Porous Microspheres Research Articles

Preparation of Fe-Lignin/Geopolymer Porous Microspheres for Catalytic Degradation of Dye Wastewater

To overcome the shortcomings of existing Fenton catalysts, such as secondary contamination caused by iron-containing sludge, harsh pH acidic conditions, poor recovery and recycling performance, and difficult separation, an Fe-loaded geopolymer microsphere (Fe-GLM) with a high specific surface area (68.5 m2/g), pore volume (0.0596 cm3/g), and excellent Fenton catalytic performance was prepared in this paper for dye wastewater treatment. Degradation experiments for organic dye wastewater show that the degradation ability and morphological structure of Fe-GLM does not change after multiple cycles, achieving a degradation and removal rate of more than 99%. Fe-GLM can be used to degrade both anionic dye and cationic dye wastewater in the pH range of 2–10 showing excellent catalytic performance.

Fabrication of an Injectable Star-polylactide/Thiolated Hyaluronate Hydrogel as a Double Drug-Delivery System for Cancer Treatment.

Unsatisfactory solid-tumor penetration or rapid metabolism of nanomaterials limits their therapeutic efficacy. Here, we designed an injectable thiolated hyaluronate (HA-SH) hydrogel as a stable drug-releasing platform for in situ tumor treatment. Biodegradable star-shaped polylactide (S-PLLA) was first synthesized and fabricated to porous microspheres to encapsulate hydrophobic curcumin (Cur@S-PLLA), which was then blended with hydrophilic doxorubicin (Dox) and the HA-SH precursor to form composite in situ formable hydrogels [Cur@S-PLLA/(Dox)HA-SH]. The results showed that adding the microspheres improved the performance of the hydrogel, such as decreasing the gelation time from 1080 s to 960 s and also the swelling ratio. The mechanical strength increased from 27 to 45 kPa. In addition, the double drug system guaranteed a sustained release of drugs, releasing Dox at the early stage, with the continuous later release of Cur after gel swelling or S-PLLA degradation to achieve long-lasting tumor suppression, which inhibits the survival of cancer cells. The inhibitory effects of the hydrogels on MCF-7 were studied. The cell activity in the double-loaded hydrogel was significantly lower than that of the control groups, and apparent dead cells appeared in 2 days and fewer living cells with time. Flow cytometry revealed that the Cur@S-PLLA/(Dox)HA-SH group had the highest apoptosis ratio of 86.60% at 12 h, and the drugs caused the cell cycle to be blocked in phase M to reduce cell division. In summary, the innovative release platform is expected to be used in long-lasting tumor suppression and provides more ideas for the design of drug carriers.

Specific recognition and separation of celastrol with molecularly imprinted polymer based on regenerated cellulose carrier

In this study, the porous cellulose microsphere carrier based on traditional Chinese medicine waste was successfully used to prepare a molecularly imprinted polymer (SPCC-CSL-MIPs) with specific selectivity for celastrol. Fourier transform infrared spectroscopy, scanning electron microscope, thermogravimetry, X-ray diffraction and binding experiments were performed to investigate and analyze the structure and adsorption performance of SPCC-CSL-MIPs. The experimental results showed that the SPCC-CSL-MIPs possessed a high adsorption capacity of 14.38 mg/g and a good imprinting factor of 2.36. Furthermore, the SPCC-CSL-MIPs could maintain a stable adsorption performance of 77.98% after 5 cycles. The above results indicated that the prepared SPCC-CSL-MIPs can be employed as an excellent adsorbent for ready and efficient celastrol enrichment and separation, and the content of celastrol in T. wilfordii extract was vastly increased from 0.46% to 3.87%, which proved that SPCC-CSL-MIPs exhibited the excellent ability of specific targeted enrichment and separation of celastrol from the complex matrix.

Synergetic effect of 3D porous microsphere structure and activation of adenosine A2B receptor signal on promoting osteogenic differentiation of BMSCs

Biodegradable microspheres offer great potential as functional building blocks for bottom-up bone tissue engineering. However, it remains challenging to understand and regulate cell behaviors in fabrication of injectable bone microtissues using microspheres. The study aims to develop an adenosine functionalized poly (lactide-co-glycolide) (PLGA) microsphere to enhance cell loading efficiency and inductive osteogenesis potential, and subsequently to investigate adenosine signaling-mediated osteogenic differentiation in cells grown on three-dimensional (3D) microspheres and flat control. Adenosine was loaded on PLGA porous microspheres via polydopamine coating, and the cell adhesion and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) were improved on these microspheres. It was found that adenosine A2B receptor (A2BR) was further activated by adenosine treatment, which consequently enhanced osteogenic differentiation of BMSCs. This effect was more obvious on 3D microspheres compared to 2D flats. However, the promotion of osteogenesis on the 3D microspheres was not eliminated by blocking the A2BR with antagonist. Finally, adenosine functionalized microspheres could fabricate injectable microtissues in vitro, and improve cell delivery and osteogenic differentiation after injection in vivo. Therefore, it is considered that adenosine loaded PLGA porous microspheres will be of good value in minimally invasive injection surgery and bone tissue repair.

