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The actual implementation of on-site analysis of biomarkers, such as miRNAs, depends on the availability of portable and easy-to-handle detection systems that can be used as point-of-care in real life applications. In this work, an automatized microfluidic platform combined with a portable Raman spectrometer is reported and tested for miR-214 detection by surface enhanced Raman scattering (SERS). A multi-chamber SERS-active chip, functionalized according to a previously optimized two-step hybridization assay, was automatically incubated with the analyte solution. Preliminary tests allowed to adjust the portable Raman spectrometer acquisition conditions and to compare the obtained results with those of a bench Raman microscope. Finally, miR-214 at different concentrations was analyzed through an automatic procedure, achieving a limit of detection (LOD) in the picomolar range.

Silicon-based thin films and nanostructures are of paramount importance in a wide range of applications, including microelectronics, photovoltaics, large area sensors, and biomedicine. The wide accessibility of silicon and its relatively low cost have driven a continuous improvement of technology based on this element. Plasma technology has been widely used for the synthesis of coatings and nanostructures based on silicon. Moreover, it has made a fundamental contribution to continuous improvement of the physicochemical properties of silicon-based materials and allows the synthesis of nanometric structures with well-defined shapes and morphologies. In this work, we have reviewed the most interesting developments in plasma-assisted processes for the synthesis of Si-based materials, both inorganic and organic, in the last five years. Special attention has been paid to new techniques, or modifications of already-existing ones, that open up new possibilities for the synthesis of materials with new properties, as well as nanostructures with novel characteristics. [ABSTRACT FROM AUTHOR]

Purpose: This research aimed to assess whether pink-shaded anodized surfaces could enhance the adhesion of soft tissue cells compared with untreated machined titanium surfaces. Materials and Methods: Two types of Ti-Al-V titanium samples were prepared: machined titanium (Ti) and anodized titanium (AnoTi). The microstructure was studied by means of a scanning electron microscope. X-ray photoelectron spectroscopy (XPS) was carried out as well. The wetting properties were investigated by the sessile drop technique with water and diiodomethane. To investigate the biologic response in vitro, the epithelial cell line HaCaT and the fibroblastic cell line NHDF were used. Cell adhesion, morphology, and proliferation were evaluated. Results: The microstructure of the tested surfaces was irregularly smooth for both types of samples with no relevant morphologic differences. The XPS and HR-XPS performed on the AnoTi samples confirmed the presence of Ti, O, and C, along with Ti oxides. Following the optical contact angle measurements, the anodization process induced a slight transition toward the hydrophobic regime. Consequently, the surface free energy values differed significantly between the anodized and the machined samples. Anodized Ti significantly increased the adhesion and proliferation of both epithelial cells and fibroblasts when compared with the pristine Ti controls. Conclusion: Compared with the clinical standard, anodized surfaces could enhance the adhesion of the two major cell types within the peri-implant soft tissues, which makes pink anodization a promising option for implant dentistry. [ABSTRACT FROM AUTHOR]

In this work graphene coatings have been deposited on aluminum alloy samples to investigate whether they can improve wear strength and promote friction reduction, which means components reliability and efficiency. Tribological performance has been tested by pin-on-disk wear tests. Three procedures to coat the samples have been explored. One is based on transferred graphene method and the other two are based on percolative graphene. Results show that graphene coatings last little time onto the sample surface, though strongly reducing the coefficient of friction of aluminum samples as far as they endure. [ABSTRACT FROM AUTHOR]

A versatile and efficient surface‐enhanced Raman scattering (SERS) substrate based on a hybrid aerogel composed of reduced graphene oxide (rGO) decorated with silver nanoparticles (AgNPs), suitable for highly sensitive label‐free detection of chemical and biological species, is presented. The simple and low‐cost one‐pot hydrothermal synthesis allows obtaining of a 3D nanostructured spongy‐like matrix that shows good spatial distribution of Ag nanoparticles in intimate contact with rGO flakes, characterized by means of several morphological, structural, and compositional techniques. The nanostructured material, tested by SERS analysis with both rhodamine 6G (R6G) and 4‐mercaptobenzoic acid (MBA), shows a satisfying SERS efficiency, quantified in terms of minimum detectable concentration of 10−10 and 10−7m, corresponding to on‐ and off‐resonant excitation, respectively. The versatility of chemical/biochemical functionalization is successfully demonstrated by exploiting different routes, by immobilizing both protoporphyrin IX (PRPIX) and hemin (H) that take advantage of π−π non‐covalent bonding with the graphene layers, as well as thiol‐ended oligonucleotides (DNA probes/aptamers) directly grafted on the AgNPs. Finally, after the successful integration of the hybrid aerogel into a microfluidic chip, the biorecognition of miR222 is obtained demonstrating the reliability of the aerogel substrate as SERS platform for biosensing. [ABSTRACT FROM AUTHOR]

The amount of hydrogen present in porous silicon (PS) nanostructures is analyzed in detail. Concentration of atomic hydrogen chemically bound to the specific surface of PS is quantitatively evaluated by means of attenuated total reflection infrared spectroscopy and temperature-programmed desorption spectroscopy.

The study brings evidence in favor of the mechanism by studying the IR spectra of the system at different NO2 equilibrium pressures. It concludes that estimation of the enthalpy of adsorption suggests that a chemisorption process is involved, which is confirmed by the kinetics having desorption being lower than that of adsorption.

