Friday, February 6, 2015


PolySciTech ( provides a wide array of block copolymers. Recently these types of block copolymers were utilized to generate DNA delivery systems. Read more: Abebe, Daniel G., Rima Kandil, Teresa Kraus, Maha Elsayed, Olivia M. Merkel, and Tomoko Fujiwara. "ThreeLayered Biodegradable Micelles Prepared by TwoStep SelfAssembly of PLAPEIPLA and PLAPEGPLA Triblock Copolymers as Efficient Gene Delivery System." Macromolecular Bioscience (2015).

“Abstract: “Three-layered micelles” (3LM) composed of two triblock copolymers, poly(L-lactide)-b-polyethyleneimine-b-poly(L-lactide) (PLLA-PEI-PLLA) and poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-PEG-PLLA) are designed to combine electrostatic interaction and solvent-induced condensation of DNA. The low molecular weight PLLA-PEI-PLLA is synthesized by a facile amine-protection/deprotection approach and employed as a gene vector, compacting DNA as a polyplex core in the organo-micelles. The individual organo-micelle is further encapsulated within a PLLA-PEG-PLLA amphiphilic micelle leading to an aqueous stable colloidal dispersion. The resulting spherical 3LM possess a hydrodynamic diameter of ca. 200 nm and zeta potential close to neutral and display excellent stability to competing polyanions such as dextran sulfate in neutral pH (7.4). Such high stability is attributed to the complete shielding of the PEI/DNA polyplex core with an impermeable hydrophobic intermediate layer. However, greater than 90% of the encapsulated DNA are released within 30 min when exposed to slightly acidic pH (4.5). Based on our findings, a new class of non-viral delivery system for nucleic acids with superb stability and stealth. Keywords: block copolymers;gene delivery;micelles;poly(lactic acid);polyethyleneimine.”

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