Sol-gel-derived glass scaffold with high pore interconnectivity and enhanced bioactivity

2009 ◽  
Vol 24 (12) ◽  
pp. 3495-3502 ◽  
Author(s):  
Ana C. Marques ◽  
Rui M. Almeida ◽  
Amath Thiema ◽  
Shaojie Wang ◽  
Matthias Falk ◽  
...  
Keyword(s):  
Exchange Process ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Three Dimensional ◽  
Average Diameter ◽  
Solvent Exchange ◽  
Sol Gel Transition ◽  
The One

We report on the preparation of a bioactive CaO–SiO2 monolithic scaffold with interconnected bimodal nanomacro porosity, which simulates the morphology of a natural trabecular bone, by a newly developed modified sol-gel process. This method inherently creates nanopores, whose average diameter can be tailored to approximately 5–20 nm by solvent exchange. To achieve interconnected macroporosity (pores ∼5–300 μm in size), a polymer [poly(ethylene oxide)] is added, which causes phase separation simultaneously with the sol-gel transition. High-resolution scanning electron microscopy and mercury intrusion porosimetry demonstrate a high degree of three-dimensional interconnectivity and sharp distributions of pore size. In vitro bioactivity tests in simulated body fluid (SBF) show bioactivity of the material after soaking for approximately 5 h, as verified by the formation of a hydroxyapatite layer deep into the scaffold structure. Analysis of the SBF after the reaction indicates the dissolution of the samples, another desired feature of temporary scaffolds for bone regeneration. MG63 osteoblast-like cells seeded on our sol-gel glass samples responded better to samples with nanopores enlarged by a solvent exchange process than to the one with normal nanopores. Thus, the benefits of the high surface area achieved by sol-gel and solvent exchange procedures are most clearly demonstrated for the first time.

Carbon Aerogels and Xerogels

1992 ◽  
Vol 270 ◽  
Author(s):  
Richard W. Pekala ◽  
Cynthia T. Alviso
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Particle Morphology ◽  
Inert Atmosphere ◽  
Vitreous Carbon ◽  
Carbon Aerogels ◽  
Structure Property ◽  
Microporous Material ◽  
Sol Gel Transition

ABSTRACTThe aqueous polycondensation of resorcinol with formaldehyde proceeds through a sol-gel transition and results in the formation of highly crosslinked, transparent gels. If the solvent is simply evaporated from the pores of these gels, large capillary forces are exerted and a collapsed structure known as a xerogel is formed. In order to preserve the gel skeleton and minimize shrinkage, the aforementioned solvent or its substitute must be removed under supercritical conditions. The microporous material that results from this operation is known as an aerogel. Because resorcinol-formaldehyde aerogels and xerogels consist of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths. The resultant porous materials are black in color and no longer transparent, yet they retain the ultrafine cell size (< 50 nm), high surface area (600-800 m2 /g), and the interconnected particle morphology of their organic precursors. The thermal, acoustic, mechanical, and electrical properties of carbon aerogels/xerogels primarily depend upon polymerization conditions and pyrolysis temperature. In this paper, the chemistry-structure-property relationships of these unique materials will be discussed in detail.

scholarly journals 3D Fuzzy Graphene Microelectrode Array for Neurotransmitter Sensing at Sub-cellular Spatial Resolution

2020 ◽  
Author(s):  
Elisa Castagnola ◽  
Raghav Garg ◽  
Sahil Rastogi ◽  
Tzahi Cohen-Karni ◽  
Xinyan Tracy Cui
Keyword(s):  
Surface Area ◽  
Spatial Resolution ◽  
Microelectrode Array ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Brain Functions

<div>Dopamine (DA) is a monoamine neurotransmitter involved in the modulation of various physiological brain functions, including learning, motivation, reward, and motor functions. The development of a high sensitivity real-time sensor for multi-site detection of DA with high spatial resolution has critical implications for both neuroscience and clinical communities to improve understanding and treatments of neurological and neuropsychiatric disorders. Here, we present high-surface area out-of-plane grown three-dimensional (3D) fuzzy graphene (3DFG) microelectrode arrays (MEAs) for highly selective, sensitive, and stable DA electrochemical sensing. 3DFG microelectrodes present a remarkable sensitivity to DA (2.87 ± 0.25 nA/nM, with</div><div>LOD of 990±15 pM), the highest reported for nanocarbon MEAs using Fast Scan Cyclic Voltammetry (FSCV). The high surface area of 3DFG allows for miniaturization of electrode down to 2 x 2 μm^2, without compromising the electrochemical performance. Moreover, 3DFG MEAs are electrochemically stable under 7.2 million scans of continuous FSCV cycling, present exceptional selectivity over the most common interferents in vitro with minimum fouling by electrochemical byproducts, and can discriminate DA and serotonin (5-HT) in response to the injection of their 50:50 mixture. These results highlight the potential of 3DFG MEAs as a promising platform for FSCV based multi-site detection of DA with high sensitivity, selectivity, and spatial resolution.</div>

scholarly journals Template-assisted, Sol-gel Fabrication of Biocompatible, Hierarchically Porous Hydroxyapatite Scaffolds

