One-Step Digital Immunoassay for Rapid and Sensitive Detection of Cardiac Troponin i

Yi Wang, Yunze Yang, Chao Chen, Shaopeng Wang, Hui Wang, Wenwen Jing, Nongjian Tao

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


A rapid and sensitive method to detect cardiac troponin I (cTnI) in human blood is critical to the diagnosis and treatment of acute myocardial infarction (AMI). Here, we describe a simple one-step digital immunoassay for single-molecule detection without washing steps. A sample containing cTnI mixed with detection antibody-conjugated gold nanoparticles (AuNPs) is added to a capture antibody-coated sensor surface and the formation of the antibody-cTnI-antibody sandwich is detected by digitally counting the binding of the individual gold nanoparticles to the sensor surface in real time using a bright-field optical imaging setup together with a differential imaging algorithm. The digital immunoassay detects cTnI in undiluted human plasma, which achieves a detection limit of 5.7 ng/L within a detection time of only 10 min, which meets the requirement of current clinical high-sensitivity troponin assay (&tild;70 ng/L cutoff). We anticipate that the one-step and real-time digital immunoassay can be applied to the detection of other disease biomarkers in blood.

Original languageEnglish (US)
Pages (from-to)1126-1131
Number of pages6
JournalACS sensors
Issue number4
StatePublished - Apr 24 2020


  • cardiac troponin I
  • digital immunoassay
  • high-sensitivity troponin assay
  • one-step immunoassay
  • single nanoparticle counting

ASJC Scopus subject areas

  • Bioengineering
  • Instrumentation
  • Process Chemistry and Technology
  • Fluid Flow and Transfer Processes


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