title: Switchable catalytic acrylamide hydrogels cross-linked by hemin/G-quadruplexes.
abstract: Copolymer chains consisting of acrylamide units and guanine (G)-containing oligonucleotide-tethered acrylamide units undergo, in the presence of K(+) ions, cross-linking by G-quadruplexes to yield a hydrogel. The hydrogel is dissociated upon addition of 18-crown-6 ether that traps the K(+) ions. Reversible formation and dissociation of the hydrogel is demonstrated by the cyclic addition of K(+) ions and 18-crown-6 ether, respectively. Formation of the hydrogel in the presence of hemin results in a hemin/G-quadruplex-cross-linked catalytic hydrogel mimicking the function of horseradish peroxidase, reflected by the catalyzed oxidation of 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid), ABTS(2-), by H2O2 to ABTS(·-) and by the catalyzed generation of chemiluminescence in the presence of luminol/H2O2. Cyclic "ON" and "OFF" activation of the catalytic functions of the hydrogel are demonstrated upon the formation of the hydrogel in the presence of K(+) ions and its dissociation by 18-crown-6 ether, respectively. The hydrogel is characterized by rheology measurements, circular dichroism, and probing its chemical and photophysical properties.
authors: Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Jerusalem 91904, Israel.
authors: Chun-Hua
authors: CH
authors: Lu
authors: Xiu-Juan
authors: XJ
authors: Qi
authors: Ron
authors: R
authors: Orbach
authors: Huang-Hao
authors: HH
authors: Yang
authors: Iris
authors: I
authors: Mironi-Harpaz
authors: Dror
authors: D
authors: Seliktar
authors: Itamar
authors: I
authors: Willner
mesh_terms: D020106:Acrylamide / Q000737:chemistry*; D002384:Catalysis; D054856:G-Quadruplexes; D006427:Hemin / Q000737:chemistry*; D020100:Hydrogels; D049449:Luminescence; D010084:Oxidation-Reduction
chemical_list: D020100:Hydrogels; D020106:Acrylamide; D006427:Hemin