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Published on: September 19, 2017
On-chip latex agglutination immunoassay readout by electrochemical impedance spectroscopy
Shalini Gupta1, Peter K Kilpatrick, Elizabeth Melvin
1Dept. of Chemical Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.
Insights
This study introduces novel impedance-based lab-on-chip immunosensors that monitor latex immunoagglutination using electrochemical impedance spectroscopy (EIS). This method offers a promising approach for developing sensitive, miniaturized sensors for rapid immunotesting.
Area of Science:
- Biomedical Engineering
- Electrochemistry
- Immunosensing
Background:
- Lab-on-chip devices offer miniaturization and potential for rapid diagnostics.
- Electrochemical impedance spectroscopy (EIS) is a sensitive technique for probing interfacial phenomena.
- Immunoagglutination assays are widely used for detecting analytes but can be time-consuming.
Purpose of the Study:
- To develop and characterize a new class of impedance-based lab-on-chip immunosensors.
- To utilize electrochemical impedance spectroscopy (EIS) for monitoring latex immunoagglutination.
- To assess the feasibility of this platform for rapid and sensitive immunotesting.
Main Methods:
- Fabrication of lab-on-chip devices with interdigitated microsized electrodes.
- Coating latex microspheres with antibodies for target antigen detection.
- Monitoring immunoagglutination via electrochemical impedance spectroscopy (EIS) in the 0.1-1 MHz range.
- Analyzing impedance spectra in relation to aggregate morphology and particle sedimentation.
Main Results:
- Reproducible impedance spectra were obtained within minutes.
- Impedance measurements correlated with aggregate morphology and sedimentation rates.
- An equivalent circuit model indicated the dominance of electric double layer interactions.
- The influence of sedimentation time, particle type, size, and concentration was characterized.
Conclusions:
- The developed lab-on-chip immunosensor effectively monitors latex immunoagglutination using EIS.
- The impedance response is sensitive to particle aggregation and sedimentation dynamics.
- This platform shows significant potential for creating sensitive, miniaturized, and rapid immunotesting devices.
Abstract:
We describe a new class of impedance-based lab-on-chip immunosensors in which the immunoagglutination of latex is monitored by electrochemical impedance spectroscopy (EIS). Antibody-coated latex microspheres agglutinated in the presence of target antigens are precipitated from solution between interdigitated microsized electrodes on a chip. Impedance spectra are reproducibly measured in the 0.1-1 MHz frequency range within several minutes and are shown to be dependent on the aggregate morphology and the sedimentation rates of the agglutinated particles. An equivalent circuit model of the system suggests that the impedance is governed primarily by the electric double layer interactions close to the electrode surface. The effects of sedimentation time, particle type, particle size, and concentration are characterized. The readout method holds promise for developing sensitive miniaturized sensors for rapid immunotesting.
