Gradient-Based Rapid Digital Immunoassay for High-Sensitivity Cardiac Troponin T (hs-cTnT) Detection in 1 μl Plasma

Wenwen Jing, Yi Wang, Chao Chen, Fenni Zhang, Yunze Yang, Guangzhong Ma, Eric H. Yang, Christine L.N. Snozek, Nongjian Tao, Shaopeng Wang

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Rapid and sensitive detection of biomarkers is the key to the diagnosis of acute diseases. One example is the detection of troponin in myocardial infarction. Here, we report a gradient-based digital immunoassay method, which can achieve high-sensitivity cardiac troponin T (hs-cTnT) detection with only 1 μL of plasma sample. We designed a multizone microfluidic channel functionalized with capture antibody specific to troponin. Taking advantage of limited sample volume, a troponin concentration gradient is created along the channel because of binding induced depletion. We quantified the concentration gradient by counting the detection antibody conjugated gold nanoparticles bound to different test zones with optical imaging. Differential counting between the zones removes most common noises and nonspecific bindings. The total analytical time is about 30 min, and the limit of quantification is 6.2 ng/L. We examined 41 clinical plasma samples from 15 patients and the change in hs-cTnT concentration in serial samples showed good linear correlation with clinical results (R2= 0.98). Therefore, this simple and sensitive gradient-based digital immunoassay method is a promising technology for clinical hs-cTnT detection and could be adapted for detection of other biomarkers.

Original languageEnglish (US)
Pages (from-to)399-407
Number of pages9
JournalACS sensors
Issue number2
StatePublished - Feb 26 2021


  • digital ELISA
  • gradient-based immunoassay
  • high-sensitivity cardiac troponin T (hs-cTnT)
  • microfluidics chip
  • plasma

ASJC Scopus subject areas

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


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