Fabrication of Novel Types of Colloidosome Microcapsules for Drug Delivery Applications
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AA5.18.1
Fabrication of Novel Types of Colloidosome Microcapsules for Drug Delivery Applications Vesselin N. Paunov,* Paul F. Noble, Olivier J. Cayre, Rossitza G. Alargova1 and Orlin D. Velev1 Department of Chemistry, University of Hull, Hull, HU6 7RX, United Kingdom. 1 Department of Chemical Engineering, North Carolina State University, Raleigh, NC 27695, U.S.A.
ABSTRACT Novel colloidosome microcapsules with aqueous gel cores and shells of different polymeric colloid particles have been prepared and characterized. Our preparation technique involves templating water-in-oil emulsions stabilized by either polymeric microrods or polystyrene (PS) latex particles and subsequent gelling of the aqueous phase with a suitable hydrocolloid. The obtained colloidosome microcapsules were transferred in water after dissolving the oil phase in ethanol and multiple centrifugation/washing cycles with ethanol and water. The presence of an aqueous gel core was found to enhance the structural integrity and mechanical stability of the obtained colloidosomes. In the case of latex particles forming the colloidosome membrane, the effect of the oil type on the final structure of the colloidosome shell was also studied. It was shown that by using appropriate oil, the latex particles within the colloidosome shell can be partially or completely swollen which not only binds them together but also allows direct control over the membrane pore size and its permeability with respect to entrapped species. Such microcapsules can find various applications for development of novel drug and vaccine delivery vehicles, slow release of cosmetic and food supplements. INTRODUCTION Colloidosomes are microcapsules with shells consisting of coagulated or partially fused colloid particles1-5. It has been recognized that the colloidosome membranes offer a great potential in controlling the release rate of entrapped species. Their major advantage is that the membrane pores size can be varied by varying the size of the particles and by controlling their degree of fusion. Here, we report fabrication of novel colloidosome microcapsules with shells of solid microparticles and aqueous gel cores. Our method mimics the recently developed Gel Trapping Technique6,7 for trapping particle monolayers at liquid surfaces by gelling the aqueous subphase. The basics of this method are illustrated in Figure 1 and involve the following three stages: (i) Hot aqueous solution of agarose is emulsified in oil in the presence of solid colloid particles to produce particle-stabilized water-in-oil emulsion and then the system is cooled off to set the agarose gel; (ii) The obtained suspension of aqueous gel microcapsules is diluted with ethanol and centrifuged to separate them from the supernatant; (iii) The microcapsules are washed with ethanol and water and finally re-dispersed in water.
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Corresponding author. Email: [email protected], Phone : +44 (0) 1482 465660, Fax : +44 (0) 1482 466410.
AA5.18.2
25°C
70°C
oil
oil 1) Emulsify 2) Cool to set the gel
1.5% Agarose in wate
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