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In this article, we propose a new strategy to build a sensor for easy handling and rapid analysis on-site. Our sensor is based on the combination of surface-enhanced Raman spectroscopy (SERS) and molecularly imprinted polymers (MIPs). SERS provides a strong sensitivity for the detection of trace molecules while MIPs offer a highly selective and specific recognition platform. The research presented here focuses on the detection of the interaction between a robust ultra-thin layer of MIPs and of paracetamol, the targeted molecule. This drug is an environmental emerging pollutant, i.e., a molecule whose presence and significance have not yet been elucidated, which gives rise to health and environmental concerns. The results are a combined analysis of the SERS spectra and a multivariate analysis. The former provides a clear demonstration of the evolution of the MIP-nanostructure interaction when the concentration of paracetamol increases. The statistical analysis produces the proof of the selectivity of the sensor. [ABSTRACT FROM AUTHOR]

Over the past two decades, important progress has been made in the development of nanomaterials, especially for biomedical applications. The surface of magnetic nanoparticles (MNPs) can be modified and functionalized with a targeting agent in order to improve their longevity in the blood, their cell internalization, and their efficiency. However, after this functionalization, some of their physical properties may be modified. In this paper, spinel iron-oxide single crystals 10 nm in diameter were elaborated and functionalized with human serum albumin (HSA) protein, to give an MNP–HSA nano-platform. Physicochemical studies were performed to evaluate this nano-platform utility in nanomedicine. X-ray photoelectron spectroscopy and thermogravimetry were used to establish the presence of protein at the surface of MNP. MNP–HSA shows very good colloidal stability with a zeta potential of −35.4 ±0.6 mV at physiological pH (7.4). MNP–HSA is superparamagnetic and exhibits a saturation magnetization (Ms) of 63 emu.g−1 at 310 K and produces localized heat in an alternating magnetic field; the specific absorption rate (SAR) of an aqueous suspension of MNP–HSA is 123 W.g−1. To identify the relative contributions of Brownian and Néel relaxations in its heating process, MNP–HSA was immobilized in an agarose gel, where the SAR was found to be the same as in water. This indicates that Néel relaxation is the dominant nanoheating mechanism. [ABSTRACT FROM AUTHOR]

In this work, we develop an original and easy-to-achieve experimental approach to produce CdS quantum dots (QDs) decorating TiO 2 nanotubes (NTs) onto Ti sheets, by combining Ti anodization technique, CdS QDs polyol production and aqueous impregnation. The obtained films were characterized by Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and UV–visible Diffuse Reflectance Spectroscopy. The realized hetero-nanostructures were used as photoanodes in a photoelectrochemical (PEC) cell to evaluate their ability to oxidize water for hydrogen generation. An enhanced photocurrent density, J of 0.4 mA/cm 2 at 0 V (vs. Ag/AgCl) was measured when immersed in a Na 2 SO 4 electrolyte aqueous solution and illuminated by a Xenon lamp. This value is about four times higher than that measured on their QDs free counterparts. The obtained results are very encouraging considering the very weak amount of grafted narrow band-gap nanocrystalline semiconductors, namely CdS QDs. Clearly, CdS QDs allow a wider solar light wavelength range absorption and a lower carrier electron-hole recombination, leading to a considerable improvement in the photoelectrochemical performances. [ABSTRACT FROM AUTHOR]

Potassium-type birnessite and lithium-containing manganese oxides were prepared by the polyol process. The Mn(III)/Mn(IV) mixed-valencies compounds are obtained through the controlled reduction of potassium permanganate in a basic water-diethylene glycol mixture at moderate temperature and very short reaction time, 70 °C and 10 min, respectively. Both solids are quite well crystallized and display high specific surface areas, 137 and 329 m g, respectively. Several polyols with variable chain lengths have been used and it is shown that the nature of the polyol has a marked influence on the textural properties of the birnessite-type solid. [ABSTRACT FROM AUTHOR]

In this work, we developed a new type of nanostructured photoanodes for photoelectrochemical water splitting. They are based on CdS–TiO 2 nanocomposite films, supported on conductive Ti sheets, prepared by an easy-to-achieve three-step method. It involves the production of TiO 2 nanofibers (NFs) using a controlled corrosion route of polished Ti sheets, the preparation of size-controlled CdS quantum dots (QDs) by the polyol process and the direct impregnation of TiO 2/Ti sheets by QDs in suspension. The photoelectrochemical (PEC) properties of the resulting nanostructures were measured, using a homemade electrochemical cell illuminated with a standard Xenon lamp, and compared to those of bare TiO 2 NFs. A net enhancement of the photocurrent was observed after CdS impregnation, suggesting a low carrier recombination rate and a higher efficiency of the PEC device for solar water splitting, as the induced photocurrent is related to the electrons needed to reduce H + ions into H 2 at the cathode electrode (Pt wire). [ABSTRACT FROM AUTHOR]

A methodology of surface chemical functionalization of equimolar HfNbTaTiZr high-entropy alloy (HEA) is presented herein. The aim is to improve the biocompatibility of this material for its application as bio-implants. X-ray Photoelectron Spectroscopy (XPS) showed that air or aqueous oxidation of HfNbTaTiZr induced the formation at its surface of unmixed monometallic oxides: TiO 2 , Nb 2 O 3 , ZrO 2 , Hf 2 O 3 , and Ta 2 O 5. Besides, it was observed that short (2 h) mild aqueous oxidation (without H 2 O 2) retains the surface stoichiometry of these elements compared to a more aggressive one (with H 2 O 2). The mild oxidation was retained to form a sol-gel chemistry platform for HfNbTaTiZr surface silanization. In practice, the oxidized HfNbTaTiZr surface was reacted with 2-methoxy [(polyethyleneoxy) 6–9 propyl] trimethoxysilane (MPTMS), dissolved in distilled ethanol, under an inert atmosphere. Both, the precursor concentration and the reaction time, were varied to define the optimized operating conditions. Infrared spectroscopy performed on all prepared samples, within an attenuated total reflectance (ATR) sampling configuration, evidenced the well-known vibrational signatures of Si O and C H bonds at 1090 cm−1 and 2980 cm−1, respectively, confirming silane grafting, and showed that the intensity of these bands increases when the reaction time and/or the siloxane precursor concentration increase. Moreover, XPS showed that a reaction time of 48 h is required to completely cover the alloy surface with an organic layer (exhibiting a thickness larger than the XPS analysis depth). Finally, as a preliminary study, mildly oxidized alloy and the grafted one for a reaction time of 48 h were contacted to a Phosphate-Buffered Saline (PBS) solution and a standard Nutrient Mixture for cell cultures, the well-known Dulbecco's Modified Eagle Medium (DMEM), up to one month to check their chemical stability. None metal release was evidenced for the treated sample highlighting the importance of surface processing before any bio-implant use. Unlabelled Image • A chemical surface treatment methodology was developed to functionalize HfNbTaTiZr High entropy Alloy (HEA) • Controlled aqueous oxidation followed by optimized surface polyethyleneglycol-based silanization were successfully performed • This coating prevents chemical surface alteration when contacted with biomimetic media for cell cultures • Results pave the way for the use of surface-silanized HfNbTaTiZr as bio-implant material [ABSTRACT FROM AUTHOR]