A Hydroxyapatite-Collagen Composite Useful to Make Bioresorbable Scaffolds for Bone Reconstruction

2010 ◽  
Vol 76 ◽  
pp. 133-138 ◽  
Author(s):  
Giulio D. Guerra ◽  
Caterina Cristallini ◽  
Elisabetta Rosellini ◽  
Niccoletta Barbani
Keyword(s):  
Weight Ratio ◽  
Average Diameter ◽  
Cross Linking ◽  
Bone Reconstruction ◽  
Scanning Calorimetry ◽  
Bioresorbable Scaffolds ◽  
Micro Particles ◽  
Ft Ir ◽  
The Cross ◽  
The Stability

Composites between hydroxyapatite (HA) and collagen (Col) may be used to make bioresorbable scaffolds for bone reconstruction. A suspension of micro-particles (average diameter ≅ 30 µm) of HA annealed at 1100°C in Col solution (80:20 HA to Col weight ratio) was manufactured in films by casting, and then some films were cross-linked by glutaraldehyde vapours. Cross-linked sponges were obtained by treating the suspension with transglutaminase, and by lyophilizing the so obtained gel. Characterization by scanning electron microscopy, water sorption test, Col release in water, thermogravimetric analysis and differential scanning calorimetry shows that the cross-linking enhances the stability of the composite. Conversely, neither the interactions between HA and Col, detected by spotlight FT-IR, nor the degradation by collagenase, which is a requirement for the bioresorbibility, are affected by the cross-linking.

Preparation and Characterization of Hydrogels Based on Chitsoan/Polyvinyl Alcohol Blends

2015 ◽  
Vol 1105 ◽  
pp. 203-207
Author(s):  
Mohammed Amine Zitouni ◽  
Sofia Borsali Kara Slimane
Keyword(s):  
Weight Ratio ◽  
Poly Vinyl Alcohol ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
Intermolecular Hydrogen Bonds ◽  
Sem Images ◽  
Structure Morphology ◽  
Ft Ir ◽  
Scanning Electron

In this study, a series of poly (vinyl alcohol) (PVA)/chitosan (CS) hydrogels with different weight ratio of PVA to CS were prepared by freezing-thawing (F-T) method. The structure, morphology, and crystallinity of hydrogels were investigated by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). FTIR demonstrated the presence of strong intermolecular hydrogen bonds between CS and PVA molecules. SEM images showed that the higher the chitosan, the greater the porous size of the hydrogel and DSC confirmed that crystallinity is higher when PVA is more in hydrogel. The mechanical properties of these hydrogels were studied by rheometry. The study of swelling ability demonstrated that the hydrogel developed with PVA and Cs was more swellable than that with PVA only because of its cross-linking interaction with PVA.

scholarly journals Synthesis of epoxy resins derivatives of naphthalene-2,7-diol and their cross-linked products

2019 ◽  
Vol 138 (6) ◽  
pp. 4349-4358 ◽  
Author(s):  
K. Fila ◽  
M. Gargol ◽  
M. Goliszek ◽  
B. Podkościelna
Keyword(s):  
Fourier Transform ◽  
Epoxy Resins ◽  
Attenuated Total Reflectance ◽  
Cross Linking ◽  
Total Reflectance ◽  
Before And After ◽  
Ft Ir ◽  
The Cross ◽  
Derivatives Of ◽  
Epoxy Groups

Abstract The aim of this study was the synthesis of three different epoxy compounds based on naphthalene-2,7-diol (2,7-NAF.EP, 2,7-NAF.WEP, 2,7-NAF.P.EP) and then their cross-linking by triethylenetetramine (TETA). All epoxides were prepared by the reaction of naphthalene-2,7-diol with epichlorohydrin but under different conditions and with other catalysts. The structures of the obtained compounds before and after the cross-linking reactions were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR). The ATR/FT-IR spectra of cross-linked compounds show disappearance of the C–O–C bands (about 915 cm−1) derived from the epoxy groups. DSC and TG/DTG measurements indicated that the obtained materials possess good thermal resistance; they are stable up to about 250 °C. The hardness of the cross-linked products was determined using the Shore D method. The highest value of hardness was obtained for the 2,7-NAF.EP-POL. Additionally, the UV–Vis absorption spectra of the obtained polymers were registered and evaluated.

