaCl crystal arrays, large intrawall mesopore tunnels (10-45nm) templated from F127, and rich micropores (surface area >1000 m2 g-1 ) and oxygen heteroatoms originated from NaCl-confined carbonization of phenolic resin. The structure formation mechanism of the HPCMs and several influencing factors on properties are elaborated. The HPCMs exhibit superior performance in gas-liquid-solid tri-phase catalytic ozonation for oxalate degradation, owing to their hierarchical pore structure for fast mass transfer and rich defects and oxygen-containing groups (especially carbonyl) for efficient O3 activation. The reactive oxygen species responsible for oxalate degradation and the influences of several structure parameters on performance are discussed. This work may provide a platform for producing hierarchically porous materials for various applications.

Realizing optimized interfacial polarization and impedance matching with CNT-confined Co nanoparticles in hollow carbon microspheres for enhanced microwave absorption

The hollow porous structure with exceptional interfacial effect and customizable internal environment shows significant potential for application as electromagnetic shielding and absorption materials. However, designing hollow porous electromagnetic absorbers with both desirable impedance matching and high loss capability remains a challenge. Herein, 3D hollow porous electromagnetic microspheres were constructed by assembling 0D Co magnetic nanoparticles, 1D carbon nanotubes, and 2D carbon nanosheets. Due to the sufficient sites for Co2+ riveting, the high loading of magnetic carbon nanotubes (CoNC) and porous carbon spheres formed high-density interfaces, enhancing the interfacial polarization. Furthermore, high-density CoNC were grown in situ on the hollow porous carbon (HPC) microsphere, forming a highly dispersed 3D magnetic network that inhibited the aggregation of magnetic nanoparticles and enhanced magnetic coupling. Therefore, the as-prepared CoNC/HPC microspheres exhibited excellent microwave absorption (MA) performance, with a minimum reflection loss of -33.2 dB and an effective bandwidth of 5.5 GHz at a thickness of only 1.8 mm. The interfacial polarization mechanism for enhanced MA performance was demonstrated by electron holography and density functional theory calculations. Magnetic holography and micromagnetic simulations also revealed magnetic confinement and coupling mechanism. This work provides a new approach for designing electromagnetic absorbers with optimized impedance matching and loss capability.

A novel target-triggered signal chemiluminescence kit for thrombin detection based on fusiform Au/MIL-53(Fe)

In this work, a fusiform Au/MIL-53(Fe) catalyst was used to construct a chemiluminescence (CL) kit for the sensitive and rapid detection of thrombin (THR). The porous silica microspheres encapsulated with luminol in holes by thrombin aptamer (THR-APT/Luminol/SPSiO2) and the fusiform Au/MIL-53(Fe) modified with thrombin aptamer complementary chains (Au/MIL-53(Fe)-SSDNA) were prepared. Then, a CL kit for THR detection was constructed by using the prepared composites. When thrombin is added to the reaction system, it binds to its aptamer (THR-APT) to open the holes of SPSiO2, which cause luminol and Au/MIL-53(Fe) release. Released luminol enters the detection system and triggers the reaction of luminol–H2O2–NaOH with the catalyst of Au/MIL-53(Fe), and produces a CL signal. The detection limit and the linear range of the kit were 4.7 × 10−15 M and 1.5 × 10−14 – 3.5 × 10−10 M, respectively. The CL kit also showed high stability, selectivity and reproducibility, and was successfully applied to the determination of THR in serum samples. Therefore, the proposed method for detecting THR has great application potential in the diagnosis of blood-related disease markers.

Extraction, characterization and controlled release application of pectin-like/chitosan hydrogels system loaded Ciprofloxacin.

