Microspheres zeta potentials

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

Fig. 5. Schematic illustration of the fluid-to-gel transition observed for colloidal silica inks. The bottom graph is a plot of zeta potential as a function of pH for PEl-coated silica and bare silica microspheres suspended in water. The upper graph is a log-log plot of shear elastic modulus as a function of shear stress for concentrated silica gels of varying strength (o) denotes weak gel pH = 9.5 and ( ) denotes strong gel pH = 9.75 (Ref. 36).

The microspheres mentioned above are all spherical and no change of the diameter and aggregation of the microspheres takes place during the reaction of surface modification. The surface charge of every microsphere can be determined by electrophoresis. For instance, the zeta potentials of our cellulose triacetate, Cell-OH, crosslinked Cell-OH, Cell-CM, Cell-SE, Cell-NHa, Cell-DEAE, Cell-DEAE(Me), and benzyl cellulose microspheres were —19.9, —2.1, —2.7, —17.1, —20.9, +4.6, +14.2, +15.1, and —65.2 mV, respectively. This result indicates that anionic and cationic microspheres with the same average diameter but different surface charges can be prepared by this method. 

The relationship between phagocytosis of the microspheres and their zeta potentials is shown in Figure 14. Phagocytosis takes place more markedly with the increasing... 

Fig. 14. Effect of the zeta potential on phagocytosis of modified cellulosic microspheres by M< >. (See Fig. 12. concerning the number in the Fig.)...

Recently, EHEC and other hydrocolloids were used for the stabilization of lipid microspheres. The coating reduced the zeta potential of the liposomes to a neutral value and decreased their surface fluidity, as measured by fluorescence... 

FIGURE 2.2 The relationship between zeta potential (open shapes) and viscosity (filled shapes) for silica suspensions as a function of suspension pH nanosize A90 versus Geltech microspheres (G). Viscosity was determined at a shear rate of 26.4 s. Particle volume fraction given in percent. 

Table 1. The amount of peptide immobilized on the microspheres and zeta potentials of the microspheres...

We recouple the two velocity components from the charged wall and the charged packing particles and obtain the overall macroscopic EOF velocity in a charged cylindrical microcapillary with charged microsphere packing. The excess zeta potential is taken into account by such a treatment that the zeta potential of the capillary wall is replaced by — Cp)> which is responsible for the electrokinetic wall effect ... 

In the following two-dimensional simulations, the channel walls are homogeneously charged with the zeta potential = — 50 mV. The channel width // is I [im. The charged microspheres are arranged as a structured array with equal spaces between the channels. The particle diameter... 

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