Zetasizer 3000

The particle size and zeta potential of each NP sample (0.1 mg/mL) was measured using a Zetasizer 3000 instrument (Malvern Instruments, Malvern, UK) after being stabilized in 150 mM PBS (pH 7.4, 6.5, or 6.0) at 25 °C for 4 h. The morphology of each NP sample was confirmed using a field-emission scanning electron microscopy (FE-SEM, Hitach S-400, Fukuoka, Japan) after being stabilized in 150 mM PBS (pH 7.4, 6.5, or 6.0) at 25 °C for 4 h [32 (link),33 (link),34 (link),35 (link),36 (link),37 (link)].

The RRRRRRRCLPFFD peptide was dissolved in ultra pure Milli Q water at a final concentration of 0.05 mg/ml. The nanodiamonds are added to this peptide solution remaining at a concentration of 0.8 nM in the final solution, and then they are incubated with vigorous stirring for 2 h. The adsorption of the peptide on the nanocrystal surface was evaluated by the change in the Zeta potential (pZ) and hydrodynamic diameter (Dh) (Zeta sizer 3000, Malvern Instruments, UK). The colloidal suspension was centrifuged and washed three times. The washed fNDs were reevaluated by Zp and Dh to ensure that the functionalization remained. Finally, we analyzed the functionalization of the nanodiamond by High Resolution Transmission Electron Microscopy (HR-TEM) staining the samples with phosphotungstic acid (1%) in order to evaluate the presence of the peptide surrounding the nanodiamond.

Electrokinetic potential measurement started with the preparation of 500 ml chromium(III) oxide suspension by adding 0.03 g of solid to the solution containing 0.01 M supporting electrolyte (NaCl) and appropriate EPS amount giving its final concentration of 0.1, 1, 10 or 50 ppm. After 3-min sonication suspensions were poured into five Erlenmeyer flasks and their pH values were adjusted to 3, 4.6, 6, 7.6 and 9 ± 0.05. Then the zeta potential was measured using Zetasizer 3000 (Malvern Instruments); the apparatus was washed twice before each measurement. One result was the average of five measurements. The measurement error did not exceed 5 %.
In the same way, the zeta potential of chromium(III) oxide particles in the supporting electrolyte solution (0.01 M NaCl) without the bacterial polymer was measured.

AuNRs and AuNPrs were characterized before and after BSA-r₈ coating by UV-Vis-NIR absorption spectra, using a Lambda 25 spectrophotometer (Perkin Elmer, Waltham, MA, USA). Dynamic light scattering (DLS) and Z potential measurements were acquired in PBS pH = 7, at 25 °C, using a Zetasizer 3000 (Malvern Instruments, Malvern, UK), as triplicates in aqueous solution at 25 °C.
TEM images of AuNRs were acquired with a JEOL JEM-1010 microscope (JEOL USA, Peabody, MA, USA), using Formvar carbon-coated copper microgrids (200 mesh; Ted Pella, Redding, CA, USA). For AuNPrs, TEM images were obtained using a Philips CM 120 transmission electron microscope with an accelerating voltage of 120 kV and a 300 mesh Formvar/Carbon-Coated Copper grid. For both AuNPs, liquid suspensions were deposited on the microgrid and allowed to stand overnight before TEM image acquisition.

The hydrodynamic diameter (HD) and size distribution of the nanogels at a concentration of 10 mg/mL were determined in a Zetasizer 3000 (Malvern Instruments, Worcestershire, UK) with a scattering angle of 173°.

The Zeta-potential measurements on PECNP dispersions in order to determine the net charge of PECNP were performed at neutral pH values (pH = 7.4) using a Zetasizer 3000 (Malvern Instruments Ltd., Worchestershire, UK).

Particle morphology of FA-DDP/PTX NLCs was observed by a Transmission Electron Microscope (TEM, Hitachi, Tokyo, Japan). Diluted FA-DDP/PTX NLCs were placed on a carbon-coated copper grid, negatively stained with 2% phosphotungstic acid, and then observed with TEM.
The mean particle size, polydispersity index (PDI), and zeta potential were analyzed by photon correlation spectroscopy (PCS), with a Zetasizer 3000 (Malvern Instruments, Malvern, England). The average particle size was expressed as volume mean diameter (Wang et al., 2012 ).