In Vitro Biocompatibility Assessment of Bioengineered PLA-Hydrogel Core-Shell Scaffolds with Mesenchymal Stromal Cells for Bone Regeneration.

Human mesenchymal stromal cells (hMSCs), whether used alone or together with three-dimensional scaffolds, are the best-studied postnatal stem cells in regenerative medicine. In this study, innovative composite scaffolds consisting of a core-shell architecture were seeded with bone-marrow-derived hMSCs (BM-hMSCs) and tested for their biocompatibility and remarkable capacity to promote and support bone regeneration and mineralization. The scaffolds were prepared by grafting three different amounts of gelatin-chitosan (CH) hydrogel into a 3D-printed polylactic acid (PLA) core (PLA-CH), and the mechanical and degradation properties were analyzed. The BM-hMSCs were cultured in the scaffolds with the presence of growth medium (GM) or osteogenic medium (OM) with differentiation stimuli in combination with fetal bovine serum (FBS) or human platelet lysate (hPL). The primary objective was to determine the viability, proliferation, morphology, and spreading capacity of BM-hMSCs within the scaffolds, thereby confirming their biocompatibility. Secondly, the BM-hMSCs were shown to differentiate into osteoblasts and to facilitate scaffold mineralization. This was evinced by a positive Von Kossa result, the modulation of differentiation markers (osteocalcin and osteopontin), an expression of a marker of extracellular matrix remodeling (bone morphogenetic protein-2), and collagen I. The results of the energy-dispersive X-ray analysis (EDS) clearly demonstrate the presence of calcium and phosphorus in the samples that were incubated in OM, in the presence of FBS and hPL, but not in GM. The chemical distribution maps of calcium and phosphorus indicate that these elements are co-localized in the same areas of the sections, demonstrating the formation of hydroxyapatite. In conclusion, our findings show that the combination of BM-hMSCs and PLA-CH, regardless of the amount of hydrogel content, in the presence of differentiation stimuli, can provide a construct with enhanced osteogenicity for clinically relevant bone regeneration.

New Poly(lactic acid)-Hydrogel Core-Shell Scaffolds Highly Support MSCs' Viability, Proliferation and Osteogenic Differentiation.

Scaffolds for tissue engineering are expected to respond to a challenging combination of physical and mechanical requirements, guiding the research towards the development of novel hybrid materials. This study introduces innovative three-dimensional bioresorbable scaffolds, in which a stiff poly(lactic acid) lattice structure is meant to ensure temporary mechanical support, while a bioactive gelatin-chitosan hydrogel is incorporated to provide a better environment for cell adhesion and proliferation. The scaffolds present a core-shell structure, in which the lattice core is realized by additive manufacturing, while the shell is nested throughout the core by grafting and crosslinking a hydrogel forming solution. After subsequent freeze-drying, the hydrogel network forms a highly interconnected porous structure that completely envelops the poly(lactic acid) core. Thanks to this strategy, it is easy to tailor the scaffold properties for a specific target application by properly designing the lattice geometry and the core/shell ratio, which are found to significantly affect the scaffold mechanical performance and its bioresorption. Scaffolds with a higher core/shell ratio exhibit higher mechanical properties, whereas reducing the core/shell ratio results in higher values of bioactive hydrogel content. Hydrogel contents up to 25 wt% could be achieved while maintaining high compression stiffness (>200 MPa) and strength (>5 MPa), overall, within the range of values displayed by human bone tissue. In addition, mechanical properties remain stable after prolonged immersion in water at body temperature for several weeks. On the other hand, the hydrogel undergoes gradual and homogeneous degradation over time, but the core-shell integrity and structural stability are nevertheless maintained during at least 7-week hydrolytic degradation tests. In vitro experiments with human mesenchymal stromal cells reveal that the core-shell scaffolds are biocompatible, and their physical-mechanical properties and architecture are suitable to support cell growth and osteogenic differentiation, as demonstrated by hydroxyapatite formation. These results suggest that the bioresorbable core-shell scaffolds can be considered and further studied, in view of clinically relevant endpoints in bone regenerative medicine.

Advances in Focused Ion Beam Tomography for Three-Dimensional Characterization in Materials Science.

