Assessment of the integrity of poly(caprolactone)-b-poly(ethylene oxide) micelles under biological conditions: a fluorogenic-based approach.
The integrity of block copolymer micelles is important for their effectiveness and successful delivery of the incorporated drugs. Here we evaluate the integrity of poly(caprolactone)-b-poly(ethylene oxide) micelles in media of varying chemical complexity and in cells by using fluorogenic micelles. Fluorogenic dye fluorescein-5-carbonyl azide diacetate was covalently attached to the micelle-core-forming part of the block copolymer, poly(caprolactone). The fluorescence was not detectable unless the poly(caprolactone)21-b-poly(ethylene oxide)45 micelles were destroyed and the fluorogenic dye was activated by deesterification. The fluorescence of the activated dye from destroyed micelles was easily detectable in various media and in cells. Micelles were stable in simple media such as phosphate-buffered saline but disassembled to varying extents with increasing chemical complexity of the media and addition of serum. The integrity of the internalized micelles within the cells showed a time-dependent decrease but remained largely preserved (80%) after 20 h of incubation with cells. A proof of principle was also demonstrated in vivo in mice. The fluorogenic approach to micelle integrity assessment presented herein should lend itself to other block copolymer micelles and assessments of their integrity in complex biological systems in vitro and in vivo.
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada H3G 1Y6.
Radoslav
R
Savić
Tony
T
Azzam
Adi
A
Eisenberg
Dusica
D
Maysinger
D000818:Animals; D045744:Cell Line, Tumor; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems; D005027:Ethylene Oxide; D019793:Fluorescein / Q000737:chemistry; D005456:Fluorescent Dyes / Q000494:pharmacology; D006801:Humans; D007783:Lactones; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008823:Micelles; D008856:Microscopy, Fluorescence / Q000379:methods; D011091:Polyesters / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D013997:Time Factors
D004337:Drug Carriers; D005456:Fluorescent Dyes; D007783:Lactones; D008823:Micelles; C400421:PLC(20)-b-PEO(44); D011091:Polyesters; C016240:polycaprolactone; D011092:Polyethylene Glycols; D005027:Ethylene Oxide; D019793:Fluorescein