Micellization and Reversible pH‐Sensitive Phase Transfer of the Hyperbranched Multiarm PEI–PBLG Copolymer

Abstract

A novel, hyperbranched, amphiphilic multiarm biodegradable polyethylenimine-poly(gamma-benzyl-L-glutamate) (PEI-PBLG) copolymer was prepared by the ring-opening polymerization of gamma-benzyl-L-glutamate-N-carboxyanhydride (BLG-NCA) with hyperbranched PEI as a macroinitiator. The copolymer could self-assemble into core-shell micelles in aqueous solution with highly hydrophobic micelle cores. As the PBLG content was increased, the size of the micelles increased and the critical micelle concentration (CMC) decreased. The surface of the micelles had a positive zeta potential. The cationic micelles were capable of complexing with plasmid DNA (pDNA), which could be released subsequently by treatment with polyanions. The PEI-PBLG copolymer formed unimolecular micelles in chloroform solution. The pH-sensitive phase-transfer behavior exhibited two critical pH points for triggering the encapsulation and release of guest molecules. Both the encapsulation and release processes were rapid and reversible. Under strong acidic or alkaline conditions, the release process became partially or completely irreversible. Thus, this copolymer system should be an attractive candidate for a gene- or drug-delivery system in aqueous media and could provide the phase-transfer carriers between water and organic media.

Hydrophobic Polyphenylalanine‐Grafted Hyperbranched Polyethylenimine and its in vitro Gene Transfection

“…PEI-25k was used as a macroinitiator and Phe-NCA as the monomer according to our previous work. [32] Briefly, PEI-25k and Phe-NCA were respectively dissolved in anhydrous DMF in flame-dried flasks to gain dilute solutions with concentration of 25 mg Á mL À1 . Then they were mixed with different Phe-NCA/PEI-25k molar ratios (40:1, 80:1 and 120:1, respectively) and stirred for 72 h at 30 8C.…”

Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

“…Besides the good stability of multiarm hyperbranched copolymers, the highly branched structure can also provide many nanocavities for drug encapsulation. Consequently, plenty of double hydrophilic or amphiphilic multiarm hyperbranched copolymers have been prepared and investigated as unimolecular micelles for intracellular drug delivery [15][16][17][18][19][20][21][22][23]. However, the concentration of active drug within cells is often insufficient owing to the inefficient release of drug from micelles into the cytoplasm.…”

A Highly Efficient siRNA Carrier of PBLG Modified Hyperbranched PEI

“…This new non-viral gene carrier is one of the best effective systems based on our previous work. [24,25] In this work, PEI-PBLG was used for siRNA-mediated gene silencing. As was expected, PEI-PBLG showed reduced toxicity in comparison to unmodified PEI.…”