Model fp 6500

The phase composition of the prepared materials was studied by X-ray diffraction (XRD) using diffractograms collected by PANalytical X'Pert Pro diffractometer with CuKα source (λ = 1.5406 Å). The morphology of the 0.1% Ag/TiO₂-1% rGO photo-composite was investigated by high-resolution TEM model JEM 2100-HRTEM (JEOL, USA, Inc.) operated at an accelerating voltage of 200 kV. Raman spectra were acquired using a WITec Alpha 300 RA confocal Raman microscope (WITec GmbH, Ulm, Germany). The ultra violet-visible light (UV–Vis) diffuse reflectance spectra (DRS) were measured by a spectrometer (JASCO, Model V730, Japan) equipped with diffuse reflectance accessories, using BaSO₄ as the reference sample,) and the photoluminescence (PL) was determined by spectrofluorometer (JASCO, Model FP-6500, Japan) at excitation wavelength 315 nm. The light source was a Xenon arc lamp (150 Watt).

Fluorescence measurements were carried out using a Cytation3® microplate reader (Bio-Tek Instruments, Winooski, USA), controlled by the Gen5 (Bio-Tek Instruments) software. Solutions were placed in 96-well microplates, suitable for fluorescence measurements (black, opaque wells, ref. 10588885, Thermo Fisher Scientific, Massachusetts, USA). The excitation wavelength was set to 484 nm while the emission wavelength was 520 nm.
The final volume of the reaction mixture was set to 260 μL and the assay procedure comprised the sequential addition of 160 μL of phosphate buffer solution (5 mM, pH 7.0), 80 μL of zinc(II) standard solution, and 20 μL of FluoZin-1 solution to each well. For sample analysis, the protocol was adapted, comprising the addition of 160 μL of water, 80 μL of zinc(II) standard solution or diluted sample digest, and 20 μL of FluoZin-1 prepared in phosphate buffer solution. Control experiments were performed by replacing each solution by their respective solvent.
A conventional fluorimeter (Model FP-6500, JASCO, Easton, USA) was applied to evaluate the excitation and emission spectra in initial studies.