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Pharm Res. 2011 Jul;28(7):1765-73. doi: 10.1007/s11095-011-0411-z. Epub 2011 Mar 18.

Lyophilization of protein-loaded polyelectrolyte microcapsules.

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  • 1Laboratory of General Biochemistry and Physical Pharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.



To evaluate if lyophilization can be used to obtain a dry formulation of polyelectrolyte microcapsules, which have emerged as a new class of microparticles for the encapsulation and delivery of biomacromolecules.


Microcapsules composed of dextran sulfate and poly-L-arginine were obtained by coating CaCO(3) microparticles by means of the layer-by-layer technique. Microcapsules were lyophilized using different stabilizers; intactness was checked by CLSM and SEM. Horseradish peroxidase was encapsulated as model enzyme and retained activity after freeze-drying was determined using a fluorescence assay. Ovalbumin was encapsulated as model antigen; immunogenicity after lyophilization was evaluated in vitro by a T-cell proliferation assay and in vivo by measuring the antibody titer in mice.


The results clearly demonstrate the necessity of using polyols in the formulation to prevent rupture of the microcapsules and to preserve the activity of encapsulated enzymes. Lyophilized microcapsules appeared as a promising adjuvant for antigen delivery, as both in vitro as in vivo assays showed higher immune activation compared to free antigen.


Lyophilization is a promising strategy towards improved stability of protein-loaded microcapsules.

[PubMed - indexed for MEDLINE]
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