Collagen-based hydrogels

The pH sensitivity of collagen refers to the possibility to accept or donate protons in response to changes in pH of the environment. Typically the degree of ionization of a polymer which exhibits weak ionizable groups suddenly changes to a specific value of pH, denoted pKa value. This status change of polymer configuration, known as phase transition, causes alteration of the hydrodynamic volmne of the polymeric system. 

Extreme acidic or basic medium leads to high ionization of collagen with denaturing of protein macromolecule. 

From the point of view of pharmaceutical appHcation, the collagen-based products, similar to sensitive polymeric materials, are of interest for loading active ingredients or proteins and releasing them in a controllable and effective way. 

Chemicals like crosslinkers can impair the biological properties of biomaterials based on collagen. 

Collagen-based hydrogels can be in-situ synthesized. The in-situ synthesis method displays the advantage that the precursor can be mixed with cells and/or bioactive 

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Hepatocytes are attachment-dependent cells [3, 25]. Without adequate extracellular matrix they lose their liver-specific functions. Therefore, it has been studied intensively which types of matrix, hydrogels, and scaffolds support differentiated hepatocyte functions and which are the key properties. One of the first commercially available hydrogels was Matrigel, an extract from mouse sarcoma cells [26]. Later Extragel, another collagen-based hydrogel [27] Alimatrix, a porous 3D scaffold [28] and PuraMatrix... 

Collagen-based hydrogels as drug delivery systems exhibit an ability to entrap different size molecules and also show advantages such as ease of application, high bioadhesion, acceptable viscosity, compatibility with numerous drugs contributing to patients compliance and product efficiency, controllable retarded release, etc. [61,93],... 

M.T. Nistor, C. Vasile, A.P. Chiriac, and L. Tar(au, Biocompatibihty, biodegradability, and drug carrier ability of hybrid collagen-based hydrogel nanocomposites, / Bioact. Compat. Pol.,28 (6), 540-556, 2013. 

P.S. Gils, N. Kumar Sahu, D. Ray, and P.K. Sahoo, Hydrolyzed collagen-based hydrogel system design, characterization and application in drug delivery. Am. /. Biomed. Sci., 4 (2), 167-177, 2012. 

Natural hydrogels are water-liking networks that are made out of naturally derived polymers, and are widely used in tissue engineering. For example, extra cellular matrix components (ECM) such as hyaluronic acid (HA), chondroitin sulfate (CS), matrigel, and collagen-based hydrogels are used as scaffolds for... 

Macaya, D.J., Hayakawa, K., Aral, K., Spector, M. Astrocyte infiltration into injectable collagen-based hydrogels conteiining FGF-2 to treat spineil cord injury. Biomaterials 34, 3591-... 

Rao, J.K. Ramesh, D.V. Rao, K.P. Implantable controlled delivery systems for proteins based on collagen-pHEMA hydrogels. Biomaterials 1994, 15 (5), 383-389. 

Fig. 1 Supramolecular systems described in this chapter. Top-. The extracellular matrix inspires most of the work and consists of fibers to resist tensile stresses such as collagens, fibers to resist compressive stresses such as the glycosaminoglycans, and soluble factors for cell signalling. Bottom Natural systems such as collagen, coiled-coil structures, p-sheet peptides such as peptide amphiphiles and multidomain peptides, hybrid systems such as streptavadin-biotin cross-linked microparticles, and synthetic systems such as the UPy-based hydrogelators...

Deng C, et al. Collagen and glycopolymer based hydrogel for potential comeal application. Acta Biomater 2010 6(1) 187—94. 

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