Open AccessBioinspired design of a polymer gel sensor for the realization of extracellular Ca2+ imaging
Author(s) -
Fumitaka Ishiwari,
Hanako Hasebe,
Satoko Matsumura,
Fatin Hajjaj,
Noriko Horii-Hayashi,
Mayumi Nishi,
Takao Someya,
Takanori Fukushima
Publication year - 2016
Publication title -
scientific reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.24
H-Index - 213
ISSN - 2045-2322
DOI - 10.1038/srep24275
Subject(s) - extracellular , chemistry , biophysics , dissociation constant , polyacrylic acid , fluorescence , intracellular , molar concentration , dissociation (chemistry) , analyte , biochemistry , polymer , chromatography , receptor , organic chemistry , biology , physics , quantum mechanics
Although the role of extracellular Ca 2+ draws increasing attention as a messenger in intercellular communications, there is currently no tool available for imaging Ca 2+ dynamics in extracellular regions. Here we report the first solid-state fluorescent Ca 2+ sensor that fulfills the essential requirements for realizing extracellular Ca 2+ imaging. Inspired by natural extracellular Ca 2+ -sensing receptors, we designed a particular type of chemically-crosslinked polyacrylic acid gel, which can undergo single-chain aggregation in the presence of Ca 2+ . By attaching aggregation-induced emission luminogen to the polyacrylic acid as a pendant, the conformational state of the main chain at a given Ca 2+ concentration is successfully translated into fluorescence property. The Ca 2+ sensor has a millimolar-order apparent dissociation constant compatible with extracellular Ca 2+ concentrations, and exhibits sufficient dynamic range and excellent selectivity in the presence of physiological concentrations of biologically relevant ions, thus enabling monitoring of submillimolar fluctuations of Ca 2+ in flowing analytes containing millimolar Ca 2+ concentrations.