Abstract: INTRODUCTION: The aim of this study is to investigate the nanocrystallization of steels caused by the transformation from the austenitic to the martensitic phase induced by a severe plastic deformation (SPD) treatment. In this framework, we applied an air blast shot peening treatment, which is a simple protocol widely used for industrial purposes. METHODS: AISI 286 and AISI 316 specimens were peened for different times and polished using diamond pastes in order to remove corrugations higher than 1 mum. The characterization of the steel surfaces was performed by atomic force microscopy (AFM) operating in contact mode. Additional EDXD measurements were performed to confirm the phase transition. RESULTS AND DISCUSSION: An AFM-based characterization at nanometric level of the steel surfaces is provided. When the peening exceeds a threshold time that, as expected, depends on the steel composition, a uniform nanostructuration is detected. It is well known that such rearrangement is associated to the growth of a martensitic phase. To date, AFM has been employed in this field only for few applications and to solve specific problems. On the other hand, our results demonstrate that this is a useful technique for the characterization of hardened surfaces, especially when non-destructive sample preparation treatments are required. Moreover, we show that AFM can be a useful tool also for in situ industrial diagnostics of metallic parts.

Abstract: We present the implementation of a tapping-mode aperture scanning near-field optical microscope (Tapping-SNOM) to a Binder CB incubator (Istituto di Struttura della Materia, Rome, Italy). The microscope operates in the intermittent contact mode using a nonbent optical fibre allowing to reduce the perturbation exerted on the sample, while the incubator maintains a constant temperature, humidity and CO(2) level. This instrument can maintain and analyse in a controlled environment different samples, both organic and nonorganic. In particular, the Tapping-SNOM can study different cell lines at nanometric resolution and in physiological buffer, following the evolution of the living cells almost indefinitely. We will present several examples of the capabilities of the tapping scanning near-field optical microscope in the study of different lines of living cells, showing corresponding topographical, optical or phase-lag images of the live samples, evidencing the excellent stability, versatility and resolution of the system.

Abstract: Carboxylic terminated monolayers have been covalently attached on phosphorous doped crystalline (100) silicon surfaces using a cathodic electro grafting technique. The functionalization concentration and efficiency have been evaluated with different techniques. In particular, topographic images, performed with an atomic force microscope, were used to optimize the protocol in order to obtain a surface whose characteristics of uniformity and reproducibility are ideal for a bio-electronic device. Phase lag images of the functionalized surfaces were also performed, and show non-topographic structures that have been interpreted as areas of different molecule self-orientation. Poly-thymine oligonucleotides have been anchored on such a surface to form a nano-biosensing device capable to react selectively with a specific target molecule, a poly-adenine oligonucleotide. AFM images of high density (approximately 3x10(12) mol/cm2) single strand and double strand covered samples show toroidal shaped structures formed by the self-assembly of the oligonucleotides on the silicon surface.

Abstract: The interaction of the cytotoxic metals cadmium, zinc, and lead with pancreatic cells was studied by atomic force/lateral Force microscopy (AFM/LFM), an approach that provides both topographic (with nanometer scale lateral resolution) and chemical information on the membrane. Different morphological modifications of the overall cell shape and roughness took place as consequence of 100 muM metal-dependent treatment. Furthermore, after exposure to Cd(Cl(2)) and Zn(Cl(2)), but not Pb(Cl(2)), the LFM images revealed several areas of the cell's surface showing lateral friction contrasts that have been interpreted as marker of different alterations of the cell physiology induced by the metal loading. Thus, the coupling of LFM detection to topographic AFM characterization allows to distinguish, through a nondestructive and surface characterising approach, between different metal-induced cytotoxic effects on cells. In this framework, the role of the LFM as an important tool to discriminate between different alteration of a biological system has to be highlighted.

Abstract: Unoxidized crystalline silicon, characterized by high purity, high homogeneity, sturdiness and an atomically flat surface, offers many advantages for the construction of electronic miniaturized biosensor arrays upon attachment of biomolecules (DNA, proteins or small organic compounds). This allows to study the incidence of molecular interactions through the simultaneous analysis, within a single experiment, of a number of samples containing small quantities of potential targets, in the presence of thousands of variables. A simple, accurate and robust methodology was established and is here presented, for the assembling of DNA sensors on the unoxidized, crystalline Si(100) surface, by loading controlled amounts of a monolayer DNA-probe through a two-step procedure. At first a monolayer of a spacer molecule, such as 10-undecynoic acid, was deposited, under optimized conditions, via controlled cathodic electrografting, then a synthetic DNA-probe was anchored to it, through amidation in aqueous solution. The surface coverage of several DNA-probes and the control of their efficiency in recognizing a complementary target-DNA upon hybridization were evaluated by fluorescence measurements. The whole process was also monitored in parallel by Atomic Force Microscopy (AFM).