Nanomechanical and topographical imaging of living cells by Atomic Force Microscopy with colloidal probes

Atomic Force Microscopy (AFM) has a great potential as a tool to characterize mechanical and morphological properties of living cells; these properties have been shown to correlate with cells' fate and patho-physiological state in view of the development of novel early-diagnostic strategies. Although several reports have described experimental and technical approaches for the characterization of cell elasticity by means of AFM, a robust and commonly accepted methodology is still lacking. Here we show that micrometric spherical probes (also known as colloidal probes) are well suited for performing a combined topographic and mechanical analysis of living cells, with spatial resolution suitable for a complete and accurate mapping of cell morphological and elastic properties, and superior reliability and accuracy in the mechanical measurements with respect to conventional and widely used sharp AFM tips. We address a number of issues concerning the nanomechanical analysis, including the applicability of contact mechanical models and the impact of a constrained contact geometry on the measured elastic modulus (the finite-thickness effect). We have tested our protocol by imaging living PC12 and MDA-MB-231 cells, in order to demonstrate the importance of the correction of the finite-thickness effect and the change in cell elasticity induced by the action of a cytoskeleton-targeting drug.Comment: 51 pages, 12 figures, 3 table

Nanomanufacturing of titania interfaces with controlled structural and functional properties by supersonic cluster beam deposition

Great emphasis is placed on the development of integrated approaches for the synthesis and the characterization of ad hoc nanostructured platforms, to be used as templates with controlled morphology and chemical properties for the investigation of specific phenomena of great relevance for technological applications in interdisciplinary fields such as biotechnology, medicine and advanced materials. Here we discuss the crucial role and the advantages of thin film deposition strategies based on cluster-assembling from supersonic cluster beams. We select cluster-assembled nanostructured titania (ns-TiO2) as a case study to demonstrate that accurate control over morphological parameters can be routinely achieved, and consequently over several relevant interfacial properties and phenomena, like surface charging in a liquid electrolyte, and proteins and nanoparticles adsorption

High strain rate effects in masonry structures under waterborne debris impacts

Masonry buildings are vulnerable to extreme hydrodynamic events such as floods or tsunamis. Post-disaster surveys have shown that waterborne debris impacts can significantly damage masonry walls during these events. To simulate these actions, the current design or research practice is to compute the force–time diagram of the impact and then use it for dynamic analyses. Standing on the current knowledge, debris impacts are highly impulsive, but it is not clear if such loads are fast enough to activate the high strain rate effects in masonry, i.e. the strain rate dependency of material properties. The present study aims to answer this question, for the first time, following nonlinear Finite Element (FE) simulations. Simulations are conducted on a masonry wall, following a micro-modelling strategy, subjected to water flow and waterborne debris impact under different scenarios. It is found that the strain rates exceed the critical threshold after which strain rate effects are considerable. Such a finding, initially obtained using the minimum design demand for log-type debris imposed by ASCE/SEI 7-22, is further extended to a range of impact force–time diagrams different in impact duration and peak force (corresponding to different debris properties or flow velocity). It is also shown that the impact location (i.e. midspan or close to the boundary) affects the strain rate magnitude because of the changes in the impact stiffness and the activated failure mechanisms. Furthermore, it is found that the dynamic tensile post-elastic behaviour of the materials is the most influencing parameter in the structural response. These results open a new area in the field of assessment and design of masonry structures to waterborne debris and guide the development of future experiments, numerical simulations or design relations

Progesterone - new therapy in mild carpal tunnel syndrome? Study design of a randomized clinical trial for local therapy

Abstract BACKGROUND: Local corticosteroid injection for carpal tunnel syndrome (CTS) provides greater clinical improvement in symptoms one month after injection compared to placebo but significant symptom relief beyond one month has not been demonstrated and the relapse of symptoms is possible.Neuroprotection and myelin repair actions of the progesterone was demonstrated in vivo and in vitro study.We report the design of a randomized controlled trial for the local injection of cortisone versus progesterone in "mild" idiopathic CTS. METHODS: Sixty women with age between 18 and 60 years affected by "mild" idiopathic CTS, diagnosed on the basis of clinical and electrodiagnostic tests, will be enrolled in one centre. The clinical, electrophysiological and ultasonographic findings of the patients will be evaluate at baseline, 1, 6 and 12 months after injection.The major outcome of this study is to determine whether locally-injected progesterone may be more beneficial than cortisone in CTS at clinical levels, tested with symptoms severity self-administered Boston Questionnaire and with visual analogue pain scale.Secondary outcome measures are: duration of experimental therapy; improvement of electrodiagnostic and ultrasonographic anomalies at various follow-up; comparison of the beneficial and harmful effects of the cortisone versus progesterone. CONCLUSION: We have designed a randomized controlled study to show the clinical effectiveness of local progesterone in the most frequent human focal peripheral mononeuropathy and to demonstrate the neuroprotective effects of the progesterone at the level of the peripheral nervous system in humans