Pd nano-catalyst supported on biowaste-derived porous nanofibrous carbon microspheres for efficient catalysis

Pd nano-catalyst supported on biowaste-derived porous nanofibrous carbon microspheres for efficient catalysis

Facile preparation of magnetic P(MMA-co-GMA)@Fe3O4@PMAA microspheres using porous microsphere as templates for removal of methylene blue

Facile preparation of magnetic P(MMA-co-GMA)@Fe3O4@PMAA microspheres using porous microsphere as templates for removal of methylene blue

Porous titanium microsphere kyphoplasty for augmentation treatment of osteoporotic vertebral fractures: Technical report and case series.

Vertebral augmentation procedures (VAPs) are used in cases of persistent and unresponsive pain in patients with vertebral compression fractures (VCFs). Although VAPs are considered a safe procedure providing quick pain relief and improved physical function, some postoperative complications can occur, for example, bone cement leakage. The material used in this procedure is almost exclusively polymethyl methacrylate (PMMA), which appears to lack biological activity and osteointegration capabilities. In this study, we introduce a new filling system consisting of cannulas preloaded with titanium microspheres, which stabilizes and consolidates the structure of the vertebral body in treating VCFs after the performance of the kyphoplasty procedure. We report a retrospective case series of six patients affected by osteoporotic vertebral fractures with worsening back pain, neurologic impairment, and failed conservative treatment who underwent the VAP at our institute, for which the SPHEROPLAST [MT ORTHO s.r.l., Aci Sant'Antonio (CT), Italy] system was used. The patients had failed an average conservative trial of 3.9 weeks before they presented to us with neurodeficit. There were two men and four women with a mean age of 74.5 years. The average hospital stay was 2 days. There were no reported perioperative complications related to cement injection, such as intraoperative hypoxia, hypotension, pulmonary embolization, myocardial infarction, neurovascular or viscera injury, or death. The VAS score significantly decreased from a mean preoperative of 7.5 (range 6-19) to 3.8 (range 3-5) immediately after surgery and 1.8 (range 1-3). We report the first clinical results in a series of six patients treated for VCF using the microsphere system after analyzing the clinical results produced by, and the complications that arose from, this new device. In patients with VCF, the VAP using titanium microspheres appears to be a feasible and safe procedure with a low risk of material leakage.

Preparation and characterization of an active packaging film loaded with tea tree oil-hydroxyapatite porous microspheres

In order to alleviate the environmental damage due to non-degradable plastic packaging, environment-friendly active packaging films were developed, using polyvinyl alcohol (PVA), sesbania gum (SG) as the film matrix and tea tree oil (TTO) as the active material, and hydroxyapatite porous microspheres (HPMS) as the loading system. The microcosmic appearance and structure of HPMS were analyzed via specific surface area and pore analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the prepared film matrix, the effects of active substance with diverse mass ratios (0%−2.5%, w/w) on the properties of packaging films were analyzed. The experimental results indicated that HPMS were successfully prepared for use as the carrier of TTO. Besides, the accession of TTO-HPMS enhanced the thermal stability, antioxidant and antibacterial capacities of the packaging films. The hydrophobicity of the packaging films was also ameliorated, which was 41.56% higher than that of the film without TTO-HPMS. However, the addition of TTO-HPMS led to a decrease in mechanical properties, and decreased the elongation at break (EB) from 437% to 286%. This study systematically studied the preparation and characterization of active packaging film to provide a theoretical basis for bio-based packaging.

