2.2. Nanoparticle Characterization

The NP characteristics were analyzed using transmission and scanning electron microscopy (TEM and SEM), and the hydrodynamic size and zeta potential were quantified.

The NPs were dispersed in distilled water and small drops were added consecutively on top of a pure carbon film copper grid (Ted Pella, Inc., Redding, CA, USA). Each time, the excess was carefully removed using filter paper. The sample was analyzed in bright field mode using a Tecnai F20 G2 TWIN Cryo-TEM (FEI, Hillsboro, OR, USA) at an acceleration voltage of 200 kV, and subjected to energy-dispersive X-ray spectroscopy (EDXS) (Oxford Instruments, Abingdon, UK).

SEM investigations were performed on Zeiss Auriga microscope (Carl Zeiss, Jena, Germany). Images were acquired at a voltage of 2 kV and contrast-enhanced for better observation. The samples were analyzed using the D8 Discover X-ray diffractometer (Bruker AXS, Karlsruhe, Germany), Cu-anode X-ray tube (40 kV, 40 mA) (Bruker AXS, Karlsruhe, Germany) and LYNX EYE detector (Bruker AXS, Karlsruhe, Germany). The crystallite size was calculated using the Debye–Scherer formula.

The hydrodynamic size and zeta potential of NPs (100 µg/mL) suspended in ultrapure Milli-Q water was assessed by dynamic light scattering (DLS) and electrophoretic light scattering (ELS), respectively, using a Malvern Nano-ZS instrument (Malvern Instruments, Malvern, Worcestershire, UK). The measurements were performed in triplicate at 25 °C.