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1274 ◽  
Author(s):  
Xingyuan Zhang ◽  
Lirong Zhang ◽  
Yuanwei Li ◽  
Youlu Hua ◽  
Yangde Li ◽  
...  
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Culture Cell ◽  
Porous Structures ◽  
Porous Hydroxyapatite ◽  
Hierarchically Porous ◽  
In Vitro Biocompatibility ◽  
Hierarchical Porous

Hierarchically porous hydroxyapatite (HHA) scaffolds were synthesized by template-assisted sol-gel chemistry. Polyurethane foam and a block copolymer were used as templates for inducing hierarchically porous structures. The HHA scaffolds exhibited open porous structures with large pores of 400–600 µm and nanoscale pores of ~75 nm. In comparison with conventional hydroxyapatite (CHA), HHA scaffolds exhibited significantly higher surface areas and increased protein adsorption for bovine serum albumin and vitronectin. Both the HHA and CHA scaffolds exhibited well in vitro biocompatibility. After 1 day, Saos-2 osteoblast-like cells bound equally well to both HHA and CHA scaffolds, but after 7 days in culture, cell proliferation was significantly greater on the HHA scaffolds (p < 0.01). High surface area and hierarchical porous structure contributed to the selective enhancement of osteoblast proliferation on the HHA scaffolds.

Development of Gelatin-Thai Silk Fibroin Microspheres for Three Dimensional Cell Culture

2014 ◽  
Vol 931-932 ◽  
pp. 200-204
Author(s):  
S. Sinthop ◽  
S. Patumraj ◽  
S. Kanokpanont
Keyword(s):  
Silk Fibroin ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Tissue Engineering Scaffolds ◽  
Gelatin Microspheres ◽  
Size And Morphology ◽  
Average Size

Microspheres have been widely used for tissue engineering scaffolds. Microspheres have many advantages over the macrostructure such as high surface area for cell adhesion and proliferation and low mass transfer limits. In this study, we fabricated microspheres from gelatin and silk fibroin using water-in-oil (w/o) emulsion technique and glutaraldehyde crosslinking. Gelatin (G) and silk fibroin (SF) were blended at different G/SF weight blending ratios of 100/0, 90/10, 70/30, and 50/50. Physical and chemical properties of the microspheres including size and morphology were characterized. The Average size of microspheres obtained were at 858.42±41.93, 832.97± 9.44 , 785.24±17.66 and 735.83 ±13.19 μm, respectively. Morphology of G/SF microspheres was observed under a scanning electron microscope. Blending of silk fibroin increased the crosslinking degrees and water absorption. It also reduced degradation rate, comparing to the gelatin microspheres. Thein vitroattachment and proliferation of rat bone marrow derived mesenchymal stem cells (MSC) cultured on G/SF microspheres were evaluated. G/SF 50/50 microspheres promoted the highest attachment of MSC on microspheres (46.0±5.8% of initial seeding at 6 hr). The G/SF 70/30 microspheres promoted the higher cell proliferation of MSC compared the others. Specific growth rate of the cells on the microspheres was at 9.85x10-3h-1.

Inorganic and Organic Aerogels

MRS Bulletin ◽  
1990 ◽  
Vol 15 (12) ◽  
pp. 30-36
Keyword(s):  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Visible Spectrum ◽  
Supercritical Drying ◽  
Porous Solids ◽  
Metal Alkoxides ◽  
Open Cell Foams ◽  
Sol Gel Transition ◽  
Organic Aerogels

