Mono-dispersed Glass Research Articles

Sol-gel synthesis of spherical monodispersed bioactive glass nanoparticles co-doped with boron and copper

In this work, an optimized sol-gel process for the synthesis of spherical and monodispersed bioactive glass nanoparticles doped with boron and copper was developed, by investigating different synthesis parameters. The obtained glasses were characterized in terms of morphology, composition, dispersibility, structure and in vitro reactivity. The performed characterizations demonstrated that shape, dimension and dispersion can be tailored by acting on the timing of the addition of the catalyst and on the synthesis process, in particular the centrifugation step. The optimized glass particles showed a spherical shape, good ions incorporation and good dispersion. In vitro bioactivity test demonstrated that the boron and copper addition did not interfere with the glass ability to induce the precipitation of hydroxyapatite. The shape, dispersion, bioactive behavior and content of boron and copper of these novel bioactive glass particles make them very promising for both hard and soft tissue engineering applications.

Snow Particle Analyzer for Simultaneous Measurements of Snow Density and Morphology

AbstractThe detailed characterization of snow particles is critical for understanding the snow settling behavior and modeling the ground snow accumulation for various applications such as prevention of avalanches and snowmelt‐caused floods, etc. In this study, we present a snow particle analyzer for simultaneous measurements of various properties of fresh falling snow, including their size, shape, type, and density. The analyzer consists of a digital inline holography module for imaging falling snow particles in a sample volume of 88 cm3 and a high‐precision scale to measure the weight of the same particles in a synchronized fashion. The holographic images are processed in real‐time using a machine learning model and post‐processing to determine snow particle size, shape, and type. Such information is used to obtain the estimated volume, which is subsequently correlated with the weight of snow particles to estimate their density. The performance of the analyzer is assessed using monodispersed spherical glass and foam beads, irregular salt crystals, and thin disks with various shapes with known density, which shows <10% density measurement errors. In addition, the analyzer was tested in a number of field deployments under different snow and wind conditions. The system is able to achieve measurements of various snow properties at single particle resolution and statistical robustness. The analyzer was also deployed for 4 hr of operation during a snow event with changing snow and wind conditions, demonstrating its potential for long‐term and real‐time monitoring of the time‐varying snow properties in the field.

Bioactive glass in the treatment of ulcerative colitis to regulate the TLR4 / MyD88 / NF-κB pathway

Ulcerative colitis (UC) is a chronic and recurrent intestinal disease of unknown aetiology, and the few treatments approved for UC have serious side effects. In this study, a new type of uniformly monodispersed calcium-enhanced radial mesoporous micro-nano bioactive glass (HCa-MBG) was prepared for UC treatment. We established cellular and rat UC models to explore the effects and mechanism of HCa-MBG and traditional BGs (45S5, 58S) on UC. The results showed that BGs significantly reduced the cellular expression of several inflammatory factors, such as IL-1β, IL-6, TNF-α and NO. In the animal experiments, BGs were shown to repair the DSS-damaged colonic mucosa. Moreover, BGs downregulated the mRNA levels of the inflammatory factors IL-1β, IL-6, TNF-α and iNOS, which were stimulated by DSS. BGs were also found to manage the expression of key proteins in NF-kB signal pathway. However, HCa-MBG was more effective than traditional BGs in terms of improving UC clinical manifestations and reducing the expression of inflammatory factors in rats. This study confirmed for the first time that BGs can be used as an adjuvant drug in UC treatment, thereby preventing UC progression.

Zinc-Containing Sol-Gel Glass Nanoparticles to Deliver Therapeutic Ions.

Zn-containing dense monodispersed bioactive glass nanoparticles (Zn-BAGNPs) have been developed to deliver therapeutic inorganic trace elements, including Si, Ca, Sr, and Zn, to the cells through the degradation process, as delivery carriers for stimulating bone regeneration because of their capacity to induce osteogenic differentiation. The sol–gel-derived dense silica nanoparticles (SiO2-NPs) were first synthesized using the modified Stöber method, prior to incorporating therapeutic cations through the heat treatment process. The successfully synthesized monodispersed Zn-BAGNPs (diameter of 130 ± 20 nm) were homogeneous in size with spherical morphology. Ca, Sr and Zn were incorporated through the two-step post-functionalization process, with the nominal ZnO ratio between 0 and 2 (0, 0.5, 1.0, 1.5 and 2.0). Zn-BAGNPs have the capacity for continuous degradation and simultaneous ion release in SBF and PBS solutions due to their amorphous structure. Zn-BAGNPs have no in vitro cytotoxicity on the murine pre-osteoblast cell (MC3T3-E1) and periodontal ligament stem cells (PDLSCs), up to a concentration of 250 µg/mL. Zn-BAGNPs also stimulated osteogenic differentiation on PDLSCs treated with particles, after 2 and 3 weeks in culture. Zn-BAGNPs were not toxic to the cells and have the potential to stimulate osteogenic differentiation on PDLSCs. Therefore, Zn-BAGNPs are potential vehicles for therapeutic cation delivery for applications in bone and dental regenerations.

