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Title: Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric Probes of Intracellular pH

Intracellular pH is a key parameter in many biological mechanisms and cell metabolism and is used to detect and monitor cancer formation and brain or heart diseases. pH-sensing is typically performed by fluorescence microscopy using pH-responsive dyes. Accuracy is limited by the need for quantifying the absolute emission intensity in living biological samples. An alternative with a higher sensitivity and precision uses probes with a ratiometric response arising from the different pH-sensitivity of two emission channels of a single emitter. Current ratiometric probes are complex constructs suffering from instability and cross-readout due to their broad emission spectra. Here, we overcome such limitations using a single-particle ratiometric pH probe based on dot-in-bulk CdSe/CdS nanocrystals (NCs). These nanostructures feature two fully-separated narrow emissions with different pH sensitivity arising from radiative recombination of core- and shell-localized excitons. The core emission is nearly independent of the pH, whereas the shell luminescence increases in the 3–11 pH range, resulting in a cross-readout-free ratiometric response as strong as 600%. In vitro microscopy demonstrates that the ratiometric response in biologic media resembles the precalibralation curve obtained through far-field titration experiments. The NCs show good biocompatibility, enabling us to monitor in real-time the pH in living cells.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [4] ;  [5] ;  [1]
  1. Univ. degli Studi di Milano-Bicocca, Milano (Italy). Dipartimento di Scienza dei Materiali
  2. Istituto Italiano di Tecnologia, Milano (Italy). Center for Nano Science and Technology
  3. Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Photo-Electronic Hybrids Research Center National Agenda Research Division
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  5. Univ. degli Studi di Milano-Bicocca, Milano (Italy). Dipartimento di Scienza dei Materiali; Politecnico di Milano (Italy)
Publication Date:
Report Number(s):
LA-UR-17-31356
Journal ID: ISSN 1616-301X
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 12; Journal ID: ISSN 1616-301X
Publisher:
Wiley
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; bioimaging; colloidal quantum dots; pH sensing; ratiometric sensing; two‐color emission
OSTI Identifier:
1481142
Alternate Identifier(s):
OSTI ID: 1400821

Bruni, Francesco, Pedrini, Jacopo, Bossio, Caterina, Santiago-Gonzalez, Beatriz, Meinardi, Francesco, Bae, Wan Ki, Klimov, Victor I., Lanzani, Guglielmo, and Brovelli, Sergio. Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric Probes of Intracellular pH. United States: N. p., Web. doi:10.1002/adfm.201605533.
Bruni, Francesco, Pedrini, Jacopo, Bossio, Caterina, Santiago-Gonzalez, Beatriz, Meinardi, Francesco, Bae, Wan Ki, Klimov, Victor I., Lanzani, Guglielmo, & Brovelli, Sergio. Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric Probes of Intracellular pH. United States. doi:10.1002/adfm.201605533.
Bruni, Francesco, Pedrini, Jacopo, Bossio, Caterina, Santiago-Gonzalez, Beatriz, Meinardi, Francesco, Bae, Wan Ki, Klimov, Victor I., Lanzani, Guglielmo, and Brovelli, Sergio. 2017. "Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric Probes of Intracellular pH". United States. doi:10.1002/adfm.201605533. https://www.osti.gov/servlets/purl/1481142.
@article{osti_1481142,
title = {Two-Color Emitting Colloidal Nanocrystals as Single-Particle Ratiometric Probes of Intracellular pH},
author = {Bruni, Francesco and Pedrini, Jacopo and Bossio, Caterina and Santiago-Gonzalez, Beatriz and Meinardi, Francesco and Bae, Wan Ki and Klimov, Victor I. and Lanzani, Guglielmo and Brovelli, Sergio},
abstractNote = {Intracellular pH is a key parameter in many biological mechanisms and cell metabolism and is used to detect and monitor cancer formation and brain or heart diseases. pH-sensing is typically performed by fluorescence microscopy using pH-responsive dyes. Accuracy is limited by the need for quantifying the absolute emission intensity in living biological samples. An alternative with a higher sensitivity and precision uses probes with a ratiometric response arising from the different pH-sensitivity of two emission channels of a single emitter. Current ratiometric probes are complex constructs suffering from instability and cross-readout due to their broad emission spectra. Here, we overcome such limitations using a single-particle ratiometric pH probe based on dot-in-bulk CdSe/CdS nanocrystals (NCs). These nanostructures feature two fully-separated narrow emissions with different pH sensitivity arising from radiative recombination of core- and shell-localized excitons. The core emission is nearly independent of the pH, whereas the shell luminescence increases in the 3–11 pH range, resulting in a cross-readout-free ratiometric response as strong as 600%. In vitro microscopy demonstrates that the ratiometric response in biologic media resembles the precalibralation curve obtained through far-field titration experiments. The NCs show good biocompatibility, enabling us to monitor in real-time the pH in living cells.},
doi = {10.1002/adfm.201605533},
journal = {Advanced Functional Materials},
number = 12,
volume = 27,
place = {United States},
year = {2017},
month = {2}
}

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