Inorganic nanoparticles (NPs) represent promising examples of engineered nanomaterials, providing interesting biomedical solutions in several fields, like therapeutics and diagnostics. Despite the extensive number of investigations motivated by their remarkable potential for nanomedicinal applications, the interactions of NPs with biological interfaces are still poorly understood. The effect of NPs on living organisms is mediated by biological barriers, such as the cell plasma membrane, whose lateral heterogeneity is thought to play a prominent role in NPs adsorption and uptake pathways. In particular, biological membranes feature the presence of rafts, that is segregated lipid micro and/or nanodomains in the so-called liquid ordered phase (L-o), immiscible with the surrounding liquid disordered phase (L-d). Rafts are involved in various biological functions and act as sites for the selective adsorption of materials on the membrane. Indeed, the thickness mismatch present along their boundaries generates energetically favourable conditions for the adsorption of NPs. Despite its clear implications in NPs internalisation processes and cytotoxicity, a direct proof of the selective adsorption of NPs along the rafts' boundaries is still missing to date. Here we use multicomponent supported lipid bilayers (SLBs) as reliable synthetic models, reproducing the nanometric lateral heterogeneity of cell membranes. After being characterised by atomic force microscopy (AFM) and neutron reflectivity (NR), multidomain SLBs are challenged by prototypical inorganic nanoparticles, that is citrated gold nanoparticles (AuNPs), under simplified and highly controlled conditions. By exploiting AFM, we demonstrate that AuNPs preferentially target lipid phase boundaries as adsorption sites. The herein reported study consolidates and extends the fundamental knowledge on NPs-membrane interactions, which constitute a key aspect to consider when designing NPs-related biomedical applications.

Motivation: Single-molecule force spectroscopy (SMFS) experiments pose the challenge of analysing protein unfolding data (traces) coming from preparations with heterogeneous composition (e.g. where different proteins are present in the sample). An automatic procedure able to distinguish the unfolding patterns of the proteins is needed. Here, we introduce a data analysis pipeline able to recognize in such datasets traces with recurrent patterns (clusters).

The mechanical properties of extracellular vesicles (EVs) are known to influence their biological function, in terms of, e.g., cellular adhesion, endo/exocytosis, cellular uptake, and mechanosensing. EVs have a characteristic nanomechanical response which can be probed via force spectroscopy (FS) and exploited to single them out from nonvesicular contaminants or to discriminate between subtypes. However, measuring the nanomechanical characteristics of individual EVs via FS is a labor-intensive and time-consuming task, usually limiting this approach to specialists. Herein, we describe a simple atomic force microscopy based experimental procedure for the simultaneous nanomechanical and morphological analysis of several hundred individual nanosized EVs within the hour time scale, using basic AFM equipment and skills and only needing freely available software for data analysis. This procedure yields a "nanomechanical snapshot" of an EV sample which can be used to discriminate between subpopulations of vesicular and nonvesicular objects in the same sample and between populations of vesicles with similar sizes but different mechanical characteristics. We demonstrate the applicability of the proposed approach to EVs obtained from three very different sources (human colorectal carcinoma cell culture, raw bovine milk, and Ascaris suum nematode excretions), recovering size and stiffness distributions of individual vesicles in a sample. EV stiffness values measured with our highthroughput method are in very good quantitative accord with values obtained by FS techniques which measure EVs one at a time. We show how our procedure can detect EV samples contamination by nonvesicular aggregates and how it can quickly attest the presence of EVs even in samples for which no established assays and/or commercial kits are available (e.g., Ascaris EVs), thus making it a valuable tool for the rapid assessment of EV samples during the development of isolation/enrichment protocols by EV researchers. As a side observation, we show that all measured EVs have a strikingly similar stiffness, further reinforcing the hypothesis that their mechanical characteristics could have a functional role.

