We present electrochemical and chemical synthesis of platinum black at room temperature in aqueous and non-aqueous media. X-ray analysis established the purity and crystalline nature. The electron micrographs indicate that the nanostructures consist of platinum crystals that interconnect to form porous assemblies. Additionally, the electron micrographs of the platinum black thin layer, which was electrochemically deposited on different metallic and semiconductive substrates (aluminium, platinum, silver, gold, tin-cooper alloy, indium-tin-oxide, stainless steel, and copper), indicate that the substrate influences its porous features but not its absorbance characteristics. The platinum black exhibited a broad absorbance and low reflectance in the ultraviolet, visible, and infrared regions. These characteristics make this material suitable for use as a high-temperature resistant absorber layer for the fabrication of microelectronics.

We report a nanoparticulate composite TiO₂–BaTiO₃ film which exhibits an increased antibacterial photocatalytic activity under visible light. The pure BaTiO₃, TiO₂ or their mixture do not attain a significant photocatalytic capacity under visible light. However, when these oxides are simultaneously synthesized under controlled conditions the resulting crystals exhibit a high catalytic effect. The effect of this material on microorganism lysis is studied and the mechanisms for the observed damage are investigated. Attenuated total reflection Fourier transform infrared spectroscopy provides the evidence of chemical changes (formation of carbonyl and carboxylic groups) in the cell membranes under visible light by TiO₂–BaTiO₃ but not by TiO₂. Cyclic voltammetry demonstrates that peroxidation occurs in the absence of UV light and in the presence of TiO₂–BaTiO₃ but not in the presence of TiO₂ alone. Atomic force microscopy reveals the morphological changes of the cells in this process.

Porous platinum is a frequently used catalyst material in electrosynthesis and a robust broadband absorber in thermoelectrics. Pore size distribution and localization determine its properties by a large extent. However, the pore formation mechanism during the growth of the material remains unclear. In this work we elucidate the mechanism underlying electrochemical growth of nanoporous platinum layers and its control by ionic concentration and current density during electrolysis. The electrode kinetics and reduction steps of PtCl₄on platinum electrodes are investigated by cyclic voltammetry and impedance measurements. Cyclic voltammograms show three reduction steps: two steps relate to the platinum cation reduction, and one step relates to the hydrogen reduction. Hydrogen is not involved in the reduction of PtCl₄, however it enables the formation of nanopores in the layers. These findings contribute to the understanding of electrochemical growth of nanoporous platinum layers in isopropanol with thickness of 100 nm to 500 nm.

In this study, we describe the design of new ratiometric fluorescent nanosensors, whose architecture is based on a gold core surrounded by a poly(vinyl alcohol)-polyacetal shell. To the gold core, indicator dyes and reference dyes are attached via a cysteine linker. This nanosensor architecture is flexible with regards to the number and types of fluorophore linkages possible. The robust poly(vinyl alcohol)-polyacetal shell protects the fluorophores linked to the core from non-specific interactions with intracellular proteins. The nanosensors developed in this way are biocompatible and can be easily incorporated into mammalian cells without the use of transfection agents. Here, we show the application of these nanosensors for intracellular pH and sodium ion measurements.