The book gives a survey on recent theoretical as well as experimental results on nanostructures in biological systems. Some possible applications will be given. In theoretical part, a unifying approach starting from the single-particle energy, deriving free energy of the system and determining the equilibrium by minimizing the free energy, is applied in describing electrical and elastic phenomena. This approach is basic, transparent and simple so that new and additional systems and interactions can be included by the readers. As the theoretical and the experimental work have been developed in the same process, they support each other in broadening the knowledge on the system. Potential use of this knowledge in clinically relevant phenomena such as hemostasis, inflammation and spreading of cancer will be presented. At the end some applications in nanotoxicology will be described such as the interactions between biological membranes and inorganic nanostructures.