A Cu(II) Indicator Platform Based on Cu(II) Induced Swelling that Changes the Extent of Fluorescein Self-Quenching

In this study, we established a new fluorescent indicator platform. The responsive element consists of poly(N-isopropylacrylamide) nanospheres that include small percentages of fluorescein and a ligand, anilinodiacetate (phenylIDA). Nanosphere diameters were determined to be in the range from 50 to...

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Bibliographic Details
Published in:Polymers 2019-11, Vol.11 (12), p.1935
Main Authors: Wang, Feifei, Planalp, Roy P, Seitz, W Rudolf
Format: Article
Language:English
Subjects:
Acidification
Acids
Binding sites
Bioavailability
Copper
Diameters
Emulsion polymerization
Fluorescein
Fluorescent indicators
High temperature
Ligands
Metal ions
Molecular weight
Nanoparticles
Nanospheres
Nitrates
Photon correlation spectroscopy
Polyacrylamide
Polyisopropyl acrylamide
Polymers
Potassium
Quenching
Scanning electron microscopy
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Summary:In this study, we established a new fluorescent indicator platform. The responsive element consists of poly(N-isopropylacrylamide) nanospheres that include small percentages of fluorescein and a ligand, anilinodiacetate (phenylIDA). Nanosphere diameters were determined to be in the range from 50 to 90 nm by scanning electron microscopy. They were entrapped in a polyacrylamide gel to prevent nanosphere aggregation. At pH 6, the ligand is negatively charged in the absence of metal ions. Charge-charge repulsion causes the nanosphere to swell. Dynamic light scattering measurements show that these nanospheres do not shrink and aggregate at high temperature. Cu(II) binding neutralizes the charge causing the particles to shrink. This brings fluoresceins closer together, increasing the degree of self-quenching. The intensity decreases by 30% as Cu(II) concentration increases. To rule out the possibility that the observed decrease in intensity was due to Cu(II) quenching of fluorescence, we also added Zn(II) and observed a decrease in intensity. This approach can be adapted to sense different metal ions and different concentrations of Cu(II) by changing the ligand.
ISSN:2073-4360
2073-4360
DOI:10.3390/polym11121935