Zetasizer nano zs apparatus

In order to determine surface charge density of cell membrane, cells were suspended in 0.9 % NaCl and put into the measuring vessel; then, electrophoretic mobility was measured using Zetasizer Nano ZS apparatus (Malvern Instruments). The measurements were carried out as a function of pH.
The surface charge density has been determined using equation σ = ηu/d, where u is the electrophoretic mobility, η is the viscosity of solution, and d is the diffuse layer thickness [16 ].
The diffuse layer thickness was determined from the formula [1 ]: $d=\sqrt{\frac{\mathit{\epsilon }·{\mathit{\epsilon }}_0·R·T}{2·F^2·I}}$ , where R is the gas constant, T is the temperature, F is the Faraday number, I is the ionic strength of 0.9 % NaCl, and εε_o is the permeability electric medium.

Zeta-potential was determined in diluted TiO₂ NP stock dispersions and TiO₂ NP/BSA dispersions (100 and 10 μg/ml) measuring electrophoretic mobility of the particles at 20 °C via laser Doppler velocimetry using a Zetasizer Nano-ZS apparatus (Malvern Instruments Ltd.) and disposable capillary cuvettes (Malvern Instruments Ltd.). Three consecutive measurements were taken of each sample. The number of runs was set automatically. The Smoluchowski approximation was used for calculation.

The synthesized materials were morphologically characterized by high resolution transmission electron microscopy (HR-TEM, Hitachi-HT7700, 120kv, Japan) to investigate the sheet-like morphology of rGO, and the formation of AuNPs and their size and dispersion patterns. A few drops of each sample were allowed to air-dry on a lacy copper grid coated with carbon film for TEM analysis. Graphene structural features were revealed using Raman spectroscopy (Renishaw inVia Raman, Gloucestershire, UK) with a 514 nm argon gas laser. Fourier-transform infrared spectroscopy (FT-IR) analysis was performed to detect functionalization, wherein the sample powder was ground with potassium bromide (KBr) into thin pellets. FT-IR spectra were recorded using a Spectrum 400 (PerkinElmer, Boston, MA, USA). X-ray diffraction patterns (XRD) were recorded using an EMPYREAN diffraction system with X-ray wavelength of 1.54060 Å. UV-Vis spectroscopic measurements were performed using PerkinElmer–Lambda 35 spectrophotometer at a wavelength range of 200–800 nm. Thermo-gravimetric analysis (TGA) was performed using a TGA/SDTA 851 (Mettler Toledo, USA) system with a heating rate of 10°C/min up to 800°C in a nitrogen environment. Dynamic light scattering (DLS) of CAG nanocomposite in cell culture RPMI-1640 medium was analyzed using Zetasizer Nano-ZS apparatus (Malvern Instruments, UK) at 25°C.