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@ARTICLE{GonzlezGaitano:200996,
author = {González-Gaitano, Gustavo and da Silva, Marcelo A. and
Radulescu, Aurel and Dreiss, Cécile A.},
title = {{S}elective {T}uning of the {S}elf-{A}ssembly and
{G}elation of a {H}ydrophilic {P}oloxamine by
{C}yclodextrins},
journal = {Langmuir},
volume = {31},
number = {20},
issn = {1520-5827},
address = {Washington, DC},
publisher = {ACS Publ.},
reportid = {FZJ-2015-03315},
pages = {5645 - 5655},
year = {2015},
abstract = {Complexes formed between cyclodextrins (CDs) and polymers -
pseudopolyrotaxanes (PPRs) - are the starting point of a
multitude of supramolecular structures, which are proposed
for a wide range of biomedical and technological
applications. In this work, we investigate the complexation
of a range of cyclodextrins with Tetronic T1307, a four-arm
block copolymer of poly(ethylene oxide)-poly(propylene
oxide)-poly(ethylene oxide) with a pH-responsive central
ethylene diamine spacer, and its impact on micellization and
the sol–gel transition. At low concentrations, small-angle
neutron scattering (SANS) combined with dynamic light
scattering (DLS) measurements show the presence of spherical
micelles with a highly hydrated shell and a dehydrated core.
Increasing the temperature leads to more compact micelles
and larger aggregation numbers, whereas acidic conditions
induce a shrinking of the micelles, with fewer unimers per
micelle and a more hydrated corona. At high concentrations,
T1307 undergoes a sol–gel transition, which is suppressed
at pH below the pKa,1 (4.6). SANS data analysis reveals that
the gels result from a random packing of the micelles, which
have an increasing aggregation number and increasingly
dehydrated shell and hydrated core with the temperature.
Native CDs (α, β, γ-CD) can complex T1307, resulting in
the precipitation of a PPR. Instead, modified CDs compete
with micellization to an extent that is critically dependent
on the nature of the substitution. 1H and ROESY NMR combined
with SANS demonstrate that dimethylated β-CD can thread
onto the polymer, preferentially binding to the PO units,
thus hindering self-aggregation by solubilizing the
hydrophobic block. The various CDs are able to modulate the
onset of gelation and the extent of the gel phase, and the
effect correlates with the ability of the CDs to disrupt the
micelles, with the exception of a sulfated sodium salt of
β-CD, which, while not affecting the CMT, is able to fully
suppress the gel phase},
cin = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
(München) ; JCNS-FRM-II / ICS-1},
ddc = {670},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)ICS-1-20110106},
pnm = {6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)KWS2-20140101},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000355382300012},
pubmed = {pmid:25938931},
doi = {10.1021/acs.langmuir.5b01081},
url = {https://juser.fz-juelich.de/record/200996},
}