Next Generation Biomaterials for Nerve Regeneration

Traditional attempts at creating improved nerve graft materials have focused on altering biomaterials chemistry (such as various polymers), however, to date, this approach has not provided the ultimate nerve regeneration material. In contrast, in recent years, nanomaterials have become promising candidates for a variety of tissue engineering applications. Nanomaterials are materials with at least one dimension less than 100 nm. Due to a set of fundamental properties, nanomaterials can be engineered to interact with cells and proteins with a greater degree of specificity. First, nanomaterials have increased surface areas compared to conventional materials. The specific surface area of a given mass of nanoparticles is greater than the specific surface area of the same dose of micron-scale particles. The increased surface to volume ratio and surface area allows for a greater degree of surface interactions. Nanoparticles will have a greater surface to which proteins can adsorb. Two-dimensional nanorough surfaces have a greater functional surface area than materials with micron-scale surface features due to increased roughness in the direction perpendicular to the material surface. This overall increase in the surface area of nanomaterials leads to the second property that makes nanomaterials superior, increased surface energy. The increase in surface area exposes more functional groups at the material surface; surface energy is increased as a result. A hydrophobic or hydrophilic material, when fabricated with nanoroughness, will exhibit increased hydrophobicity or hydrophilicity properties, respectively. This can also enhance the adsorption of proteins and increase cell adhesion. Third, nanomaterials are biomi-metic. A material with nanoroughness more accurately resembles native tissue. ECM proteins including laminin, fibronectin, and collagen fibrils have dimensions on the nanoscale. Though cell adhesion occurs on top of a layer of proteins adsorbed to a material's surface, tissue architecture suggests that nanomaterials provide a superior foundation for tissue regeneration. In comparison to conventional materials, a protein adsorbed onto a nanomaterial can maintain a conformation more conducive to cellular adhesion (Webster et al. 2001). The combination of nanoscale control over a material's surface roughness and surface energy allow for a more precise interaction with proteins. This is critical due to the relationship between protein conformation and cell function. Studies have shown greater neural cell (PC12) adhesion, osteoblast adhesion, and ECM protein adsorption to nanoma-terials compared to conventional materials with similar chemistry (Khang et al. 2007; Webster et al. 2001, Webster and Ejiofor 2004; Webster et al. 2004). Enhanced cell activity has been attributed, in part, to greater amounts of fibronectin and vitronectin adsorbed to materials with greater surface roughness (Degasne et al. 1999). Further studies have shown that the proteins adsorbed to nanomaterial surfaces may expose more amino acid binding sequences than proteins adsorbed to conventional materials (Webster et al. 2001). Specifically, vitronectin adsorbed to nanophase alumina demonstrated more unfolding to expose amino acid binding sequences such as Arginine-Glycine-Aspartic Acid-Serine (RGDS) in comparison to vitronectin adsorbed to conventional alumina (Webster et al. 2001). Though these studies relate to proteins important to osteoblast adhesion, the same concepts of protein conformational optimization on nanomaterials are relevant to materials, proteins, and cells in the neural tissue engineering field as well.

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Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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