"Schizophrenic" micellization associated with coil-to-helix transitions based on polypeptide hybrid double hydrophilic rod-coil diblock copolymer

Jingyi Rao, Zhaofeng Luo, Zhishen Ge, Hao Liu, Shiyong Liu

Research output: Contribution to journalArticle

124 Citations (Scopus)

Abstract

A polypeptide hybrid double hydrophilic diblock copolymer (DHBC), poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) (PNIPAM-b-PLGA), was synthesized via the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) using monoamino-terminated PNIPAM as the macroinitiator, followed by deprotection of benzyl groups under alkaline conditions. Containing a thermoresponsive PNIPAM block and a pH-responsive PLGA block, the obtained polypeptide hybrid diblock copolymer molecularly dissolves in aqueous solution at alkaline pH and room temperature but supramolecularly self-assembles into PNIPAM-core micelles at alkaline pH and elevated temperatures and PLGA-core micelles at acidic pH and room temperature accompanied with coil-to-helix transition of the PLGA sequence. The pH- and thermoresponsive "schizophrenic" micellization behavior of PNIPAM-b-PLGA diblock copolymer has been investigated by 1H NMR, optical transmittance, fluorescence probe measurement, transmission electron microscopy (TEM), dynamic and static laser light scattering (LLS), and circular dichroism (CD) spectroscopy. Moreover, the micellization process was investigated employing stopped-flow light scattering technique. The pH-induced micelle growth of PNIPAM-b-PLGA in aqueous solution exhibits drastically different kinetics compared to that of conventional pH-responsive DHBCs, probably due to the stabilization effects exerted by the formed (x-helix secondary structures within the PLGA core at low pH. Exhibiting "schizophrenic" micellization, the polypeptide sequence of PNIPAM-b-PLGA can either locate within micelle cores or stabilizing coronas. The incorporation of polypeptide block into DHBCs can endow them with structural versatility, tunable spatial arrangement of chain segments within self-assembled nanostructures, and broader applications in the field of biomedicines.

Original languageEnglish
Pages (from-to)3871-3878
Number of pages8
JournalBiomacromolecules
Volume8
Issue number12
DOIs
Publication statusPublished - 2007 Dec 1
Externally publishedYes

Fingerprint

Micellization
Polypeptides
Micelles
Block copolymers
Peptides
Glutamic Acid
Acids
Light scattering
Circular dichroism spectroscopy
Ring opening polymerization
Opacity
Temperature
Nanostructures
Stabilization
Fluorescence
Nuclear magnetic resonance
Transmission electron microscopy
Kinetics
poly-N-isopropylacrylamide
Lasers

ASJC Scopus subject areas

  • Bioengineering
  • Biomaterials
  • Polymers and Plastics
  • Materials Chemistry

Cite this

"Schizophrenic" micellization associated with coil-to-helix transitions based on polypeptide hybrid double hydrophilic rod-coil diblock copolymer. / Rao, Jingyi; Luo, Zhaofeng; Ge, Zhishen; Liu, Hao; Liu, Shiyong.

In: Biomacromolecules, Vol. 8, No. 12, 01.12.2007, p. 3871-3878.

Research output: Contribution to journalArticle

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title = "{"}Schizophrenic{"} micellization associated with coil-to-helix transitions based on polypeptide hybrid double hydrophilic rod-coil diblock copolymer",
abstract = "A polypeptide hybrid double hydrophilic diblock copolymer (DHBC), poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) (PNIPAM-b-PLGA), was synthesized via the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) using monoamino-terminated PNIPAM as the macroinitiator, followed by deprotection of benzyl groups under alkaline conditions. Containing a thermoresponsive PNIPAM block and a pH-responsive PLGA block, the obtained polypeptide hybrid diblock copolymer molecularly dissolves in aqueous solution at alkaline pH and room temperature but supramolecularly self-assembles into PNIPAM-core micelles at alkaline pH and elevated temperatures and PLGA-core micelles at acidic pH and room temperature accompanied with coil-to-helix transition of the PLGA sequence. The pH- and thermoresponsive {"}schizophrenic{"} micellization behavior of PNIPAM-b-PLGA diblock copolymer has been investigated by 1H NMR, optical transmittance, fluorescence probe measurement, transmission electron microscopy (TEM), dynamic and static laser light scattering (LLS), and circular dichroism (CD) spectroscopy. Moreover, the micellization process was investigated employing stopped-flow light scattering technique. The pH-induced micelle growth of PNIPAM-b-PLGA in aqueous solution exhibits drastically different kinetics compared to that of conventional pH-responsive DHBCs, probably due to the stabilization effects exerted by the formed (x-helix secondary structures within the PLGA core at low pH. Exhibiting {"}schizophrenic{"} micellization, the polypeptide sequence of PNIPAM-b-PLGA can either locate within micelle cores or stabilizing coronas. The incorporation of polypeptide block into DHBCs can endow them with structural versatility, tunable spatial arrangement of chain segments within self-assembled nanostructures, and broader applications in the field of biomedicines.",
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T1 - "Schizophrenic" micellization associated with coil-to-helix transitions based on polypeptide hybrid double hydrophilic rod-coil diblock copolymer

