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Quantum-dot/dopamine bioconjugates function as redox coupled assemblies for in vitro and intracellular pH sensing

Academic Article
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Overview

authors

  • Medintz, I. L.
  • Stewart, M. H.
  • Trammell, S. A.
  • Susumu, K.
  • Delehanty, J. B.
  • Mei, B. C.
  • Melinger, J. S.
  • Blanco-Canosa, J. B.
  • Dawson, Philip
  • Mattoussi, H.

publication date

  • 2010

journal

  • Nature Materials  Journal

abstract

  • The use of semiconductor quantum dots (QDs) for bioimaging and sensing has progressively matured over the past decade. QDs are highly sensitive to charge-transfer processes, which can alter their optical properties. Here, we demonstrate that QD-dopamine-peptide bioconjugates can function as charge-transfer coupled pH sensors. Dopamine is normally characterized by two intrinsic redox properties: a Nernstian dependence of formal potential on pH and oxidation of hydroquinone to quinone by O(2) at basic pH. We show that the latter quinone can function as an electron acceptor quenching QD photoluminescence in a manner that depends directly on pH. We characterize the pH-dependent QD quenching using both electrochemistry and spectroscopy. QD-dopamine conjugates were also used as pH sensors that measured changes in cytoplasmic pH as cells underwent drug-induced alkalosis. A detailed mechanism describing the QD quenching processes that is consistent with dopamine's inherent redox chemistry is presented.

subject areas

  • Animals
  • Biocompatible Materials
  • Biosensing Techniques
  • COS Cells
  • Cercopithecus aethiops
  • Cytoplasm
  • Dopamine
  • Hydrogen-Ion Concentration
  • Materials Testing
  • Nanotechnology
  • Oxidation-Reduction
  • Oxygen
  • Peptides
  • Quantum Dots
  • Spectrophotometry
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Identity

International Standard Serial Number (ISSN)

  • 1476-1122

Digital Object Identifier (DOI)

  • 10.1038/nmat2811

PubMed ID

  • 20651808
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Additional Document Info

start page

  • 676

end page

  • 684

volume

  • 9

issue

  • 8

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