Synthesis and characterization of star poly(epsilon-caprolactone)-b-poly(ethylene glycol) and poly(L-lactide)-b-poly(ethylene glycol) copolymers: evaluation as drug delivery carriers.
Two types of 32 arm star polymers incorporating amphiphilic block copolymer arms have been synthesized and characterized. The first type, stPCL-PEG 32, is composed of a polyamidoamine (PAMAM) dendrimer as the core with radiating arms having poly(epsilon-caprolactone) (PCL) as an inner lipophilic block in the arm and poly(ethylene glycol) (PEG) as an outer hydrophilic block. The second type, stPLA-PEG 32, is similar but with poly(L-lactide) (PLA) as the inner lipophilic block. Characterization with SEC, (1)H NMR, FTIR, and DSC confirmed the structure of the polymers. Micelle formation by both star copolymers was studied by fluorescence spectroscopy. The stPCL-PEG 32 polymer exhibited unimolecular micelle behavior. It was capable of solubilizing hydrophobic molecules, such as pyrene, in aqueous solution, while not displaying a critical micelle concentration. In contrast, the association behavior of stPLA-PEG 32 in aqueous solution was characterized by an apparent critical micelle concentration of ca. 0.01 mg/mL. The hydrophobic anticancer drug etoposide can be encapsulated in the micelles formed from both polymers. Overall, the stPCL-PEG 32 polymer exhibited a higher etoposide loading capacity (up to 7.8 w/w % versus 4.3 w/w % for stPLA-PEG 32) as well as facile release kinetics and is more suitable as a potential drug delivery carrier.
EIC Laboratories, Incorporated, 111 Downey Street, Norwood, Massachusetts 02062, USA. feiwang@eiclabs.com
Fei
F
Wang
Tatiana K
TK
Bronich
Alexander V
AV
Kabanov
R David
RD
Rauh
Jacques
J
Roovers
D000970:Antineoplastic Agents / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D004337:Drug Carriers / Q000138:chemical synthesis* / Q000737:chemistry; D005026:Ethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D005047:Etoposide / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D011721:Pyrenes / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013696:Temperature
D000970:Antineoplastic Agents; D004337:Drug Carriers; D005026:Ethylene Glycols; D005456:Fluorescent Dyes; D008823:Micelles; D011091:Polyesters; D011721:Pyrenes; C476300:poly(epsilon-caprolactone)-b-poly(ethylene glycol); D011092:Polyethylene Glycols; C083464:poly(ethyleneglycol-lactide); D005047:Etoposide