Any matter, surface, or construct that interacts with biological systems. Drug delivery, Tissue engineering (field that seeks to replace, repair, or enhance biological function at the scale of a tissue or organ by manipulating cells via extracellular environment. Cells vs Scaffolds vs bioactive regulators. Strategies in Tissue Engineering: Addition of soluble factors (growth factors or genes) environmental factors (metchanical loading). Tissue Engineering Scaffolds – scaffold properties need to be optimized to direct cells to acquire a specific function and regenerate the desired tissue/organ. There are more than 200 types of cells in the human body, cell morphology depends on type of cell as well as cell environment. The complex structure of organs: Liver functions : bile drainage, blood glucose regulation, blood filtration and detox, synthesis/storage of proteins, vitamins, and fats. Amorphous polymers degrade faster than crystallized (more SA) The structure of a material: affects macroscopic properties. For a screw dislocation, Burgers vector is parallel to dislocation line. Line defects: dislocations. Ionic bonding is a result of eletron transfer from cations to anions. [110 cubic] = [11 -2 0]. For two pure undoped semiconductors at a temp T, more carriers for ____. Covalently bonded materials are generally less dense than ionically or metallically bonded ones. For cubic crystals, as values of planar indices h, k, and l increase, distance between