Zetasizer

The zeta potential of the formulations was determined by Doppler velocimetry and PCS on a Zetasizer 4 (Malvern Instruments, U.K.), without further dilution. The zeta potential of LC-AmB under these conditions was —44 mV, slightly lower than that measured for the same lipid composition without AmB, —55 mV, but remaining consistent with colloidal stability. This reduction in the absolute value of the zeta potential could be due to the presence of AmB at the surface, because free AmB dispersed in water under the same conditions had a less negative zeta potential about —27 mV. 

Photon correlation spectroscopy (PCS) for size measurement was performed using a Zetasizer HS3000 (Malvern, Herrenberg, Germany). Samples were diluted until a count rate of 50 to 250 kilocounts was achieved. 

The content of vaccine within the small liposomes is estimated as in the section Estimation of Vaccine Entrapment in Dehydration-Rehydration Vesicles Liposomes for both microfluidized and sucrose liposomes and expressed as percentage of DNA and/or protein in the mixture subjected to freeze drying as in the section Preparation of Vaccine-Containing Small Liposomes by the Sucrose Method in the case of sucrose small liposomes or in the original DRV preparation (obtained in the section Estimation of Vaccine Entrapment in DRV Liposomes ) for microfluidized liposomes. Vesicle size measurements are carried out by PCS as described elsewhere (6,8,17). Liposomes can also be subjected to microelectrophoresis in a Zetasizer to determine their zeta potential. This is often required to determine the net surface charge of DNA-containing cationic liposomes. 

The amount of polymer adsorbed on each sample was measured by pressure filtration through a 0.1 m filter, followed by analysis of the filtrate for residual polymer by gel permeation chromatography with refractive index determination. Particle zeta potentials were measured by taking a small sample of the solids from the centrifuge and re-suspending them in the supernatant prior to analysis in a Malvern Instruments Zetasizer . The concentration of all other types of ions in the supernatant was analysed by ICP atomic emission spectroscopy. 

The Mg-Al-C03-LDH used as adsorbent and sorbent was prepared with an Mg Al ratio of 2 1 by the coprecipitation method at variable pH [6], The material obtained was characterised by powder X-ray diffraction (PXRD, using a Siemens D-5005 X-ray diffractometer), and elemental and thermal analyses. The material showed the characteristic lamellar structure with a basal spacing of 7.6 A, specific surface area of 87.1 m2 g 1, determined by the N2-BET adsorption isotherm, and an approximate minimum molecular formula [Mg, MAt, (oh) m ](CO, ) 5 2.3 i(h2o) The size distribution and the average size of the LDH particles were determined by light scattering, using a Zetasizer 4 from Malvern. 

Figure 2 Zeta potential of DNA-protamine sulfate complexes. Plasmid DNA was condensed with protamine sulfate in increasing ratios (w/w). The surface charge (zeta-potential) was determined using a Nicomp 380 ZLS Zetasizer (Particle Sizing Systems, Santa Barbara, CA).

Malvern Zetasizer nano zs uses non-invasive back-scatter technology to measure particles in the 0.6 nm to 6 pm size range together with molecular weight and zeta potential measurements. 

Determine liposome size and size distribution by photon correlation spectroscopy (PCS) using a Zetasizer 3000HS. 

Correlate the raw data to Z average mean size using a cumulative analysis by the Zetasizer 3000HS software package. 

Determine the zeta potential of liposomes by Laser Doppler Anemometry, using the Zetasizer 3000HS. 

For surface charge determination, ARSL dispersions are diluted with filtered PBS pH 7.40 and their electrophoretic mobility is measured at 25°C by Photon Correlation Spectroscopy [PCS] (Zetasizer 5000, Malvern Instruments, UK). Finally, the zeta potential values of the dispersions are calculated by the instrument from their electrophoretic mobility, by application of the Smolowkovski equation. 

Particle size, polydispersity index, and zeta potential measurements of mannosylated liposomes are determined by Zetasizer nano ZS-90. 

Particle size and 1 -potential of liposomes diluted with PBS were measured by the use of a Zetasizer Nano ZS (MALVERN, Worcestershire UK, USA). 

Size or charge characterization equipment such as Zetasizer (Malvern). 

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