Over the years, FIB-SEM tomography has become an extremely important technique for the three-dimensional reconstruction of microscopic structures with nanometric resolution. This paper describes in detail the steps required to perform this analysis, from the experimental setup to the data analysis and final reconstruction. To demonstrate the versatility of the technique, a comprehensive list of applications is also summarized, ranging from batteries to shale rocks and even some types of soft materials. Moreover, the continuous technological development, such as the introduction of the latest models of plasma and cryo-FIB, can open the way towards the analysis with this technique of a large class of soft materials, while the introduction of new machine learning and deep learning systems will not only improve the resolution and the quality of the final data, but also expand the degree of automation and efficiency in the dataset handling. These future developments, combined with a technique that is already reliable and widely used in various fields of research, are certain to become a routine tool in electron microscopy and material characterization.

From Water for Water: PEDOT:PSS-Chitosan Beads for Sustainable Dyes Adsorption.

This study investigates the viability of developing chitosan-based hydrogels derived from waste shrimp shells for the removal of methylene blue and methyl orange, thereby transforming food waste into advanced materials for environmental remediation. Despite chitosan-based adsorbents being conventionally considered ideal for the removal of negative pollutants, through targeted functionalization with poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) at varying concentrations, we successfully enhance the hydrogels' efficacy in also adsorbing positively charged adsorbates. Specifically, the incorporation of PEDOT:PSS at a concentration of 10% v/v emerges as a critical factor in facilitating the robust adsorption of dyes. In the case of the anionic dye methyl orange (MO, 10-5 M), the percentage of removed dye passed from 47% (for beads made of only chitosan) to 66% (for beads made of chitosan-PEDOT:PSS 10%), while, in the case of the cationic dye methylene blue (MB, 10-5 M), the percentage of removed dye passed from 52 to 100%. At the basis of this enhancement, there is an adsorption mechanism resulting from the interplay between electrostatic forces and π-π interactions. Furthermore, the synthesized functionalized hydrogels exhibit remarkable stability and reusability (at least five consecutive cycles) in the case of MB, paving the way for the development of cost-effective and sustainable adsorbents. This study highlights the potential of repurposing waste materials for environmental benefits, introducing an innovative approach to address the challenges regarding water pollution.

Early signs of pneumoconiosis in a dental technician in Italy: a case report.

BACKGROUND: Dental technicians are at high risk of pneumoconiosis, usually driven by inhalation of mixed dusts, including metals. An etiological diagnosis is not easy to be performed, particularly in advanced stages. CASE PRESENTATION: We describe the case of an early pneumoconiosis occurring in a 47-year-old dental technician who developed respiratory symptoms shortly after beginning work. She described the work environment as dusty and lacking relevant primary prevention tools. A chest CT showed multiple peripheral pseudonodular lesions in both lower lobes; bronchoalveolar lavage and bronchial aspirate evidenced numerous macrophages with reflective metal bodies included into the cytoplasm, that at scanning electron microscopy coupled to Energy Dispersive X-Ray Analysis resulted Zirconium and Aluminum, whereas Tungsten (W) was localized outside cells. End of shift urinary concentrations of W were substantially raised as compared to pre-shift (1.1 vs. 0.2 µg/L). CONCLUSIONS: We concluded for diagnosis of early work-related pneumoconiosis due to abnormal occupational exposure to metals. The case demonstrates the need also for dental professionals to comply with industrial hygiene standards and to be monitored by occupational health physicians.

An Analysis of the Effect of ZIF-8 Addition on the Separation Properties of Polysulfone at Various Temperatures.

The transport of H2, He, CO2, O2, CH4, and N2 at three temperatures up to 65 °C was measured in dense, thick composite films formed by amorphous Polysulfone (PSf) and particles of the size-selective zeolitic imidazolate framework 8 (ZIF-8) at loadings up to 16 wt%. The morphological and structural properties of the membranes were analyzed via SEM and density measurement. The addition of ZIF-8 to PSf enhances the H2 and He permeabilities up to 480% with respect to the pure polymer, while the ideal H2/CO2 and He/CO2 selectivities of MMMs reach values up to 30-40% higher than those of pure PSf. The relative permeability and diffusivity enhancements are higher than those obtained in other polymers, such as PPO, with the same amount of filler. The Maxwell-Wagner-Sillars model is able to represent the MMM H2/CO2 separation performance for filler volume fractions below 10%.

Mineralization of 3D Osteogenic Model Based on Gelatin-Dextran Hybrid Hydrogel Scaffold Bioengineered with Mesenchymal Stromal Cells: A Multiparametric Evaluation.