Cells of the facultative photosynthetic bacterium Rhodobacter capsulatus exploit the simultaneous presence in the cultural medium of the toxic oxyanion tellurite (TeO32-) and the redox mediator lawsone (2-hydroxy-1,4-naphthoquinone) by reducing tellurite to metal Te-0 nanoprecipitates (TeNPs) outside the cells. Here we have studied the mechanism by which lawsone interacts with metabolically active cells and analysed both structure and composition of the TeNPs collected from the growth medium of phototrophycally grown R. capsulatus. High Resolution Transmission Electron Microscopy (HR-TEM) images and Energy-Dispersive X-ray (EDX) microanalysis of TeNPs showed a central core of polycrystalline tellurium interspersed in an organic matrix with a predominant protein-based composition. The main proteins from Te-0 nanostructures were identified by Liquid Chromatography tandem-Mass Spectrometry and were all correlated with the cell outer membrane composition. The interaction of reduced lawsone with tellurite and with the bacterial cells was probed by Cyclic Voltammetry and Scanning ElectroChemical Microscopy (SECM). We concluded that lawsone is required for the reduction of tellurite to metal Te-0 in a reaction mechanism dependent on reducing equivalents deriving from the cell photosynthetic metabolism. SECM experiments demonstrate that lawsone, by diffusing inside the bacterial cells, is effectively available at the membrane site of the photosynthetic electron transport chain. (C) 2020 Published by Elsevier B.V.

Organic field-effect transistors (OFETs) are key enabling devices for plastic electronics technology, which has a potentially disruptive impact on a variety of application fields, such as health, safety, and communication. Despite the tremendous advancements in understanding the OFET working mechanisms and device performance, further insights into the complex correlation between the nature of the charge-injecting contacts and the electrical characteristics of devices are still necessary. Here, an in-depth study of the metal-organic interfaces that provides a direct correlation to the performance of OFET devices is reported. The combination of synchrotron X-ray spectroscopy, atomic force microscopy, electron microscopy, and theoretical simulations on two selected electron transport organic semiconductors with tailored chemical structures allows us to gain insights into the nature of the injecting contacts. This multiple analysis repeated at the different stages of contact formation provides a clear picture on the synergy between organic/metal interactions, interfacial morphology, and structural organization of the electrode. The simultaneous synchrotron X-ray experiments and electrical measurements of OFETs in operando uncovers how the nature of the charge-injecting contacts has a direct impact on the injection potential of OFETs.

Mechanically exfoliated two-dimensional (2D) black phosphorus (bP) is epitaxially terminated by monolayers and multilayers of tetracosane, a linear alkane, to form a weakly interacting van der Waals heterostructure. Atomic force microscopy (AFM) and computational modelling show that epitaxial domains of alkane chains are ordered in parallel lamellae along the principal crystalline axis of bP, and this order is extended over a few layers above the interface. Epitaxial alkane multilayers delay the oxidation of 2D bP in air by 18 hours, in comparison to 1 hour for bare 2D bP, and act as an electrical insulator, as demonstrated using electrostatic force microscopy. The presented heterostructure is a technologically relevant insulator-semiconductor model system that can open the way to the use of 2D bP in micro- and nanoelectronic, optoelectronic and photonic applications.

We demonstrate the label-free and selective detection of interleukin-6 (IL-6), a key cell-signaling molecule in biology and medicine, by integrating an OECT with an immuno-affinity regenerated cellulose membrane. The objective of the membrane is to increase the local concentration of IL-6 at the sensing electrode and, thereby, enhance the device response for concentrations falling within the physiological concentration range of cytokines. The OECT gate electrode is functionalized with an oligo(ethylene glycol)-terminated self-assembled alkanethiolate monolayer (SAM) for both the immobilization of anti IL-6 antibodies and the inhibition of non-specific biomolecule binding. The OECT gate/electrolyte interface is exploited for the selective detection of IL-6 through the monitoring of antigen-antibody binding events occurring at the gate electrode.