Some properties of 2-5A binding/nucleolytic activities in gel filtered rabbit reticulocyte lysates

1985 ◽  
Vol 5 (12) ◽  
pp. 1041-1051 ◽  
Author(s):  
Joseph M. Wu ◽  
Stanley J. Wertheimer ◽  
Behruz Eslami ◽  
Joanne C. Figuereido ◽  
Biswendu B. Goswami
Keyword(s):  
Binding Activity ◽  
Time Dependent ◽  
Cross Linking ◽  
Elution Profile ◽  
Viral Mrna ◽  
Reticulocyte Lysates ◽  
Atp Analogs ◽  
The Cross ◽  
The Stability

Rabbit reticulocyte lysates, gel filtered on Sephadex G-25 with or without ATP (or its analogs), were preincubated at 37°C and their subsequent binding to p3A4,3′-[32P]pCp was studied. Lysates filtered without ATP or in the presence of 0.1 mM 8-bromo-ATP, 1,N6-etheno-ATP, or ITP showed a time-dependent decrease in binding activity. This decrease was completely prevented when lysates were filtered with 0.1 mM ATP, 2′-deoxy-ATP, β-γ-methylene-ATP, or ATP-γ-S. The stability of binding provided by ATP or 2′-deoxy-ATP analogs corresponds to a more active 2–5A dependent endonucleolytic (RNAase L) activity based on studies using [3H] viral mRNA. Chromatography on heparin-agarose showed that ATP-supplemented gel-filtered reticulocyte lysates had a different p3A4,3′-[32P]pCp binding activity elution-profile than lysates gel-filtered in the absence of ATP. Covalent cross-linking of periodate-oxidized p3A4,3′-[32P]pC to gelfiltered lysates, preincubated at 0°C or 37°C for 30 min, showed the following results: (1) all lysates gave a major cross-linking of the radioactive ligand to an 80 000 dalton polypeptide, regardless of the temperature of preincubation, (2) Iysates gel-filtered without ATP, with 0.1 mM ITP, or β-γ-methylene-ATP, showed a significant reduction in the cross-linking of the 80 000 dalton protein, after preincubation at 37°C for 30 min. This decrease was accompanied by an increase in the labeling of two smaller polypeptides.

Preparation of Stable Hydrophilic Polyethyleneimine Cross-Linked Graphene Oxide/Titanium Dioxide Membranes for Dye Separation

NANO ◽  
2021 ◽  
pp. 2150008
Author(s):  
Hongwei Liu ◽  
Jinhua Liu ◽  
Jun Li ◽  
Zhanchao Liu ◽  
Weifu Wu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Titanium Dioxide ◽  
Graphene Oxide ◽  
Water Flux ◽  
Cross Linking ◽  
Sunset Yellow ◽  
Water Contact ◽  
Static Water ◽  
The Cross ◽  
The Stability

An excellent novel laminar and hierarchical polyethyleneimine cross-linked graphene oxide/titanium dioxide (GO–TiO2–PEI) membrane was successfully prepared by vacuum filtration technology using polyethyleneimine (PEI) as the cross-linking agent and a GO–TiO2 nanocomposite as the substrate. The resultant membrane (GO–TiO2–PEI) displayed a favorable antifouling performance with bovine serum albumin (BSA) and showed good hydrophilicity and wettability, with a static water contact angle of 13.2∘. The stability of the GO–TiO2–PEI membrane in aqueous solution obviously improved with the cross-linking of PEI compared with that of the GO and GO–TiO2 membranes. The GO–TiO2–PEI membrane also exhibited a satisfactory water flux of 48.6[Formula: see text]L m[Formula: see text] h[Formula: see text] bar[Formula: see text]. The GO–TiO2–PEI membrane exhibited a good performance for effectively separating different dyes including methylene blue (MB), rhodamine B (RB), methyl orange (MO), sunset yellow (SY), new coccine (NC) and amaranth. All the above results suggested that the GO–TiO2–PEI membrane could be used as an excellent stable hydrophilic membrane for efficiently separating dyes from aqueous solution.

scholarly journals Crosslink the Novel Group of Polymeric Binders BioCo by the UV-radiation

