Conformational properties of biocompatible poly(2-ethyl-2-oxazoline)s in phosphate buffered saline

Alexander S. Gubarev, Bryn D. Monnery, Alexey A. Lezov, Ondrej Sedlacek, Nikolai V. Tsvetkov, Richard Hoogenboom, Sergey K. Filippov

Research output

7 Citations (Scopus)

Abstract

Inspired by the increasing popularity of poly(2-ethyl-2-oxazoline) (PEtOx) for biomedical applications, this study reports the complete and thorough solution analysis of the homologous series of biocompatible PEtOx samples in a very broad range of molecular weights ranging from 11.2 × 103 g mol-1 up to 260 × 103 g mol-1. The main focus of the research was on the determination of the conformational properties of PEtOx macromolecules at a temperature of 37 °C in phosphate buffered saline (PBS) simulating the parameters of physiological media. The polymers were studied in PBS solutions by analytical ultracentrifugation, dynamic light scattering (DLS), translational diffusion, and intrinsic viscosity measurements in a temperature range from 15 °C up to 72 °C. The complete set of Kuhn-Mark-Houwink-Sakurada scaling relationships revealed linear trends over the whole range of the studied molar masses, while the determined scaling indices at 37 °C correspond to the coil conformation in a thermodynamically good solvent ([η] = 0.045 × M0.62, s0 = 0.010 × M0.46 and D0 = 1750 × M-0.54). Based on the intrinsic viscosity values (most sensitive characteristic to the size variations of polymer coils, [η] ∼ r3), it was demonstrated that PEtOx macromolecules in PBS solutions undergo a transition from swollen polymer coils with gradual deterioration of thermodynamic quality of solutions within the temperature range of 15-45 °C, reaching conditions at 55 °C with further precipitation at 62-72 °C. Also, to the best of our knowledge, the conformational parameters (equilibrium rigidity/the Kuhn segment length and the diameter of the polymer chain) of PEtOx macromolecules were evaluated under physiological conditions for the first time and constitute A = 1.8 ± 0.3 nm and d = 0.7 ± 0.4 nm. These equilibrium rigidity values classify PEtOx as a flexible macromolecule with rigidity similar to that of poly(ethylene glycol). For the first time, we were able to demonstrate a direct influence of thermosensitivity on the rigidity of the biocompatible polymer: PEtOx. The Kuhn segment length is undoubtedly decreasing when approaching the LCST.

Original languageEnglish
Pages (from-to)2232-2237
Number of pages6
JournalPolymer Chemistry
Volume9
Issue number17
DOIs
Publication statusPublished - 1 May 2018

Fingerprint

Phosphates
Macromolecules
Rigidity
Polymers
Sodium Chloride
Viscosity
Temperature
Molar mass
Viscosity measurement
Dynamic light scattering
Polyethylene glycols
Deterioration
Conformations
Ethylene Glycol
Ultracentrifugation
Molecular weight
poly(2-ethyl-2-oxazoline)
Thermodynamics
Molecular Weight
Research

Scopus subject areas

  • Bioengineering
  • Biochemistry
  • Polymers and Plastics
  • Organic Chemistry

Cite this

@article{cb8c2530b47b4afc9a82923ae4fcb539,
title = "Conformational properties of biocompatible poly(2-ethyl-2-oxazoline)s in phosphate buffered saline",
abstract = "Inspired by the increasing popularity of poly(2-ethyl-2-oxazoline) (PEtOx) for biomedical applications, this study reports the complete and thorough solution analysis of the homologous series of biocompatible PEtOx samples in a very broad range of molecular weights ranging from 11.2 × 103 g mol-1 up to 260 × 103 g mol-1. The main focus of the research was on the determination of the conformational properties of PEtOx macromolecules at a temperature of 37 °C in phosphate buffered saline (PBS) simulating the parameters of physiological media. The polymers were studied in PBS solutions by analytical ultracentrifugation, dynamic light scattering (DLS), translational diffusion, and intrinsic viscosity measurements in a temperature range from 15 °C up to 72 °C. The complete set of Kuhn-Mark-Houwink-Sakurada scaling relationships revealed linear trends over the whole range of the studied molar masses, while the determined scaling indices at 37 °C correspond to the coil conformation in a thermodynamically good solvent ([η] = 0.045 × M0.62, s0 = 0.010 × M0.46 and D0 = 1750 × M-0.54). Based on the intrinsic viscosity values (most sensitive characteristic to the size variations of polymer coils, [η] ∼ r3), it was demonstrated that PEtOx macromolecules in PBS solutions undergo a transition from swollen polymer coils with gradual deterioration of thermodynamic quality of solutions within the temperature range of 15-45 °C, reaching conditions at 55 °C with further precipitation at 62-72 °C. Also, to the best of our knowledge, the conformational parameters (equilibrium rigidity/the Kuhn segment length and the diameter of the polymer chain) of PEtOx macromolecules were evaluated under physiological conditions for the first time and constitute A = 1.8 ± 0.3 nm and d = 0.7 ± 0.4 nm. These equilibrium rigidity values classify PEtOx as a flexible macromolecule with rigidity similar to that of poly(ethylene glycol). For the first time, we were able to demonstrate a direct influence of thermosensitivity on the rigidity of the biocompatible polymer: PEtOx. The Kuhn segment length is undoubtedly decreasing when approaching the LCST.",
author = "Gubarev, {Alexander S.} and Monnery, {Bryn D.} and Lezov, {Alexey A.} and Ondrej Sedlacek and Tsvetkov, {Nikolai V.} and Richard Hoogenboom and Filippov, {Sergey K.}",
year = "2018",
month = "5",
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doi = "10.1039/c8py00255j",
language = "English",
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journal = "Polymer Chemistry",
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TY - JOUR

