Introduction to special issue on nanophysics

Nanophysics combines the study with the development of nanomaterials that have been designed and characterized for functional control at the nanoscale. These new nanomaterials have strong potential for applications in nanobio-technology including a growing number of medical areas. Both organic (including biological) and inorganic systems, within a scale ranging from single molecules to particles or to larger molecular complexes are studied, and designed for functionality at the nanoscale. Nanophysics in our work deals with the development of new strategies for the assembly at the nanometer level of such systems for the production of composite materials with synergistic properties that would not be possible otherwise. This special issue is concerned with work on representative Nanophysics projects with the idea of establishing a future series of focused special issues on this theme, as assembling at the nanoscale is being exploited in a rapidly growing number of areas of interest. To get insights into the laws of nanometer-scale physics which dominates the function of nanoscale objects and devices and to accurately predict behaviours at the nanometer scale, microscopy methods and techniques have to be considered as key tools in this field. In this issue, Magrassi et al. (2010) report on the formation of nanostructured hybrid objects, made up of living cells encapsulated in a protective multilayer shell assembly of nanostructured polyelectrolyte. Fluorescence microscopy observations have helped to find the optimal conditions for cell encapsulation within a shell, designed and constructed from large molecules. This encapsulation could in principle protect foreign cells inserted into the human body from the immune system. Moving from micron scale encapsulated cells into nanoscale designed shells to nanosized objects, Kalyva et al. (2010) study the use of laser pulses of ns and fs duration for the production of Au nanoparticles with different average sizes and size distributions, by laser ablation of a solid Au target into very pure deionized water. Highly monodispersed colloidal solutions, in which the average nanoparticle size ranges from 3 to 10 nm are possible to be produced. Transmission electron microscopy (TEM), in combination with UV–Vis spectroscopy have been employed for the characterization of these samples. In addition, the structure and composition of different types of PbTe nanocrystals that were found to be sensitive to high-intensity electron beam, have been studied by means of Cs-corrected High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Transmission Electron Microscopy (STEM) together with Energy Dispersive X-Ray Spectrometry (EDX) (Falqui et al. 2010). Fragouli and colleagues (2010) present a microscopic investigation of nanocomposite films composed of polymers and of magnetic iron oxide (c-Fe2O3) aligned nanowires (NWs), formed upon evaporation of solutions of acrylate polymer/magnetic nanoparticles under a magnetic field (MF). The achieved systems have been studied by means of scanning, transmission electron, and atomic force microscopy, in the latter case using the magnetic force microscopy (MFM) technique. These films can be used in sensor devices applied in various fields ranging from biology to the environmental sciences. Diverse Atomic Force Microscopy methods are proved to be of great usefulness in acquiring high-resolution understanding of surface properties in Nanophysics studies. Melzak and colleagues (2010) present two methods to determine the contact point in force–distance curves obtained with the atomic force microscope. More specifically, the methods described are demonstrated with a glycopolymer brush compressed with a colloidal silica particle on the tip of the AFM cantilever. Atomic force microscopy in force spectroscopy mode (FS) as a tool to investigate the properties of Supported Lipid Membranes (SLB), which have been used extensively as a model for cell membranes, is presented in the paper by Canale et al. (2010). Force spectroscopy determines the local mechanical properties of lipid membranes supported on mica and on a polymer cushion. The force yield distribution of membranes on the polymer cushion was found to be bimodal, compared to the unimodal force yield distribution obtained on mica. Using Atomic Force Microscopy and Principal Component Analysis in combination is proved to be a good general method for direct recognition of the functional and structural domains in nanonocomposite materials. The main features of this method are demonstrated on a nanocomposite sample in the paper by Torre et al., 2010. Salerno et al. (2010) report on the stiffness of layers of agarose gel patterned with polylysine using AFM measurements. Data were fitted to the Hertz model of purely elastic tip-surface interaction. Under appropriate assumptions on both tip shape and optimum indentation depth one can determine the Young’s modulus of the agarose layer and quantitatively evaluate the stiffening due to polylysine. Such approach is fundamental for a better understanding of the mechanical properties of an artificial surface used to attach biological cells or negatively charged molecules. Other methods can also produce fundamental information for the understanding of the properties and the interpretation of the behaviour of nanoscale objects. In the paper by Das et al. (2010), Raman, Fourier Transform Infrared (FT-IR) absorption spectroscopy, and Resonance Raman scattering were performed for the vibrational characterization of doxorubicin molecules. Density function theorem (DFT) modeling of Raman and FT-IR spectra were used for the assignment of the vibrational frequencies. The simulation for vibrational bands, based on the calculations for internal force constants and potential energy distribution matrices, was performed and matched with experimental observations (FT-IR absorption and Raman scattering). As mentioned at the beginning of this short note, since the Nanophysics domain is very broad I would be happy to receive proposals for future focused topics in Nanophysics for the next special issue, Nanophysics II. VC 2010 WILEY-LISS, INC.