Synthesis of fluoride-releasing strontium-substituted porous apatite microspheres for bone osteoporosis treatment

Synthesis of fluoride-releasing strontium-substituted porous apatite microspheres for bone osteoporosis treatment

MICROSPONGES: AN INNOVATIVE TECHNIQUE FOR BIOMEDICAL RESEARCH

A microsponge delivery system (MDS) is a cutting-edge and distinctive method of structured drug delivery. Controlled drug delivery is now possible with the use of microsponge technology. MDS consists of porous microspheres with a substantially porous structure and a very small spherical shape, ranging in size from 5 to 300 microns. MDS is typically used to administer medications through topical channels, but new research has demonstrated the promise of this technique for parenteral, oral, and ocular drug delivery. While reducing the drug's side effects, MDS can readily change the pharmaceutical release shape and enhance formulation stability. Reaching the highest peak plasma concentration in the blood is the main goal of microsponge medication delivery. The most notable quality of MDS is their ability to self-sterilize. MDS is employed in countless studies as an anti-allergic, anti-mutagenic, and non-irritant. This review discusses formulation, eligibility requirements for medications to be included in MDS, formulation processes, evaluation criteria, and the function of MDS in the treatment of various illnesses. In the future, while researching MDS in other illnesses, this review will be quite helpful.

Porous Stainless Steel Microsphere Synthesis by a Nonconventional Powder Metallurgy Process Useful in the Cermet-Type Advanced Nuclear Fuel Fabrication

The fabrication of SS (stainless steel)-UO2 cermet-type advanced nuclear fuel pellets suitable for use in power reactors depends on the development of metallic (SS), ceramic (UO2), and cermet (SS-UO2) microspheres with special characteristics. In this work, a nonconventional powder metallurgy process was developed to produce porous SS microspheres aiming to contribute to solve the bottlenecks found in the SS-UO2 cermet pellet manufacturing. SS, UO2, and SS-UO2 microspheres and SS-UO2 cermet pellets were fabricated and characterized (XRD, EDX, EDS, and SEM). Hard (153 ± 5 µm; 132.2 ± 24.7 MPa; 72% TD) and soft (216 ± 10 µm; 1.3 ± 0.4 MPa; 17% TD) SS, hard (176 ± 6 µm; 147.4 ± 25.0 MPa; 99% TD) UO2, and cermet (SS-UO2) microspheres were obtained. The soft porous SS microspheres did not micronize properly in situ, but their high compressibility favors the compaction of the green SS-UO2 cermet pellet; in this pellet, the UO2 microspheres behaved as rigid inclusions. This favored the obtainment of sintered SS-UO2 cermet pellets with high geometric densities (93% TD), excellent metal–ceramic interaction, and the preservation of the physical integrity of the UO2 microspheres. The usage of high fractions of the SS-UO2 cermet microspheres obtained mixed with low fractions of the said soft porous SS microspheres is already under development. This will enable the fabrication of SS-UO2 cermet pellets with a volume fraction greater than 42 vol% UO2, a homogeneous distribution of UO2 microspheres in the metallic matrix, and null connection between them. The oxide–metal reduction mechanisms were discussed. The applicability of the process is already being explored in the manufacture of porous NdFeB microspheres.

Starch-based porous carbon microsphere composited NiCo2O4 nanoflower as bifunctional electrocatalyst for zinc-air battery

It is significant to explore and design outstanding bifunctional oxygen electrocatalysts to promote the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in zinc–air batteries. Herein, a novel porous carbon microspheres (CMS2) modified by NiCo2O4 nanoflower (CMS2–NiCo2O4) have been prepared as an ORR and OER catalyst. The hierarchical porous structure of CMS provides high conductivity and abundant active sites for ORR, whereas the synergistic effect of NiCo2O4 nanosheets and a small amount of FeZn oxides act as the positive phase for OER. The efficient oxygen catalytic activity is gained by creating a coupling interface between NiCo2O4 and CMS. The optimized CMS2–NiCo2O4 shows a half–wave potential of 0.82 V toward ORR and an overpotential of 392 mV toward OER. Particularly, CMS2–NiCo2O4 also exhibits an excellent peak power density (175.5 mW cm−2) as a catalyst for zinc–air batteries, which is superior to the commercial Pt/C + RuO2 catalyst (120.5 mW cm−2), and it also demonstrates a remarkable stability even after the charge–discharge cycles of 167 h. The prepared CMS2–NiCo2O4 is promising for the application of the bimetallic oxide catalyst for zinc–air battery.