Gelatin-dextran hydrogel scaffolds (G-PEG-Dx) were evaluated for their ability to activate the bone marrow human mesenchymal stromal cells (BM-hMSCs) towards mineralization. G-PEG-Dx1 and G-PEG-Dx2, with identical composition but different architecture, were seeded with BM-hMSCs in presence of fetal bovine serum or human platelet lysate (hPL) with or without osteogenic medium. G-PEG-Dx1, characterized by a lower degree of crosslinking and larger pores, was able to induce a better cell colonization than G-PEG-Dx2. At day 28, G-PEG-Dx2, with hPL and osteogenic factors, was more efficient than G-PEG-Dx1 in inducing mineralization. Scanning electron microscopy (SEM) and Raman spectroscopy showed that extracellular matrix produced by BM-hMSCs and calcium-positive mineralization were present along the backbone of the G-PEG-Dx2, even though it was colonized to a lesser degree by hMSCs than G-PEG-Dx1. These findings were confirmed by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), detecting distinct lipidomic signatures that were associated with the different degree of scaffold mineralization. Our data show that the architecture and morphology of G-PEG-Dx2 is determinant and better than that of G-PEG-Dx1 in promoting a faster mineralization, suggesting a more favorable and active role for improving bone repair.

A carnosine analog with therapeutic potentials in the treatment of disorders related to oxidative stress.

Interactive relationships among metabolism, mitochondrial dysfunction and inflammation at skeletal muscle level play a key role in the pathogenesis of disorders related to oxidative stress. Mitochondrial dysfunction and oxidative stress result in cellular energy deficiency, inflammation and cell death inducing a vicious cycle that promotes muscle wasting. The histidine-containing dipeptides, carnosine and anserine, are carbonyl scavengers whose cytoprotective contributions extend beyond the antioxidant defence, but the physiological meaning of these capacities is actually limited. In the present study, we compared and investigated the potential protective effects of three different histidine-containing dipeptides: carnosine, anserine and carnosinol, a carnosine-mimetic new compound, against oxidative stress induction in rat L6 skeletal muscle cells. The hydrogen peroxide induced-oxidative stress significantly altered cell morphology, induced apoptosis, oxidative stress and inflammation, decreased mitochondrial peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)/sirtuin3 pathway and the antioxidant system. Notably, all three investigated dipeptides in the present study, with a different extent and in a concentration-dependent manner, reduced myotube oxidative stress, apoptosis and inflammation. The present study underlined that carnosinol, maintaining the safety condition of carnosine and anserine, was the more efficient studied dipeptide in the preservation of mitochondrial environment mediated by PGC-1α and sirtuin3 expression and thereby in the reduction of oxidative stress-related alterations in this in vitro skeletal muscle model. Furthermore, we observed that carnosinol's antioxidant effects are not blocked inhibiting sirtuin3, but are maintained with almost the same extend, indicating its multiple capacities of reactive carbonyl species-scavenging and of mitochondrial modulation through PGC-1α. In conclusion, carnosinol retained and surpassed the efficacy of the well-known investigated histidine-containing dipeptides improving oxidative stress, inflammation and also cell metabolism and so becoming a greatly promising therapeutic carnosine derivate.

Non-Plasmonic SERS with Silicon: Is It Really Safe? New Insights into the Optothermal Properties of Core/Shell Microbeads.

Silicon is one of the most interesting candidates for plasmon-free surface-enhaced Raman scattering (SERS), because of its high-refractive index and thermal stability. However, here we demonstrate that the alleged thermal stability of silicon nanoshells irradiated by conventional Raman laser cannot be taken for granted. We investigated the opto-thermal behavior of SiO2/Si core/shell microbeads (Si-rex) irradiated with three common Raman laser sources (λ = 532, 633, 785 nm) under real working conditions. We obtained an experimental proof of the critical role played by bead size and aggregation in heat and light management, demonstrating that, in the case of strong opto-thermal coupling, the temperature can exceed that of the melting points of both core and shell components. In addition, we also show that weakly coupled beads can be utilized as stable substrates for plasmon-free SERS experiments.

Metal Oxide Nanowire Preparation and Their Integration into Chemical Sensing Devices at the SENSOR Lab in Brescia.