Particularly‐shaped silver nanostructures are successfully applied in many scientific fields, such as nanotechnology, catalysis, (nano)engineering, optoelectronics, and sensing. In recent years, the production of shape‐controlled silver‐based nanostructures and the knowledge around this topic has grown significantly. Hence, on the basis of the most recent results reported in the literature, a critical analysis around the driving forces behind the synthesis of such nanostructures are proposed herein, pointing out the important role of surface‐regulating agents in driving crystalline growth by favoring (or opposing) development along specific directions. Additionally, growth mechanisms of the different morphologies considered here are discussed in depth, and critical points highlighted.Box of tricks: The performance of nanomaterials is strictly correlated to their size and morphology; thus, great effort has been devoted to obtaining particularly shaped nanoscopic geometries. The main relevant strategies concerning the growth of particularly shaped metallic nanostructures (and the role of surface‐regulating agents) are discussed in depth. Particular emphasis is devoted to the growth mechanisms involved for silver‐based nanostructures. [ABSTRACT FROM AUTHOR]

Ruthenium active species containing Ruthenium Sulphide (RuS2) is synthesized together with a self-assembled reduced graphene oxide (RGO) aerogel by a one-pot hydrothermal synthesis. Ruthenium Chloride and L-Cysteine are used as reactants. The hydrothermal synthesis of the innovative hybrid material occurs at 180 °C for 12 h, by using water as solvent. The structure and morphology of the hybrid material are fully characterized by Raman, XRD, XPS, FESEM and TEM. The XRD and diffraction pattern obtained by TEM display an amorphous nanostructure of RuS2 on RGO crystallized flakes. The specific capacitance measured in planar configuration in 1 M NaCl electrolyte at 5 mV s−1 is 238 F g−1. This supercapacitor electrode also exhibits perfect cyclic stability without loss of the specific capacitance after 15,000 cycles. In summary, the RGO/Ruthenium active species hybrid material demonstrates remarkable properties for use as active material for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In this work, SERS-based microfluidic PDMS chips integrating silver-coated porous silicon membranes were used for the detection and quantitation of microRNAs (miRNAs), which consist of short regulatory non-coding RNA sequences typically over- or under-expressed in connection with several diseases such as oncogenesis. In detail, metal–dielectric nanostructures which provide noticeable Raman enhancements were functionalized according to a biological protocol, adapted and optimized from an enzyme-linked immunosorbent assay (ELISA), for the detection of miR-222. Two sets of experiments based on different approaches were designed and performed, yielding a critical comparison. In the first one, the labelled target miRNA is revealed through hybridization to a complementary thiolated DNA probe, immobilized on the silver nanoparticles. In the second one, the probe is halved into shorter strands (half1 and half2) that interact with the complementary miRNA in two steps of hybridization. Such an approach, taking advantage of the Raman labelling of half2, provides a label-free analysis of the target. After suitable optimisation of the procedures, two calibration curves allowing quantitative measurements were obtained and compared on the basis of the SERS maps acquired on the samples loaded with several miRNA concentrations. The selectivity of the two-step assay was confirmed by the detection of target miR-222 mixed with different synthetic oligos, simulating the hybridization interference coming from similar sequences in real biological samples. Finally, that protocol was applied to the analysis of miR-222 in cellular extracts using an optofluidic multichamber biosensor, confirming the potentialities of SERS-based microfluidics for early-cancer diagnosis. [ABSTRACT FROM AUTHOR]

Surface modification of dental implants is a key process in the production of these medical devices, and especially titanium implants used in the dental practice are commonly subjected to surface modification processes before their clinical use. A wide range of treatments, such as sand blasting, acid etching, plasma etching, plasma spray deposition, sputtering deposition and cathodic arc deposition, have been studied over the years in order to improve the performance of dental implants. Improving or accelerating the osseointegration process is usually the main goal of these surface processes, but the improvement of biocompatibility and the prevention of bacterial adhesion are also of considerable importance. In this review, we report on the research of the recent years in the field of surface treatments and coatings deposition for the improvement of dental implants performance, with a main focus on the osseointegration acceleration, the reduction of bacterial adhesion and the improvement of biocompatibility. [ABSTRACT FROM AUTHOR]

In this study, a novel SERS sensor has been developed for repeatable detection of organic molecules and biological assays. Vertically oriented titania nanotube (TiO2 NT) arrays were grown by ultra-fast anodic oxidation of flexible titanium foils and then decorated with Ag nanoparticles (NPs) through d.c. sputtering deposition at room temperature. A parametric study was carried out taking into account the effect of sputtering parameters on the Ag NP arrangements on the NT surface. The structure morphology was investigated by means of scanning and transmission electron microscopy, evidencing the formation of hexagonal close-packed TiO2 NTs coated with Ag nanoparticles showing tunable diameter and distribution. The substrates were employed in a SERS optofluidic device, consisting of a polydimethylsiloxane cover irreversibly sealed to the silver-coated TiO2 NTs, able to detect Rhodamine molecules in ethanol over a wide range of concentrations down to 10−14 M, taking advantage of both electromagnetic and chemical enhancements. In order to evaluate the performances of the SERS substrates in terms of biosensing, an optimized protocol for the immobilization of oligonucleotide probes on the metal-dielectric surfaces was developed for verifying the hybridization events. [ABSTRACT FROM AUTHOR]