T1 - Conformational properties of biocompatible poly(2-ethyl-2-oxazoline)s in phosphate buffered saline

AU - Gubarev, Alexander S.

AU - Monnery, Bryn D.

AU - Lezov, Alexey A.

AU - Sedlacek, Ondrej

AU - Tsvetkov, Nikolai V.

AU - Hoogenboom, Richard

AU - Filippov, Sergey K.

PY - 2018/5/1

Y1 - 2018/5/1

N2 - Inspired by the increasing popularity of poly(2-ethyl-2-oxazoline) (PEtOx) for biomedical applications, this study reports the complete and thorough solution analysis of the homologous series of biocompatible PEtOx samples in a very broad range of molecular weights ranging from 11.2 × 103 g mol-1 up to 260 × 103 g mol-1. The main focus of the research was on the determination of the conformational properties of PEtOx macromolecules at a temperature of 37 °C in phosphate buffered saline (PBS) simulating the parameters of physiological media. The polymers were studied in PBS solutions by analytical ultracentrifugation, dynamic light scattering (DLS), translational diffusion, and intrinsic viscosity measurements in a temperature range from 15 °C up to 72 °C. The complete set of Kuhn-Mark-Houwink-Sakurada scaling relationships revealed linear trends over the whole range of the studied molar masses, while the determined scaling indices at 37 °C correspond to the coil conformation in a thermodynamically good solvent ([η] = 0.045 × M0.62, s0 = 0.010 × M0.46 and D0 = 1750 × M-0.54). Based on the intrinsic viscosity values (most sensitive characteristic to the size variations of polymer coils, [η] ∼ r3), it was demonstrated that PEtOx macromolecules in PBS solutions undergo a transition from swollen polymer coils with gradual deterioration of thermodynamic quality of solutions within the temperature range of 15-45 °C, reaching conditions at 55 °C with further precipitation at 62-72 °C. Also, to the best of our knowledge, the conformational parameters (equilibrium rigidity/the Kuhn segment length and the diameter of the polymer chain) of PEtOx macromolecules were evaluated under physiological conditions for the first time and constitute A = 1.8 ± 0.3 nm and d = 0.7 ± 0.4 nm. These equilibrium rigidity values classify PEtOx as a flexible macromolecule with rigidity similar to that of poly(ethylene glycol). For the first time, we were able to demonstrate a direct influence of thermosensitivity on the rigidity of the biocompatible polymer: PEtOx. The Kuhn segment length is undoubtedly decreasing when approaching the LCST.

AB - Inspired by the increasing popularity of poly(2-ethyl-2-oxazoline) (PEtOx) for biomedical applications, this study reports the complete and thorough solution analysis of the homologous series of biocompatible PEtOx samples in a very broad range of molecular weights ranging from 11.2 × 103 g mol-1 up to 260 × 103 g mol-1. The main focus of the research was on the determination of the conformational properties of PEtOx macromolecules at a temperature of 37 °C in phosphate buffered saline (PBS) simulating the parameters of physiological media. The polymers were studied in PBS solutions by analytical ultracentrifugation, dynamic light scattering (DLS), translational diffusion, and intrinsic viscosity measurements in a temperature range from 15 °C up to 72 °C. The complete set of Kuhn-Mark-Houwink-Sakurada scaling relationships revealed linear trends over the whole range of the studied molar masses, while the determined scaling indices at 37 °C correspond to the coil conformation in a thermodynamically good solvent ([η] = 0.045 × M0.62, s0 = 0.010 × M0.46 and D0 = 1750 × M-0.54). Based on the intrinsic viscosity values (most sensitive characteristic to the size variations of polymer coils, [η] ∼ r3), it was demonstrated that PEtOx macromolecules in PBS solutions undergo a transition from swollen polymer coils with gradual deterioration of thermodynamic quality of solutions within the temperature range of 15-45 °C, reaching conditions at 55 °C with further precipitation at 62-72 °C. Also, to the best of our knowledge, the conformational parameters (equilibrium rigidity/the Kuhn segment length and the diameter of the polymer chain) of PEtOx macromolecules were evaluated under physiological conditions for the first time and constitute A = 1.8 ± 0.3 nm and d = 0.7 ± 0.4 nm. These equilibrium rigidity values classify PEtOx as a flexible macromolecule with rigidity similar to that of poly(ethylene glycol). For the first time, we were able to demonstrate a direct influence of thermosensitivity on the rigidity of the biocompatible polymer: PEtOx. The Kuhn segment length is undoubtedly decreasing when approaching the LCST.

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