Surface functionalization with phosphazene substrates, Part IV: Silica and Si(100) surface functionalization using cyclophosphazenes partially substituted with trialkoxysilane derivatives and PEG-750 monomethylether, 2,2,3,3-tetrafluoropropanol and 4-hydroxyazobenzene

This paper deals with the possibility of functionalizing the surface of silicon-based materials by exploiting cyclophosphazenes containing suitable substituent groups. Thus, phosphazene trimers were prepared, containing about 50% of the reactive sites substituted by γ-aminopropyltriethoxy silane (APTES), while the residual positions in the cycle contain poly(ethylene glycol) monomethylether (MW approx. 750; PEG-750-ME), tetrafluoropropanol (TFP) and 4-hydroxyazobenzene (AzB). Using these novel materials we succeeded in surface functionalizing SiO2 beads in the coating of silicon wafers or sodalime slides and in the preparation of cyclophosphazene-based monoliths in the presence of hydrolyzed TEOS by sol–gel technique. The whole series of products has been characterized by standard spectroscopic (IR, UV-Vis, 1H-, 13C-, 29Si- and 31P-NMR, both in solution and in solid state) and thermal (DSC and DMTA) techniques. This approach to the surface functionalization of silicon-based materials containing carefully ..

Perceived organizational support and work engagement: the role of psychosocial variables

PurposeThis study aims to test the role that organizational sociopsychological variables may play in influencing job stress and work engagement in an organizational identity change scenario.Design/methodology/approachOn a sample of 118 employees of an Italian company in the personnel training services sector, multivariate statistical analysis tests a pattern where organizational variables such as work support (by supervisors and coworkers, independent variables) – moderated by corporate identification (moderating variable) – and mediated by organizational trust (mediating variable) – boosts employee work engagement and lowers psychosocial risks (dependent variables).FindingsThe mediating effect of "organizational trust" is significant in the relationships of "supervisor social support" and "coworker social support" with the "absence of psychosocial risks." Moreover, an increase in supervisor social support can lead to a statistically significant increase in work engagement. This occurs only for employees with low or medium identification and not in highly identified individuals.Originality/valueThe findings from the analysis on moderation are of primary importance because they show us a new perspective that can play the role of a guiding and practical principle on how to act on an organization's human resources, specifically targeting those with lower or medium corporate identification

Learning and Using Abstract Words: Evidence from Clinical Populations

Lorusso ML, Burigo M, Tavano A, et al. Learning and Using Abstract Words: Evidence from Clinical Populations. BioMed Research International. 2017;2017:1-8

Imidazolium-based ionic liquids affect morphology and rigidity of living cells : an atomic force microscopy study

The study of the toxicity, biocompatibility, and environmental sustainability of room-temperature ionic liquids (ILs) is still in its infancy. Understanding the impact of ILs on living organisms, especially from the aquatic ecosystem, is urgent, since large amounts of these substances are starting to be employed as solvents in industrial chemical processes, and on the other side, evidence of toxic effects of ILs on microorganisms and single cells have been observed. To date, the toxicity of ILs has been investigated by means of macroscopic assays aimed at characterizing the effective concentrations (like the EC50) that cause the death of a significant fraction of the population of microorganisms and cells. These studies allow us to identify the cell membrane as the first target of the IL interaction, whose effectiveness was correlated to the lipophilicity of the cation, i.e., to the length of the lateral alkyl chain. Our study aimed at investigating the molecular mechanisms underpinning the interaction of ILs with living cells. To this purpose, we carried out a combined topographic and mechanical analysis by atomic force microscopy of living breast metastatic cancer cells (MDA-MB-231) upon interaction with imidazolium-based ILs. We showed that ILs are able to induce modifications of the overall rigidity (effective Young's modulus) and morphology of the cells. Our results demonstrate that ILs act on the physical properties of the outer cell layer (the membrane linked to the actin cytoskeleton), already at concentrations below the EC50. These potentially toxic effects are stronger at higher IL concentrations, as well as with longer lateral chains in the cation