A data-matrix (DM)-technology approach in cell biology is implemented as an efficient method for the multiparameter monitoring of cell cultures. The proposed method takes advantage of the know-how developed for fault tolerance in digital information technology by measuring the amount of errors induced by intervening cells upon checking a DM code placed behind them. It gives continuous access to several quantitative parameters of the observed culture, such as cell coverage, mean size, viability, and transfection efficiency.

We investigate the solvatochromic effect of a Fe-based spin-crossover (SCO) compound via ambient pressure soft X-ray absorption spectroscopy (AP-XAS) and atomic force microscopy (AFM). AP-XAS provides the direct evidence of the spin configuration for the Fe(II) 3d states of the SCO material upon in situ exposure to specific gas or vapor mixtures; concurrent changes in nanoscale topography and mechanical characteristics are revealed via AFM imaging and AFM-based force spectroscopy, respectively. We find that exposing the SCO material to gaseous helium promotes an effective decrease of the transition temperature of its surface layers, while the exposure to methanol vapor causes opposite surfacial and bulk solvatochromic effects. Surfacial solvatochromism is accompanied by a dramatic reduction of the surface layers stiffness. We propose a rationalization of the observed effects based on interfacial dehydration and salvation phenomena.

The toxic oxyanion tellurite (TeO32-) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te-0 in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te-0 nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600-700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te-0 to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents. (C) 2016 Published by Elsevier B.V.

A new Multi-Walled Carbon Nanotubes (MWCNTs) based conducting cotton fabric was properly designed and achieved, as a useful component for the development of humidity and temperature sensors. A synthetic strategy was optimized through subsequent steps of MWCNTs functionalization and dispersion in a polymer matrix, by first reacting functionalized MWCNTs, 1,2,3,4-butanetetracarboxylic acid (BTCA), polyvinyl alcohol (PVA), and then adding a polyacrylic resin. The polymeric paste thus obtained, containing a synthetic thickener, was applied by a knife-over-roll coating technique onto cotton fabric, then dried and finally cured. The polymeric coated textile sample was analyzed with different chemical-physical techniques to determine its morphological features, thermal behavior and surface resistance. Changes in surface resistance of the film were monitored as a function of relative humidity and temperature variation. The electrical resistance properties of the film deposited on cotton surface seem to be clearly influenced by the presence of water molecules interacting with MWCNTs junctions. This efficient functional fabric may be a helpful starting point to develop technical textiles, or the component of a humidity sensor, useful as dual-functional sensing material for detection of environmental humidity/temperature variations.

The analysis of the ?-synuclein (aS) aggregation process, which is involved in Parkinson's disease etiopathogenesis, and of the structural feature of the resulting amyloid fibrils may shed light on the relationship between the structure of aS aggregates and their toxicity. This may be considered a paradigm of the ground work needed to tackle the molecular basis of all the protein-aggregation-related diseases. With this aim, we used chemical and physical dissociation methods to explore the structural organization of wild-type aS fibrils. High pressure (in the kbar range) and alkaline pH were used to disassemble fibrils to collect information on the hierarchic pathway by which distinct ?-sheets sequentially unfold using the unique possibility offered by high-pressure Fourier transform infrared spectroscopy. The results point toward the formation of kinetic traps in the energy landscape of aS fibril disassembly and the presence of transient partially folded species during the process. Since we found that the dissociation of wild-type aS fibrils by high pressure is reversible upon pressure release, the disassembled molecules likely retain structural information that favors fibril reformation. To deconstruct the role of the different regions of aS sequence in this process, we measured the high-pressure dissociation of amyloids formed by covalent chimeric dimers of aS (syn-syn) and by the aS deletion mutant that lacks the C-terminus, i.e., aS (1-99). The results allowed us to single out the role of dimerization and that of the C-terminus in the complete maturation of fibrillar aS.

