Block length affects secondary structure, nanoassembly and thermosensitivity of poly(ethylene glycol)-poly(l-alanine) block copolymers

Choi, Yun Young; Jang, Ji Hye; Park, Min Hee; Choi, Bo Gyu; Chi, Bo; Jeong, Byeongmoon

doi:10.1039/b922956f

Cited by 96 publications

(141 citation statements)

References 44 publications

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“…The synthesis of glycosylated polypeptides has been achieved using direct polymerization of glycosylated NCA or post-modification by conventional chemistry as well as click chemistry [24][25][26][27][28][29][30][31]. On the other hand, a range of thermoresponsive polypeptides have been described in the literature [21,[32][33][34][35]. Notably, Hammond described the ring opening polymerization of poly(c-propargyl-L-glutamate) (PPLG) to obtain a polypeptide platform on which they attached different oligo(ethylene glycols) through copper catalyzed click reaction in order to induce thermoresponsiveness [36].…”

Section: Introductionmentioning

confidence: 99%

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Kapetanakis

Heise

2015

European Polymer Journal

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Section: Introductionmentioning

confidence: 99%

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Kapetanakis

Heise

2015

European Polymer Journal

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“…17,18 Briefly, PEG-PA was synthesized by ring-opening polymerization of the N-carboxy anhydrides of L-alanine in the presence of PEG. PEG-PLA was synthesized by ring-opening polymerization of the L-lactide in the presence of PEG, where the stannous octoate was used as a catalyst.…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, it is surprising that aqueous solutions of poly(ethylene glycol)-poly(L-alanine) (PEG-PA) diblock copolymers with similar molecular weights undergo sol-to-gel transition (thermal gelation) as the temperature increases. 17,18 Previous reports independently carried out on the sol-gel transition mechanism of the PEG-PA and PEG-PLA suggested that micelle aggregation, dehydration of PEG, and changes in secondary structures might be involved in the sol-gel transition. [17][18][19][20][21] Then, why do aqueous solutions of the two polymers show opposite trends against temperature change?…”

mentioning

confidence: 99%

Thermal gelation or gel melting: (ethylene glycol)₁₁₃‐(l‐alanine)₁₂ and (ethylene glycol)₁₁₃‐(l‐lactic acid)₁₂

Jung

Park

Moon

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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When PEG (M.W.5000 Daltons) is conjugated to poly(L-alanine), the polymer aqueous solutions (<10.0 wt.%) undergo sol-to-gel (thermal gelation), whereas it is conjugated to poly(L-lactic acid), the polymer aqueous solutions (>30.0 wt.%) undergo gel-to-sol (gel melting) as the temperature increases. In the search for molecular origins of such a quite different phase behavior, poly(ethylene glycol)-poly(L-alanine) (PEG-PA; EG 113 -A 12 ) and poly(ethylene glycol)-poly(L-lactic acid) (PEG-PLA; EG 113 -LA 12 ) are synthesized and their aqueous solution behavior is investigated. PEG-PAs with an a-helical core assemble into micelles with a broad size distribution, and the dehydration of PEG drives the aggregation of the micelles, leading to thermal gelation, whereas increased molecular motion of the PLA core overwhelms the partial dehydration of PEG, thus gel melting of the PEG-PLA aqueous solutions occurs. The core-rigidity of micelles must be one of the key factors in determining whether a polymer aqueous solution undergoes sol-to-gel or gel-to-sol transition, as the temperature increases. V C 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2434-2441 KEYWORDS: sol-gel transition; block copolymers; stimuli-sensitive polymers; self-assembly; micelles INTRODUCTION Polymer aqueous solutions that undergo temperature-sensitive sol-gel transition have been extensively investigated during the last decade, not only for their biomedical applications, but also for their unique transition mechanism.1-10 Basically, the sol-gel transition is observed for aqueous solutions of polymers with a delicate balance of hydrophilicity and hydrophobicity. The sol-gel transition behavior is affected by the architecture and chemical structure of a polymer. AB-type diblock copolymers and ABA-type triblock copolymers, where A is hydrophilic and B is hydrophobic, tend to form spherical micelles, whereas BAB-type triblock copolymers tend to form flower-like micelles or intermicellar bridges.11 In addition, the molecular architecture of the block copolymer affects the secondary structure of polypeptide.12-14 Therefore, the sol-gel transition behavior can be different for the polymers with different architectures even though total molecular weight is similar. In this article, we designed AB-type diblock copolymers with the same number of repeating units to focus on the effect of ester versus amide bonds on the sol-gel transition behavior. Even though, there have been extensive reports on the poly(ethylene glycol)/poly(L-lactic acid-co-glycolic acid) (PEG/PLGA) and poly(ethylene glycol)/poly(L-lactic acid) (PEG/PLA) block

