Journal article
A hydrogel based nanosensor with an unprecedented broad sensitivity range for pH measurements in cellular compartments
Technical University of Denmark1
Department of Micro- and Nanotechnology, Technical University of Denmark2
Colloids and Biological Interfaces, Department of Micro- and Nanotechnology, Technical University of Denmark3
Department of Chemistry, Technical University of Denmark4
Physical and Biophysical Chemistry, Department of Chemistry, Technical University of Denmark5
Shanghai Jiao Tong University6
Organic Chemistry, Department of Chemistry, Technical University of Denmark7
Optical pH nanosensors have been applied for monitoring intracellular pH in real-time for about two decades. However, the pH sensitivity range of most nanosensors is too narrow, and measurements that are on the borderline of this range may not be correct. Furthermore, ratiometric measurements of acidic intracellular pH (pH < 4) in living cells are still challenging due to the lack of suitable nanosensors.
In this paper we successfully developed a multiple sensor, a fluorophore based nanosensor, with an unprecedented broad measurement range from pH 1.4 to 7.0. In this nanosensor, three pH-sensitive fluorophores (difluoro-Oregon Green, Oregon Green 488, and fluorescein) and one pH-insensitive fluorophore (Alexa 568) were covalently incorporated into a nanoparticle hydrogel matrix.
With this broad range quadruple-labelled nanosensor all physiological relevant pH levels in living cells can be measured without being too close to the limits of its pH-range. The nanosensor exhibits no susceptibility to interference by other intracellular ions at physiological concentrations. Due to its positive surface charge it is spontaneously internalized by HeLa cells and localizes to the lysosomes where the mean pH was measured at 4.6.
This quadruple-labelled nanosensor performs accurate measurements of fluctuations of lysosomal pH in both directions, which was shown by treatment with the V-ATPase inhibitor bafilomycin A1 or its substrate ATP in HeLa cells. These measurements indicate that this novel quadruple-labelled nanosensor is a promising new tool for measuring the pH of acidic compartments in living cells.
Language: | English |
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Publisher: | The Royal Society of Chemistry |
Year: | 2015 |
Pages: | 7246-7253 |
ISSN: | 13645528 and 00032654 |
Types: | Journal article |
DOI: | 10.1039/c5an01014d |
ORCIDs: | Henriksen, Jonas Rosager , Clausen, Mads Hartvig and Andresen, Thomas Lars |
Biosensing Techniques Calibration Carboxylic Acids Fluorescein Fluorescent Dyes HeLa Cells Heterocyclic Compounds, 4 or More Rings Humans Hydrogels Hydrogen-Ion Concentration Ions Lysosomes Microscopy, Confocal Microscopy, Fluorescence Nanoparticles Nanotechnology Oregon Green 488 carboxylic acid Reproducibility of Results alexa 568