The work function of emersed electrodes

Surface activity and emulsification properties of hydrophobically modified dextrans.

Sterically stabilized biocompatible poly(lactic acid) (PLA) nanospheres were prepared by an o/w emulsion/evaporation technique, using hydrophobically modified dextrans (DexP) as the emulsion stabilizer. Photon correlation spectroscopy, zetametry, and differential scanning calorimetry studies corroborated that interfacial adhesion between immiscible dextran and PLA chains was achieved by compatibilization of polymer segments via hydrophobic groups grafted onto dextran and thus leading to the formation of entanglements between the hydrophobic dextran parts and the PLA matrix. The presence of dextran exposed at the particle surface was confirmed by X-ray photoelectron spectroscopy and by the fact that the suspensions showed an increased stability in concentrated NaCl solutions and a reduction of bovine serum albumin adsorption compared to uncoated PLA nanoparticles. A comparison of the characteristics of PLA nanospheres DexP-coated via the emulsion procedure (NSem) with those of PLA particles coated by DexP adsorption (NSad) suggests that the conformation of the polymer in the superficial layers may be different. However, both DexP layers behave similarly in terms of stability and protein adsorption. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 50, 557–565, 2000.

Surface modification of poly(lactic acid) nanospheres using hydrophobically modified dextrans as stabilizers in an o/w emulsion/evaporation technique

Influence of polymeric surfactants on the properties of drug-loaded PLA nanospheres

Adsorption of plasma proteins onto polymer latices.

Assuming that the ions in solution near a charged wall are subjected only to electrostatic and kinetic forces, it is shown that the potential gradient normal to the wall is determined principally by the valence and concentration of the ion of opposite charge to the wall. Assuming that the valence and concentration of this ion determine the effect of the salt on the electrokinetic potential of the wall, the surface potential of the wall and the thickness of the immobilized liquid layer are calculated from electrokinetic potential data. Salts of ``normal'' ions (NaCl, BaCl2, etc.) cause relatively small changes in the surface potential and thickness of the immobilized layer at a glass surface and these changes occur only at very low salt concentrations. Salts containing ``abnormal'' ions (H+, OH—, La+++, etc.) produce larger changes and the change continues over a much wider concentration range. The extreme effectiveness of salts like AlCl3 and ThCl4 in lowering negative electrokinetic potentials cannot be accounted for by the higher valence of the ions.

W. G. Eversole

Papers

The Effect of Electrostatic Forces on Electrokinetic Potentials