During some research on PLGA microspheres we found this interesting article published in European Cells and Materials Vol 7 Suppl 2. 2004 (pages 11-12).?? They were able to achieve a significant change in the zeta potential of their microspheres just by increasing the dosage of Chitosan.?? The authors conclusions and a graph of their data follow.
Discussion and Conclusions by the authors:
The increase in zeta potential from ?70.8 mV (chitosan-free PLGA particles) to +20.5 mV with increasing chitosan concentrations in the W2-phase used for particle preparation strongly suggests that the polycationic chitosan was firmly adsorbed to the particle surface. This finding was confirmed by X-ray photoelectron spectroscopy (data not shown). The coupling of biotin via a NHS-PEGlinker showed that the amino groups of? chitosan represent suitable sites for covalent bioconjugation of different ligands. The process allows the production of particles with a mean diameter between 1 and 10 um, a useful size range for the phagocytosis by? phagocytes like dendritic cells or macrophages.