ao7b00787_si_001.pdf (1.51 MB)
Embedding Well-Defined Responsive Hydrogels with Nanocontainers: Tunable Materials from Telechelic Polymers and Cyclodextrins
journal contribution
posted on 2017-10-12, 08:14 authored by Mehmet Arslan, Duygu Aydin, Aysun Degirmenci, Amitav Sanyal, Rana SanyalDesign, synthesis, and application
of cyclodextrin (CD) containing
thermoresponsive hydrogels fabricated from thiol-reactive telechelic
polymers are reported. Hydrophilic polymers containing 2-hydroxyethyl
methacrylate and/or di(ethylene glycol)methylether methacrylate monomers
as side chains and thiol-reactive groups at chain ends were synthesized.
A series of hydrogels was fabricated using thiol–ene conjugation
of these thiol-reactive polymers with multivalent thiol-containing
CDs as crosslinkers. Clear and transparent hydrogels were obtained
with good conversion (79–89%) by utilizing the “nucleophilic”
and “radical” thiol–ene “click”
reactions. Analysis of the amount of residual thiol groups in these
hydrogels using Ellman’s reagent suggested that gels with a
moderately well-defined network structure were obtained. Hydrogels
fabricated using different telechelic polymers were examined for their
properties such as morphology, equilibrium water uptake, and rheological
characteristics. Cytocompatibility of these hydrogels was ascertained
by a cell viability assay that demonstrated low toxicity toward fibroblast
cells. Thereafter, the CD-containing hydrogels were evaluated for
the loading and controlled release of puerarin, an antiglaucoma drug.
Utilization of thermoresponsive polymers as the matrix for these hydrogels
allows use of temperature as a stimulus to modulate the drug release.
A slower and more sustained drug release was observed at physiological
temperatures compared to ambient conditions. The effect of temperature
on the elasticity of the hydrogel was investigated rheologically to
demonstrate that the collapse of the network structure occurs near
physiological temperatures. The increased hydrophobicity and compactness
of the gel matrix at higher temperatures results in a slower drug
release. The strategy employed here demonstrates that tuning the matrix
composition of hydrogels with well-defined network structures through
appropriate choice of responsive copolymers allows design of materials
with control of their physical properties and drug-release behavior.