Solid Microspheres Research Articles

Synthesis of chiral hollow polymer microspheres and their applications in the spectroscopic chiral discrimination of tryptophan isomers

Hollow polymer microspheres (HPMs) were synthesized, which were then hydrolyzed in aqueous ammonia to produce carboxyl (–COOH) groups on their surface. L-phenylalanine (L-Phe) was grafted to the hydrolyzed HPMs (H-HPMs) through amidation reactions, endowing the H-HPMs with chirality. The resultant chiral HPMs (C-HPMs) were used for the chiral discrimination of tryptophan (Trp) isomers. Due to the same rotatorydirection of L-Phe and L-Trp, the C-HPMs showed greatly higher selectivity toward L-Trp than its isomer. After being adsorbed by the C-HPMs, the absorbance of the residual L-Trp is significantly lower than that of the residual D-Trp, and thus spectroscopic chiral discrimination of the Trp isomers was successfully achieved. The Trp isomers were also discriminated by the chiral solid polymer microspheres (C-SPMs), while the difference in the absorbance of the residual L-Trp and D-Trp is remarkably smaller than that obtained by the C-HPMs. The outstanding discrimination capability of the C-HPMs might be ascribed to their high surface permeability resulted from their unique hollow structure.

Hierarchically Structured Biodegradable Microspheres Promote Therapeutic Angiogenesis.

Promoting neovascularization is a prerequisite for many tissue engineering applications and the treatment of cardiovascular disease. Delivery of a pro-angiogenic stimulus via acellular materials offers several benefits over biological therapies but has been hampered by interaction of the implanted material with the innate immune response. However, macrophages, a key component of the innate immune response, release a plurality of soluble factors that can be harnessed to stimulate neovascularization and restore blood flow to damaged tissue. This study investigates the ability of biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres to restore tissue perfusion in a hind limb model of ischaemia. Microspheres exhibiting a hierarchical porous structure are associated with an increase in blood flow at day 21 post-implantation compared with solid microspheres composed of the same polymer. This corresponds with an increase in blood vessel density in the surrounding tissue. In vitro simulation of the foreign body response observed demonstrates M2-like macrophages incubated with the porous microspheres secreted increased amounts of vascular endothelial growth factor (VEGF) compared with M1-like macrophages providing a potential mechanism for the increased neovascularization. The results from this study demonstrate implantable biodegradable porous microspheres provide a novel approach for increasing neovascularization that could be exploited for therapeutic applications.

Unconventionally microspheric quasi-solid electrolyte interface approach for durable and highly reactive phosphorus for lithium-ion storage

Solid electrolyte interface (SEI) film is the most important separation layer between nonaqueous electrolytes and anodes to protect anode from corrosion and maintain continuous ionic diffusion tunnels. However, SEI film, especially for high-capacity anode materials, is still confined to continuous and stable ionic conductive layer despite the conventional SEI film is intrinsically poor to resist against the drastic volumetric changes of active centers. Herein, an unconventional spheric quasi-SEI film is thus strategically configured on cost-effective red phosphorus electrode materials by moderate phosphorylation combined with pore-forming process. Microstructure adjustment from solid microspheres structure to hollowed core–shell spheres is visibly taken place on this amazing spheric quasi-SEI film during the stabilization. Benefiting from the highly activated surface with weakened PP bond strength and the strengthened binding force between phosphorus and binders, the optimized phosphorus anode presents an outstanding long-term durability with a high discharge capacity of 1126.4 mAh/g over 400 cycles at 200 mA g−1 even at a high phosphorus load ratio of 70 wt%. This revolutionary configuration of quasi-SEI film provides high-capacity anode materials subject to large volumetric changes an unconventional approach from dependence on conductive framework/matrix.

Low-molecular-weight microspheres with soft-shell characteristics for remarkable signal enhancement in LOCI applications

