Visible-light-activated photocatalysts based on samarium-doped, europium-doped, and gadolinium-doped nickel aluminates (SmNA, EuNA, GdNA) were synthesized. The spinel crystalline structures of the doped mixed metal oxides were demonstrated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. The presence of the rare-earth metals (REMs) was confirmed by the energy-dispersive X-ray (EDX) studies. Ultraviolet-visible-near-infrared (UV-Vis-NIR) spectra revealed that the REMs-doped catalysts absorb in the full solar spectrum range covering both visible and near infrared wavelengths. Scanning electron microscopy (SEM) visualized the profound morphological alterations of the doped nickel aluminate samples. Consequently, the pore volume and the Brunauer-Emmett-Teller (BET) surface area decreased, while nanoparticles sizes increased. Fourier-transform infrared spectroscopy (FTIR) exposed that surfaces of REMs-doped nickel aluminates are rich in hydroxyl groups. Finally, the photocatalytic performance was notably increased through doping nickel aluminate (NA) with REMs; the highest activity was observed for EuNA.

Pristine nickel aluminate and the one decorated with graphene quantum dots were prepared via a cost-effective co-precipitation method. Both were fully characterized by thermogravimetry (TGA), differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), and UV–Vis techniques. The photocatalytic activity of nickel aluminate under simulated solar light irradiation was demonstrated towards potential pollutants, including a series of dyes (rhodamine B, quinoline yellow, eriochrome black T, methylene blue), toxic phenol and fungicide (thiram). Further profound enhancement of the photocatalytic activity of nickel aluminate was achieved after its decoration with graphene quantum dots. The mechanism of the photocatalytic degradation in the presence of the NiAl₂O₄/graphene quantum dots (GQDs) composite was investigated; hydroxyl radicals were found to play the leading role. This work offers new insight into the application of the conjunction of the inorganic spinel and the carbon nanostructure (i.e., GQDs), but also provides a simple and highly efficient route for potential water remediation from common pollutants, including dyes and colorless harmful substances.

In recent years, many scientists have studied the effects of polymer micro- and nanostructures on living organisms. As it turns out, plastic can be a component of the blood of livestock, eaten by humans around the globe. Thus, it seems important to investigate possible changes in the physicochemical parameters and morphology of the cell membranes of blood morphotic elements (red blood cells and platelets) under the influence of polymer particles. The article presents research in which cell membranes were exposed to plain polystyrene (PS) and amino-functionalized polystyrene (PS-NH₂) of two different sizes. The polymers were characterized by infrared spectroscopy and dynamic light-scattering methods. To analyze possible changes caused by polymer exposure in the structure of the membranes, their zeta potentials were measured using the electrophoretic light-scattering technique. The concentration of the polymers, as well as the exposure time, were also taken into the consideration during the research. Based on the obtained results, we concluded that 100 and 200 nm PS, as well as 100 nm PS-NH₂, internalize into the cells. On the contrary, 200 nm PS-NH₂ particles attach to cell membranes. Our study clearly shows that particle size and surface chemistry determine the interaction with biological membranes.

The main goal of this paper was to develop a biosensor containing three types of structures: graphene oxide (GO), silica nanoparticles (SNs) and gold nanoparticles (GNPs) for effective electrochemical and optical determination of dihydronicotinamide adenine dinucleotide dehydrogenase (NADH). The subsequent steps in biosensor formation, the manner of structure organization and the layer thickness were verified by different methods. Electrochemical oxidation of NADH was performed with the usage of differential pulse voltammetry method (DPV). Results show that obtained biosensor catalyzes the process of NADH electrochemical oxidation. The shift of oxidation potential toward less positive values and the increment of oxidation current were clearly noted. Additionally, the oxidized NAD form was found to exhibit an electrostatic affinity to the top layer of sensor giving a possibility to SPR detection. DPV and SPR signals registered for different amount of NADH were correlated with its concentration into linear relationship: y = 8.6388x − 0.0109; R² = 0.9997 and y = 1305.8x − 74.098; R² = 0.9913, respectively. Enhancement of the electrochemical sensitivity toward NADH, as a result of electrode modification, was proved by lower values of LOD (0.0236 mM) and LOQ (0.0707 mM) in comparison with corresponding parameters calculated for non-modified gold electrode.