Zetasizer nano zs device

A liquid LB medium (Biocorp) was inoculated with bacterial strains and incubated for 24 h at 37 °C with continuous shaking (160 rpm). Grown cultures were washed with phosphate saline buffer PBS (pH 7.4) in triplicate to discard medium residues. Washed cells were resuspended in PBS to obtain density equal 0.5 McFarland standard. Zetasizer Nano ZS device equipped with DTS1070 cuvettes (Malvern Instrument, Malvern, UK) was used for measuring the zeta potential (ζ), which is determined from electrophoretic mobility (μ) based on Smoluchowski’s formula.

All the chemicals used were purchased from Sigma Aldrich. SPIONs of average size of 12 nm were synthesized by thermal decomposition method.^{7,26,27 (link)} Briefly, iron(iii) acetylacetonate was added to oleic acid and benzyl ether and heated under nitrogen purging to 110 °C, in order to remove moisture. The temperature was later increased to 160 °C, to initiate nucleation. The reaction was maintained at 280 °C with reflux, to promote growth of the SPIONs. The size of the as-synthesized SPIONs were characterized using transmission electron microscope (TEM, JEOL 100CX). The magnetization properties of the SPIONs were characterized using vibrating sample magnetometer (VSM, Lake Shore Model 7407). The crystal phase and purity of the sample was studied using X-ray diffractometer (XRD, Bruker D8 Advanced Diffractometer System) with Cu Kα (1.5418 Å) source. The as-synthesized hydrophobic SPIONs were stabilized using surfactant cetyltrimethyl ammonium bromide (CTAB) and used in our studies. Dynamic light scattering (DLS) and zeta-potential measurements were performed in a Malvern Zetasizer Nano-ZS device to determine the hydrodynamic size and zeta-potential of CTAB-SPIONs in a colloidal suspension.

The surface zeta potential data were obtained from a Zetasizer Nano ZS device (Malvern Instruments). X-ray diffraction (XRD) data were recorded using a Bruker Advanced D8 (Bruker Corp., Germany) instrument. Fourier transform infrared (FTIR) spectra were recorded by a Nicolet Nexus 470 instrument (Nicolet Instrument Corp., USA). X-ray photoelectron spectra (XPS) were analyzed by an ESCALAB 250 XPS instrument. Nitrogen (N₂) adsorption–desorption were determined by a Tristar 3000 analyzer. Transmission electron microscopy (TEM) images were taken using a JEM-2100F microscope (JEOL, Japan). UV-VIS-NIR absorption spectra were measured by a Cary 5000 spectrophotometer. Electrochemical impedance spectra (EIS) and photocurrent response curves were obtained through a CHI660C electrochemical workstation. Electron spin resonance (ESR) spectra were recorded by a Bruker model A300 spectrometer at room temperature. Phosphorescence spectra were tested on a Hitachi F-4600 spectrometer under an excitation wavelength of 808 nm.

The DLS technique was used to determine the mean hydrodynamic diameter (D_h), polydispersity index (PDI), and zeta potential (ZP) of the synthesised microparticles. Determinations were performed using the Zetasizer Nano ZS device from Malvern Panalytical, Worcestershire, UK. equipped with a 633 nm wavelength red laser (He/Ne). The system uses a non-invasive back scattering technology, NIBST, in order to reduce the multiple scanning effects. Briefly, 2 mL of 0.25% w/v microparticle solution in water and 2 mL of 2% w/v NRF solution in DMSO were analysed in the whole measurement range (0.6 nm to 6 μm) using the Mie methods. The hydrodynamic diameter (D_h) was calculated by using the following Equation (1): $${\mathrm{D}}_{\mathrm{h}}=\frac{\mathrm{kT}}{3\mathsf{\pi }\mathsf{\eta }\mathrm{D}},$$
where D_h is the hydrodynamic diameter, k—Boltzmann constant, T—temperature, η—viscosity, and D—diffusion coefficient.
Zeta potential was determined on the same apparatus using the Smoluchowski relationship (2): $$\mathsf{\zeta }=\frac{\mathsf{\eta }\mathsf{\mu }}{\mathsf{\epsilon }},$$
with η—viscosity, electrophoretic mobility—noted μ and ε, which represent the dielectric constant of the medium. All the data are expressed as a mean ± standard deviation (SD).

Dispersion characteristics of suspensions were evaluated by visual inspection, particle size measurements, and zeta potential analysis. The nanoparticle suspension stability was measured for 30 min using Turbiscan LabExpert (Formulaction, Toulouse, France). Samples were loaded into cylinder glass tubes (Formulaction, Toulouse, France) and analyzed for 30 min for the entire length of the holder. Particle size and zeta potential measurements were conducted using a Zetasizer Nano ZS device (Malvern Panalytical Ltd, Malvern, UK). The particle concentration to perform the measurements was under 25 mg/mL. The mean dimension of clusters of PG/W-based ZnO nanofluids was estimated utilizing dynamic light scattering (DLS), repeating each measurement three times for each sample.