Visible light assisted organosilane assembly on mesoporous silicon films and particles

Porous silicon (PSi) is a versatile matrix with tailorable surface reactivity, which allows the processing of a range of multifunctional films and particles. The biomedical applications of PSi often require a surface capping with organic functionalities. This work shows that visible light can be used to catalyze the assembly of organosilanes on the PSi, as demonstrated with two organosilanes: aminopropyl-triethoxy-silane and perfluorodecyl-triethoxy-silane. We studied the process related to PSi films (PSiFs), which were characterized by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (ToF-SIMS) and field emission scanning electron microscopy (FESEM) before and after a plasma patterning process. The analyses confirmed the surface oxidation and the anchorage of the organosilane backbone. We further highlighted the surface analytical potential of 13 C, 19 F and 29 Si solid-state NMR (SS-NMR) as compared to Fourier transformed infrared spectroscopy (FTIR) in the characterization of functionalized PSi particles (PSiPs). The reduced invasiveness of the organosilanization regarding the PSiPs morphology was confirmed using transmission electron microscopy (TEM) and FESEM. Relevantly, the results obtained on PSiPs complemented those obtained on PSiFs. SS-NMR suggests a number of siloxane bonds between the organosilane and the PSiPs, which does not reach levels of maximum heterogeneous condensation, while ToF-SIMS suggested a certain degree of organosilane polymerization. Additionally, differences among the carbons in the organic (non-hydrolyzable) functionalizing groups are identified, especially in the case of the perfluorodecyl group. The spectroscopic characterization was used to propose a mechanism for the visible light activation of the organosilane assembly, which is based on the initial photoactivated oxidation of the PSi matrixWe acknowledge MSC funding provided by the European Commission through FP7 grant THINFACE (ITN GA 607232) and by Ministerio de Economía y Competitividad through grant NANOPROST (RTC-2016-4776-1

The death of libraries? Towards the e-evolution

Starting from the premise that future information flows will be transmitted exclusively via electronic formats and that the future of books in their current structure is uncertain, the article analyzes the situation of uncertainty for libraries’ survival in the new systems of global information, where the immediacy of access to sources and collaboration are becoming standard. The authors invite a rethinking of paradigm tools that prevail in libraries. The study also aims to discuss the old paradigms as opposed to the changes that are taking place and focuses on defining a model of innovative thinking which can sustain the e-evolution” of libraries. Analyzing the perspectives from a qualitative research method founded on the triangulation of three or more different perspectives, the methodology-driven approach defines the paradigm changes that will be more influential in the near future and hence poses new ways to think about the interrelationship between different actors that will positively affect a sustainable e-evolution” of libraries if they are considered and seen from a global human-centered point of view

Porous silicon bragg reflector and 2D gold-polymer nanograting: a route towards a hybrid optoplasmonic platform

Photonic and plasmonic systems have been intensively studied as an effective means to modify and enhance the electromagnetic field. In recent years hybrid plasmonic–photonic systems have been investigated as a promising solution for enhancing light-matter interaction. In the present work we present a hybrid structure obtained by growing a plasmonic 2D nanograting on top of a porous silicon distributed Bragg reflector. Particular attention has been devoted to the morphological characterization of these systems. Electron microscopy images allowed us to determine the geometrical parameters of the structure. The matching of the optical response of both components has been studied. Results indicate an interaction between the plasmonic and the photonic parts of the system, which results in a localization of the electric field profileThis research was funded by the EU Commission through FP7 action THINFACE ITN GA 607232 and Ministerio de Ciencia, Innovación y Universidades (Spain) through RETOS action CTQ2017-84309-C2-2-

Near ambient pressure X-ray photoelectron spectroscopy monitoring of the surface immobilization cascade on a porous silicon-gold nanoparticle FET biosensor

Porous silicon (PSi) offers extremely attractive optical, electronic and biofunctional properties for the development of biosensors. In the present work, we have studied the step by step sandwich biofunctionalization cascade of a PSi platform by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and, in parallel, we have developed a three electrode PSi device sensitive to changes in surface conductance. Prior to the NAP-XPS characterization, the organosilanization with glycidyloxy-propyl-trimethoxy-silane, the bioconjugation, and the gold nanoparticle (AuNP) sensitization layer were monitored by spectroscopic ellipsometry. The NAP-XPS analysis revealed outstanding results: a) the NAP-XPS chamber allows detecting the pristine PSi with negligible adventitious carbon contamination, b) the single oxygen bonded carbon component of the Glycidyl group dominates the C1s core level after organosilanization, c) the good progress of the biofunctionalization/recognition is confirmed by the increase of the silica to silicon component ratio in the Si2p core level and, d) the N1s core level describes identical features from the presence of aminoacid sequences in the capture/detection steps. A FET sensing of a prostate specific antigen (PSA) marker was performed through conjugation with AuNPs. For a given concentration of PSA (and AuNPs) the conductance increased with the increase of the gate voltage. For a given gate voltage, the conductance was observed to increase for increasing concentration of PSA. This allowed proposing a calibration line for the biosensor, which is valid from a clinically relevant range of 0.1 ng/mLWe acknowledge MSC funding provided by the European Commission through FP7 grant THINFACE (ITN GA 607232) and from Ministerio de Economía y Competitividad, Spain, through grant SPECTRASENSE (RTC-2017-6311-1