Light-Activated Oxygen Channel Immunoassay (LOCI) is very attractive in immunoassay due to its advantages of simplicity, sensitivity and automation. The preparation of donor/acceptor beads (DBs/ABs) in LOCI is crucial to the detection sensitivity. In this study, microspheres with “hard core-soft shell” structure were prepared by stepwise dosing with a chain transfer agent (CTA), 2,4-diphenyl-4-methyl-1-pentene (a-MSD). The soft-shell structure facilitated the penetration of the photosensitizer into the microsphere and was encapsulated at the shell layer, thereby significantly improving the activity of singlet oxygen (1O2, λ< 200 nm) in LOCI. With the amount of a-MSD added increased to 20 wt%, the molecular weight of the microspheres decreased to 7235, and the loading of the photosensitizer in the microspheres could be as high as 80.6%, which enhanced the signal of LOCI detection by about 12.77 times. When the addition of a-MSD was 10 wt%, the optimal molecular weight and soft-shell structure were obtained, with the best signal-to-noise ratio (S/N) of 58.24. Compared with solid microspheres, the S/N was improved by about 4.22 times. These findings indicated that low-molecular-weight soft-shell microspheres have great potential in immune-medical applications, and the idea of soft-shell microspheres provides a new strategy for the preparation of immune-magnetic beads and immune-fluorescence microspheres.

Recent Advances in Combating Acne with Novel Drug Delivery Systems: A Review

Abstract: Acne vulgaris is an inflammatory disorder of the skin that occurs when hair follicles get clogged with sebum and dead skin cells resulting in pustules, papules, or nodules. This condi-tion affects a large number of people throughout the world. Over time, various conventional ther-apies like topical, systemic and hormonal treatments have been prescribed by doctors to patients for managing acne. Amongst these, topical therapy is the first-line therapy dominated by retinoid and antibiotic drugs. However, conventional topical treatments have many drawbacks concerning physicochemical instability, poor ability to penetrate the skin, and wide-ranging side effects. Novel drug delivery systems are the formulations that were first devised to overcome the issues faced by traditional methods. Researchers have developed novel therapies for topical use, such as niosomes, transfersomes, solid lipid nanoparticles, microsponges, microemulsion, microspheres, nanocochleates, and liposomes, which can be used to target acne. These nanoparticulate systems aim to overcome the disadvantages of conventional treatment and provide higher safety and effi-cacy, along with an increase in the stability of the formulation. Many comparative studies have been conducted between the novel and conventional methods, which give us a better understand-ing of the safety and efficacy of drugs present in the formulation and prove that novel drug deliv-ery systems are more favorable than their conventional counterparts. This review article provides a brief insight into the conventional methods, discusses in depth the earlier mentioned novel ther-apies that can be used successfully in treating acne, and provides patent information on the drug delivery systems.

Biomimetic hybrid porous microspheres with plant membrane-wall structure for evaluating multiscale mechanisms of ultrasound-assisted mass transfer

Determination of mass transfer during ultrasound-assisted extraction (UAE) has always been a challenge, not to mention the novel breakthrough of mechanisms for its positive effects. Herein, versatile porous microspheres (PM) with membrane-wall structure like plant tissues, which were made from sodium alginate/polyacrylamide dual crosslinking gels loaded with liposomes, were prepared to reveal the micro mass transfer effects during UAE. Results showed that prepared PM kept stable microstructure during extraction and ultrasound significantly accelerated the pore diffusion rather than surface diffusion. This effect resulted in higher UAE efficiency of PM with 60 % porosity than solid microspheres (143.72 to 155.47 mg/L), and the finding can be further explained as the accelerated internal diffusion (14.25 %) under ultrasound treatment. Moreover, multi-physics coupling simulations were performed to elucidate the enhanced pore flow and UAE efficiency. Acoustic streaming induced by cavitation effect increased the seepage velocity within the PM, and the pore structure would undergo compression and expansion deformation with alternated acoustic pressure due to its elastic characteristic. Both microscale effects improved the mass transfer and increase the UAE efficiency without structural damage from cavitation. This study fills the UAE mechanisms from micro view and provides a novel method for the study of vital micro processes.

Pickering emulsion droplets and solid microspheres acting synergistically for continuous-flow cascade reactions

Pickering emulsion droplets and solid microspheres acting synergistically for continuous-flow cascade reactions

Biodegradable Polymeric Microspheres as Drug Carriers for Anti- Microbial Agent

Introduction: Microspheres, the novel drug delivery system that offers therapeutic alternatives to single-unit dosage forms, both conventional and quick release. Microspheres are solid microspheres having a diameter of 1-1000 µm. Microspheres can be made utilising various procedures that vary in their effectiveness and dosage form administration when compared to standard dosage forms. Background: The idea of targeted drug delivery is to concentrate the treatment in the target tissues while lowering the relative concentration of the drug in the non-target tissues. As a result, the medication is concentrated at the desired location. Thus, the medication has no effect on the tissues nearby. Therefore, by combining the drug with carrier particle like microspheres, nanoparticles, liposomes, niosomes, etc., that regulates the release and absorption characteristics of the drug, carrier technology offers an intelligent way for drug delivery. Results: Microspheres are naturally biodegradable materials made of proteins or synthetic polymers that flow freely. Its formulation is approachable, maintaining the desired concentration at the site of interest without unfavorable effects and reliably delivering the drug to the target site with specificity. Conclusion: Microspheres attracted a lot of interest for their sustained release as well as their ability to direct anti-cancer medications to the tumour using biodegradable polymers. Due to this, future drug delivery systems for innovative medications will heavily rely on microspheres.