Metal oxide 1D nanowires are probably the most promising structures to develop cheap stable and selective chemical sensors. The purpose of this contribution is to review almost two-decades of research activity at the Sensor Lab Brescia on their preparation during by vapor solid (n-type In2O3, ZnO), vapor liquid solid (n-type SnO2 and p-type NiO) and thermal evaporation and oxidation (n-type ZnO, WO3 and p-type CuO) methods. For each material we've assessed the chemical sensing performance in relation to the preparation conditions and established a rank in the detection of environmental and industrial pollutants: SnO2 nanowires were effective in DMMP detection, ZnO nanowires in NO2, acetone and ethanol detection, WO3 for ammonia and CuO for ozone.

Biological application of Compressed Sensing Tomography in the Scanning Electron Microscope.

The three-dimensional tomographic reconstruction of a biological sample, namely collagen fibrils in human dermal tissue, was obtained from a set of projection-images acquired in the Scanning Electron Microscope. A tailored strategy for the transmission imaging mode was implemented in the microscope and proved effective in acquiring the projections needed for the tomographic reconstruction. Suitable projection alignment and Compressed Sensing formulation were used to overcome the limitations arising from the experimental acquisition strategy and to improve the reconstruction of the sample. The undetermined problem of structure reconstruction from a set of projections, limited in number and angular range, was indeed supported by exploiting the sparsity of the object projected in the electron microscopy images. In particular, the proposed system was able to preserve the reconstruction accuracy even in presence of a significant reduction of experimental projections.

Probing the spatial extension of light trapping-induced enhanced Raman scattering in high-density Si nanowire arrays.

This paper reports an experimental investigation of surface-enhanced Raman scattering in high-density Si nanowire arrays obtained by electroless etching. A direct relationship between light trapping capabilities of Si nanowires and enhanced Raman scattering was demonstrated. Optimized arrays allowed for a remarkable increase of Raman sensitivity in comparison to reference planar samples. As a result, the detection limit of molecular probes under resonant excitation (e.g. methylene blue) can be extended by three orders of magnitude. In addition, continuous ultrathin films, that cannot be analyzed in conventional Raman experiments, are made detectable. In the case of anatase thin films, the detection limit of 5 nm was reached. Raman spectra of Si/TiO2 core/shell heterostructures demonstrate that the enhanced field resulting from surface multiple scattering is characterized by a large spatial extension (about fifty nanometers), making these materials a potential alternative to plasmonic metals for SERS experiments.

Integration of ZnO and CuO nanowires into a thermoelectric module.

Zinc oxide (ZnO, n-type) and copper oxide (CuO, p-type) nanowires have been synthesized and preliminarily investigated as innovative materials for the fabrication of a proof-of-concept thermoelectric device. The Seebeck coefficients, electrical conductivity and thermoelectric power factors (TPF) of both semiconductor materials have been determined independently using a custom experimental set-up, leading to results in agreement with available literature with potential improvement. Combining bundles of ZnO and CuO nanowires in a series of five thermocouples on alumina leads to a macroscopic prototype of a planar thermoelectric generator (TEG) unit. This demonstrates the possibility of further integration of metal oxide nanostructures into efficient thermoelectric devices.

Taurine rescues cisplatin-induced muscle atrophy in vitro: a morphological study.

Cisplatin (CisPt) is a widely used chemotherapeutic drug whose side effects include muscle weakness and cachexia. Here we analysed CisPt-induced atrophy in C2C12 myotubes by a multidisciplinary morphological approach, focusing on the onset and progression of autophagy, a protective cellular process that, when excessively activated, may trigger protein hypercatabolism and atrophy in skeletal muscle. To visualize autophagy we used confocal and transmission electron microscopy at different times of treatment and doses of CisPt. Moreover we evaluated the effects of taurine, a cytoprotective beta-amino acid able to counteract oxidative stress, apoptosis, and endoplasmic reticulum stress in different tissues and organs. Our microscopic results indicate that autophagy occurs very early in 50 µM CisPt challenged myotubes (4 h-8 h) before overt atrophy but it persists even at 24 h, when several autophagic vesicles, damaged mitochondria, and sarcoplasmic blebbings engulf the sarcoplasm. Differently, 25 mM taurine pretreatment rescues the majority of myotubes size upon 50 µM CisPt at 24 h. Taurine appears to counteract atrophy by restoring regular microtubular apparatus and mitochondria and reducing the overload and the localization of autophagolysosomes. Such a promising taurine action in preventing atrophy needs further molecular and biochemical studies to best define its impact on muscle homeostasis and the maintenance of an adequate skeletal mass in vivo.

