Nanobrook 90plus pals

To determine the size and surface charge, nanoparticle suspension was added to a transparent cuvette and was then inserted into the ZetaPALS dynamic light scattering (DLS) detector (NanoBrook 90Plus PALS, Brookhaven Instruments, Holtsville, NY) as previously described (36 (link)). Scanning electron microscopy (SEM, Hitachi S-3000N, Hitachi, Pleasanton, CA) was used to visualize the morphology of nanoparticles. Briefly, 50 μl of the nanoparticle suspension air-dried on a coverslip was silver sputter-coated and inserted into the SEM instrument. To determine the in vitro stability, nanoparticles were suspended in saline (0.9% Sodium Chloride, NaCl, Crystalline, Fisher Scientific, Hampton, NH, USA) or Vasculife VEGF basal cell media with 10% Fetal Bovine Serum (LL-0003, Lifeline Cell Technologies) and incubated at 37°C for 48 h. Particle size was measured on predetermined time points using DLS as described earlier. The stability of the nanoparticles was represented as the percentage change of nanoparticle size measured at each time point with respect to initial particle size according to the following equation:

A NanoBrook 90plus PALS (Brookhaven Instruments Corporation, USA) particle size analyzer was used to measure nanoemulsion droplet sizes and polydispersity index (PDI). Hydrodynamic droplet size was analyzed by dynamic light scattering. Samples were diluted to approximately 0.001 volume fraction. The dilution was performed to eliminate multiple scattering effects arising from components other than the nanodroplets and their inherent effects on the continuous phase viscosity.

Particle size distribution and zeta-potential of the PG solutions (1 mg/mL) were measured using a NanoBrook 90Plus PALS instrument (Brookhaven Instruments, Holtsville, NY, USA) and analyzed by Particle Solutions v.3.6.07122 (Holtsville, NY, USA).

The surface charge and average particle size was measured at 25 °C using a NanoBrook 90 Plus PALS (Brookhaven Instruments, USA).

The preliminary assessment of the particle size and size distribution was carried out by dynamic light scattering (DLS) measurements on a NanoBrook 90 Plus PALS instrument (Brookhaven Instruments Corporation), equipped with a 35 mW red diode laser (λ = 660 nm) at a scattering angle of 90 °. The measurements were taken at 25 °C and 37 °C applying a dust cut-off of 30 micellar dispersions at concentrations of 1 mg·mL⁻¹ and fixed volumes of 1.7 mL.
The apparent hydrodynamic radii (R_h⁹⁰) were determined according to the Stokes–Einstein equation:
where k is the Boltzmann constant, η is the solvent viscosity at temperature T in Kelvin and D₉₀ is the diffusion coefficient measured at an angle of 90°. Each measurement was performed in triplicate.
The electrophoretic light scattering measurements were carried out on the same instrument at a scattering angle of 15° and 25 °C and 37 °C. The principle of phase analysis light scattering (PALS) was applied for the measurements of electrophoretic mobility. The ζ potentials were calculated using the Smoluchowski equation:
where η is the solvent viscosity, υ is the electrophoretic mobility, and ε is the dielectric constant of the solvent.

The freeze-dried Ng liposomes were dissolved in PBS for analysis. Before use, the samples were obtained by extruding the solution through a .22 μm microporous membrane three times at 25°C. The particle size distribution of the sample was determined using dynamic light scattering (DLS) via a particle size analyzer (NanoBrook 90plus PALS; Brookhaven Instruments Corporation, Holtsville, NY, United States) at 25°C, and the intensity was detected at 90°. The PDI and zeta potential of the freeze-dried Ng liposomes were determined using the same instrument. All measurements were averaged using at least three replicates, and Brookhaven software was used for the analysis.