The Fluorosome technique for investigating membrane on- and off-loading of drugs by beta-CD and sonicated SUV.

The application of the Fluorosome technique to test drug delivery systems is described. Fluorosomes, egg phosphatidylcholine liposomes with bilayer embedded fluorophores, were employed to investigate the ability of sonicated small unilamellar vesicles (sSUV) and beta-cyclodextrins (beta-CD) to deliver drugs into or extract drugs from the fluorosome's phospholipid bilayer. The addition of phloretin to a fluorosome suspension resulted in fluorescence reduction reflecting phloretin entering the bilayer and quenching fluorophore fluorescence. Subsequent addition of sSUV to phloretin pretreated fluorosomes showed an increase in fluorescence reflecting phloretin extraction from the fluorosome membrane. Sequential additions of beta-estradiol loaded beta-CD to fluorosomes as well as the addition of beta-estradiol alone resulted in fluorescence reduction due to beta-estradiol insertion into the membrane. Further addition of pure beta-CD resulted in a fluorescence increase indicating beta-estradiol extraction from the fluorosome membrane.