Solvent-structured PEDOT:PSS surfaces: fabrication strategies and nanoscale properties

We present the preparation of nanostructured conducting PEDOT:PSS thin films by solvent vapor annealing (SVA), using the low boiling point solvent tetrahydrofuran (THF). An Atomic Force Microscopy (AFM) study allowed the observation of distinct nanostructure development as a function of solvent exposure time. Moreover, the nanostructures’ physical properties were evaluated by nanomechanical, nanoelectrical, and nano-FTIR measurements. In this way, we were able to differentiate the local response of the developed phases and to identify their chemical nature. The combination of these techniques allowed to demonstrate that exposure to THF is a facile method to effectively and selectively modify the surface nanostructure of PEDOT:PSS, and thereafter its final properties. Moreover, our nanoscale studies provided evidence about the molecular rearrangements that PEDOT:PSS suffers during nanostructure fabrication, a fundamental fact in order to expand the potential applications of this polymer in thermoelectric and optoelectronic devices.

Tellurium-Incorporated Nickel-Cobalt Layered Double Hydroxide and Its Oxygen Evolution Reaction

Transition-metal-based layered double hydroxides (LDHs) have attracted substantial attention as highly efficient oxygen evolution reaction (OER) catalysts because they are earth-abundant, low-cost, and environmentally friendly materials with favorable adsorption/desorption energies for intermittent reactants. However, the application of these LDHs as high-performance electrocatalysts is often hindered by their relatively sluggish electronic transport kinetics resulting from their intrinsically low conductivity. Here, we report the effects of incorporating a metalloid into transition metal LDHs on their electrocatalytic activity. In this study, Te-incorporated NiCo LDH (χTe-NiCo LDH) was grown on a three-dimensional porous nickel foam (NF) using a facile solvothermal method with χ = 0.2, 0.4, 0.6 and 0.8. The crystal structure and surface nanostructure were investigated by X-ray diffraction and field-emission scanning electron microscopy. A homogeneous nanosheet structure on the NF was clearly observed for the NiCo LDH and χTe-NiCo (χ = 0.2, 0.4, 0.6) LDHs. However, irregular and collapsed nanostructures were found on the surface of the NF when the Te precursor ratio (χ) exceeded 0.6. The electrocatalytic OER properties were analyzed by linear sweep voltammetry and electrochemical impedance spectroscopy. The amount of Te used in the electrocatalytic reaction was found to play a crucial role in improving the catalytic activity. The optimum Te amount (χ) introduced into the NiCo LDH is discussed with respect to the OER performance.

Micro-/Nano-Structured Ceramic Scaffolds That Mimic Natural Cancellous Bone

Micro-/nano-structured scaffolds with a weight composition of 46.6% α-tricalcium phosphate (α-TCP)—53.4% silicocarnotite (SC) were synthesized by the polymer replica method. The scanning electron microscopy (SEM) analysis of the scaffolds and natural cancellous bone was performed for comparison purposes. Scaffolds were obtained at three cooling rates via the eutectoid temperature (50 °C/h, 16.5 °C/h, 5.5 °C/h), which allowed the surface nanostructure and mechanical strength to be controlled. Surface nanostructures were characterized by transmission electron microscopy (TEM) and Raman analysis. Both phases α-TCP and SC present in the scaffolds were well-identified, looked compact and dense, and had neither porosities nor cracks. The non-cytotoxic effect was evaluated in vitro by the proliferation ability of adult human mesenchymal stem cells (ah-MSCs) seeded on scaffold surfaces. There was no evidence for cytotoxicity and the number of cells increased with culture time. A dense cell-hydroxyapatite layer formed until 28 days. The SEM analysis suggested cell-mediated extracellular matrix formation. Finally, scaffolds were functionalized with the alkaline phosphatase enzyme (ALP) to achieve biological functionalization. The ALP was successfully grafted onto scaffolds, whose enzymatic activity was maintained. Scaffolds mimicked the micro-/nano-structure and chemical composition of natural cancellous bone by considering cell biology and biomolecule functionalization.

Diagnostics possibilities of erythrocytes analysis by the method of laser interference microscopy

The morphofunctional state of erythrocytes significantly changes by the onset and progression of various diseases, as well as in critical conditions, injuries, accompanied by severe tissue damage. This leads to a violation of microcirculation and has an effect on hemorheology in general. In connection with this, there is a need for the development of adequate methods for assessing the functional activity of erythrocytes. The aim of the work was to study the possibilities of laser interference microscopy in the analysis of the functional state of erythrocytes. The results allowed us to quantify the state of the phase height and phase diameter of erythrocytes. Analysis of the surface nanostructure gave a qualitative assessment of the functional activity of cells. The following patterns were revealed: the action of adrenaline causes the appearance of echinocytes with an increase in phase height and decrease phase diameter and the appearance of spicules on the surface of cells. The action of cortisol leads to a decrease in the phase height and the phase diameter with the appearance of numerous loosening of the structure of the cell surface. Moreover, the traditional method of analyzing the distribution of erythrocytes in a population by morphology (discocytes, stomatocytes, and degeneratively altered cell forms) did not reveal statistically significant differences. Thus, the results indicate that the interference microscopy method allows a qualitative assessment of the morphofunctional activity of native cells. This increases the information content of the analysis and leads to the objectification of data on the functional capabilities of erythrocytes.

Nano-surface Monocrystalline BiVO4 Nanoplate Photoanode for Enhanced Photoelectrochemical Performance

The single-crystal BiVO4 photoanode with surface nanostructure is prepared by a low-cost and simple etching process. As a result, the modified photoanode shows a higher photocurrent density and a lower...