Nano- and microcapsules as drug-delivery systems

Preparation of nano- and micrometer-size capsules with lipid core might have several biomedical applications for delivery of lipophilic drugs. Successful usage of these nano- and microcarriers depends on their colloidal stability. Emulsion based carriers for drug delivery: nanoemulsions, colloidosomes, and solid lipid particles have been investigated in this work. Diameters of oil droplets in nanoemulsions are equal to 15 and 20 nm, however they are not stable to phase separation. In spite of large droplet diameters (several tens of micrometer), colloidosomes stabilized by heteroaggregates of oppositely charged SiO2 nanoparticles are stable toward creaming. Paraffin emulsions stabilized by Carbopol 940 have particles 190 nm in size and are also stable to creaming during several months. Encapsulation of lipophilic drugs tocopherol, hydrocortisone, nimesulide or curcumin does not cause changing diameters of nanoemulsion based nanocapsules. Incorporation of these drugs in paraffin particles leads to decreased or increased particle sizes, but in all specimens the sizes are equal or less than 700 nm and such particles can be used as microcapsules for lipophilic drug delivery.

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