Size-Dependent Response of Hydrothermally Grown SnO2 for a High-Performance NO2 Sensor and the Impact of Oxygen.

A NO2 sensor with a detection limit down to the ppb level based on pristine SnO2 has been developed through a facile poly(acrylic acid)-mediated hydrothermal method. SnO2 particles of solid microsphere, hollow microsphere, and nanosphere morphologies were synthesized, with respective constitutional crystallite of size ∼2 μm in length and 10-20 nm and ∼7 nm in diameter. All sensors show great selectivity to NO2. The hollow microsphere sensor exhibits the best performance, with medium specific surface area (SSA), followed by the nanosphere sensor with the largest SSA. This is attributed to the superposition of two opposite effects on sensor response with increased SSA: more adsorption sites and fewer electrons to be taken out with overly small crystallite that may reach complete depletion. O2 is found to speed up the response and recovery times but reduce the response because O adsorbates facilitate the adsorption/desorption of NO2 thermodynamically, and the two oxidizing gases compete in harvesting electrons from SnO2. The adverse effect of humidity can be minimized by operating the sensor at 110 °C. The response of the hollow microsphere sensor to 50 ppb of NO2 is 8.8 (Rg/Ra) at room temperature, and it increases to 15.1 at 110 °C. These findings are useful for developing other oxidizing gas semiconductor sensors.

Fabricating a high-performance anode by coating a carbon layer on a yolk-shell bimetallic selenide microsphere for enhanced lithium storage.

The rational synthesis of an electrode material with a highly active and stable architecture is very critical to achieving high-performance electrochemical energy storage. Herein, N-doped carbon restricting yolk-shell CoSe2/Ni3Se4 (CoSe2/Ni3Se4@NC) flower-like microspheres were successfully synthesized from solid CoNi-glycerate microspheres using a coating technology as an anode material for lithium-ion batteries (LIBs). The unique yolk-shell CoSe2/Ni3Se4@NC microspheres with hierarchical pores can increase the contact area with the electrolyte and provide enough transfer channels for the diffusion of Li+. The carbon layer on the surface of CoSe2/Ni3Se4@NC can not only improve the conductivity of the electrode but also provide the protective effect of active nanosheets during the process of synthesis, avoiding the overall structure collapse during the charge/discharge process of LIBs. Benefiting from the high conductivity, hollow structure, and elastic NC shell bestowed by the unique architecture, the yolk-shell CoSe2/Ni3Se4@NC anode shows excellent lithium storage performances, such as an excellent reversible specific capacity of 319 mA h g-1 at a current density of 1000 mA g-1 after 500 cycles and excellent cycling stability. This synthesis strategy provides a new way to optimize the lithium storage performance of transition metal compound electrode materials, which is helpful to the design of the next generation of high-performance LIBs.

Large-scale production of chiral nematic microspheres.

The membrane emulsification technique enables the self-assembly of cellulose nanocrystals (CNCs) confined within a spherical geometry for large-scale production. The resulting solid microspheres show long-range ordering with chiral nematic structures, and this fascinating hierarchical architecture can even be transferred to mesoporous carbon or silica microparticles by a sacrificial template method.

In vitro immunomodulatory effect of solid versus porous phosphate-based glass microspheres using macrophages

