This book is a survey on the theoretical as well as experimental results on nanostructures in biological systems. It shows how a unifying approach starting from single-particle energy, deriving free energy of the system and determining the equilibrium by minimizing the free energy, can be applied to describe electrical and elastic phenomena. It helps the readers to use this basic, transparent, and simple approach to develop additional new systems and interactions and describes the theoretical and experimental aspects together so that they support each other in broadening the knowledge on biological systems. It suggests potential use of this knowledge in clinically relevant phenomena such as hemostasis, inflammation, and spreading of cancer and describes some applications in nanotoxicology, such as the interactions between biological membranes and inorganic nanostructures.