2 research outputs found
Novel Highly Selective and Reversible Chemosensors Based on Dual-Ratiometric Fluorescent Electrospun Nanofibers with pH- and Fe<sup>3+</sup>-Modulated Multicolor Fluorescence Emission
Novel dual-ratiometric fluorescent
electrospun (ES) nanofibers featuring high sensitivity for pH and
ferric ion (Fe<sup>3+</sup>) were prepared using binary blends of
poly(2-hydroxyethyl methacrylate<i>-<i>co</i>-N</i>-methylolacrylamide<i>-<i>co</i>-</i>nitrobenzoxadiazolyl
derivative) (poly(HEMA<i>-<i>co</i>-</i>NMA<i>-<i>co</i>-</i>NBD)) and a spirolactam rhodamine derivative
(SRhBOH) by employing a single-capillary spinneret. The HEMA, NMA,
and NBD moieties were designed to exhibit hydrophilic properties,
chemical cross-linking, and fluorescence (fluorescence resonance energy
transfer (FRET) donor), respectively. The fluorescence emission of
SRhBOH was highly selective for pH and Fe<sup>3+</sup>; when SRhBOH
detected acidic media and Fe<sup>3+</sup>, the spirocyclic form of
SRhBOH, which is nonfluorescent, was transformed into the opened cyclic
form and exhibited strong fluorescence emission. The emission colors
of ES nanofibers in acidic or Fe<sup>3+</sup> aqueous solutions changed
from green to red because of FRET from NBD (donor) to SRhBOH (acceptor).
The off/on switching of the FRET process was modulated by adjusting
the SRhBOH blending ratio, pH, and Fe<sup>3+</sup> concentration.
Poly(HEMA<i>-<i>co</i>-</i>NMA<i>-<i>co</i>-</i>NBD) ES fibers blended with 20% SRhBOH showed
high sensitivity in sensing Fe<sup>3+</sup> and pH because of the
substantial 57 nm red shift in emission as well as substantial reversible
dual photoluminescence. The prepared FRET-based dual-ratiometric fluorescent
ES nanofibrous membranes can be used as “naked eye”
sensors and have potential for application in multifunctional environment
sensing devices