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Composite Gels (composite + gel)

Distribution by Scientific Domains
Medical Sciences40%
Chemistry30%

Selected Abstracts

Potential of Fortified Fibrin/Hyaluronic Acid Composite Gel as a Cell Delivery Vehicle for Chondrocytes

ARTIFICIAL ORGANS, Issue 6 2009
Sang-Hyug Park
Abstract Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 ± 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 ± 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel. [source]

Novel Gelling Systems of , -, , - and , -Carrageenans and their Composite Gels with Cellulose Using Ionic Liquid

MACROMOLECULAR BIOSCIENCE, Issue 4 2009
Kamalesh Prasad
Abstract Gels of three types of carrageenans (, -, , - and , -), as well as their composite gels with cellulose, were prepared using an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), by a heating-cooling process. , -Carrageenan gave the formation of hard gel while the other two carrageenans gave the formation of softer gels with BMIMCl. The gels were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DSC), scanning electron microscope (SEM) and compressive testing. The results indicated that, among the three types of carrageenans, , - and , -carrageenans gave better miscible gels with BMIMCl, followed by , -carrageenan. On the other hand, , -carrageenan gave a better miscible composite gel with cellulose and BMIMCl, followed by , - and , -carrageenans. The stress-strain curves indicated that the mechanical properties of the above gel systems on the compressive mode were much better than those of the hydrogels of , - and , -carrageenans as well as the cellulose gel with BMIMCl. [source]

Electroconductive Hydrogels: Electrical and Electrochemical Properties of Polypyrrole-Poly(HEMA) Composites

ELECTROANALYSIS, Issue 7 2005
Sean Brahim
Abstract Composites of inherently conductive polypyrrole (PPy) within highly hydrophilic poly(2-hydroxyethyl methacrylate)-based hydrogels (p(HEMA)) have been fabricated and their electrochemical properties investigated. The electrochemical characteristics observed by cyclic voltammetry suggest less facile reduction of PPy within the composite hydrogel compared to electropolymerized PPy, as shown by the shift in the reduction peak potential from ,472,mV for electropolymerized polypyrrole to ,636,mV for the electroconductive composite gel. The network impedance magnitude for the electroconductive hydrogel remains quite low, ca. 100,,, even upon approach to DC, over all frequencies and at all offset potentials suggesting retained electronic (bipolaronic) conductivity within the composite. In contrast, sustained application of +0.7 V (vs. Ag/AgCl, 3,M Cl,) for typically 100,min. (conditioning) to reduce the background amperometric current to <1.0,,A, resulted in complete loss of electroactivity. Nyquist plots suggest that sustained application of such a modest potential to the composite hydrogel results in impedance characteristics that resembles p(HEMA) without evidence of the conducting polymer component. PPy composite gels supported a larger ferrocene monocarboxylate diffusivity (Dappt=7.97×10,5,cm2,s,1) compared to electropolymerized PPy (Dappt=5.56×10,5,cm2,s,1), however a marked reduction in diffusivity (Dappt=1.01×10,5,cm2,s,1) was observed with the conditioned hydrogel composite. Cyclic voltammograms in buffer containing H2O2 showed an absence of redox peaks for electrodes coated with PPy-containing membranes, suggesting possible chemical oxidation of polypyrrole by the oxidant [source]

Novel Gelling Systems of , -, , - and , -Carrageenans and their Composite Gels with Cellulose Using Ionic Liquid

MACROMOLECULAR BIOSCIENCE, Issue 4 2009
Kamalesh Prasad
Abstract Gels of three types of carrageenans (, -, , - and , -), as well as their composite gels with cellulose, were prepared using an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), by a heating-cooling process. , -Carrageenan gave the formation of hard gel while the other two carrageenans gave the formation of softer gels with BMIMCl. The gels were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DSC), scanning electron microscope (SEM) and compressive testing. The results indicated that, among the three types of carrageenans, , - and , -carrageenans gave better miscible gels with BMIMCl, followed by , -carrageenan. On the other hand, , -carrageenan gave a better miscible composite gel with cellulose and BMIMCl, followed by , - and , -carrageenans. The stress-strain curves indicated that the mechanical properties of the above gel systems on the compressive mode were much better than those of the hydrogels of , - and , -carrageenans as well as the cellulose gel with BMIMCl. [source]

Potential of Fortified Fibrin/Hyaluronic Acid Composite Gel as a Cell Delivery Vehicle for Chondrocytes

ARTIFICIAL ORGANS, Issue 6 2009
Sang-Hyug Park
Abstract Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 ± 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 ± 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel. [source]

Electroconductive Hydrogels: Electrical and Electrochemical Properties of Polypyrrole-Poly(HEMA) Composites