Experimental and numerical investigations on the local wall heat transfer coefficient in a narrow packed bed with spheres

Packed beds are used at the laboratory scales to model and understand the phenomena of water flow through soil and rocks. The behaviour of local wall heat transfer coefficient with randomised packing of mono-dispersed spheres is examined in the present study. Under steady-state conditions, the high-resolution local wall temperature data is obtained by placing the infrared (IR) camera in close proximity to the test section. The local wall heat transfer coefficient is computed using the measured bulk fluid temperature, local wall temperature data and applied heat flux. Physical and numerical experiments were conducted for the narrow bed to particle diameter ratio of 1.25 using random packing of mono-dispersed (impermeable) glass spheres (diameter 6 mm) in order to be able to recreate similar geometry for numerical simulations of fluid flow and heat transfer. An attempt is made for recreation of the experimental narrow bed geometry by using the technique of method of gaps and computational fluid dynamics simulations were performed. The results of simulations are presented in appropriate velocity vectorial plots and flow stream lines revealing complex 3D mixing patterns inside void spaces of the narrow bed. Local variations of wall heat transfer coefficient are found along the packed bed and the numerical simulations of fluid flow and heat transfer reveal interesting complex flow patterns inside the bed.

A facile synthesis of mono-dispersed, spherical and mesoporous bioactive glass nanoparticles for biomedical applications

Bioactive glasses (BG) have become a popular class of biomaterials for a range of medical applications due to their enhanced dissolution rate, cell internalization capability and ionic dissolution products with therapeutic benefits. Here, we introduce, for the first time, a simplified synthesis procedure in order to create nanoparticles with uniform, spherical and mesoporous BG structure with a ternary composition of SiO2-CaO-P2O5. The hydroxyapatite forming ability is also evaluated to confirm the bioactivity. Doxorubicin, a model drug, is loaded within BG nanoparticles with an encapsulation efficiency was 35%. Cytotoxicity evaluations confirmed the non-toxic nature of the nanoparticles when exposed to MG63 cell line. Overall, results suggest the diverse orthopedic and dental application of mesoporous bioactive glass (MBG) nanoparticles.

Facile synthesis and in vitro bioactivity of radial mesoporous bioactive glass with high phosphorus and calcium content

A novel uniform monodispersed radial mesoporous bioactive glass nanosphere (MBG) with high phosphorus and calcium content has been successfully synthesized. The synthesis was first taken place in a cyclohexane-water biphasic stratification reaction system, which fabricated the radial mesoporous SiO2-P2O5 nanosphere (SPN) using hexadecyltrimethyl ammonium bromide (CTAB) as a template agent and triethanolamine (TEA) as a hydrolysis catalyst. Solid reactions were then carried out to synthesize SiO2-CaO-P2O5 MBG using SPN as both the silicon source and phosphorus source, and Ca(NO3)2 as the calcium source. The prepared MBG not only displayed the radial structure and high specific surface area (~321 m2/g), but also had high phosphorus and calcium content. The results of energy dispersive spectrometer (EDS) demonstrated that P2O5 content was enhanced by properly increasing the reaction temperature. The in vitro bioactivity test showed that MBG had an excellent ability of inducing apatite formation. Furthermore, the MBG showed excellent biocompatibility at a low concentration of 50–100 μg/mL in vitro, and it would have a promising prospect as drug delivery system for bone tissue regeneration.

Engineering a Biodegradable Multifunctional Antibacterial Bioactive Nanosystem for Enhancing Tumor Photothermo-Chemotherapy and Bone Regeneration.