In recent decades, drug delivery applications have extensively utilized hydrogel systems based on natural polymers. Among the numerous biopolymer-based hydrogel drug delivery systems reported, a novel pectin-like substance was extracted from fig leaves and copolymerized with chitosan. The hydrogel was reformed into microspheres using glutaraldehyde (chemical cross-linker) and sodium hexametaphosphate (physical cross-linker). The extracted polysaccharide and the prepared hydrogels were characterized by FTIR, GC/MS, SEC/MALS/DRI as well as XRD, SEM, BET, and thermal analysis. SEM images revealed the formation of porous microspheres with an average size of 50 μm in diameter. Degrees of swelling in pH7 at 35°C have shown the hydrogels reached two to three times their weights. This has been reflected in their ability to load drugs or any other chemicals. The loading formula shows that hydrogels have maximum loading efficiency more than one-third of the weight of hydrogel. The antimicrobial ciprofloxacin was used as a model for loading on prepared hydrogels. The loaded hydrogels were tested for their biological activities against staphylococcus aureus (S. aureus) bacteria. The antimicrobial growth inhibition zone of the cultured (S. aureus) by ciprofloxacin-loaded hydrogel was followed, which shows controlled growth in inhibition zone sizes and for long time intervals. Results showed that the pectin-chitosan hydrogels exhibited significant antibacterial activity against gram - positive bacteria (S. aureus), with an inhibition zone of 45 mm for (CH-co-FLP)/GLU hydrogel. In vitro, the ciprofloxacin-loaded hydrogels were studied and the cumulative release of ciprofloxacin under suitable conditions was found in a controlled manner and kept release for a long time interval. Data exhibited that the cumulative release profile of ciprofloxacin from the hydrogel demonstrated sustained release over 48 hours, with a value of 6.9% released within the first 24 hours and 7.0 and 6.9% % released at the end of the study for the (CH-co-FLP)/GLU and (CH-co-FLP)/SMP hydrogels, respectively. The novel pectin-chitosan hydrogels hold the potential to enhance the quality of life for numerous patients by minimizing the need for frequent intake of chronic medications.

SiNPs Porous Microspheres Promote Proliferation and Differentiation of hDPSCs

SiNPs Porous Microspheres Promote Proliferation and Differentiation of hDPSCs

Mechanistic Study of the Formation of Multicomponent Oxide Porous Microspheres (MICROSCAFS®) by Cryo-Scanning Electron Microscopy.

Multicomponent oxide microspheres with interconnected macroporosity (MICROSCAFS®) are new materials with great potential as support materials for photocatalysis, optimized for real life applications and for other uses that are still being explored. They are obtained from an adapted sol-gel process combined with phase separation phenomena that occur within the water droplets of an emulsion. We present here a methodology based on cryogenic scanning electron microscopy (cryo-SEM) that allows, with minimal specimen preparation, the direct and in situ visualization of 'wet' alkoxide-derived microstructures, for the mechanistic study of the complex process of MICROSCAFS® generation. It is simultaneously combined with energy dispersive X-ray spectroscopy (EDS) to visualize phase separation phenomena and study the chemical elemental composition at specific regions of the sample and reaction times.

Formulation of Microsponge of Thyme for Acne Treatment

The main goal of the present work was to improve the release of drugs i.e. Thyme for the prolonged action it is made possible for us by studying more about the novel formulation i.e. Microsponge. Microsponge is porous in nature and therefore it can release drugs for a longer time. For the preparation of the Microsponge, we use the quasi-emulsion method. White-colored porous Microsponge of thyme with ethylcellulose was obtained. Microsponge polymeric delivery systems are composed of a porous microsphere of an inert polymer that can entrap active ingredients and control their delivery rate, therefore we prepared Microsponge. Drug content, entrapment efficacy, % and yield ch 95.20±0.02, 93.15±0.02, 77.32±0.02 were determined in the Prepared Microsponge. The scanning electron microscopy showed that they were spherical in shape and contain pores. Thyme Microsponge was encapsulated into a gel for release study. It was found that 06 hours of in vitro drug release study of Microsponge was best studied by the Franz diffusion cell method. For identification of anti-acne activity of thyme oil, thyme Microsponge and thyme Microsponge gel was performed by cup plate method, from which we a get maximum zone of inhibition of thyme Microsponge gel. We have prepared, thyme Microsponge gel in various 8 batches out of which the batch shows this better potential for the of the delivery system as compared to others. From the recent work, it was assured that the thyme Microsponge gel can be considered a reliable delivery system for the treatment of acne. In future thyme Microsponge gel should be the best formulation for antiacne treatment.