2016 ◽  
Vol 16 (2) ◽  
pp. 85-88
Author(s):  
B. Grabowska ◽  
K. Kaczmarska ◽  
A. Bobrowski ◽  
Ż. Kurleto-Kozioł ◽  
Ł. Szymański
Keyword(s):  
Uv Radiation ◽  
Uv Curing ◽  
Polymer Composition ◽  
Cross Linking ◽  
Entire Volume ◽  
Acid Sodium Salt ◽  
Polymeric Binders ◽  
Ft Ir ◽  
Mineral Matrix ◽  
The Cross

Abstract The spectroscopic FT-IR and FT-Raman methods allowed to identify the cross-linking process of the aqueous composition of poly(acrylic acid)/sodium salt of carboxymethyl starch (PAA/CMS-Na) applied as a binder for moulding sands (as a novel group binders BioCo). The cross-linking was performed by physical agent, applying the UV-radiation. The results of structural studies (IR, Raman) confirm the overlapping of the process of cross-linking polymer composition PAA/CMS-Na in UV radiation. Taking into account the ingredients and structure of the polymeric composition can also refer to a curing process in a binder - mineral matrix mixture. In the system of binder-mineral matrix under the influence of ultraviolet radiation is also observed effect of binding. However, the bonding process does not occur in the entire volume of the investigated system, but only on the surface, which gives some possibilities for application in the use of UV curing surface of cores, and also to cure sand moulds in 3D printing technology.

Perfluoropolyether Modified Waterborne Shape Memory Polyurethaneurea Ionomers for Potential Medical Implant Application

2012 ◽  
Vol 499 ◽  
pp. 53-57
Author(s):  
Qun Xia Li ◽  
Zhong Yu Hou
Keyword(s):  
Molecular Structure ◽  
Differential Scanning Calorimetry ◽  
Transition Temperature ◽  
Shape Memory ◽  
Soft Segment ◽  
Cross Linking ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Weight Percentage ◽  
Ft Ir

A series of cross-linked fluorinated waterborne shape memory polyurethaneurea (PUU) ionomers were synthesized from polycaprolactone diol, perfluoropolyether diol (PFPE), dimethylolproionic acid, isophorone diisocyanate, ethylenediamine (EDA) and diethylenetriamine (DETA). The effect of PFPE content in the soft segment and the degree of cross-linking on the molecular structure and the properties of for these PUU films was examined and studied. Differential scanning calorimetry showed that the transition temperature for these Tm type shape memory PUU could be facially tuned by PFPE weight percentage and EDA/DETA ratio in the range between 30°C to 50°C, in the vicinity of body temperature. The dependence of their properties on hydrogen-bonds evaluated by FT-IR was also discussed.

Preparation of epoxy/urethane graft interpenetrating polymer networks and study of mechanical, thermal and morphological properties

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Mehdi Ghafghazi ◽  
Masoud Esfandeh ◽  
Jalil Morshedian
Keyword(s):  
Mechanical Properties ◽  
Polymer Networks ◽  
Weight Ratio ◽  
Interpenetrating Polymer Networks ◽  
Morphological Properties ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Degradation Temperature ◽  
Ft Ir

AbstractThis paper describes the preparation of Epoxy/Urethane (EP/PU) graft interpenetrating polymer networks (g-IPNs) and investigates the effect of EP/PU weight ratio and urethane's prepolymer molecular weight on the mechanical, morphological and thermal properties of the IPN system. Here, g-IPN was prepared by thorough mixing of an isocyanate-terminated urethane prepolymer with an epoxy resin followed by simultaneous curing of the resins. Polytetra hydrofuranate (PTHF), molecular weights (Mw) 1000, 2000 and 3000 g/gmol, was used to prepare urethane prepolymers. EP/PU weight ratios were 75/25, 50/50, 30/70 and 15/85. Disappearance of epoxide and isocyanate functional groups was followed by Fourier Transform Infrared spectroscopy (FT-IR), showing curing of the resins. Differential Scanning Calorimetry (DSC) was used to investigate the glass transition temperature (Tg) of the IPNs. Thermal Gravimetric Analysis (TGA), Dynamic Mechanical Thermal Analysis (DMTA), tensile measurements and Scanning Electron Microscopy (SEM) were used to study thermal, mechanical and morphological properties of the prepared systems. The best mechanical properties were obtained at EP/PU weight ratio 75/25 which also shows a fine and uniformly dispersed morphology. Moreover, at this ratio, with increasing PTHF Mw in the urethane prepolymer, the mechanical properties were improved whereas a decrease was observed in Tg and thermal degradation temperature of g-IPNs.

