The study of biotribology attracts increasingly attention because it holds great promise to have profound impact on the way people live their lives. This study presents two cases of contact mechanics study on tissue engineering: one in soft tissue and the other one in hard tissue. In the study of soft tissue, we conducted a theoretical investigation into the effect of particle on the adhesion of a biological nanostructure system. Based on a three-body contact model and JKR theory our results show that geckos' spatulas provides robust adhesions even with trapped particles in the interface. In the case of hard tissue, we utilized nanoindentation technique to characterize the mechanical property and tribology behavior of calcium fluoride-like deposits on human tooth. The low nanohardness and high nano-wear depth characteristics of the surface deposits identified in this study account for the natural loss of the surface deposits days or weeks after topical fluoride treatment as a result of daily brushing and mastication.