Abstract While the widespread emergence of nanoscience and nanotechnology can be dated back to the early eighties, the last decade has witnessed a true coming of age of this research field, with novel nanomaterials constantly finding their way into marketed products. The performance of nanomaterials being dominated by their nanoscale morphology, their quantitative characterization with respect to a number of properties is often crucial. In this context, those imaging techniques able to resolve nanometer scale details are clearly key players. In particular, atomic force microscopy can yield a fully quantitative tridimensional (3D) topography at the nanoscale. Herein, we will review a set of morphological analysis based on the scaling approach, which give access to important quantitative parameters for describing nanomaterial samples. To generalize the use of such morphological analysis on all D-dimensions (1D, 2D and 3D), the review will focus on specific soft matter aggregates with fractal dimension ranging from just above 1 to just below 3.

This work explored polysulfone (PS) - graphene oxide (GO) based porous membranes (PS-GO) as adsorber of seven selected organic contaminants of emerging concern (EOCs) including pharmaceuticals, personal care products, a dye and a surfactant from water. PS-GO was prepared by phase inversion method starting from a PS and GO mixture (5% w/w of GO). The porous PS-GO membranes showed asymmetric and highly porous micrometer sized pores on membrane top (diameter ?20 ?m) and bottom (diameter ?2-5 ?m) surfaces and tens of microns length finger like pores in the section. Nanomechanical mapping reveals patches of a stiffer material with Young modules comprised in the range 15-25 GPa, not present in PS pure membranes that are compatible with the presence of GO flakes on the membrane surfaces. PS-GO was immersed in EOCs spiked tap water and the adsorbance efficiency at different contact times and pH evaluated by HPLC analysis. Ofloxacin (OFLOX), benzophenone-3 (BP-3), rhodamine b (Rh), diclofenac (DCF) and triton X-100 (TRX) were removed with efficiency higher than 90% after 4 h treatments. Regeneration of PS-GO and reuse possibilities were demonstrated by washing with ethanol. The adsorption efficiencies toward OFLOX, Rh, DCF and carbamazepine (CBZ) were significantly higher than those of pure PS membrane. Moreover, PS-GO outperformed a commercial granular activated carbon (GAC) at low contact times and compared well at longer contact time for OFLOX, Rh, BP-3 and TRX suggesting the suitability of the newly introduced material for drinking water treatment.

Diamond like carbon (DLC) films are becoming materials of choice for mechanical and corrosion protection barrier films due to their excellent properties of low-friction and chemical inertness. As DLC functional properties are strictly dependent on process parameters, different DLC coatings have been de- posited onto silicon substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) evaluating the effect of the variation of argon and hydrogen gas flows on the coating resistance properties. It has been observed that the hydrogen variation is the main factor affecting the DLC films resistance in aggressive environments, while DLC samples deposited by varying Ar showed significant delamination phenomena. These differences have been related to the morphological and microstructural characteristics of DLC films taking into account for the specific role of both Ar and H 2 in the mechanism of DLC formation. In par- ticular, it has been observed that the resistance against corrosive environment for DLC coatings may be related to the compressive residual stress values in conjunction with surface and structural properties of the film. This can be considered an understanding at the atomic scale providing the key for the optimization of the protective coating performance.

The hybrid GPTMS (3-glycidoxypropyltrimethoxysilane) gel containing the chromophore molecule of the litmus dye, Resorufin (7-Hydroxy-3H-phenoxazin-3-one), was prepared by sol-gel method through epoxy ring opening reaction catalyzed by traces of 1-methylimidazole in acidic ethanol solutions. The wet-gel solution was fully characterized by means of different spectroscopic techniques. Proton and heteronuclear NMR and FT-IR spectroscopy have confirmed the immobilization of the Resorufin into the GPTMS polyethylene oxide polymer, through GPTMS epoxy ring opening and monomer diol-GPTMS condensation/hydrolysis. The halochromic activity of the Resorufin-GPTMS hybrid sol-gel was monitored by UV-vis spectroscopy, in buffered solutions at different pH values, in comparison with the corresponding dye. FT-IR spectroscopy was also used on solid xerogel residue covering glass surface to demonstrate the attempted GPTMS epoxy-ring opening. The morphology of the treated and washed cotton samples, compared to the original one, was investigated by SEM, SEM-EDX and AFM microscopy analysis, in order to assess the aspect of the fibers after the different finishing treatments in the micrometric scale.

