Atomic force microscopic investigation of commercial pressure sensitive adhesives for forensic analysis

Pressure sensitive adhesive (PSA), such as those used in packaging and adhesive tapes, are very often encountered in forensic investigations. In criminal activities, packaging tapes may be used for sealing packets containing drugs, explosive devices, or questioned documents, while adhesive and electrical tapes are used occasionally in kidnapping cases. In this work, the potential of using atomic force microscopy (AFM) in both imaging and force mapping (FM) modes to derive additional analytical information from PSAs is demonstrated. AFM has been used to illustrate differences in the ultrastructural and nanomechanical properties of three visually distinguishable commercial PSAs to first test the feasibility of using this technique. Subsequently, AFM was used to detect nanoscopic differences between three visually indistinguishable PSAs

'Tragico fecit exemplo'. La tragedia greca nel commento di Servio a Virgilio

Nei commenti di Servio e di Servio Danielino compaiono riferimenti ai tre maggiori tragici greci (Eschilo, Sofocle, soprattutto Euripide) e talora anche accenni ad elementi scenici e drammaturgici tipici della tragedia greca. Si vuole qui studiare in primo luogo quale consapevolezza del genere tragico avessero i commentatori e, in seguito, stabilire se quanto conoscevano contribuisse all’esegesi del testo virgiliano oppure venisse riportato per curiosità o completezza d’informazione.In their commentaries on Virgil’s poems Servius and Servius Auctus often mention Aeschylus, Sophocles and Euripides and at times they allude to theatrical elements typical of the Greek tragedies. The present paper scrutinizes how deep was the commentators’ knowledge of the tragic genre and whether this knowledge was an instrument to explain Virgil’s poetry or was referred to just out of curiosity

Nano-imaging and its applications to biomedicine

Nanotechnology tools, such as Atomic Force Microscopy (AFM), are now becoming widely used in life sciences and biomedicine. AFM is a versatile technique that allows studying at the nanoscale the morphological, dynamic, and mechanical properties of biological samples, such as living cells, biomolecules, and tissues under physiological conditions. In this article, an overview of the principles of AFM will be first presented and this will be followed by discussion of some of our own recent work on the applications of AFM imaging to biomedicine

Euforione e Virgilio nel commento di Servio all’Eneide

L’analisi di tre note serviane all’Eneide che menzionano il poeta ellenistico Euforione di Calcide (ad Aen. II 32; II 79; II 201), tutte a commento di quella parte che potremmo definire ‘sequenza di persuasione’ (Aen. II 32-233), permette di stabilire da un lato in che modo Servio intendesse e spiegasse la relazione tra Euforione e Virgilio, dall’altro in che modo Virgilio stesso traesse materiale mitologico dall’opera del poeta greco.The analysis of three annotations by Servius on the Aeneid (ad Aen. II 32; II 79; II 201), all of them commenting on a passage that may be called the ‘persuasion sequence’ (Aen. II 32-233) and mentioning the Hellenistic poet Euphorion of Chlacis, permits to understand on one hand how Servius explained the relation between Euphorion and Vergil, on the other how Vergil himself drew mythological material from the Greek poet’s works

Morphological changes in textile fibres exposed to environmental stresses:atomic force microscopic examination

The ability of the atomic force microscope (AFM) to investigate the nanoscopic morphological changes in the surfaces of fabrics was examined for the first time. This study focussed on two natural (cotton and wool), and a regenerated cellulose (viscose) textile fibres exposed to various environmental stresses for different lengths of times. Analyses of the AFM images allowed us to measure quantitatively the surface texture parameters of the environmentally stressed fabrics as a function of the exposure time. It was also possible to visualise at the nanoscale the finest details of the surfaces of three weathered fabrics and clearly distinguish between the detrimental effects of the imposed environmental conditions. This study confirmed that the AFM could become a very powerful tool in forensic examination of textile fibres to provide significant fibre evidence due to its capability of distinguishing between different environmental exposures or forced damages to fibres

Correlating yeast cell stress physiology to changes in the cell surface morphology:atomic force microscopic studies

Yeasts are unicellular haploid fungi that help us to bake bread and ferment alcoholic beverages, but in some cases, they can cause infections that are sometimes fatal. Over 1000 different known species of yeasts are widely distributed in nature[1]. Although the majority of these (e.g., Saccharomyces cerevisiae) live in the general environment, a few species (e.g., Candida) are associated with humans and sometimes become pathogenic[1]. This occurs when our immune system weakens and Candida yeasts start to grow in an uncontrolled way, thereby causing candidiasis and nosocomial infections that result in high patient morbidity and mortality rates[2]

Influence of cell surface and nanomechanical properties on the flocculation ability of industrial <i>Saccharomyces cerevisiae</i> strains

