The development of sensitive graphene-based surface acoustic wave sensors for NO2 detection at room temperature.

Bilayer graphene (Bl-Gr) and sulphur-doped graphene (S-Gr) have been integrated with LiTaO3 surface acustic wave (SAW) sensors to enhance the performance of NO2 detection at room temperature. The sensitivity of the Bl-Gr SAW sensors toward NO2, measured at room temperature, was 0.29º/ppm, with a limit of detection of 0.068 ppm. The S-Gr SAW sensors showed 0.19º/ppm sensitivity and a limit of detection of 0.140 ppm. The origin of these high sensitivities was attributed to the mass loading and elastic effects of the graphene-based sensing materials, with surface changes caused by the absorption of the NO2 molecules on the sensing films. Although there are no significant differences regarding the sensitivity and detection limit of the two types of sensors, the measurements in the presence of interferent gases and various humidity conditions outlined much better selectivity and sensing performances towards NO2 gas for the Bl-Gr SAW sensors.

Green synthesis of aminated hyaluronic acid-based silver nanoparticles on modified titanium dioxide surface: Influence of size and chemical composition on their biological properties.

This is the first report on an efficient, "environmentally friendly" chemical reduction method for the synthesis of aminated hyaluronic acid-based silver nanoparticles on the modified surface of titanium dioxide nanoparticles aimed for biological applications. Silver nanoparticles exhibit well-known physical-chemical and optical properties appropriate for different biological applications. Modifying the nanoparticles leads to a change in their expected bioactivity. This represents an important topic for the current research. We have developed a novel aminated hyaluronic acid (HA-EDA)-based protocol to obtain silver nanoparticles, in which HA-EDA was used for the first time as a reducing and stabilizing agent. The effect of the size of silver nanoparticles on the titanium dioxide surface and the chemical composition of the obtained materials were investigated by TEM, XRD, XPS, ATR-FTIR, Raman spectroscopy, NMR and H2-TPR analyses. The antioxidant, in vitro biocompatibility, and antimicrobial activity of the fabricated composites have been evaluated. The results prove that the prepared materials exhibit antimicrobial, antioxidant, and anti-inflammatory activity, thus providing protection against infection and supporting tissue regeneration, these two key effects being of paramount importance for promoting wound healing.

Hybrid nanomaterial-based indirect electrochemical sensing of glyphosate in surface water: a promising approach for environmental monitoring.

Glyphosate (GLY), a widely utilized pesticide, poses a significant threat to human health even at minute concentrations. In this study, we propose an innovative electrochemical sensor for the indirect detection of GLY in surface water samples. The sensor incorporates a nanohybrid material composed of multi-layer graphene decorated with gold nanoparticles (AuNPs), synthesized in a single-step electrochemical process. To ensure portability and on-site measurements, the sensor is developed on a screen-printed electrode, chosen for its integration and miniaturization capabilities. The proposed sensor demonstrates remarkable sensitivity and selectivity for GLY detection in surface water samples, with an exceptional limit of detection (LOD) of 0.03 parts per billion (ppb) in both buffer and surface water matrices. Moreover, it exhibits a remarkably high sensitivity of 0.15 µA ppb-1. This electrochemical sensor offers a promising approach for accurate GLY monitoring, addressing the urgent need for reliable pesticide detection in environmental samples. The proposed sensor showed high selectivity towards GLY, when analysed in the presence of other pesticides such as phosmet, chlorpyrifos and glufosinate-ammonium. The recovery percentages of GLY from spiked surface water samples were between 93.8 and 98.9%. The study's broader implications extend to revolutionizing the way environmental chemistry addresses pesticide contamination, water quality assessment, and sustainable management of environmental pollutants. By pushing the boundaries of detection capabilities and offering practical solutions, this research contributes to the advancement of knowledge and practices that are essential for preserving and protecting our environment.

Functional Enhancement and Characterization of an Electrophysiological Mapping Electrode Probe with Carbonic, Directional Macrocontacts.

Electrophysiological mapping (EM) using acute electrode probes is a common procedure performed during functional neurosurgery. Due to their constructive specificities, the EM probes are lagging in innovative enhancements. This work addressed complementing a clinically employed EM probe with carbonic and circumferentially segmented macrocontacts that are operable both for neurophysiological sensing ("recording") of local field potentials (LFP) and for test stimulation. This paper illustrates in-depth the development that is based on the direct writing of functional materials. The unconventional fabrication processes were optimized on planar geometry and then transferred to the cylindrically thin probe body. We report and discuss the constructive concept and architecture of the probe, characteristics of the electrochemical interface deduced from voltammetry and chronopotentiometry, and the results of in vitro and in vivo recording and pulse stimulation tests. Two- and three-directional macrocontacts were added on probes having shanks of 550 and 770 µm diameters and 10-23 cm lengths. The graphitic material presents a ~2.7 V wide, almost symmetric water electrolysis window, and an ultra-capacitive charge transfer. When tested with clinically relevant 150 µs biphasic current pulses, the interfacial polarization stayed safely away from the water window for pulse amplitudes up to 9 mA (135 µC/cm2). The in vivo experiments on adult rat models confirmed the high-quality sensing of LFPs. Additionally, the in vivo-prevailing increase in the electrode impedance and overpotential are discussed and modeled by an ionic mobility-reducing spongiform structure; this restricted diffusion model gives new applicative insight into the in vivo-uprisen stimulation overpotential.

A polycarboxylic chelating ligand for efficient resin purification of His-tagged proteins expressed in mammalian systems.

We describe the synthesis of a novel polyamino polycarboxylic ligand, its ability to coordinate metal-ions and attachment to a solid support designed for protein purification through Immobilised Metal-ion Affinity Chromatography (IMAC). The resin was found to be highly efficient for purification of His-tagged HCV E2 glycoproteins expressed in 293T mammalian cells.