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pH triggered release of protective poly(ethylene glycol)-b-polycation copolymers from liposomes

Paper ID Volume ID Publish Year Pages File Format Full-Text
12106 778 2006 10 PDF Available
Title
pH triggered release of protective poly(ethylene glycol)-b-polycation copolymers from liposomes
Abstract

Triggered release of adsorbed polymers from liposomes enables protection against immune recognition during circulation and subsequent intracellular delivery of DNA. Polycationic blocks, poly[2-(dimethylamino) ethyl methacrylate] (DMAEMA) (0.8, 3.1, 4.9, or 9.8 kg/mol) or polylysine (K) (3 kg/mol), act as anchors for poly(ethylene glycol) (PEG) (2 or 5 kg/mol) protective blocks. In addition, a copolymer with 15 strictly alternating blocks of PEG (2 kg/mol) and cationic amine sites was evaluated as a protective coating. Incorporation of 1,2-dioleoyl-3-dimethylammonium-propane, a titratable lipid with a pKa of ∼6.7, allows the liposome's net charge to increase as the pH shifts from 7.4 in the bloodstream to 5.5 in the endosome. The increased net liposome cationicity results in decreased cationic polymer adsorption. The EMPEG113–DMAEMA31 and EMPEG113–DMAEMA62 association constants decrease from 3.1 and 6.2 (mg/m2)/(mg/ml) at pH 7.4 to 1.7 and 3.2 (mg/m2)/(mg/ml) at pH 5.5, respectively. However, EMPEG45–DMAEMA5, EMPEG45–DMAEMA20, and EMPEG45–N–DP15 did not show a strong response to changes in pH. Cationic polymer adsorption exceeds calculated values for liposome neutralization, resulting in adsorption profiles in the brush regime.

Keywords
Adsorption; Drug delivery; Controlled drug release; Gene therapy; Polyethylene oxide; Liposomes
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pH triggered release of protective poly(ethylene glycol)-b-polycation copolymers from liposomes
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 27, Issue 12, April 2006, Pages 2599–2608
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us