This study aimed to investigate the immunomodulatory effect of two different forms of phosphate-based glass microspheres (solid and porous), on human macrophages. Human THP-1 monocytes were converted to M0 macrophages after being treated with 100 ng/mL phorbol 12-myristate 13-acetate for 48 h. The differentiated cells were analysed for the CD14 marker using flow cytometry. The adhesion, spreading, and viability of M0 macrophages grown directly or indirectly (extracts) at varying concentrations of solid and porous glass microspheres (GMs) were analysed via phase contrast microscopy, confocal microscopy, and XTT assay. The expression of IL-8, IL-1β, IL-6, IL-10, TNF-α, and IL-12p70 cytokines was investigated using flow cytometry. The conversion to M0 macrophages was confirmed by their adherent nature, increased granularity, and CD14 expression. The results showed that both solid and porous GMs or extracts favored the attachment, spreading, and proliferation of macrophages in a comparable manner to cells grown in a normal tissue culture medium. Only the higher concentration of porous GMs (10 mg/mL) changed the morphology of M0 macrophages and increased the expression of IL-1β and IL-8 pro-inflammatory cytokines; this could be related to the fast degradation nature of porous GMs. Of the six cytokines analysed, M0 macrophages grown directly or indirectly with GMs only expressed IL-1β, IL-10, and IL-8. Accordingly, solid microspheres may have advantages as regenerative agents due to their controlled degradation.

Study of the effect of composite energetic binder on the performance of DAAF at ambient and elevated temperatures

AbstractTo investigate the effect of composite energetic binders on the performance of DAAF at ambient as well as elevated temperatures, DAAF solid microspheres with uniform particle size were prepared using droplet microfluidics. The morphology, particle size distribution, structure, thermal properties and mechanical susceptibility of the microspheres were characterized and analyzed. The results show that the use of composite binder can effectively improve the thermal stability of DAAF, and the activation energy is increased from 168.87 to 218.53 kJ ⋅ mol−1. The crystal shape is not changed after cladding, and the impact sensitivity value is improved by 5 J over the submicron DAAF. Composite energetic binder DAAF microspheres and submicron DAAF were selected for experiments under high temperature environment. The results showed that at high temperatures, when the mass loss was more than 16 %, the submicron DAAF was better than the DAAF microspheres in terms of storage time.

Synthesis of Calcium Carbonate Hollow Microspheres and the Pelletization Mechanism by Electrostatic Attraction of PEG-SDS.

Calcium carbonate is a common natural mineral with a wide range of applications. In this study, hollow calcite microspheres were successfully synthesized by using calcium chloride and sodium carbonate as raw materials in an SDS-PEG system. The results suggested that the appropriate concentration of SDS is necessary during the spherical crystallization of calcium carbonate. It was found that the crystals started to aggregate under the effect of SDS, and aggregation was enhanced with an increase in SDS concentration, leading to the transformation from hollow to solid microspheres. However, high temperatures will lead to the transformation from calcite to aragonite, resulting in the collapse of the formed spherical structure. Infrared spectroscopy and conductivity analysis suggested that when the concentration of SDS reached 0.3 g/L in the PEG-SDS system, SDS and PEG formed a spherical supramolecular structure. This structure could act as a template, leading to the aggregation of calcite through electrostatic attraction and finally to the formation of a hollow spherical structure.

Hollow silicon carbide microspheres for excellent and lightweight electromagnetic wave absorber

Developing semiconductor ceramic materials with lightweight, outstanding stability, and high-performance electromagnetic wave (EMW) absorption are attractive for harsh environments. Due to thermal and chemical stability, designable microstructure, and tunable dielectric property, microstructured silicon carbide (SiC) ceramics offer promising potential as excellent EMW absorbers while limited by the scarce fabricating methods. Here, a simple coaxial electrospinning technology and the high-temperature calcination process are developed for the first time to fabricate hollow SiC microspheres (HSCMs) for EMW absorbers. Owing to the sizeable SiC-free space interface in the shell and internal void, the inner hollow structure also endows HSCMs with excellent EMW absorbing properties. By comparing with the composite of 40 wt% solid SiC microspheres (SSCMs)/paraffine, it is found that the 40 wt% HSCMs/paraffin composite exhibits superior dielectric properties and a minimum reflection loss (RL) value of − 61.6 dB at 7.7 GHz and 3.4 mm thickness, associated with the most considerable adequate absorption bandwidth of 4.9 GHz (from 12.6 to 17.5 GHz) at 1.9 mm thickness. This work gives rise to a handy method for fabricating hollow SiC with lightweight and high-efficiency EMW absorption. It will potentially boost the development of next-generation EMW absorbers for harsh environment applications.

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.

Exploration on the multi-structural morphology regulation and microwave absorption performance of LDHs

In this paper, the microstructure of MgAl-layered-double-hydroxides (MgAlLDHs) was adjusted by one-step hydrothermal method, and the MgAlLDHs with various stacking structures were prepared successfully. It is found that the different stacking structures have significant effects on the microwave absorption performance of LDHs. The minimum reflection loss (RL) of the solid microsphere LDHs is 63% higher than that of the layered LDHs, and the effective absorption bandwidth (EAB) is also increased from 1 GHz to 2.50 GHz. The results show that adjusting the microstructure and morphology of the material is an effective way to improve microwave absorption performance.