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“…[8][9][10][11] The solto-gel transition temperature and the gel modulus are key parameters in designing a thermogelling biomaterial because they determine injectability, formulation temperature, applicability, and even the fates of incorporated cells or stem cells. 9,[11][12][13][14] In this study, we designed an ion/temperature dual stimuli-sensitive polymer. 5 The polymer aqueous solution undergoes sol-to-gel transition which is supposed to be modulated by the specific cations as well as temperature.…”

Section: Introductionmentioning

confidence: 99%

Ion and Temperature Sensitive Polypeptide Block Copolymer

Joo

Moon

et al. 2014

Biomacromolecules

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A poly(ethylene glycol)/poly(L-alanine) multiblock copolymer incorporating ethylene diamine tetraacetic acid ([PA-PEG-PA-EDTA(m)) was synthesized as an ion/temperature dual stimuli-sensitive polymer, where the effect of different metal ions (Cu(2+), Zn(2+), and Ca(2+)) on the thermogelation of the polymer aqueous solution was investigated. The dissociation constants between the metal ions and the multiblock copolymer were calculated to be 1.2 × 10(-7), 6.6 × 10(-6), and 1.2 × 10(-4) M for Cu(2+), Zn(2+), and Ca(2+), respectively, implying that the binding affinity of the multiblock copolymer for Cu(2+) is much greater than that for Zn(2+) or Ca(2+). Atomic force microscopy and dynamic light scattering of the multiblock copolymer containing metal ions suggested micelle formation at low temperature, which aggregated as the temperature increased. Circular dichroism spectra suggested that changes in the α-helical secondary structure of the multiblock copolymer were more pronounced by adding Cu(2+) than other metal ions. The thermogelation of the multiblock copolymer aqueous solution containing Cu(2+) was observed at a lower temperature, and the modulus of the gel was significantly higher than that of the system containing Ca(2+) or Zn(2+), in spite of the same concentration of the metal ions and their same ionic valence of +2. The above results suggested that strong ionic complexes between Cu(2+) and the multiblock copolymer not only affected the secondary structure of the polymer but also facilitated the thermogelation of the polymer aqueous solution through effective salt-bridge formation even in a millimolar range of the metal ion concentration. Therefore, binding affinity of metal ions for polymers should be considered first in designing an effective ion/temperature dual stimuli-sensitive polymer.

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Block length affects secondary structure, nanoassembly and thermosensitivity of poly(ethylene glycol)-poly(l-alanine) block copolymers

Cited by 96 publications

References 44 publications

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Thermal gelation or gel melting: (ethylene glycol)₁₁₃‐(l‐alanine)₁₂ and (ethylene glycol)₁₁₃‐(l‐lactic acid)₁₂

Ion and Temperature Sensitive Polypeptide Block Copolymer

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Block length affects secondary structure, nanoassembly and thermosensitivity of poly(ethylene glycol)-poly(l-alanine) block copolymers

Cited by 96 publications

References 44 publications

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Thermoresponsive glycopolypeptides with temperature controlled selective lectin binding properties

Thermal gelation or gel melting: (ethylene glycol)113‐(l‐alanine)12 and (ethylene glycol)113‐(l‐lactic acid)12

Ion and Temperature Sensitive Polypeptide Block Copolymer

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Thermal gelation or gel melting: (ethylene glycol)₁₁₃‐(l‐alanine)₁₂ and (ethylene glycol)₁₁₃‐(l‐lactic acid)₁₂