Application of nanomaterials in medical sciences

Introduction Nanotechnology deals with objects with at least one dimension not exceeding 100 nm [1]. The notion of nanotechnology is strictly related to Richard Feynman’s lecture There’s plenty of room at the bottom, given in 1959 at the California Institute of Technology. In his lecture Feynman outlined the theoretical foundations of the arrangement of structures based on individual atoms and particles. However, at that time the practical methods of implementing Feynman’s ideas had not yet been discovered [1]. The term “nanotechnology” in modern meaning of the word was first used in 1974 by Norio Taniguchi to describe the total set of processes related to manipulating individual atoms or particles [2, 3]. The key milestone for the development of nanotechnology was the invention of the Scanning Tunnelling Microscope (STM) [4] in 1982 and the Atomic Force Microscope (AFM) in 1986 [5]. With those devices it became possible to observe structures on the atomic scale [2, 3]. The development of nanotechnology also benefited from Eric Drexler’s 1986 book Engines of Creation, which introduced the knowledge of this branch of science to the general public [6]. Two major developments for the synthesis of nanostructures were the discovery of fullerene in 1985 [7] and obtaining carbon nanotubes in 1991 [8]. 2003 saw the first application of nanomaterials to the treatment of cancer [2]. Rapid development of nanotechnology and discoveries of new structures, varying in terms of shape and properties, forces the scientific world to constantly update the definition of “nanomaterials”. The majority of currently applied definitions, based on the regulations of the European Parliament or other relevant European and American organizations dealing with nanotechnology, describe nanomaterials as structures of size not exceeding 100 nm, with specific composition and physico-chemical properties [9]. Nanostructures can form agglomerates that are larger than 100 nm, while retaining the specific properties of the original structure, hence the postulate voiced by Kreyling et al. [9] to introduce a new definition of nanomaterials, based on the specific volume of the surface area. The volume depends on the specific surface area and density of the structure. According to the authors, the limit value for categorizing the given structure as nanomaterial is 60 m2/cm3 [9].