Em 400t microscope

Submicron particle size and polydispersity index (PDI) analysis were performed using a Zeta Sizer Nano-ZS90 (Malvern Instrument Ltd., Worcs, England) equipped with a 5 mW solid-state laser with a wavelength of 670 nm. Measurements were performed at 20 ± 0.2 °C at an angle of 90°. The zeta potential (ZP, ξ) was measured by electrophoretic light scattering (ELS) using the same instrument. The measurements were recorded at 25 °C, using three sets of measures up to 100 to achieve an average value. Both analyses were carried out on samples previously diluted with bidistilled water in a 1:10 v:v ratio. Each value was measured at least in triplicate.
Morphological characteristics of LN-ODAF were investigated using TEM (Philips EM 400T microscope, Eindhoven, The Netherlands). TEM samples were prepared by deposition of diluted (100-fold) LN-ODAF formulation onto an aluminum specimen stub covered with a double-sided adhesive carbon disk. After water vaporization, the samples were spray coated with chromium prior to imaging (Quorum Q150T ES East Grinstead, West Sussex, UK).

NLC morphology was evaluated by means of transmission electron microscopy (TEM) (Philips EM 400T microscope, Eindhoven, Netherlands) and field emission scanning electron microscopy (FE-SEM) (LEO 1525 equipped with a GEMINI column, ZEISS, Germany). TEM samples were prepared by deposition of a drop of diluted (100 folds) NLC suspension on the surface of a 200 mesh Formvar^®-coated copper grid (TAAB Laboratories Equipment, Ltd., Aldermaston, England) and letting drop to evaporate at room temperature overnight. To investigate particle internal morphology by FE-SEM, the suspension was lyophilized, then particles were broken up in dry ice and, after CO₂ complete vaporization, re-dispersed in water. Specimens were prepared by deposition of diluted (100 folds) NLC suspension onto an aluminum specimen stub covered with a double sided adhesive carbon disk. After water vaporization at room temperature, samples were sputter coated with chromium prior to imaging (Quorum Q150T ES East Grinstead, West Sussex, United Kingdom). Coating was done at 120 mA for 30 s.