The simultaneous therapy of tumors and bone defects resulting from tumor surgery is still a challenge in clinical orthopedics. Few nanomaterial systems simultaneously possess multifunctional capacities, including biodegradability, tumor treatment, and enhanced bone regeneration. Herein, we designed a biodegradable monodispersed bioactive glass nanoparticle (BGN) platform with multifunctional properties for enhanced colon cancer photothermo-chemotherapy and bone repair. The mussel-inspired surface assembly with BGN was established as a stable NIR-excited photothermal nanoplatform (BGN@PDA) for ablating tumors. BGN@PDA shows an ultrahigh anticancer drug (DOX) loading with on-demand (pH/NIR-responsive) drug release behavior and antibacterial activity for enhanced tumor chemotherapy (BGN@PDA-DOX). The growth of colon cancer cells (Hct116 cells) and cervical cancer cells (HeLa cells) was significantly inhibited in vitro, and superior local anticancer efficacy could be achieved by synergic chemo-photothermal therapy in vivo. BGN@PDA underwent a gradual degradation in vivo during 60 days and showed negligible toxic side effects. Meanwhile, BGN@PDA could positively induce the osteogenesis of osteoblasts in vitro and possess excellent in vivo bone repair ability in rat cranial defects. This work presents a distinctive strategy to design a bioactive multifunctional nanoplatform for treating tumor disease-resulted bone tissue regeneration.

Experimental study of the effect of wettability on the relative permeability for air–water flow through porous media

A two-phase flow through porous media is studied experimentally. Considering a classical permeameter array, the value of permeability is obtained for cores made of nearly monodispersed spherical glass beads. In particular, we investigate the effect of changing the wettability condition of the glass beads on the relative permeability in a co-current air–water flow. We found that when the surfaces become more hydrophobic, the water relative permeability increases significantly for all cases tested. The effect is more pronounced when the pore size is smaller than the capillary length. Our measurements are in good qualitative agreement with some results in the literature. The increase of permeability resulting by the addition of a surface-modifying wetting agent could be of use for the secondary recovery of oil and gas in the petroleum industry.

Local wall heat transfer coefficient measurement in a packed bed of cylinders using infrared (IR) thermography technique and application of random packing of cylindrical particles inside concentric tube heat exchangers with water as working medium

Heat transfer enhancement is challenging area in which different techniques are utilized to dissipate the generated heat during operation. Packed beds are devices which enhance heat transport while being compact and are used in several applications such as energy storage, heat exchange devices, catalysis, food processing etc. In the present study, the behavior of wall heat transfer coefficient with randomized packing of equal aspect ratio cylinders is investigated. In this work, the local wall heat transfer coefficient is calculated from local wall temperature data obtained using infrared (IR) thermography in packed beds with randomized packing of cylinders under steady state conditions with water as the working fluid. The randomized packing of cylinders is done inside a concentric tube heat exchanger and the heat transfer enhancement is studied. Experiments are conducted for bed to equivalent particle diameter ratio 2 using random packing of mono-dispersed glass cylinders (dcyl = 6 mm and lcyl = 6 mm). The local wall temperatures are measured using an infrared (IR) camera while the fluid flow takes place through the packed beds. In literature, it is found that wall region contribution to heat transfer is above 90%. The comparison of enhancement in heat transfer for both packing of spheres and cylinders inside concentric tube heat exchangers is done and it is observed that the random sphere packing is superior to cylinder packing.

Shaping monodispersed azo molecular glass microspheres using polarized light.

Azo molecular glass (IAC-4) microspheres with a monodispersed diameter over ten microns were fabricated by microfluidics and unique shape manipulation was achieved based on their fascinating photoinduced deformation behaviour. After irradiation with a polarized laser beam (λ = 488 nm), the IAC-4 microspheres were transformed into uniform mushroom-like particles, and their three-dimensional (3D) asymmetric shapes were precisely manipulated by adjusting the irradiation time and the polarization state of light. By observing the particle morphology in three orthogonal views (top view, front view and side view) by scanning electron microscopy (SEM), the photoinduced deformation behaviour of the ten-micron-sized particles was comprehensively revealed in the 3D space for the first time. It was observed that the photoinduced deformation asymmetrically occurred on the upper part of the microspheres due to the strong optical absorption of the azo chromophores. Besides, the deformation manner of the upper part was decided by the direction of the electric vibration of the refracted light. This work not only depicts a clear picture of the photoinduced deformation behaviour of the ten-micron-sized azo particles upon polarized light irradiation, but also provides a new method to controllably manipulate the particle shape from spheres to complex 3D architectures.

