Rapid Lipid-Based Approach for Normalization of Quantum-Dot-Detected Biomarker Expression on Extracellular Vesicles in Complex Biological Samples

Meryl Rodrigues, Nicole Richards, Bo Ning, Christopher J. Lyon, Tony Y. Hu

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Extracellular vesicles (EVs) are of considerable interest as tumor biomarkers because tumor-derived EVs contain a broad array of information about tumor pathophysiology. However, current EV assays cannot distinguish between EV biomarker differences resulting from altered abundance of a target EV population with stable biomarker expression, altered biomarker expression in a stable target EV population, or effects arising from changes in both parameters. We now describe a rapid nanoparticle- and dye-based fluorescent immunoassay that can distinguish among these possibilities by normalizing EV biomarker levels to EV abundance. In this approach, EVs are captured from complex samples (e.g., serum), stained with a lipophilic dye, and hybridized with antibody-conjugated quantum dot probes for specific EV surface biomarkers. EV dye signal is used to quantify EV abundance and normalize EV surface biomarker expression levels. EVs from malignant and nonmalignant pancreatic cell lines exhibited similar staining, and probe-to-dye ratios did not change with EV abundance, allowing direct analysis of normalized EV biomarker expression without a separate EV quantification step. This EV biomarker normalization approach markedly improved the ability of serum levels of two pancreatic cancer biomarkers, EV EpCAM and EV EphA2, to discriminate pancreatic cancer patients from nonmalignant control subjects. The streamlined workflow and robust results of this assay are suitable for rapid translation to clinical applications and its modular design permits it to be rapidly adapted to quantitate other EV biomarkers by the simple expedient of swapping the antibody-conjugated quantum dot probes for those that recognize a different disease-specific EV biomarker.

Original languageEnglish (US)
Pages (from-to)7623-7631
Number of pages9
JournalNano Letters
Volume19
Issue number11
DOIs
StatePublished - Nov 13 2019

Keywords

  • Extracellular vesicles
  • cancer-associated markers
  • exosomes
  • normalization
  • protein expression
  • quantum dots

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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