Metal-bioorganic compounds of vanadium pentoxide and bovine serum albumin (BSA) (Fraction V) were obtained by using sol-gel method. Series of the samples (BSA)xV2O5?nH2O, where x=0, 0.01 and 0.001, were originally produced by the synthesis of vanadium pentoxide xerogels and subsequent blending with water-dissolved BSA in appropriate molar ratios. It was evident that the gelation process does not occur for x>0.01. For the X-ray photoelectron spectroscopy (XPS) studies, the thin layers of these materials were prepared by drying the gel onto the glass and mica substrates. The surface morphology of the samples was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. It follows from the analysis of experimental XPS spectra of (BSA)xV2O5?nH2O that the nitrogen ions in pure albumin and in (BSA)0.01V2O5?nH2O are present in imine, amine and protonated amine groups. The additional protonated amine arises when the concentration of albumin in (BSA)xV2O5?nH2O is low (x=0.001). Increasing the amount of albumin results in decrease of the number of oxygen ions bonded to vanadium. At the same time (with increase of albumin), the component of oxygen bounded to carbon and nitrogen is increasing. In the samples with greater amount of albumin, the reduction of vanadium ions occurs. This means that the trivalent and tetravalent vanadium ions are present together with pentavalent ones.

Self-assembled monolayers (SAMs), combined with the lithography, were employed to fabricate functional surfaces. A new strategy in SAM technology, by using reiterated micro contact printing process, was proposed to produce a multi-level fluorescent TAG (multi-TAG), which consists of two overlapping micrometric patterns, made of a fluorescent oligothiophene SAM bonded with a Si/3-aminopropylthriethoxysilane substrate. The samples were characterized by fluorescence microscopy, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). In particular, the process of chemical interaction occurring during the self-assembling was investigated. The obtained results showed that the SAM process occurred with the amidic bond formation. Moreover, the grazing-angle XPS measurements indicated that the horizontal arrangement of oligothiophene molecules on the substrate surface was preferred.

Hydroxyapatite films enriched with magnetite have been fabricated via a Pulsed Plasma Deposition (PPD) system with the final aim of representing a new platform able to disincentivate bacterial adhesion and biofilm formation. The chemical composition and magnetic properties of films were respectively examined by X-ray photoelectron spectroscopy (XPS) and Superconducting Quantum Interference Device (SQUID) measurements. The morphology and conductive properties of the magnetic films were investigated via a combination of scanning probe technologies including atomic force microscopy (AFM), electrostatic force microscopy (EFM), and scanning tunneling microscopy (STM). Interestingly, the range of adopted techniques allowed determining the preservation of the chemical composition and magnetic properties of the deposition target material while STM analysis provided new insights on the presence of surface inhomogeneities, revealing the presence of magnetite-rich islands over length scales compatible with the applications. Finally, preliminary results of bacterial adhesion tests, indicated a higher ability of magnetic hydroxyapatite films to reduce Escherichia coli adhesion at 4 h from seeding compared to control hydroxyapatite films.

The toxic oxyanion tellurite (TeO32-) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te0 in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te0 nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration. We report that growing cultures over a 10 days period with daily additions of 1 mM tellurite led to the accumulation in the growth medium of TeNPs with dimensions from 200 up to 600-700 nm in length as determined by atomic force microscopy (AFM). This result suggests that nucleation of TeNPs takes place over the entire cell growth period although the addition of new tellurium Te0 to pre-formed TeNPs is the main strategy used by R. capsulatus to generate TeNPs outside the cells. Finally, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) analysis of TeNPs indicate they are coated with an organic material which keeps the particles in solution in aqueous solvents.