In the past few years, atomic force microscopy (AFM) has provided novel information on the ultrastructural and nanomechanical properties of yeast cell walls that play a major role in determining the flocculation characteristics of the yeasts. In this study, we used AFM to visualize at the nanoscale the cell surface topography and to determine cell wall nanomechanical properties (e.g. elasticity) of different strains of S. cerevisiae employed for brewing, winemaking and fuel alcohol production. Cell surface topography was found to correlate with the flocculation behaviour of these strains during their late stationary phase, with the cell surface of flocculent cells being rougher than that of weakly flocculent cells. The elastic modulus of the yeast cell walls showed that weakly flocculent strains had a more rigid cell wall than highly flocculent strains. This difference in elasticity seemed to have an effect on the adhesive properties of the yeast cell walls, with weakly flocculent yeasts displaying higher adhesion energy than the highly flocculent strains. These findings seem to indicate that yeast cell surface nanomechanical properties play an important role in governing flocculation

Discrimination of bladder cancer cells from normal urothelial cells with high specificity and sensitivity:combined application of atomic force microscopy and modulated Raman spectroscopy

Atomic force microscopy (AFM) and modulated Raman spectroscopy (MRS) were used to discriminate between living normal human urothelial cells (SV-HUC-1) and bladder tumour cells (MGH-U1) with high specificity and sensitivity. MGH-U1 cells were 1.5-fold smaller, 1.7-fold thicker and 1.4-fold rougher than normal SV-HUC-1 cells. The adhesion energy was 2.6-fold higher in the MGH-U1 cells compared to normal SV-HUC-1 cells, which possibly indicates that bladder tumour cells are more deformable than normal cells. The elastic modulus of MGH-U1 cells was 12-fold lower than SV-HUC-1 cells, suggesting a higher elasticity of the bladder cancer cell membranes. The biochemical fingerprints of cancer cells displayed a higher DNA and lipid content, probably due to an increase in the nuclear to cytoplasm ratio. Normal cells were characterized by higher protein contents. AFM studies revealed a decrease in the lateral dimensions and an increase in thickness of cancer cells compared to normal cells; these studies authenticate the observations from MRS. Nanostructural, nanomechanical and biochemical profiles of bladder cells provide qualitative and quantitative markers to differentiate between normal and cancerous cells at the single cellular level. AFM and MRS allow discrimination between adhesion energy, elasticity and Raman spectra of SV-HUC-1 and MGH-U1 cells with high specificity (83, 98 and 95%) and sensitivity (97, 93 and 98%). Such single-cell-level studies could have a pivotal impact on the development of AFM–Raman combined methodologies for cancer profiling and screening with translational significance

Metal·locarborans i biologia molecular: la sorprenent interacció de dos mons aparentment independents

La capacitat d'autoassemblatge dels metal·locarborans ha estat molt investigada recentment. La seva habilitat per formar membranes monocapa ens induí a l'estudi de la interacció d'aquestes membranes sintètiques amb membranes biològiques. Aquest treball evidencia que l'anió cobaltabisdicarballur, [3,3'-Co(C2B9H11)2]&#8722; (COSAN), i el seu derivat diiodat, [3,3'-Co(8-I-C2B9H10)2]&#8722; (I2-COSAN), poden interaccionar amb membranes biològiques i creuar-les, de manera que s'acumulen a l'interior de cèl·lules vives. En aplicar aquests compostos a diferents tipus de cèl·lules en cultiu, s'indueix una inhibició completa, però alhora reversible, de la proliferació cel·lular, amb una recuperació total de l'activitat de divisió cel·lular un cop extret el metal·locarborà del medi.Metallacarborane’s self-assembly has been recently widely investigated. Its ability to form monolayer membranes led us to study the interaction of these synthetic membranes with biological membranes. This work evidences that the cobaltibisdicarbollide anion, [3,3’-Co(C2B9H11)2]&#8722; (COSAN), and its di-iodinated derivative, [3,3’-Co(8-I-C2B9H10)2]&#8722; (I2-COSAN), can interact with biological membranes and cross them, accumulating inside living cells. When applying these compounds to different cells in culture, complete but reversible cell proliferation suppression is induced, with a total recovery of the cell division activity after removal of the metallacarborane from the media

Multiphase modelling of tumour growth and extracellular matrix interaction: mathematical tools and applications

Resorting to a multiphase modelling framework, tumours are described here as a mixture of tumour and host cells within a porous structure constituted by a remodelling extracellular matrix (ECM), which is wet by a physiological extracellular fluid. The model presented in this article focuses mainly on the description of mechanical interactions of the growing tumour with the host tissue, their influence on tumour growth, and the attachment/detachment mechanisms between cells and ECM. Starting from some recent experimental evidences, we propose to describe the interaction forces involving the extracellular matrix via some concepts coming from viscoplasticity. We then apply the model to the description of the growth of tumour cords and the formation of fibrosis