Porous cellulose microspheres loaded with dry Nile water algae for removal of MB dye and copper ions from aqueous media

AbstractLow‐cost‐effective applied technologies for water and wastewater treatment, such as microalgae, have growing attention due to their mutual benefit in wastewater treatment and for valuable algae biomass production. A newly constructed Nile water algae cross‐linked cellulose microsphere (NACS) was applied by functionalization of cross‐linked cellulose acetate with dry Nile water algae forming an efficient adsorptive microsphere. The adsorption capacity of microspheres was evaluated for the removal of basic dye (Methylene blue: MB) and heavy metal copper ions (Cu+2). The molecular structure revealed that the prepared microspheres have several functional groups and elements that have a high affinity for heavy metals and dye removal; furthermore, the morphological structure emphasizes this removal affinity by the presence of micropores at the surface of the microsphere. The results of maximum biosorption conditions showed both MB and Cu through the microsphere were 20 mg/L MB and (10 and 20) mg/L Cu concentrations, 2 g/L of adsorbent dose, pH (MB = 6 and Cu = 5.5), and contact time of 60 min. The maximum adsorption capacities (qmax) were significantly enhanced at 200 and 153.2 mg/g for MB and Cu (II), respectively. The possibility of removal, recovery, and reuse of MB by prepared microsphere was efficiently achieved.

Preparation of Fe2O3 porous microspheres modified pumice and its adsorption performance on phosphate removal

Fe2O3 porous microspheres modified pumice (Fe2O3@pumice) was generated in this study using a simple hydrothermal method. XRD, SEM, TEM, BET, and TG-DSC analyses were employed for characterization. The results show that the pumice is encapsulated by a large amount of Fe2O3 porous microspheres. Fe2O3@pumice exhibits good phosphate adsorption property. The adsorption process follows the Freundlich isothermal adsorption model and Pseudo-secondary adsorption kinetic model, and the adsorption capacity is more than 378.8 mg/g. It shows outstanding phosphate removal capacity throughout the pH range of 3–11. The adsorbent has fewer effects on coexisting anions and good performances of reusability. The adsorption mechanism is mainly attributed to ligand exchange. Electrostatic attraction also existed in the adsorption process. The column test indicated that the adsorption column can continuously treat 2106 bed volumes of sewage with 2 mg/L phosphate.

A novel hydroxyapatite-based hollow microsphere nanocomposite for copper ion adsorption

Hydroxyapatite (HAp) is an inorganic material that can be used as an adsorption material. Here we report a novel HAp-based hollow porous microsphere, in which Fe3O4 nanoparticles are uniformly embedded in the HAp microsphere shell. The specific surface area is 98.6 m2/g with an average pore size of 11.4 nm. The microsphere has been demonstrated to be a high-efficient absorbent for copper ion. Owing to the superparamagnetic property of Fe3O4 nanoparticles, the microspheres can be well dispersed in water and effectively segregated by magnet. Therefore, HAp-Fe3O4 hollow microsphere is a promising candidate for copper ion treatment.

Facile synthesis and enhanced electromagnetic interference shielding performance for porous magnetic microspheres/Ti3C2Tx MXene nanocomposite film

Owing to the rapid development of information and electronic technologies, it is urgent to design and prepare new materials with electromagnetic interference (SEI) shielding function to reduce electromagnetic pollution. Herein, a thin magnetic Ti3C2Tx MXene (MMX) nanocomposite film with excellent EMI shielding performance was obtained by combining Ti3C2Tx MXene nanosheets with porous magnetic microspheres (PMMs). The lamellar structure of Ti3C2Tx MXene nanosheets provides flexibility to the MMX nanocomposite film, enabling it to bend and deform in a flat plane. Furthermore, PMMs possess magnetic and dielectric properties, enhancing the attenuation ability of the MMX nanocomposite film to electromagnetic wave energy. The rough surface of PMM can improve the electromagnetic wave consumption through multiple reflection and enhance the performance of Ti3C2Tx MXene EMI shielding nanocomposites. MMX nanocomposite exhibits excellent EMI shielding performance (SET: 66.9 dB, SSEt: 5251 dB cm2 g−1). We anticipate that this flexible nanocomposite film with excellent EMI shielding effect will be widely used in different fields.

Injectable, High Specific Surface Area Cryogel Microscaffolds Integrated with Osteoinductive Bioceramic Fibers for Enhanced Bone Regeneration

Organic-inorganic composites with high specific surface area and osteoinductivity provide a suitable microenvironment for cell ingrowth and effective ossification, which could greatly promote bone regeneration. Here, we report gelatin methacryloyl (GelMA) cryogel microspheres that are reinforced with hydroxyapatite (HA) nanowires and calcium silicate (CS) nanofibers to achieve the goal. The prepared composite cryogel microspheres with open porous structure and rough surface greatly facilitate cell anchoring, simultaneously exhibiting excellent injectability. Compared to the only HA- or CS-containing counterparts, the GelMA cryogel microspheres composited with HA:CS (termed as GMHC) achieve sustained release of bioactive Ca, P, and Si elements, which are conducive to osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs). These composite microspheres can prevent from forming peralkalic conditions, which is beneficial for cell growth. After injection of cryogel microspheres into rat calvarial defects, neo-bone tissue grows into their pores, showing tight integration. The embedded bioceramic components significantly promote bone regeneration, with the GMHC achieving the best regenerative outcomes. Promisingly, porous organic-inorganic composite cryogel microspheres, with high specific surface area, biodegradability, and osteoinductivity, can act as injectable microscaffolds to repair bone defects with enhanced efficiency, which may widen the scaffold strategy for bone tissue engineering.

