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.
Preparation of these novel modular microparticulate delivery? systems is straightforward. Particle size and surface characteristics can be easily adjusted and controlled, and drugs and antigens can be readily embedded.? Thus, these novel carriers may serve as multifunctional delivery system for various applications. Its applicability as a modular delivery platform will be further investigated.