Chitosan Cross-Linking with a Water-Soluble, Blocked Diisocyanate. 2. Solvates and Hydrogels

2003 ◽  
Vol 4 (5) ◽  
pp. 1357-1361 ◽  
Author(s):  
Eric R. Welsh ◽  
Ronald R. Price
Keyword(s):  
1977 ◽  
Vol 25 (3) ◽  
pp. 163-174 ◽  
Author(s):  
R C Spaur ◽  
G C Moriarty

The technique for using the water-soluble embedding medium glycol methacrylate has been improved for ultrastructural studies by the simplification of the method of formation of prepolymers used in embedding the tissue, by the addition of a cross-linking agent so that sections are stable in the electron beam, and by improving the softness of the blocks by the addition of a plasticizing agent. The preservation of tissue morphology has been improved by complete dehydration in glycol methacrylate monomer prior to infiltration with the prepolymer. Preservations of tissue morphology is further enhanced by complete dehydration in ethanols and embedding in the improved glycol methacrylate medium.


Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Francisco López-Suevos ◽  
Charles E. Frazier

Abstract Parallel-plate rheological analysis was conducted on two types of cross-linking poly(vinyl acetate) latex films: dry freestanding films, and dry films bonded directly to wood (composites). For each sample type, three levels of cross-linking were used: (1) little or no cross-linking of unaltered latex; (2) substantial cross-linking through AlCl3 catalysis of N-methylolacrylamide co-monomer; and (3) greater cross-linking from a phenol-formaldehyde resol additive, in addition to AlCl3 catalysis. Simple thermal scans revealed a strong wood/adhesive interaction; wood increased the base polymer T g by ∼5°C in all adhesives. Relative to the simple thermal scans, time-temperature master curves provided more insight and information about the wood/adhesive interaction. Storage modulus and tan δ master curves both indicated that wood retarded adhesive cross-linking. Using time-temperature superposition, a segmental coupling analysis demonstrated that wood actually narrowed the breadth of the glass transition, or reduced segmental coupling. Cross-linking influenced segmental coupling, but in a fashion that was dependent on the presence or absence of wood. Wood-induced reductions in cross-linking and in segmental coupling were attributed to the diffusion of water-soluble reactive compounds away from the adhesive layer and into the bulk wood. Time/temperature equivalence provides a sensitive means to detect interactions between wood and viscoelastic adhesives.


2020 ◽  
Vol 21 (20) ◽  
pp. 7577
Author(s):  
Noriyuki Uchida ◽  
Takahiro Muraoka

Peptide-based fibrous supramolecular assemblies represent an emerging class of biomaterials that can realize various bioactivities and structures. Recently, a variety of peptide fibers with attractive functions have been designed together with the discovery of many peptide-based self-assembly units. Cross-linking of the peptide fibers is a key strategy to improve the functions of these materials. The cross-linking of peptide fibers forming three-dimensional networks in a dispersion can lead to changes in physical and chemical properties. Hydrogelation is a typical change caused by cross-linking, which makes it applicable to biomaterials such as cell scaffold materials. Cross-linking methods, which have been conventionally developed using water-soluble covalent polymers, are also useful in supramolecular peptide fibers. In the case of peptide fibers, unique cross-linking strategies can be designed by taking advantage of the functions of amino acids. This review focuses on the current progress in the design of cross-linked peptide fibers and their applications.


2010 ◽  
Vol 51 (5) ◽  
pp. 718-727 ◽  
Author(s):  
R. Nagao ◽  
T. Suzuki ◽  
A. Okumura ◽  
A. Niikura ◽  
M. Iwai ◽  
...  

2004 ◽  
Vol 823 ◽  
Author(s):  
Catherine Picart ◽  
Ludovic Richert ◽  
René Elkaim ◽  
Pierre Schaaf ◽  
Jean-Claude Voegel ◽  
...  

AbstractThe adhesion of primary osteoblastic cells on top of biocompatible polyelectrolyte multilayer (PEM) films was investigated for native films and after changing the films properties either with a chemical stimulus (film functionalization), with a mechanical stimulus (film cross-linking), or with both stimuli combined. For the functionalization, a 15 amino acid peptide containing a –RGD- (-Arg-Gly-Asp) sequence was grafted to poly(L-glutamic) acid and deposited on top of poly(L-lysine)/poly(L-glutamic) (PLL/PGA), PLL/Poly(alginic), and PLL/Poly(galacturonic) films. The film buildup and the adsorption of the PGA-RGD was followed by Optical Waveguide Lightmode Spectroscopy and by Atomic Force Microscopy. The mechanical stimulus was achieved by crosslinking the films with a water soluble carbodiimide (EDC) in combination with N-hydroxysulfo-succinimide (sulfo-NHS) to induce amide formation. Fourier Transform Infrared Spectroscopy evidenced the conversion of amine and carboxylic groups into amide groups.The alkaline phosphatase (ALP) activity test was used to assess osteoblast adhesion and proliferation on top of the different films over a period of eight days in culture. Whereas the native films are poorly adherent, the RGD-functionalized films exhibit an increased short time adhesion. The native films could also be successfully cross-linked thereby dramatically enhancing cell proliferation. The cells did not react similarly on the different types of films investigated : the cross-linked (PLL/Palg) and (PLL/Pgal) films were much more efficient than the native or functionalized films in terms of proliferation. On the other hand, for the (PLL/PGA) films, functionalization and film cross-linking had a similar long term effect. Very interestingly, for these latter films, both stimuli could be combined.


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