Zeta potentials laser doppler anemometry

The size and charge analysis was done using a Coulter DELSA 440SX (Coulter Beckman Corp., Miami, FL). This particular instrument measured the size distribution on the basis of photon correlation spectrometry (PCS) and was limited to particle diameters between 0.02 pm and 3 pm. Measurements were taken at four different angles simultaneously with 256-channel resolution each. Comparison of the spectra allowed for the detection of very small particles. The zeta potential was assessed on the basis of electrophoretic mobility (laser Doppler anemometry, LDA). This was defined as the particle velocity per unit of applied electrical field, with units usually given as pm s 1/V cm-1, while zeta potential is defined as the electrical potential between the bulk solution and the... 

PLGA microspheres. Methods to measure the zeta potential of microspheres are laser doppler anemometry [105] and photon correlation spectroscopy [110]. 

The original Acoustosizer used a single frequency whereas a later development has a range of 13 frequencies between 0.3 and 13 MHz. This allows the measurement of the dynamic mobility spectrum and the determination of the zeta potential and particle size. In order to invert the mobility spectrum into a size distribution a log-normal distribution of particle size is assumed. A comparison with photon correlation spectroscopy for determining particle size and laser Doppler anemometry for particle charge eonfirmed the results using ACS [266]. These and additional sedimentation measurements confirmed that changes in particle size and zeta potential due to dilution effects are likely to occur in aqueous and non-stabilized systems. 

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

Zeta potential measurements are also performed on the NanoZS. All samples are diluted 1 10 (v v) with water. A folded electrophoresis cell is used (Malvern instruments GmbH, Germany) for Laser Doppler Anemometry (LDS) measurements. 

The graft copolymers (25-26) have well-defined hydrophobic-hydrophilic regions, and are therefore ideally suitable for surface modification (coating) in aqueous media. Table 12 shows the result of coating of clean polystyrene latex particles (nanospheres) by the graft copolymers (25a-25d) in aqueous solutioa The coat layer thickness measured by Photon Correlation Spectroscopy (PCS) and Laser Doppler Anemometry (LDA) are in good agreement. They also correlate well with the zeta potential data [47]. 

One method for the measurement of the zeta potential is based on the measurement of the relative electrophoretic motion of particles and electrolytes in an electric field. To measure the velocity of the particles laser doppler anemometry can be used. A typical apparatus is shown in Figure 12.4. 

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