Synthesis and Thermal Responses of Polygonal Poly(ethylene glycol) Analogues

Abstract

As a new type of topological poly(ethylene glycol) (PEG) analogue, a series of polygonal PEGs with digonal to hexagonal structures were developed. Polygonal PEGs with structures between the digonal and tetragonal types showed molecular-level dispersion in water at 20 °C, whereas the pentagonal and hexagonal PEGs aggregated, which is suggestive of enhanced hydrophobicity by ring expansion. Heating induced conformational changes in the polygonal PEGs and increased their hydrophobicity. Among the polygonal PEGs, only the trigonal and hexagonal PEGs showed a distinct thermal response to form and increase the size of the aggregates, respectively. Given that tetragonal and pentagonal PEGs only marginally responded to heat treatment, the thermal responses are likely due to a topological effect. At low temperatures, the larger polygonal PEGs are more restricted despite the expanded rings. The trigonal PEG showed the largest change in mobility, whereas the tetragonal PEG exhibited the smallest change. Hence, the topology of the polygonal PEGs influences the intramolecular packing and the local dynamics.

RETRACTED: Soft Nanotubes Derivatized with Short PEG Chains for Thermally Controllable Extraction and Separation of Peptides

“…Specifically, owing to the high water solubility, low toxicity and antigenicity, and thermal responsivity of PEGs, they have been widely used to increase the water solubility of peptides and proteins, − improve their cellular internalization, prolong their blood circulation time, , facilitate their condensation and separation − and crystallization, , control their adsorption, − suppress their aggregation, , and accelerate their refolding. − However, only polydisperse PEGs , with relatively high molecular weights have been used to date. Recent studies have suggested that the physicochemical properties of PEGs depend strongly not only on their molecular weights and topology − but also on whether or not they are confined in nanospaces. , …”

Thermo-driven self-assembly of a PEG-containing amphiphile in a bilayer membrane

“…As reported previously, an oligoethylene glycol chain responses to temperature elevation to increase the hydrophobicity by a conformational change. [41][42][43][44][45][46][47][48][49] Such a thermal response of the TEG chains in bola-AkDPA to increase the hydrophobicity likely promotes the self-assembly in a bilayer membrane. Under the optical microscopic observations of GUVs DOPC$bola-AkDPA (90/10), uorescent domain formation was not observed during heating and cooling processes between 25 and 60 C, and the spherical morphology of the GUV was essentially unchanged without showing budding or membrane deformation (Fig.…”