Zetasizer pro red label

Dynamic light scattering was used to determine the hydrodynamic diameter and zeta potential of empty and natamycin-loaded transethosomes and LNPs. Measurements were performed with a Malvern Zetasizer Pro Red Label (Malvern, Worcestershire, UK), with backscatter collection angle (173°) and keeping the temperature at 25 °C. The reported values for size and zeta potential are the means of three experiments performed on each sample.

The morphology of standardized PEA-LNPs was observed using scanning electron microscopy (SEM, Nova NanoSEM 450, Fei, Eindhoven, The Netherlands) with a TDL detector. Particle suspension was dropped on an aluminum stub, and after drying, coated with carbon under vacuum conditions (Carbon Coater, Balzers CED-010, Oerlikon Balzers, Balzers, Liechtenstein).
Size, polydispersity index (PDI), and surface charge (Z-potential) were measured by light scattering using Zetasizer PRO—Red Label (Malvern Panalytical, Worcs, UK) equipped with a 10 mW He-Ne laser (632.8 nm) and ZS Xplorer software (version n. 3.1.0.64).

Zeta potential (ζ)
measurements were performed with a Zetasizer Pro Red Label (Malvern).
LUVs were covesiculated with 5 μM of each AM at a total lipid
concentration of 1 mg/mL. About 600 μL of each LUV sample was
diluted to obtain a total lipid concentration of 0.25 mg/mL, with
phosphate buffer, 5.57 mM ionic strength, pH 7, 20 °C, and put
in a disposable folded capillary cell (polycarbonate, Malvern). Each
ζ potential value is the average of three independent runs;
for each temperature, the ζ potential was determined as the
mean of 5–8 measurements. The reported error is the standard
deviation of the measurements. The measurements were performed in
the range 10–60 °C, every 2 °C (except every 1 °C
in the range 38–50 °C for ENT-03 containing LUVs, to better
appreciate the transition). The electrophoretic mobility measurements
were converted into ζ values according to the Smoluchowsky model.⁴¹ The temperature was internally controlled (accuracy
±0.1 °C). The ζ potential measurements were also used
to determine the transition temperature (T_m) in LUV systems.^{42 (link)} The T_m values were determined by analyzing the first-order
derivative of ζ with respect to temperature (dζ/dT) as a function of temperature: the T_m corresponds to the minimum of the curve, while the amplitude
of the transition was assumed to correspond to the full width at half
maximum (FWHM) of the derivative curves.