ELECTROANALYSIS, Issue 7 2005
Sean Brahim
Abstract Composites of inherently conductive polypyrrole (PPy) within highly hydrophilic poly(2-hydroxyethyl methacrylate)-based hydrogels (p(HEMA)) have been fabricated and their electrochemical properties investigated. The electrochemical characteristics observed by cyclic voltammetry suggest less facile reduction of PPy within the composite hydrogel compared to electropolymerized PPy, as shown by the shift in the reduction peak potential from ,472,mV for electropolymerized polypyrrole to ,636,mV for the electroconductive composite gel. The network impedance magnitude for the electroconductive hydrogel remains quite low, ca. 100,,, even upon approach to DC, over all frequencies and at all offset potentials suggesting retained electronic (bipolaronic) conductivity within the composite. In contrast, sustained application of +0.7 V (vs. Ag/AgCl, 3,M Cl,) for typically 100,min. (conditioning) to reduce the background amperometric current to <1.0,,A, resulted in complete loss of electroactivity. Nyquist plots suggest that sustained application of such a modest potential to the composite hydrogel results in impedance characteristics that resembles p(HEMA) without evidence of the conducting polymer component. PPy composite gels supported a larger ferrocene monocarboxylate diffusivity (Dappt=7.97×10,5,cm2,s,1) compared to electropolymerized PPy (Dappt=5.56×10,5,cm2,s,1), however a marked reduction in diffusivity (Dappt=1.01×10,5,cm2,s,1) was observed with the conditioned hydrogel composite. Cyclic voltammograms in buffer containing H2O2 showed an absence of redox peaks for electrodes coated with PPy-containing membranes, suggesting possible chemical oxidation of polypyrrole by the oxidant [source]

Influence of magnesium aluminium silicate on rheological, release and permeation characteristics of diclofenac sodium aqueous gels in-vitro

JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2005
Thaned Pongjanyakul
The effect of magnesium aluminium silicate (MAS) on rheological, release and permeation characteristics of diclofenac sodium (DS) aqueous gels was investigated. DS aqueous gels were prepared using various gelling agents, such as 15% w/w poloxamer 407 (PM407), 1% w/w hydroxypropylmethylcellulose (HPMC), and 1% w/w high and low viscosity grades of sodium alginate (HV-SA and LV-SA, respectively). Different amounts of MAS (0.5, 1.0 and 1.5% w/w) were incorporated into the DS gels. Incorporation of MAS into the DS gels prepared using SA or PM407 caused a statistical increase in viscosity (P<0.05) and a shift from Newtonian flow to pseudoplastic flow with thixotropic property. The DS release rates of these composite gels were significantly decreased (P<0.05) when compared with the control gels. This was due to an interaction between MAS and PM407 or SA, and adsorption of DS onto MAS particles. Moreover, a longer lag time and no change in DS permeation flux were found when MAS was added to the gels. The findings suggest that the rheological characteristics of gels prepared using PM407 or SA could be improved by incorporating MAS. However, the use of MAS could retard the DS release and extend the lag time of DS permeation. [source]

Novel Gelling Systems of , -, , - and , -Carrageenans and their Composite Gels with Cellulose Using Ionic Liquid

MACROMOLECULAR BIOSCIENCE, Issue 4 2009
Kamalesh Prasad
Abstract Gels of three types of carrageenans (, -, , - and , -), as well as their composite gels with cellulose, were prepared using an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), by a heating-cooling process. , -Carrageenan gave the formation of hard gel while the other two carrageenans gave the formation of softer gels with BMIMCl. The gels were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DSC), scanning electron microscope (SEM) and compressive testing. The results indicated that, among the three types of carrageenans, , - and , -carrageenans gave better miscible gels with BMIMCl, followed by , -carrageenan. On the other hand, , -carrageenan gave a better miscible composite gel with cellulose and BMIMCl, followed by , - and , -carrageenans. The stress-strain curves indicated that the mechanical properties of the above gel systems on the compressive mode were much better than those of the hydrogels of , - and , -carrageenans as well as the cellulose gel with BMIMCl. [source]

Potential of Fortified Fibrin/Hyaluronic Acid Composite Gel as a Cell Delivery Vehicle for Chondrocytes

ARTIFICIAL ORGANS, Issue 6 2009
Sang-Hyug Park
Abstract Numerous treatment methods have been applied for use in cartilage repair, including abrasion, drilling, and microfracture. Although chondrocyte transplantation is the preferred treatment, it has some shortcomings, such as difficulty of application (large and posterior condylar regions), poor chondrocyte distribution, and potential cell leakage from the defect region. The cell delivery system of the tissue engineering technique can be used to overcome these shortcomings. We chose fibrin/hyaluronan (HA) composite gel as an effective cell delivery system to resolve these issues. Both components are derived from natural extracellular matrix. In the first trial, fortified fibrin/HA composite gels with rabbit chondrocytes were tested by implantation in nude mice. At 4 weeks, glycosaminoglycan contents in the fibrin/HA composite (0.186 ± 0.006 mg/mg) were significantly higher than those in the presence of fibrin alone (0.153 ± 0.017 mg/mg). As a next step, we applied the fibrin/HA composite gel to animal cartilage defects using full thickness cartilage defect rabbit models. The fibrin/HA composite gel with rabbit chondrocytes (allogenic) was implanted into the experimental group, and the control group was implanted with the fibrin/HA composite gel alone. Implanted chondrocytes with the fibrin/HA composite showed improved cartilage formation. In conclusion, the key to successful regeneration of cartilage is to provide the repair site with a sufficient supply of chondrogenic cells with a suitable delivery vehicle to ensure maximal differentiation and deposition of the proper extracellular matrix. This study suggests the feasibility of tissue-engineered cartilage formation using fibrin/HA composite gel. [source]

Light-Driven Thermoelectric Conversion Based on a Carbon Nanotube,Ionic Liquid Gel Composite

CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 8 2009
Eijiro Miyako Dr.
A photoinduced thermoelectric conversion system based on single-walled carbon nanotube,room temperature ionic liquid composite gels is reported. These new types of gel-based near-infrared laser-driven thermoelectric convertors generate high electrical energy. [source]