scholarly journals Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Assunta Borzacchiello ◽  
Luisa Russo ◽  
Birgitte M. Malle ◽  
Khadija Schwach-Abdellaoui ◽  
Luigi Ambrosio
Keyword(s):  
Hyaluronic Acid ◽  
Viscoelastic Properties ◽  
Structural Parameters ◽  
Weight Ratio ◽  
Rheological Behaviour ◽  
Biological Properties ◽  
Cross Linking ◽  
In Vitro Tests ◽  
The Cross

Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests.

scholarly journals Post-electrospinning crosslinking of guar/polyvinyl alcohol membrane

2016 ◽  
Vol 20 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Jingjing Shi ◽  
Enlong Yang
Keyword(s):  
Heat Treatment ◽  
Citric Acid ◽  
Polyvinyl Alcohol ◽  
Guar Gum ◽  
Weight Ratio ◽  
Average Diameter ◽  
Alcohol Solution ◽  
Electrospun Nanofiber ◽  
Ft Ir ◽  
Nanofiber Membranes

College of Material and Textile Engineering, Jiaxing University, Jiaxing, China The present study reports post-electrospinning crosslinking of guar/polyvinyl alcohol (PVA)/citric acid nanofiber membranes by heat treatment. Porous, interconnected nonwoven nanofiber membranes (average diameter 194?23 nm) were electrospun from a homogeneous blend of 1wt% guar gum and 8wt% polyvinyl alcohol solution (3:7 weight ratio) containing 5 wt% (by the total weight of the solution) citric acid. The electrospun nanofiber membranes were then cured at 140 oC for 2 h. The crosslinked nanofiber membranes were insoluble in water, while the non-crosslinked membranes dissolved instantaneously. FT-IR spectrum investigates that crosslinking of guar/PVA occurred through esterfication reaction during heat treatment.

Preparation of Chitosan-Thiamine Pyrophosphate/Polyvinyl Alcohol Blend Electrospun Nanofibers

2012 ◽  
Vol 506 ◽  
pp. 118-121 ◽  
Author(s):  
Natthan Charernsriwilaiwat ◽  
Theerasak Rojanarata ◽  
Tanasait Ngawhirunpat ◽  
Praneet Opanasopit
Keyword(s):  
Polyvinyl Alcohol ◽  
Electrospun Fiber ◽  
Weight Ratio ◽  
Electrospun Nanofibers ◽  
Average Diameter ◽  
Thiamine Pyrophosphate ◽  
Scanning Calorimetry ◽  
Fiber Mats ◽  
Transdermal Drug Delivery Systems ◽  
Nanofiber Mats

Electrospinning of chitosan (CS) has been interested due to the excellent properties of CS such as biocompatibility, biodegradability, antibacterial and non toxic. In this study, chitosan-thiamine pyrophosphate (CS-TPP)/polyvinyl alcohol (PVA) blend nanofibers were prepared using electrospinning techniques without acidic and organic solvent. CS was dissolved with TPP aqueous solution and then blended with PVA solution at various weight ratios. Physicochemical properties of CS-TPP/PVA solution such as viscosity, conductivity and surface tension were evaluated. The morphology and diameter of the electrospun fiber mats were investigated by using scanning electron microscopy (SEM). The chemical structure was characterized by Fourier Transform Infrared (FT-IR) spectroscopy and Differential Scanning Calorimetry (DSC). The morphology and diameter of the nanofibers were mainly affected by the weight ratio of the blend polymers. Nanofibers were obtained when the CS-TPP content was less than 50 % wt. The average diameter of the nanofibers was 99.91-216.42 nm, and the fiber diameter decreased with increasing CS-TPP content. Cytotoxicity tests in human fibroblast cells showed that the fibers had low toxic to the cells. In conclusion, these CS electrospun nanofiber mats can be applied for the wound dressing or transdermal drug delivery systems.

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