Aerogels are a special class of open-cell foams derived from the supercritical drying of highly cross-linked inorganic or organic gels. These materials have ultrafine cell/pore sizes (less than 1,000 Å), continuous porosity, high surface area (400–1000 m2/g), and a microstructure composed of interconnected colloidal-like particles or polymeric chains with characteristic diameters of 100 Å. This microstructure is responsible for the unusual optical, acoustic, thermal, and mechanical properties of aerogels. For example, aerogels can be prepared as transparent, porous solids because their ultrafine cell/pore size minimizes light scattering in the visible spectrum. Figure 4.1 shows the different aerogels that will be discussed in this article.The hydrolysis and condensation of metal alkoxides is the most common synthetic route for the formation of inorganic aerogels. Inorganic aerogels have been prepared from monomers such as tetraisopropoxy titanate, aluminum secbutylate, and zirconium isopropoxide. Nevertheless, the majority of scientific research has concentrated on the sol-gel polymerization of tetramethoxysilane (TMOS), or the less toxic tetraethoxysilane (TEOS). The resultant silica aerogels are being investigated for applications ranging from window insulation to the collection of hypervelocity partis cles in space.The sol-gel polymerization of a multifunctional monomer in solution, leading to the formation of an aerogel, is not unique to metal alkoxides. Organic reactions that proceed through a sol-gel transition have been discovered recently.

scholarly journals 3D Fuzzy Graphene Microelectrode Array for Neurotransmitter Sensing at Sub-cellular Spatial Resolution

2020 ◽  
Author(s):  
Elisa Castagnola ◽  
Raghav Garg ◽  
Sahil Rastogi ◽  
Tzahi Cohen-Karni ◽  
Xinyan Tracy Cui
Keyword(s):  
Surface Area ◽  
Spatial Resolution ◽  
Microelectrode Array ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Brain Functions

<div>Dopamine (DA) is a monoamine neurotransmitter involved in the modulation of various physiological brain functions, including learning, motivation, reward, and motor functions. The development of a high sensitivity real-time sensor for multi-site detection of DA with high spatial resolution has critical implications for both neuroscience and clinical communities to improve understanding and treatments of neurological and neuropsychiatric disorders. Here, we present high-surface area out-of-plane grown three-dimensional (3D) fuzzy graphene (3DFG) microelectrode arrays (MEAs) for highly selective, sensitive, and stable DA electrochemical sensing. 3DFG microelectrodes present a remarkable sensitivity to DA (2.87 ± 0.25 nA/nM, with</div><div>LOD of 990±15 pM), the highest reported for nanocarbon MEAs using Fast Scan Cyclic Voltammetry (FSCV). The high surface area of 3DFG allows for miniaturization of electrode down to 2 x 2 μm^2, without compromising the electrochemical performance. Moreover, 3DFG MEAs are electrochemically stable under 7.2 million scans of continuous FSCV cycling, present exceptional selectivity over the most common interferents in vitro with minimum fouling by electrochemical byproducts, and can discriminate DA and serotonin (5-HT) in response to the injection of their 50:50 mixture. These results highlight the potential of 3DFG MEAs as a promising platform for FSCV based multi-site detection of DA with high sensitivity, selectivity, and spatial resolution.</div>

High surface area hierarchical porous Al2O3 prepared by the integration of sol–gel transition and phase separation

RSC Advances ◽  
2016 ◽  
Vol 6 (62) ◽  
pp. 57217-57226 ◽  
Author(s):  
A. R. Passos ◽  
S. H. Pulcinelli ◽  
V. Briois ◽  
C. V. Santilli
Keyword(s):  
Phase Separation ◽  
Surface Area ◽  
Porous Alumina ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Gelation Process ◽  
Hierarchical Porous ◽  
Sol Gel Transition ◽  
Gel Transition

Mechanism of gelation process and phase separation for production of hierarchical porous alumina with high surface area.

Bi-layered electrospun nanofibrous polyurethane-gelatin scaffold with targeted heparin release profiles for tissue engineering applications

2017 ◽  
Vol 37 (9) ◽  
pp. 933-941 ◽  
Author(s):  
Mohammad Mahdi Safikhani ◽  
Ali Zamanian ◽  
Farnaz Ghorbani ◽  
Azadeh Asefnejad ◽  
Mostafa Shahrezaee
Keyword(s):  
Tissue Engineering ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Coagulation Factor ◽  
Volume Ratio ◽  
Fibroblast Cell ◽  
Porous Scaffolds ◽  
Nanofibrous Scaffolds

Abstract Tissue engineering is a biotechnology that is used to develop biological substitutes to restore, maintain, or improve functions. Thus, the porous scaffolds are used to accommodate cells in tissue engineering. In this research, three dimensional (3D) bi-layered polyurethane (PU)-gelatin nanofibrous scaffolds were prepared by the electrospinning method, after which the capability of the released heparin as an anti-coagulation factor was evaluated. Electrospinning has been extensively investigated for the preparation of fibers that exhibit a high surface area to volume ratio. Results showed that scanning electron microscopy (SEM) micrographs exhibited a smooth surface as well as a highly porous and bead-free structure, in which fibers were distributed in the range of 100–600 nm. The modulus and ultimate tensile strength (UTS) decreased and increased, respectively, after crosslinking the reaction of polymers. This process also reduced swelling ratio, the hydrolytic biodegradation rate, and the release rate as a function of time. Moreover, an in vitro assay demonstrated that 3D nanofibrous scaffolds supported L929 fibroblast cell viability and that cells adhered and spread on the fibers. Based on the obtained results, the heparin-loaded electrospinning nanofibrous scaffolds have initial physicochemical and mechanical properties to protect neo-tissue formation.

