Electrophoretic build-up of multi nanoparticle array for a highly sensitive immunoassay

Jin Hee Han, Hee Joo Kim, L. Sudheendra, Elizabeth A. Hass, Shirley J. Gee, Bruce D. Hammock, Ian M. Kennedy

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


One of the challenges in shrinking immunoassays to smaller sizes is to immobilize the biological molecules to nanometer-scaled spots. To overcome this complication, we have employed a particle-based immunoassay to create a nanostructured platform with a regular array of sensing elements. The technique makes use of an electrophoretic particle entrapment system (EPES) to immobilize nanoparticles that are coated with biological reagents into wells using a very small trapping potential. To provide useful information for controlling the trapping force and optimal design of the nanoarray, electrophoretic trapping of a nanoparticle was modeled numerically. The trapping efficiency, defined as the fraction of wells occupied by a single particle, was 91%. The performance of the array was demonstrated with a competitive immunoassay for a small molecule analyte, 3-phenoxybenzoic acid (214.2gmole-1). The limit of detection determined with a basic fluorescence microscope was 0.006μgl-1 (30pM); this represented a sixteen-fold improvement in sensitivity compared to a standard 96-well plate-based ELISA; the improvement was attributed to the small size of the sample volume and the presence of light diffraction among factors unique to this structure. The EPES/nanoarray system promises to offer a new standard in applications that require portable, point-of-care and real-time monitoring with high sensitivity.

Original languageEnglish (US)
Pages (from-to)302-308
Number of pages7
JournalBiosensors and Bioelectronics
Issue number1
StatePublished - Mar 15 2013


  • 3-phenoxybenzoic acid (3-PBA)
  • Electrophoretic particle entrapment system
  • Immunoassay
  • Nanoarray

ASJC Scopus subject areas

  • Biophysics
  • Biomedical Engineering
  • Biotechnology
  • Electrochemistry
  • Medicine(all)


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