Nanotechnologies: a general introduction

After a brief description of what is nanotechnology (a triple definition will be attempted) and of its importance for the society, this first lecture manly aims at showing how nanoscience makes various nanotechnologies possible. The surprising story of direct imaging and manipulation of atoms (scanning probe microscopies will be the specific subject of the third lecture by prof. Andrea Li Bassi) is told to naturally introduce the crucial role of quantum confinement and surface defects. The electronic and vibrational properties of nanostructures are then discussed to understand the connection between the deeply modified (with respect to the bulk) quantum spectra and the physico-chemical properties of nanoscopic objects. In this context the concept of superatom (and its generalizations) is stressed. The essential role of both size and size control is finally emphasized discussing some significant applications in the fields of materials, devices and medicine. To this last argument (nanomedicine) the second lecture (by prof. Mauro Ferrari) is entirely devoted. With its ability to interface with biology on multiple dimensional scales, all the way down to the molecular and atomic domains, nanotechnology emerges as a promising candidate to help negotiate some of the bottlenecks that have impeded progress in the conquest of cancer, cardiovascular disease, and the multitude of bodily afflictions that "flesh is heir to". No, the Bard himself was not active in nanomedicine, as far as history as reported - but vast swaths of human knowledge are currently developed, refined and reinterpreted to provide new nanoscopic tools against disease. From physics, chemistry, engineering, mathematics, biology, the clinical disciplines and many others fields still, alliances are being formed to score successes in the early detection of disease from biological fluids, the molecular identification of pathological lesions in radiological imaging, the directed localization of therapeutic agents that maximize efficacy while reducing undesired collateral damage, and the intelligent release of drugs from implants inspired by the body's own immune and endocrine functionalities. Scanning probe microscopies (SPM), and in particular Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), allow high resolution imaging in the direct space of surfaces and represent thus an essential tool for the investigation of surfaces and supported nanostructures down to the nanometer and atomic scale. After a brief historical introduction, the lecture provides an overview of the basic principles of STM and AFM, and a description of the experimental setups required for STM and AFM measurements. It will also be shown that measurement of surface electronic properties (i.e. of the surface LDOS, Local electron Density of States) is possible by means of Scanning Tunneling Spectroscopy (STS). Examples drawn from the fields of surface science and bio-nanotechnologies will be illustrated, ranging from the study of nanostructured thin films and clusters deposited on surfaces to the imaging of proteins and biomolecules.