Wide dynamic range sensing with single quantum dot biosensors

Stacey R. Opperwall, Anand Divakaran, Elizabeth G. Porter, Jeffrey A. Christians, Andrew J. Denhartigh, David E. Benson

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Single-particle analysis of biosensors that use charge transfer as the means for analyte-dependent signaling with semiconductor nanoparticles, or quantum dots, was examined. Single-particle analysis of biosensors that use energy transfer show analyte-dependent switching of nanoparticle emission from off to on. The charge-transfer-based biosensors reported here show constant emission, where the analyte (maltose) increases the emission intensity. By monitoring the same nanoparticles under various conditions, a single charge-transfer-based biosensor construct (one maltose binding protein, one protein attachment position for the reductant, one type of nanoparticle) showed a dynamic range for analyte (maltose) detection spanning from 100 pM to 10 μM while the emission intensities increase from 25 to 175% at the single-particle level. Since these biosensors were immobilized, the correlation between the detected maltose concentration and the maltose-dependent emission intensity increase could be examined. Minimal correlation between maltose detection limits and emission increases was observed, suggesting a variety of reductant-nanoparticle surface interactions that control maltose-dependent emission intensity responses. Despite the heterogeneous responses, monitoring biosensor emission intensity over 5 min provided a quantifiable method to monitor maltose concentration. Immobilizing and tracking these biosensors with heterogeneous responses, however, expanded the analyte-dependent emission intensity and the analyte dynamic range obtained from a single construct. Given the wide dynamic range and constant emission of charge-transfer-based biosensors, applying these single molecule techniques could provide ultrasensitive, real-time detection of small molecules in living cells.

Original languageEnglish (US)
Pages (from-to)8078-8086
Number of pages9
JournalACS nano
Issue number9
StatePublished - Sep 25 2012
Externally publishedYes

Bibliographical note

Copyright 2012 Elsevier B.V., All rights reserved.


  • biosensors
  • charge transfer
  • dark state
  • hole transfer
  • particle tracking
  • quantum dots
  • single-molecule analysis


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