Chitosan microspheres prepared by spray drying

Spray drying has been used in the production of fine powders from emulsions for many years, but it is not a process in which most people associate the production of microspheres.? This journal article shows how the authors were able to produce highly spherical microspheres in the 2-10um range by controlling the levels of Chitosan and crosslinking agents used.

Chitosan MicrospheresThe key items I found of interest in this article were:

The quality of the microspheres that were produced, as seen the the attached SEM micrograph.

How the process variables did not affect the zeta potential of the microspheres produced (Table 4 below), and how the size can be varied by varying the concentrations of Chitosan or the Molecular weight (MW).

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Chitosan Coated PLGA-Microspheres – A Modular System for Targeted Drug Delivery

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.

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