Functionalized Nano-graphene Oxide as Multi-modal Clinic for Effective Drug Delivery

2017 ◽  
Vol 10 (4) ◽  
pp. 3768-3771
Author(s):  
Soumitra Satapathi ◽  
Rutusmita Mishra ◽  
Manisha Chatterjee ◽  
Partha Roy ◽  
Somesh Mohapatra
Keyword(s):  
Drug Delivery ◽  
Graphene Oxide ◽  
Cancer Cell ◽  
High Surface ◽  
High Surface Area ◽  
Cancer Cell Line ◽  
Xrd Analysis ◽  
Graphene Derivatives ◽  
Nano Graphene

Nano-materials based drug delivery modalities to specific organs and tissues has become one of the critical endeavors in pharmaceutical research. Recently, two-dimensional graphene has elicited considerable research interest because of its potential application in drug delivery systems. Here we report, the drug delivery applications of PEGylated nano-graphene oxide (nGO-PEG), complexed with a multiphoton active and anti-cancerous diarylheptanoid drug curcumin. Specifically, graphene-derivatives were used as nanovectors for the delivery of the hydrophobic anticancer drug curcumin due to its high surface area and easy surface functionalization. nGO was synthesized by modified Hummer’s method and confirmed by XRD analysis. The formation of nGO, nGO-PEG and nGO-PEG-Curcumin complex were monitored through UV-vis, IR spectroscopy. MTT assay and AO/EB staining found that nGO-PEG-Curcumin complex afforded highly potent cancer cell killing in vitro with a human breast cancer cell line MCF7.

Smart Gn-Keto Nanohybrid Embedded Topical System for Effective Management of Dermatophytosis

2019 ◽  
Vol 9 (1) ◽  
pp. 21-28
Author(s):  
Nisha Sharma ◽  
Shashikiran Misra
Keyword(s):  
Antifungal Activity ◽  
Fungal Infections ◽  
High Surface ◽  
High Surface Area ◽  
Vital Role ◽  
Common Disease ◽  
Microdilution Method ◽  
Enhanced Solubility ◽  
Bioactive Agents

Background and Objectives: Dermatophytosis (topical fungal infection) is the 4th common disease in the last decade, affecting 20-25% world’s population. Patients of AIDS, cancer, old age senescence, diabetes, cystic fibrosis become more vulnerable to dermatophytosis. The conventional topical dosage proves effective as prophylactic in preliminary stage. In the advanced stage, the therapeutics interacts with healthy tissues before reaching the pathogen site, showing undesirable effects, thus resulting in pitiable patient compliance. The youngest carbon nano-trope “Graphene” is recently used to manipulate bioactive agents for therapeutic purposes. Here, we explore graphene via smart engineering by virtue of high surface area and high payload for therapeutics and developed graphene–ketoconazole nanohybrid (Gn-keto) for potent efficacy towards dermatophytes in a controlled manner. </P><P> Methods: Polymethacrylate derivative Eudragit (ERL100 and ERS 100) microspheres embedded with keto and Gn-keto nanohybrid were formulated and characterized through FTIR, TGA, and SEM. In vitro drug release and antifungal activity of formulated Gn-keto microspheres were assessed for controlled release and better efficacy against selected dermatophytes. </P><P> Results: Presence of numerous pores within the surface of ERL100 microspheres advocated enhanced solubility and diffusion at the site of action. Controlled diffusion across the dialysis membrane was observed with ERS100 microspheres owing to the nonporous surface and poor permeability. Antifungal activity against T. rubrum and M. canis using microdilution method focused on a preeminent activity (99.785 % growth inhibition) of developed nanohybrid loaded microspheres as compared to 80.876% of keto loaded microspheres for T. rubrum. The culture of M. canis was found to be less susceptible to formulated microspheres. Conclusion: Synergistic antifungal activity was achieved by nanohybrid Gn-Keto loaded microspheres against selected topical fungal infections suggesting a vital role of graphene towards fungi.

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