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AU - Liu, Shiyong

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N2 - A polypeptide hybrid double hydrophilic diblock copolymer (DHBC), poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) (PNIPAM-b-PLGA), was synthesized via the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) using monoamino-terminated PNIPAM as the macroinitiator, followed by deprotection of benzyl groups under alkaline conditions. Containing a thermoresponsive PNIPAM block and a pH-responsive PLGA block, the obtained polypeptide hybrid diblock copolymer molecularly dissolves in aqueous solution at alkaline pH and room temperature but supramolecularly self-assembles into PNIPAM-core micelles at alkaline pH and elevated temperatures and PLGA-core micelles at acidic pH and room temperature accompanied with coil-to-helix transition of the PLGA sequence. The pH- and thermoresponsive "schizophrenic" micellization behavior of PNIPAM-b-PLGA diblock copolymer has been investigated by 1H NMR, optical transmittance, fluorescence probe measurement, transmission electron microscopy (TEM), dynamic and static laser light scattering (LLS), and circular dichroism (CD) spectroscopy. Moreover, the micellization process was investigated employing stopped-flow light scattering technique. The pH-induced micelle growth of PNIPAM-b-PLGA in aqueous solution exhibits drastically different kinetics compared to that of conventional pH-responsive DHBCs, probably due to the stabilization effects exerted by the formed (x-helix secondary structures within the PLGA core at low pH. Exhibiting "schizophrenic" micellization, the polypeptide sequence of PNIPAM-b-PLGA can either locate within micelle cores or stabilizing coronas. The incorporation of polypeptide block into DHBCs can endow them with structural versatility, tunable spatial arrangement of chain segments within self-assembled nanostructures, and broader applications in the field of biomedicines.

AB - A polypeptide hybrid double hydrophilic diblock copolymer (DHBC), poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) (PNIPAM-b-PLGA), was synthesized via the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) using monoamino-terminated PNIPAM as the macroinitiator, followed by deprotection of benzyl groups under alkaline conditions. Containing a thermoresponsive PNIPAM block and a pH-responsive PLGA block, the obtained polypeptide hybrid diblock copolymer molecularly dissolves in aqueous solution at alkaline pH and room temperature but supramolecularly self-assembles into PNIPAM-core micelles at alkaline pH and elevated temperatures and PLGA-core micelles at acidic pH and room temperature accompanied with coil-to-helix transition of the PLGA sequence. The pH- and thermoresponsive "schizophrenic" micellization behavior of PNIPAM-b-PLGA diblock copolymer has been investigated by 1H NMR, optical transmittance, fluorescence probe measurement, transmission electron microscopy (TEM), dynamic and static laser light scattering (LLS), and circular dichroism (CD) spectroscopy. Moreover, the micellization process was investigated employing stopped-flow light scattering technique. The pH-induced micelle growth of PNIPAM-b-PLGA in aqueous solution exhibits drastically different kinetics compared to that of conventional pH-responsive DHBCs, probably due to the stabilization effects exerted by the formed (x-helix secondary structures within the PLGA core at low pH. Exhibiting "schizophrenic" micellization, the polypeptide sequence of PNIPAM-b-PLGA can either locate within micelle cores or stabilizing coronas. The incorporation of polypeptide block into DHBCs can endow them with structural versatility, tunable spatial arrangement of chain segments within self-assembled nanostructures, and broader applications in the field of biomedicines.

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