Collagen/synthetic polymer blends

Poly(ethylene glycol) (PEG), also known as poly(ethylene oxide) (PEO), is a hydrophilic, biocompatible polyether. PEG usually refers to a material with relatively low molecular weight (e.g., several thousands), while PEO to a material with high molecular weight (e.g., over tens or hundreds of thousands). PEO is wafer soluble and therefore can be electrospun into nanofibres from its water solution (Deitzel et al., 2001). However, water solubility makes the material unstable in a biological environment. Consequently, PEO or PEG is usually used in combination with other natural (e.g., collagen, chitosan) or synthetic polymers (e.g., PLA) in blends or copolymers (Subramanian et al., 2005 Szentivanyi et al., 2009). 

Hydroxyapatite (HA) nanoparticles are osteoconductive bioactive ceramics that can support bone cell adhesion and proliferation and accelerate bone defects healing. HA is typically added to polymeric nanofibers to increase their mechanical strength. HA, often in the form of needle-like nanoparticles, was electrospun in the presence of synthetic biocompatible and biodegradable polymers such as PLA [5, 58-60] and PLA-PEG-PLA [61], natural polymers such as chitosan [62] and collagen [63, 64], and blends of natural and synthetic polymers such as PVA/chitosan [65] and PCL/gelatin [66]. 

As an alternative approach to blending, natural and synthetic polymers can be combined in fibrous scaffolds fabricated by core—shell techniques. Chen et al. (2010) prepared nanofibrous scaffolds by core—shell electrospinning based on a commercial thermoplastic PUR and collagen as the fibre core and shell, respectively. The collagen shell was cross-linked by glutaraldehyde vapours. The electrospun mats showed an intermediate mechanical behaviour as compared to the pure component electrospun membranes moreover, the core—shell electrospun membranes were found to support in vitro adhesion and proliferation of pig iliac endothelial cells. 

Wong et al. (2010) smdied blends of natural and synthetic polymers with the aim of creating biomimetic materials for heart valve leaflets. They examined electrospun gelatin-chitosan PUR, polyglycoUde (PGA)/PLA and collagen-coated bovine pericardium. Ovine endothelial cells were seeded onto these materials and exposed to a range of shear stresses for a period of 1-3 h. 

Sionkowska A, Kaczmaiek H, Wisniewski M, El-Feninat F, Mantovani D. Ultraviolet irradiation of synthetic polymer/collagen blends preliminary results of atomic force microscopy. In Mantovani D, editor. Advanced materials for biomedical applications. Quebec Canadian Institute of Mining, Metallurgy and Petroleum 2002. p. 27-40. 

Blends based on collagen without chemical modification with natural or synthetic polymers, or hybrid materials prepared with inorganic component in the form of nanoparticles or bulk material, can have great potential application in pharmaceutical areas due to their ability to mimic the extracellular matrix both morphologically and chemically (also see Table 13.3). Reasons for preparation of collagen-based blends are related to improvement of collagen properties, low cost of preparation method, simplification or improvement of preparation technology, etc. 

The process of blending collagen tvith synthetic polymers suffers from the problem of the solubility of the polymeric components in a common solvent. Collagen... 

Figure 20.28 (a) Hydrogen bonding in collagen/PVP blend (b) Hydrogen bonding between chi-tosan and synthetic polymer. Reproduced with permission from Ref. [121] 2011, Elsevier. 

Figure 7.3 Stress-strain curves from tensile testing experiments performed on electrospun nanofiber scaffolds made by blends of collagen/elastin and various synthetic polymers. Reproduced with permission from Ref. 80, J. Biomed. Mater. Res. A, 2007, 83, 999-1008. Doi 10.1002/jbm.a.31287. Copyright 2007, Wiley Periodicals, Inc.

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