Ammonium perchlorate catalyzed with novel porous Mn-doped Co3O4 microspheres: superior catalytic activity, advanced decomposition kinetics and mechanisms

Mn-doped Co3O4 nanoparticles of 15 nm were developed via solvothermal synthesis. Mn@Co3O4 microspheres were developed via controlled annealing treatment at 600 °C. Mn@Co3O4 microspheres demonstrated an average diameter of 5.5 µm, with specific area (BET) of 73.7 m2 g−1. The pore diameter was centered at 13.1 nm, and the mean pore size was 16 nm; porous structure could secure extensive interfacial surface area. Mn@Co3O4 microspheres were integrated into ammonium perchlorate (AP) matrix. The catalytic activity of Mn@Co3O4 on AP decomposition was assessed via DSC and TGA/DTG. Whereas Mn@Co3O4/AP nanocomposite demonstrated decomposition enthalpy of 1560 J g−1, pure AP demonstrated 836 J g−1. While Mn@Co3O4/AP nanocomposite demonstrated one decomposition temperature at 310 °C,pure AP exposed two decomposition stages at 298 °C, and 453 °C. Decomposition kinetics was investigated via isoconversional (model free) and model fitting. Kissinger, Kissinger–Akahira–Sunose (KAS), integral isoconversional method of Ozawa, Flyn and Wall (FWO), and differential isoconversional method of Friedman. Mn@Co3O4/AP demonstrated apparent activation energy of 149.7 ± 2.54 kJ mol−1 compared with 173.16 ± 1.95 kJ mol−1 for pure AP. While AP demonstrated sophisticated decomposition models starting with F3 followed by A2, Mn@Co3O4/AP nanocomposite demonstrated A3 decomposition model. Mn@Co3O4 can expose active surface sites; surface oxygen could act as electron donor to electron deficient perchlorate group. Furthermore, Mn@Co3O4/AP could act as adsorbent of released NH3 gas with efficient combustion. This study shaded the light on Mn@Co3O4 as potential catalyst for AP decomposition.

Construction of hollow heterogeneous microspheres containing energy storage fibers by electric spray to promote combustion of nano aluminum

To solve the problem of nano-aluminum (nAl) powder easy agglomeration and improve its thermal reaction, nAl was combined with adhesive (Viton A, F2602) and oxidizer (Ammonium perchlorate, AP) forming microspheres by electrostatic spray method. The morphology and structure were analyzed by SEM, EDS and XPS. The results showed that the microspheres (diameter≈Φ10–15 μm) were hollow structures formed by winding of fluoropolymer fibers, while AP and nano aluminum particles were embedded on the fibers. By controlling the electric spray process, the well-dispersed AP and nAl nanocrystals were assembled on the fiber. Thermal analysis indicated that the gas phase products decomposed by AP were absorbed by porous microspheres, and part of the heat was stored in polymer fibers, thus promoting the breakdown of the alumina shell and accelerating the pre-ignition reaction. The combustion and laser ignition experiments proved hollow heterogeneous microspheres have excellent thermodynamic properties. The assembled microspheres not only solved the problem of poor rheology caused by the agglomeration of nAl, but also improved the insufficient combustion of nAl and the condensation of products.

Ni-BTC-derived CoP-NiCoP/NC microspheres as an efficient catalyst for NaBH4 hydrolysis

The development of a low cost, high performance and stable catalyst is an important prerequisite for the widespread application of efficient hydrogen production from sodium borohydride (NaBH4). Herein, Ni-BTC is derived into CoP-NiCoP/NC catalyst consisting of CoP-NiCoP nanorods and nitrogen-doped carbon (NC) microsphere by hydrothermal and gas-phase phosphorylation methods. The CoP-NiCoP/NC catalyst exhibits good catalytic activity, with a high hydrogen evolution rate of NaBH4 reaching 7052 mL·min−1·g−1 at 303 K, and an activation energy of only 35.57 kJ·mol−1. This is significantly better than most catalysts reported previously. In addition, the CoP-NiCoP/NC catalyst demonstrates good durability with 75 % of the original catalytic activity after 10 performance testing. This excellent catalytic performance is achieved thanks to its porous microsphere structural design and the cooperative effect between CoP and NiCoP. This catalyst with high catalytic performance and mild preparation conditions is promising for future actual applications.