Measurement of local wall heat transfer coefficient in randomly packed beds of uniform sized spheres using infrared thermography (IR) and water as working medium

The needs for compact and effective heat transfer equipments are in growing demand and porous media caters to this need. Packed beds are a simple type of porous media devices which help in transport of mass, momentum and heat. The applications of packed beds are in chemical reactors, distillation, catalysis, thermal energy storage, food processing, solar power plants and several other areas. They act as enhancement devices for different transport processes. In the present study, the behavior of wall heat transfer coefficient with randomized packing of uniformly sized spheres is investigated.In the present work, the local wall heat transfer coefficient is estimated from local wall temperature data obtained using infrared (IR) thermography for the packed beds with randomized packing of uniformly sized spheres under steady state conditions with water as the working fluid. The experiments are conducted for bed to particle diameter ratios of 6, 3 and 2 using random packing of mono-dispersed glass spheres. The two-layer model theory for heat transfer in packed beds is examined in terms of contribution or core zone and wall zone in packed beds. The comparison of heat transfer enhancement aspects with different insert configurations is done and packed beds are found effective.

Monodispersed lysozyme-functionalized bioactive glass nanoparticles with antibacterial and anticancer activities

In this study, highly monodispersed spherical bioactive glass nanoparticles (BGS) with a particle size of 408 ± 36 nm were synthesized using a modified Stöber method. The BGS was then functionalized with lysozyme (LY) via a simple electrostatic interaction routine under selected conditions. The LY-functionalized BGS (LY-BGS) exhibited monodispersity, spherical morphology and homogeneity in size. The incorporated content of LY could be tailored conveniently by adjusting the initial concentration of the LY precursor for functionalization. Hydroxyapatite (HA) formed on the LY-BGS after soaking in simulated body fluid (SBF) for 7 d, but the formation was retarded compared to the non-functionalized BGS. The LY-BGS showed antibacterial activity towards Gram-positive B. subtilis and >90% of the bacteria was killed within 24 h after culture with the LY-BGS at a concentration of 1 mg ml−1. The LY-BGS also showed cytotoxicity towards the human hepatocellular carcinoma (HepG2) cell line. In addition, the relative cytotoxicity increased with an increase in the concentration of the LY-BGS in contact with the cells. As a comparison, the LY-BGS exhibited reduced or no cytotoxicity towards human umbilical vein endothelial cells (HUVECs) at the same concentration with respect to the HepG2 groups. Notably, the relative cell viability of HepG2 was 45.9% after exposure to the LY-BGS at a concentration of 10 μg ml−1 for 24 h, while no decrease in relative viability for the HUVECs was observed under the same conditions. This cytotoxicity window between cancerous cells and healthy cells could be expected for cancer treatment. Furthermore, the antibacterial properties and the bioactivity of LY-BGS make it a promising material for biomedical applications, particularly in the treatment of bone defects caused by tumors.

Accurate bulk density determination of irregularly shaped translucent and opaque aerogels

We present a volumetric method for accurate determination of bulk density of aerogels, calculated from extrapolated weight of the dry pure solid and volume estimates based on the Archimedes' principle of volume displacement, using packed 100 μm-sized monodispersed glass spheres as a “quasi-fluid” media. Hard particle packing theory is invoked to demonstrate the reproducibility of the apparent density of the quasi-fluid. Accuracy rivaling that of the refractive index method is demonstrated for both translucent and opaque aerogels with different absorptive properties, as well as for aerogels with regular and irregular shapes.

Acute toxicity and in vivo biodistribution of monodispersed mesoporous bioactive glass spheres in intravenously exposed mice.

The use of biomaterials from laboratories to clinics requires exhaustive and elaborate studies involving the biodistribution, clearance, and biocompatibility of biomaterials for in vivo biomedical applications. This study aimed to evaluate the acute toxicity and biodistribution of intravenously administrated sub-micrometer mesoporous bioactive glass spheres (SMBGs) in mice. The lethal dose 50 (LD50) of SMBGs was higher than 250 mg/kg. The acute toxicity was evaluated at 14 days after intravenous injection of SMBGs at 20, 100 and 180 mg/kg in ICR mice. The mortality, coefficients of major organs, hematology data and blood biochemical indexes revealed the low in vivo toxicity of SMBGs at all doses. However, the histological examination showed lymphocytic infiltration and granuloma formation in hepatocyte and megakaryocyte hyperplasia in the spleen at high dose. The silicon content analysis using ICP-OES and TEM results indicated that SMBGs mainly distributed in the resident macrophages of the liver and spleen, and could be cleared from the body more than 2 weeks. These findings can be important for the toxicity assessment of sub-micrometer particles and the development of bioactive glass based drug delivery system for biomedical applications.