Osteogenic potential of solid and porous phosphate glass microspheres as pulp capping materials

This study investigated the morphology (Scanning Electron Microscope), chemistry (Elemental Analysis (EDX), Raman Spectroscopy and X-ray diffraction), thermal characteristics, cytocompatibility, and osteogenic potential of solid and porous phosphate-based glass microspheres for potential use as pulp-capping materials. Cytocompatibility was investigated using human dental pulp stem cells (hDPSCs) through both direct and indirect (extracts) contact tests. Cells grown in normal cell culture medium and 10% dimethyl sulfoxide served as positive and negative controls, respectively. Unlike solid glass microspheres (GMs), porous GMs showed higher CaO mol% and crystalline structure. Both types of GMs supported the attachment, spreading, and viability of hDPSCs similar to the positive control. Cells grown in GMs’ extracts showed even higher viability, but less mineralization than those grown in direct contact with GMs. The presence of osteogenic supplements however did not have a significant effect on mineralisation. Accordingly, both solid and porous GMs show useful applicability as pulp-capping materials.

Construction of PLGA Porous Microsphere-Based Artificial Pancreatic Islets Assisted by the Cell Centrifugation Perfusion Technique.

Pancreatic islet transplantation is a promising treatment that could potentially reverse diabetes, but its clinical applicability is severely limited by a shortage of organ donors. Various cell loading approaches using polymeric porous microspheres (PMs) have been developed for tissue regeneration; however, PM-based multicellular artificial pancreatic islets' construction has been scarcely reported. In this study, MIN6 (a mouse insulinoma cell line) and MS1 (a mouse pancreatic islet endothelial cell line) cells were seeded into poly(lactic-co-glycolic acid) (PLGA) PMs via an upgraded centrifugation-based cell perfusion seeding technique invented and patented by our group. Cell morphology, distribution, viability, migration, and proliferation were all evaluated. Results from glucose-stimulated insulin secretion (GSIS) assay and RNA-seq analysis suggested that MIN6 and MS1-loaded PLGA PMs exhibited better glucose responsiveness, which is partly attributable to vascular formation during PM-dependent islet construction. The present study suggests that the PLGA PM-based artificial pancreatic islets may provide an alternative strategy for the potential treatment of diabetes in the future.

Fe-Ni bimetallic nanoparticles encapsulated into nanofibrous carbon microspheres as a catalytic nanoreactor for highly selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dihydroxymethylfuran or 2,5-dihydroxymethyltetrahydrofuran

BackgroundThe highly efficient conversion of renewable biomass-derived platform compounds to high value-added chemicals is one of the most promising solution to the current rapid consumption of fossil resources. MethodsNanofibrous and porous carbon microspheres (NPCMs) were developed from chitin biomass and used to encapsulate Fe-Ni bimetallic nanoparticles for the formation of a novel catalytic nanoreactor (Fe-Ni/NPCMs), which was then used for the selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) or 2,5-dihydroxymethyltetrahydrofuran (DHMTHF). Significant findingsThe NPCMs consisted of N-doped carbon nanofibers with a high surface area. The Fe-Ni bimetallic nanoparticles were uniformly dispersed on the carbon nanofiber surfaces of the Fe-Ni/NPCMs, resulting in abundant catalytic sites and excellent catalytic performance. Importantly, the Fe-Ni/NPCMs showed highly-selective hydrogenation of HMF to DHMF or DHMTHF with high yields of 93.6% or 94.9% through simply modulating the reaction conditions. Increasing the zero valent iron (Fe0) content in the Fe-Ni/NPCMs significantly promoted the DHMTH selectivity from HMF hydrogenation. Moreover, the Fe-Ni/NPCMs presented high stability and recyclability, and thus they are applicable to other biomass conversions. Therefore, Fe-Ni/NPCMs have promising industrial application in the production of high value-added chemicals from biomass-derived feed-stocks.