RESUMO
Hybrid rod-rod diblock copolymers, poly(γ-benzyl L-glutamate)-poly(4-cyano-benzoic acid 2-isopropyl-5-methyl-cyclohexyl ester) (PBLG-PPI), with determined chirality are facilely synthesized through sequential copolymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) and phenyl isocyanide monomers bearing chiral menthyl pendants using a Ni(cod)(bpy) complex as the catalyst in one-pot. Circular dichroism and absorption spectra reveal that each block of the block copolymers possesses a stable helical conformation with controlled helicity in solution due to the induction of chiral pendants. The two diastereomeric polymers self-assemble into helical nanofibrils with opposite handedness due to the different chiral induction of the L- and D-menthyl pendants, confirmed by transmission electron microscopy (TEM). Deprotection of the benzyl groups of the PBLG segment affords biocompatible amphiphilic diblock copolymers, poly(L-glutamic acid)-poly(4-cyano-benzoic acid 2-isopropyl-5-methyl-cyclohexyl ester) (PLGA-PPI), that can self-assemble into well-defined micelles by cosolvent induced aggregation. Very interestingly, a chiral rhodamine chromophores RhB(D) can be selectively encapsulated into the chiral polymeric micelles, which is efficiently internalized into living cells when directly monitored with a confocal microscope. This contribution will be useful for developing novel rod-rod biocompatible hybrid block copolymers with a controlled helicity, and may also provide unique chiral materials for potential bio-medical applications.
Assuntos
Anidridos/química , Glutamatos/química , Imagem Molecular , Ácido Poliglutâmico/análogos & derivados , Anidridos/síntese química , Materiais Biocompatíveis/química , Rastreamento de Células , Glutamatos/síntese química , Humanos , Isotiocianatos/química , Conformação Molecular , Peptídeos/química , Ácido Poliglutâmico/síntese química , Ácido Poliglutâmico/química , Soluções/químicaRESUMO
A series of poly(3-hexylthiophene)-b-poly(hexadecyloxylallene) copolymers has been synthesized in one pot via sequential monomer addition by using Ni(dppp)Cl2 as a single catalyst. The copolymerization has been revealed to proceed by a controlled chain extension mechanism and the block copolymer can self-assemble into a well-defined supramolecular structure in solution and exhibit microphase separation in the solid state.