The effect of submicron bioactive glass particles on in vitro osteogenesis

Mono-dispersed submicron bioactive glass could enhance the adhesion and osteogenesis of MG-63 cells.

Gas–Gas Dispersion Coefficient Measurements Using Low-Field MRI

The dispersion coefficient of displacing fluids within porous media is an important parameter to measure accurately for a range of applications. For example, enhanced gas recovery is an emerging technology where carbon dioxide is injected into natural gas reservoirs as a means of maintaining the pressure of the reservoir and to hence enhance the natural gas recovery, with the additional benefit of carbon dioxide sequestration. Research is currently being done to measure the dispersion coefficient of carbon dioxide into methane because carbon dioxide is a contaminant that reduces the value of the natural gas. Such dispersion experiments are difficult to perform in the laboratory using conventional rock core flooding equipment as erroneous contributions to the dispersion process from entry and exit effects (into and out of the rock core respectively) are impossible to eliminate completely. Previously, we have estimated the resultant error to be of the order of 25 % (Hughes et al., Int J Greenh Gas Control 9:457–468, 2012). Here we effectively deploy spatially resolved breakthrough curves which are characteristic of the dispersion process for carbon dioxide replacing methane. These are obtained from time-resolved 1D magnetic resonance imaging (MRI) profiles. By analysis of the additional dispersion between these time-resolved profiles, we are able to eliminate the entry/exit effects and obtain more accurate values for the dispersion coefficient. We demonstrate this using a model porous medium (mono-dispersed glass beads) in a cell capable of holding gas pressures up to 80 bar in a low-field MRI rock core analyser. Via simultaneous conventional IR analysis of the carbon dioxide effluent to determine the dispersion coefficient, we are also able to directly quantify the magnitude of the error due to these entry/exit effects.

Fabrication and characterization of dodecylamine derived monodispersed mesoporous bioactive glass sub-micron spheres

This paper reports a facile method for fabricating monodispersed mesoporous bioactive glass sub-micron spheres (MBGS) using dodecylamine (DDA) as a catalyst and template agent in sol–gel process. The effects of synthesis conditions including the amount of DDA, temperature of hydrolysis and the volume ratio of alcohol to water (AW ratio) on the resulting particle size, morphology, monodispersity and pore size distribution of MBGS are investigated and discussed. The results indicate that the particle size, morphology, monodispersity and pore size distribution of MBGS depend on the amount of DDA, the temperature of hydrolysis and the AW ratio. Meanwhile, using DDA as the structure directing agent and hydrolysis catalyst under optimal synthesis conditions (e.g. 4 g DDA, hydrolysis temperature at 40 °C and AW ratio at 4) is in favor of obtaining MBGS with mesoporous surface structure, large specific surface area (362.073 m2 g−1), relatively homogeneous particle size (~560 nm) as well as good apatite-forming activity. The unique structure and properties may turn MBGS into a good candidate as a drug delivery carrier or an injectable biomaterial for bone tissue regeneration.

Facile synthesis and in vitro bioactivity of monodispersed mesoporous bioactive glass sub-micron spheres

This paper reports a facile method for fabricating monodispersed mesoporous bioactive glass sub-micron spheres (MBGS) using dodecylamine (DDA) as a catalyst and template agent in sol–gel process. The morphology, structure and in vitro bioactivity of MBGS were investigated by various methods. The results indicate that using DDA as the structure directing agent and hydrolysis catalyst is in favor of preparing the MBGS with mesoporous surface structure, large specific surface area (362.073m2g−1), relatively homogeneous particle size (~560nm) and good apatite-forming activity. The unique structure and properties may turn MBGS into a good candidate as a drug delivery carrier or an injectable biomaterial for bone tissue regeneration.

Numerical prediction of heat transfer between a bubbling fluidized bed and an immersed tube bundle

In this paper a numerical analysis of the heat transfer between a bubbling fluidized bed of mono-dispersed glass beads of Geldart type B and an immersed heated tube bundle is investigated. The numerical procedure is based on a solution of the mass, momentum and energy equations of both phases with an Eulerian approach. Different physical models for the thermal transport coefficient of the solid phase were used. The results are compared with new experimental data. The numerical and the experimental results show a strong correlation between fluid dynamics and heat transfer similar to the packet theory of Mickley and Fairbanks (1955).