H₂O Dissociation-Induced Aluminum Oxide Growth on Oxidized Al(111) Surfaces

Ultrasensitive electrochemical determination of the cancer biomarker protein sPD-L1 based on a BMS-8-modified gold electrode

This work describes the modification of a gold electrode with the BMS-8 compound that interacts with the Programmed Death-Ligand 1 (PD-L1), an immune checkpoint protein. The results show that we can confirm the presence of the sPD-L1 in the concentration range of 10^-18 to 10^-8 M using electrochemical impedance spectroscopy (EIS) with a limit of detection (LOD) of 1.87 × 10^-14 M for PD-L1 (S/N = 3.3) and at a concentration of 10^-14 M via cyclic voltammetry (CV). Additionally, high-resolution X-ray photoelectron spectroscopy (XPS), contact angle, and surface free energy measurements were applied to confirm the functionalization of the electrode. We investigated the selectivity of the electrode for other proteins: Programmed Death-1 (PD-1), cluster of differentiation 160 (CD160), and B- and T-lymphocyte attenuator (BTLA) at concentrations of 10^-8 M. Differentiation between PD-L1 and PD-1 was achieved based on the analysis of the capacitance effect frequency dispersion at the surface of the modified Au electrode with BMS-8 after incubation at various concentrations of PD-L1 and PD-1 proteins in the range of 10^-18 to 10^-8 M. Significant differences were observed in the heterogeneity of PD-L1 and PD-1. The results of the quasi-capacitance studies demonstrate that BMS-8 strongly and specifically interacts with the PD-L1 protein.

Evolution of Temperature-Driven Interfacial Wettability and Surface Energy Properties on Hierarchically Structured Porous Superhydrophobic Pseudoboehmite Thin Films

Interaction of water on heterogeneous nonwetting interfaces has fascinated researchers' attention for wider applications. Herein, we report the evolution of hierarchical micro-/nanostructures on superhydrophobic pseudoboehmite surfaces created from amorphous Al₂O₃ films and unraveled their temperature-driven wettability and surface energy properties. The influence of hot water immersion temperature on the dissolution-reprecipitation mechanism and the surface geometry of the Al₂O₃ film have been extensively analyzed, which helped in attaining the optimal Cassie-Baxter state. The evolution of pseudoboehmite films has been structurally characterized using grazing incidence X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Interfacial surface energy components on the structured superhydrophobic surface exhibited a very low surface energy of ∼4.6 mN/m at room temperature and ultrahigh water contact angle >175°. The interaction between water droplets on the nonwetting surface was comprehended and correlated to the temperature-dependent surface energy properties. The surface energy and wettability of the structured pseudoboehmite superhydrophobic surface exhibited an inverse behavior as a function of temperature. Interestingly, the superhydrophobic surface exhibited "Leidenfrost effect" below the boiling point of water (67 °C), which is further correlated with the intermolecular forces, interfacial water molecules and surface-terminated groups. These high-temperature wetting transition studies could be potentially valuable for solid-liquid systems working at nonambient temperatures, and also this approach can pave new pathways for better understanding of the solid/liquid interfacial interactions on nanoengineered superhydrophobic surfaces.

Influence of p-n junction mechanism and alumina overlayer on the photocatalytic performance of TiO2 nanotubes

Modified hybrid structures of TiO₂ nanotubes (TONT), p-Al doped TONT/n-TONT with an additional overlayer of alumina, are constructed to achieve 99.57% photodegradation of the stable organic pollutant methylene blue (MB) within 180 min, a degradation rate 17 times higher than pure TONTs. The anodization at three different temperatures 2, 28 and 40 °C followed by impregnation of Al is used for their preparation. The analyses of structure, chemical composition and morphology are completed using x-ray diffraction, x-ray photoelectron spectroscopy (XPS) and high resolution transmission microscopy, respectively, Rutherford back scattering and field emission scanning electron microscopy confirm the formation of the hybrid structure. This structure exhibits the highest photodegradation rate with TONT based catalysts to date for MB blue, by enhancing the electron-hole separation, the absorption of visible photons and the adsorption sites for the pollutant. The optical data coupled with valence band XPS is used for elucidating the energy band structure of the p-n junctions and to gain insight into the effect of the junction mechanism on photoactivity. The rectification ratios of the impregnated p-n junctions, determined by current-voltage measurements, are found to vary from 10² to 10⁶.

Effect of cobalt addition on the corrosion behavior of near equiatomic NiTi shape memory alloy in normal saline solution: electrochemical and XPS studies

The electrochemical and corrosion (uniform and localized) behavior of a binary Ni₅₂Ti₄₈ shape memory alloy (SMA) and two ternary Ni₅₂Ti_48−xCo_x (x = 1.5 and 4.0 wt%) SMAs were studied. Measurements were conducted in 0.9% NaCl solution at 37 °C employing various electrochemical methods. These include: linear polarization resistance (LPR), linear sweep voltammetry (LSV), chronoamperometry and dynamic electrochemical impedance spectroscopy (DEIS). Such measurements were complemented with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. Results revealed that the addition of alloyed Co to NiTi significantly reduced the uniform corrosion rate of the studied SMA and greatly enhanced its pitting corrosion resistance. XPS measurements evidenced high stability of the passive layer and limited adsorption of chloride ions. Additionally, it was found that the passive layer remained primarily composed of titanium oxides. Microstructure changes accompanying the addition of Co were also used to account for its role in improving the corrosion resistance of these materials.

The electrochemical and corrosion (uniform and localized) behavior of a binary Ni₅₂Ti₄₈ shape memory alloy (SMA) and two ternary Ni₅₂Ti_48−xCo_x (x = 1.5 and 4.0 wt%) SMAs were studied.

Wettability and drag reduction of a superhydrophobic aluminum surface

The friction drag versus the velocity of the water flowing over surfaces with different adhesion properties.