Impact of Saccharomyces cerevisiae yeast inoculation mode on wine composition

Inoculation modes are known to affect yeast behavior. Here, we characterized the impact of ADY and pre-culturing on the composition of the resulting wine, fermented by four commercial strains of Saccharomyces cerevisiae. Classical oenological parameters were not affected by the yeast inoculation mode. Using an untargeted metabolomic approach, a significant distinction in wine composition was noted regardless of the strain between the two inoculation modes, each associated with a specific metabolomic signature. 218 and 895 biomarkers were annotated, respectively, for ADYs associated with the preservation of wine polyphenols, and for pre-cultures related to the modulation of yeast nitrogen metabolism. Volatilome analysis revealed that the ester family was that most impacted by the inoculation mode whatever the strain. Ester production was enhanced in ADY condition. For the first time, the complete reprogramming of the yeast metabolism was revealed as a function of yeast preparation, which significantly impacts its volatilome and exometabolome

Insulin-mimetic compound hexaquis (benzylammonium) decavanadate is antilipolytic in human fat cells

This study investigates in murine and human adipocytes the antilipolytic properties of a conjugate of benzylamine and decavanadate (B6V10), already reported to lower hyperglycaemia in diabetic rodents. Data indicated that the conjugate dose-dependently inhibited submaximal activation of lipolysis in all the species studied. Such antilipolytic action deals with the in vivo FFA-lowering properties already described for B6V10 in diabetic rats. B6V10 also activated lipogenesis and glucose transport in fat cells. B6V10 should therefore be useful in preventing the lipotoxicity constituted by the unrestrained lipolytic activity of insulin-resistant adipocytes in obese individuals presenting type 2 diabetes, a state named diabesity

Search for 22^{22}Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of $^{26}$Al and $^{22}$Na. While gamma rays from the decay of the former radioisotope have been observed throughout the Galaxy, $^{22}$Na remains untraceable. The half-life of $^{22}$Na (2.6 yr) would allow the observation of its 1.275 MeV gamma-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of the nuclear reactions involved in the production and destruction of this nucleus. The $^{22}$Na($p,\gamma$)$^{23}$Mg reaction remains the only source of large uncertainty about the amount of $^{22}$Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in $^{23}$Mg. In the present work, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this novel method to the study of the $^{23}$Mg states, combining magnetic and highly-segmented tracking gamma-ray spectrometers, places strong limits on the amount of $^{22}$Na produced in novae, explains its non-observation to date in gamma rays (flux < 2.5x$10^{-4}$ ph/(cm$^2$s)), and constrains its detectability with future space-borne observatories.Comment: 18 pages, 3 figures, 1 tabl

Porous Silicon Bragg Reflector and 2D Gold-Polymer Nanograting: A Route Towards a Hybrid Optoplasmonic Platform

Photonic and plasmonic systems have been intensively studied as an effective means to modify and enhance the electromagnetic field. In recent years hybrid plasmonic&ndash;photonic systems have been investigated as a promising solution for enhancing light-matter interaction. In the present work we present a hybrid structure obtained by growing a plasmonic 2D nanograting on top of a porous silicon distributed Bragg reflector. Particular attention has been devoted to the morphological characterization of these systems. Electron microscopy images allowed us to determine the geometrical parameters of the structure. The matching of the optical response of both components has been studied. Results indicate an interaction between the plasmonic and the photonic parts of the system, which results in a localization of the electric field profile

Bringing immuno-assemblies to optoelectronics: sandwich assay integration of a nanostructured porous-silicon/gold-nanoparticle phototransistor

The exquisite specificity of biomolecular interactions can be used to integrate photonic and electronic components into nanomaterial-based architectures. In this line, a field-effect phototransistor based on Si/porous silicon (PSi) structures was fabricated by quantitatively attaching Gold nanoparticles (AuNPs) to the PSi surface by an immunoassay. Two antibodies, linked onto PSi and AuNPs, were used against different epitopes of prostate specific antigen, the common conjugating marker for these antibodies. Under white light illumination the photocurrent increases with increasing AuNP surface density. The gate voltage is effective in decoupling electron-hole pairs created at the nanostructured PSi interface. In turn, the main effect of the immune-assembled AuNPs is the optimization of charge transport through the surface. The analysis of the photocurrent shows an outstanding spectral selectivity in the 980 ± 50 nm NIR bandwidth. This report underlines the potential of the insertion of immune-assay protocols for the development of optoelectronic devicesThe current research was funded by grant SPECTRASENSE, RTC-2017-6311-1 from the Government of Spai