Structural hierarchy is an important concept in the design of new materials for biomedical applications. Because natural materials exhibit structural hierarchy from the nanoscale to the macroscale, biomaterials should ideally exhibit a similar hierarchy. Current research in biomaterials is often limited to chemicals available "off the shelf", which are either naturally occurring materials or bioco
mpatible synthetic polymers. Collagen, heparin, hyaluronic acid, and agarose are examples of natural materials used for biomedical applications, but there is limited control over their chemical and physical properties and thus they are only suitable for specific applications. Poly(ethylene glycol) (PEG), poly(vinyl alcohol), poly(caprolactone) and poly(D,L-lactic-co-glycolic acid) are examples of biocompatible synthetic polymers with the physical and chemical behaviors that can be controlled and/or modified, but that exhibit very little structural hierarchy. In order to mimic, influence or control natural processes, we need to rationally design new materials from the nanoscale to the macroscale, with control over the chemical and physical properties at multiple levels. By controlling molecular structure, assembly and interaction on multiple levels, we can better replicate the critical aspects of physiological materials and processes.