Four-Arm Polymer-Guided Formation of Curcumin-Loaded Flower-Like Porous Microspheres as Injectable Cell Carriers for Diabetic Wound Healing.

Stem cell injection is an effective approach for treating diabetic wounds; however, shear stress during injections can negatively affect their stemness and cell growth. Cell-laden porous microspheres canprovide shelter for bone mesenchymal stem cells (BMSC). Herein, curcumin-loaded flower-like porous microspheres (CFPM) are designed by combining phase inversion emulsification with thermally induced phase separation-guided four-arm poly (l-lactic acid) (B-PLLA). Notably, the CFPM shows a well-defined surface topography and inner structure, ensuring a high surface area to enable the incorporation and delivery of a large amount of -BMSC and curcumin. The BMSC-carrying CFPM (BMSC@CFPM) maintains the proliferation, retention, and stemness of -BMSCs, which, in combination with their sustainable curcumin release, facilitates the endogenous production of growth/proangiogenic factors and offers a local anti-inflammatory function. An in vivobioluminescence assay demonstrates that BMSC@CFPM cansignificantly increase the retention and survival of BMSC in wound sites. Accordingly, BMSC@CFPM, with no significant systemic toxicity, couldsignificantly accelerate diabetic wound healing by promoting angiogenesis, collagen reconstruction, and M2 macrophage polarization. RNA sequencing further unveils the mechanisms by which BMSC@CFPM promotes diabetic wound healing by increasing -growth factors and enhancing angiogenesis through the JAK/STAT pathway. Overall, BMSC@CFPM represents a potential therapeutic tool for diabetic wound healing.

Construction of mesoporous N-doped carbon-coated MXene-MoS2 heterostructured microspheres via a spray-drying method as a high capacity and long cycle-life anode for potassium-ion batteries

Heterostructured materials with 2D architecture capitalizing on the unique benefits of each component and the emergent properties from their synergy have ignited considerable interest in the field of rechargeable batteries. Nevertheless, inhibiting the restacking issue inherent to 2D materials and optimizing the structural design to enhance the electrochemical reactions continue to pose substantial challenges. In this study, we successfully fabricated porous 3D N-doped carbon microspheres consisting of MXene and molybdenum disulfide (MX/MoS2 @NC) for use as an electrode material in potassium-ion batteries via a facile spray-drying method. The MX/MoS2 @NC electrode showcased excellent electrochemical properties as an anode, delivering stable cycling performance and minimal capacity decay (350 mA h g−1 at 0.5 A g−1 after 400 cycles). It also exhibits improved rate capability and enhanced ion transport kinetics (219 mA h g−1 at 2.0 A g−1). The high performance of this composite can be traced back to its 3D microspherical structure facilitating efficient ion transport, the synergy between MXene and N-doped carbon enhancing its structural robustness and electrical conductivity, and the 2D MXene nanosheets preventing MoS2 restacking. This investigation underscores the MX/MoS2 @NC composite as a promising candidate for potassium-ion battery applications.

Hygroscopic La2O3 hybridized LaCoO3-based composite catalyst for efficient ozone decomposition under humidity conditions

Herein we first report the unique hygroscopic oxide hybrid LaCoO3-based composite catalyst derived from dual-metal metal organic framework (MOF) for ozone decomposition. First, dual-metal La,Co-MOF is synthesized by solvothermal method, then La,Co-MOF is calcined at high temperature, the hygroscopic oxide (La2O3) and active oxides (LaCoO3 and Co3O4) were uniformly hybridized to form porous microspheres. Benefiting from the hybrid action of the two types of oxides, this composite catalyst exhibits highly efficient O3 removal activity within 12 h over the entire humidity conditions. The outstanding humidity resistance is attributed to the preferential adsorption of water vapor on hygroscopic oxide (La2O3), preventing the adsorption of gaseous water molecules on the surface of active oxides. In-situ FTIR further indicates that this composite catalyst possesses superior humidity resistance in the ozone catalytic decomposition.