Modulating zinc metal reversibility by confined antifluctuator film for durable and dendrite-free zinc ion batteries.

Aqueous Zn ion batteries (ZIBs) are promising systems due to their intrinsic safety, low cost and non-toxicity, and the Zn corrosion and dendrite growth will cause the poor reversibility of Zn anode. Herein, we developed the porous Zn@C solid, hollow and yolk-shell microspheres film as Zn anode antifluctuator (ZAAF). The prepared yolk-shell microspheres (ZCYSM) film with superior buffering can effectively restrict the deposition of Zn metal in its interior and inhibit the volume expansion during plating/stripping process, thus modulating the Zn2+ flux and enabling stable Zn cycling. As a proof of concept, the ZCYSM@Zn symmetric cells achieve the excellent cyclic stability over 4,000h and cumulative plated capacity of 4 Ah cm-2 at a high current density of 10mA cm-2 . Concomitantly, the suppressed corrosion reactions and dendrite-free ZAAF significantly improve the durability of full cells (coupled to CaV6 O16 ·3H2 O). Additionally, we integrate durable pouch cell and electrochemical neuromorphic inorganic device (ENIDe) to simulate neural network, providing a strategy for extreme interconnectivity comparable to the human brain. This article is protected by copyright. All rights reserved.

Enhanced anti-inflammatory and ulcerogenicity of Ibuprofen microsphere formulations using Irvingia wombolu fat (IRW) and moringa oil (MO) as co-lipids

Ibuprofen is a member of the propionic acid class of nonsteroidal anti-inflammatory drugs (NSAIDs) with anti-inflammatory, analgesic, and antipyretic activities used to relieve a variety of pains. The objective of this study was to formulate, characterize and evaluate the in vitro and in vivo properties of ibuprofen formulated as solid lipid microspheres (SLMs) for enhanced delivery. The mixtures of Irvingia wombolu fat (IRW) and moringa oil (MO) each with Phospholipon® 90G (PL90G) at the ratio of 2:1 w/w were prepared by fusion, characterized and used to prepare SLMs. The SLMS were thereafter evaluated using the following parameters: particle size and morphology, stability, and encapsulation efficiency EE (%). In vitro release was carried out in phosphate buffer (pH 7.4). The ibuprofen based SLMs were also evaluated for anti-inflammatory and anti-ulcer effects using animal models. The pH showed significant increase after two months of formulation with a maximum value of 6.4 while the EE obtained were 95.6, 89.4 and 61.6% for SLMs formulated with lipid matrix of Phospholipon® 90G (1% and 2%), and MO (1%) respectively. The in vitro release showed maximum release of 87.8 and 98.97% of the two different lipid-based formulations while anti-inflammatory effect was up to 89.90% after 5 h of inducing inflammation. The SLMs did not show any lesion thus conferring gastroprotection on the formulations. The SLMs exhibited good anti-inflammatory property with gastroprotective action.

Flower-like Thiourea-Formaldehyde Resin Microspheres for the Adsorption of Silver Ions.

Around a quarter of annual worldwide silver consumption comes from recycling. It remains a primary target for researchers to increase the silver ion adsorption capacity of the chelate resin. Herein, a series of flower-like thiourea-formaldehyde microspheres (FTFM) possessing diameters of 15-20 μm were prepared via a one-step reaction under acidic conditions, and the effects of the monomer molar ratio and reaction time on the micro-flower morphology, specific surface area, and silver ion adsorption performance were explored. The nanoflower-like microstructure showed the maximum specific surface area 18.98 ± 0.949 m2/g, which was 55.8 times higher than that of the solid microsphere control. As a result, the maximum silver ion adsorption capacity was 7.95 ± 0.396 mmol/g, which was 10.9 times higher than that of the control. Kinetic studies showed that the equilibrium adsorption amount of FT1F4M was 12.61 ± 0.016 mmol/g, which was 11.6 times higher than that of the control. Additionally, the isotherm study of the adsorption process was performed, and the maximum adsorption capacity of FT1F4M was 18.17 ± 1.28 mmol/g, which was 13.8 times that of the control according to the Langmuir adsorption model. Its high absorption efficiency, convenient preparation strategy, and low cost recommend FTFM bright for further use in industrial applications.