title: Phospholipid decoration of microcapsules containing perfluorooctyl bromide used as ultrasound contrast agents.
abstract: We present here an easy method to modify the surface chemistry of polymeric microcapsules of perfluorooctyl bromide used as ultrasound contrast agents (UCAs). Capsules were obtained by a solvent emulsification-evaporation process with phospholipids incorporated in the organic phase before emulsification. Several phospholipids were reviewed: fluorescent, pegylated and biotinylated phospholipids. The influence of phospholipid concentration on microcapsule size and morphology was evaluated. Only a fraction of the phospholipids is associated to microcapsules, the rest being dissolved with the surfactant in the aqueous phase. Microscopy shows that phospholipids are present within the shell and that the core/shell structure is preserved up to 0.5 mg fluorescent phospholipids, up to about 0.25 mg pegylated phospholipids or biotinylated phospholipids (for 100 mg of polymer, poly(lactide-co-glycolide) (PLGA)). HPLC allows quantifying phospholipids associated to capsules: they correspond to 10% of pegylated phospholipids introduced in the organic phase. The presence of pegylated lipids at the surface of capsules was confirmed by X-ray photon electron spectroscopy (XPS). The pegylation did not modify the echographic signal arising from capsules. Finally biotinylated microcapsules incubated with neutravidin tend to aggregate, which confirms the presence of biotin at the surface. These results are encouraging and future work will consist of nanocapsule surface modification for molecular imaging.
authors.affiliation: Univ. Paris Sud, UMR CNRS 8612, IFR 141, Faculté de Pharmacie, 5 Rue Jean-Baptiste Clément, Châtenay-Malabry, France.
authors.forename: Raquel
authors.initials: R
authors.lastname: Díaz-López
authors.forename: Nicolas
authors.initials: N
authors.lastname: Tsapis
authors.forename: Danielle
authors.initials: D
authors.lastname: Libong
authors.forename: Pierre
authors.initials: P
authors.lastname: Chaminade
authors.forename: Carole
authors.initials: C
authors.lastname: Connan
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Chehimi
authors.forename: Romain
authors.initials: R
authors.lastname: Berti
authors.forename: Nicolas
authors.initials: N
authors.lastname: Taulier
authors.forename: Wladimir
authors.initials: W
authors.lastname: Urbach
authors.forename: Valérie
authors.initials: V
authors.lastname: Nicolas
authors.forename: Elias
authors.initials: E
authors.lastname: Fattal
mesh_terms: D001360:Avidin / Q000378:metabolism; D019921:Biotinylation; D002214:Capsules / Q000737:chemistry*; D003287:Contrast Media / Q000138:chemical synthesis* / Q000737:chemistry; D004602:Elements; D005453:Fluorescence; D005466:Fluorocarbons / Q000737:chemistry*; D006842:Hydrocarbons, Brominated; D018613:Microscopy, Confocal; D010316:Particle Size; D010714:Phosphatidylethanolamines / Q000737:chemistry* / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry; D012235:Rhodamines / Q000378:metabolism; D013057:Spectrum Analysis; D019809:Streptavidin / Q000378:metabolism; D013499:Surface Properties; D014465:Ultrasonics
chemical_list: D002214:Capsules; D003287:Contrast Media; D004602:Elements; D005466:Fluorocarbons; D006842:Hydrocarbons, Brominated; D010714:Phosphatidylethanolamines; D012235:Rhodamines; C093483:neutravidin; D001360:Avidin; C038089:1,2-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; D019809:Streptavidin; C003072:perflubron