A better understanding of the bioresponse of naturally occurring systems will help to optimize the engineering of synthetic biomaterials. The aim of this thesis was to characterize the mechanical and chemical behavior of two distinct biological composite systems, human teeth and wool fibers. These mechanical and chemical properties were also studied as a function of natural structure and environmental conditions. Human teeth are composite systems consisting primarily of hydroxylapatite and protein. This project investigated how the use of clinical dental treatments and procedures, such as whitening and etching, affects mechanical properties. Analysis of nanoindentation with the Oliver-Pharr model provided elastic modulus and hardness across the DEJ. Mechanical properties of autoclaved and non-autoclaved teeth were measured to ensure both comparability to published values and relevance to clinical applications. Large increases were observed in the elastic modulus of enamel with autoclaving (52.0GPa versus 113.4GPa), while smaller increases were observed in the dentin (17.9GPa versus 27.9GPa). There was a similar trend in the increase in hardness of enamel (2.0GPa versus 4.3GPa) and dentin (0.5GPa versus 0.7GPa) when subjected to autoclaving. This work shows that the range of values previously reported in literature may be due largely to the sterilization procedures. Treatment of the exterior of nonautoclaved teeth with Crest Whitestrips, Opalescence or UltraEtch caused changes in the mechanical properties of both the enamel and dentin. Those treated with Crest Whitestrips showed a reduction in the elastic modulus of enamel (55.3GPa to 32.7GPa) and increase in the elastic modulus of dentin (17.2GPa to 24.3GPa). Opalescence treatments did not show a significant affect on the enamel properties, but did result in a decrease in modulus of dentin (18.5GPa to 15.1GPa). Additionally, UltraEtch treatment decreased the modulus and hardness of enamel (48.7GPa to 38.0GPa and 1.9GPa to 1.5GPa, respectively) and dentin (21.4GPa to 15.0GPa and 1.9GPa to 1.5GPa, respectively). These changes were linked to the change in protein content, verified by FTIR and fluorescence microscopy. The second study characterized the amino acid distribution on the surface of Merino wool fibers. Although previous research identified which amino acids compose wool fibers, this was the first study to determine the amino acids distribution along the surface. Specifically, which amino acids have high concentrations near topographical surface features, such as the scale ridges. The distribution and types of amino acids along the surface of wool fibers was analyzed using force spectroscopy techniques. Initial measurements in phosphate buffer solution (PBS) showed carboxyl acid groups, aspartic acids and glutamic acids, are randomly distributed over the surface of wool fibers. Clusters of sulfur groups, cysteines, are uniformly distributed. In addition, the amine groups, arginine and lysine, are concentrated near the edge of scales. SEM images of wool fibers coated with functionalized nanoparticles were used to verify these results. The SEM images showed the binding sites of various charged chemical groups. To distinguish between positively charged surface groups, force spectroscopy was done under elevated pH, indicating a high contribution of lysine just below the edge of the scale
