Cell encapsulation unit) and N-acetyl-D-glucosamine (acetylated unit). It is derived from the N-deacetylation of chitin and has been used for several applications such as drug delivery, space-filling implants and in wound dressings. However, one drawback of this polymer is its weak mechanical properties and is thus often combined with other polymers such collagen to form a polymer with stronger mechanical properties for cell encapsulation applications. Agarose is a polysaccharide derived from seaweed used for nanoencapsulation of cells and the cell/agarose suspension can be modified to form microbeads by reducing the temperature during preparation. However, one drawback with the microbeads so obtained is
Polymer physics 50 nm, it behaves like a flexible chain. Reptation is the thermal motion of very long linear, "entangled" macromolecules in polymer melts or concentrated polymer solutions. Derived from the word reptile, reptation suggests the movement of entangled polymer chains as being analogous to snakes slithering through one another. Pierre-Gilles de Gennes introduced (and named) the concept of reptation into polymer physics in 1971 to explain the dependence of the mobility of a macromolecule on its length. Reptation is used as a mechanism to explain viscous flow in an amorphous polymer. Sir Sam Edwards and Masao Doi later refined reptation theory.