Nanostructured metal oxide gas sensors, a survey of applications carried out at SENSOR lab, Brescia (Italy) in the security and food quality fields.

In this work we report on metal oxide (MOX) based gas sensors, presenting the work done at the SENSOR laboratory of the CNR-IDASC and University of Brescia, Italy since the 80s up to the latest results achieved in recent times. In particular we report the strategies followed at SENSOR during these 30 years to increase the performance of MOX sensors through the development of different preparation techniques, from Rheotaxial Growth Thermal Oxidation (RGTO) to nanowire technology to address sensitivity and stability, and the development of electronic nose systems and pattern recognition techniques to address selectivity. We will show the obtained achievement in the context of selected applications such as safety and security and food quality control.

High degree of polarization of the near-band-edge photoluminescence in ZnO nanowires.

We investigated the polarization dependence of the near-band-edge photoluminescence in ZnO strain-free nanowires grown by vapor phase technique. The emission is polarized perpendicular to the nanowire axis with a large polarization ratio (as high as 0.84 at 4.2 K and 0.63 at 300 K). The observed polarization ratio is explained in terms of selection rules for excitonic transitions derived from the k·p theory for ZnO. The temperature dependence of the polarization ratio evidences a gradual activation of the XC excitonic transition.PACS: 78.55.Cr, 77.22.Ej, 81.07.Gf.

Quasi-monodimensional polyaniline nanostructures for enhanced molecularly imprinted polymer-based sensing.

Recent advances in nanotechnology have allowed significant progress in utilising cutting-edge techniques associated with nanomaterials and nano-fabrication to expand the scope and capability of biosensors to a new level of novelty and functionality. The aim of this work was the development and characterisation of conductive polyaniline (PANI) nanostructures for applications in electrochemical biosensing. We explore a simple, inexpensive and fast route to grow PANI nanotubes, arranged in an ordered structure directly on an electrode surface, by electrochemical polymerisation using alumina nanoporous membranes as a 'nano-mould'. The deposited nanostructures have been characterised electrochemically and morphologically prior to grafting with a molecularly imprinted polymer (MIP) receptor in order to create a model sensor for catechol detection. In this way, PANI nanostructures resulted in a conductive nanowire system which allowed direct electrical connection between the electrode and the synthetic receptor (MIP). To our knowledge, this is the first example of integration between molecularly imprinted polymers and PANI nanostructured electrodes. The advantages of using nanostructures in this particular biosensing application have been evaluated by comparing the analytical performance of the sensor with an analogous non-nanostructured MIP-sensor for catechol detection that was previously developed. A significantly lower limit of detection for catechol has been obtained (29 nM, one order of magnitude), thus demonstrating that the nanostructures are capable of improving the analytical performance of the sensor.

Direct integration of metal oxide nanowires into an effective gas sensing device.

A simple and large-area scalable methodology has been set up for direct integration of metal oxide nanowire bundles into a functional device for gas sensing. It is based on sequential application of two consolidated techniques, namely high temperature vapour transport and condensation for fabrication of metal oxide nanowires, and wet etching of a sacrificial layer. The alumina substrate patterned with a silicon dioxide sacrificial layer does not influence the growth of nanowires and remains unaltered under the high temperature process. The sacrificial layer is finally removed under hydrofluoric acid, the metal oxide nanowires do not suffer modifications and a clean substrate surface can be obtained for deposition of stable metal contacts. The methodology was proven effective for application in a gas sensor device. Electrical measurements indicate that a slightly rectifying Schottky junction is present at low temperatures (up to T = 150 degrees C) between nanowires and platinum electrodes, which vanishes as the temperature increases and under high voltage (bias voltage above approximately 3 V). The results foresee the possibility of growth and integration of nanowire bundles directly into devices, overcoming the need for expensive and time-consuming nanomanipulation techniques.

In situ plasmon-heating-induced generation of Au/TiO2 "hot spots" on colloidal crystals.

SERS you right: The plasmon heating of gold nanoshells is exploited to yield the local conversion of amorphous TiO(2) into anatase on the surface of polymeric colloidal crystals (see scheme). The resulting Au/TiO(2) spots are active substrates for surface-enhanced Raman spectroscopy and allow surface reactions and processes to be followed directly on-site.