Microsoft word - mrk575-01 size and zeta potential characterisation of lipo.

Size and zeta potential characterisation of anionic and cationic liposomes on the Zetasizer Nano Introduction
predict the fate of the liposomes in cell containing the particle dispersion. oil soluble materials in the lipid bilayer specific applications through control of the lipid composition or modification of Experimental
Liposome Preparation
scattering (DLS). This technique measures the time-dependent fluctuations in the intensity of Table 1: Weights of DPPC and DPPG used in the preparation of a series of
anionic liposomes in phosphate buffered saline (PBS) DPPC (mg)
DPPG (mg)
DPPG (mole %)
motion. Analysis of these intensity fluctuations enables the determination of the diffusion coefficients of the particles which are converted into a overall charge that the particle acquires in a particular medium. Zetasizer Nano application note MRK575-01 Liposome Characterisation
All sizing and zeta potential
Table 2: Weights of DPPC, cholesterol and DDAB used in the preparation of a
series of cationic liposomes in phosphate buffered saline (PBS). Zetasizer Nano ZS at 25°C. Sizing measurements were made on the DPPC (mg)
Cholesterol
DDAB (mg)
PBS for the zeta potential measurements. The Nano ZS (NIBS™) optics for sizing measurements. The detection angle of 173°enables size measurements of concentrated, turbid samples to be Table 3: The z-average diameters in nm, polydispersity index values and zeta
potentials in mV of various anionic liposomes prepared in PBS. The standard deviation values from the repeat measurements are shown in brackets. laser beam needs to penetrate the sample and as a consequence, the Mole % DPPG
z-Average
Polydispersity
Zeta Potential
Diameter in nm
in mV (SD)
Anionic Liposomes
The results of the particle sizing and zeta potential measurements of the summarised in table 3. This table shows the z-average diameters (the mean diameters based upon the intensity of scattered light), the polydispersity index (an estimate of the width of the distribution) and the mean zeta potential values obtained for the various liposome samples. The z-average diameter values are the means of 3 repeat measurements (standard deviations in brackets) made on the neat liposome samples. The zeta potential values are the means of 5 repeat measurements (standard deviations in brackets) made on diluted samples (1 in 10 with PBS). Figure 1: Zeta potential and size values obtained as a function of the mole%
DPPG content for a series of anionic liposomes.
Zetasizer Nano application note MRK575-01 The sizing results obtained for these anionic liposome preparations show Table 4: The z-average diameters in nm, polydispersity index values and zeta
potentials in mV of various cationic liposomes prepared in PBS. The standard deviation values from the repeat measurements are shown in brackets. z-Average
Polydispersity
Zeta Potential
plotted in figure 1 as a function of the Mole % DDAB
Diameter in nm
in mV (SD)
the measurements are very repeatable for each liposome sample and show the expected trend of becoming more negatively charged addition, the results show that the size is independent of the liposome Cationic liposomes
Table 4 summarises the sizing and
zeta potential results obtained for the
series of cationic liposomes. Similar
size distributions were obtained
compared to the anionic liposome
preparations. Figure 2 shows a plot of
the zeta potential and size results
obtained as a function of the mole%
DDAB and shows a gradual increase
in positive charge as the DDAB
content of the liposomes increases.
Conclusions
The physical characterization of
liposomes is of great importance in
understanding their suitability for a
range of applications. Knowledge of
the zeta potential of a liposome
preparation can help to predict the fate of the liposomes in vivo. Figure 2: Zeta potential and size values obtained as a function of the mole%
DDAB content for a series of cationic liposomes monitored by measuring the zeta potential of the resulting complex. characterization of both size and zeta potential of liposomes as detailed in Zetasizer Nano application note MRK575-01 References
A Practical Approach, IRL Press, Oxford, UK. S., Pires, S. Faneca, H. and Duzgunes, N. (2001) Adv. Drug Deliv. Malvern Instruments Ltd Enigma Business Park • Grovewood Road • Malvern • Worcestershire • UK • WR14 1XZ Tel: +44 (0)1684 892456 • Fax: +44 (0)1684 892789 Sales and service centers in over 50 countries for details visit www.malvern.co.uk/contact Zetasizer Nano application note MRK575-01

Source: http://www.pct.hu/lipo.pdf