Everything about Microspheres
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  • Measurement Techniques for Electrostatic Charged Microspheres

    Charged Microspheres Measurement TechniquesElectrostatic charge (also known as triboelectric charge) on microparticles and microspheres have been of interest to scientists in chemical, pharmaceutical, cosmetic, drug delivery, displays and other industries for many years. Until recently there were no reliable techniques to measure or quantify electrostatic charge on microparticles, with too many uncontrolled variables the measurements were inconsistent. As a result scientists were treating charging as a black box process, performing the experiments blindly as trial and error. With recent advances in microsphere manufacturing, techniques have been developed that promise not only to quantify the charge on microspheres, but control it in the manufacturing process.

    Continue reading “Measurement Techniques for Electrostatic Charged Microspheres” »

  • 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). Continue reading “Chitosan microspheres prepared by spray drying” »

  • 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. Continue reading “Chitosan Coated PLGA-Microspheres – A Modular System for Targeted Drug Delivery” »