Much research has imparted specific functionalities, such as encouraging proliferation or differentiation, to biomaterials by grafting, incorporating or delivering molecules with defined biologic functions. An alternative approach might have been to use rational design to construct biomaterials with those functions, but that is very difficult, although it is a goal of some aspects of glycomics (62)—the study of information encoded in the structure of carbohydrates—and structural biochemistry. Instead, some investigators have used high-throughput methods to perform rapid nanoliter-scale synthesis of thousands of potential biomaterials, followed by screening of the thousands of cell-polymer interactions on chip-like systems (63) (Fig. 2). This approach revealed that some polymers were markedly better than others in making human embryonic stem cells differentiate into epithelial cells. Furthermore, the various polymers had widely differing effects on the cellular response to a bioactive molecule, retinoic acid. It is possible, as has been suggested, that the effects of the biomaterials were actually mediated by adsorbed proteins (64) or other factors, but that does not alter the fact that the variable driving the differences in cellular response was the variety in polymeric structure. It is possible that approaches of this sort will allow for rapid identification of biomaterials—with or without addition of specific ligands—for specific tissue engineering applications.