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Wash-free, electrochemical platform for the quantitative, multiplexed detection of specific antibodies
Ryan J White1, Hannah M Kallewaard, Wen Hsieh
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States.
Insights
A new electrochemical sensor detects specific antibodies in blood serum rapidly and quantitatively. This point-of-care diagnostic tool offers sensitive, specific results for various diseases, improving diagnostics.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Immunology
Background:
- Accurate antibody detection is crucial for diagnosing and managing infectious and autoimmune diseases.
- Current point-of-care diagnostics often lack the sensitivity or specificity required for comprehensive antibody analysis.
- A need exists for rapid, direct measurement of antibodies in unprocessed biological samples.
Purpose of the Study:
- To develop a wash-free, electrochemical method for rapid, quantitative detection of specific antibodies.
- To demonstrate the platform's versatility and sensitivity for various antibody targets.
- To enable simultaneous measurement of multiple antibodies in small sample volumes.
Main Methods:
- Designed an electrochemical sensor using electrode-bound nucleic acid scaffolds with polypeptide epitopes and a methylene blue redox reporter.
- Antibody binding to the epitope alters the redox reporter's electron exchange efficiency, generating a measurable current change.
- Fabricated six distinct sensors for different monoclonal antibodies and tested their performance.
Main Results:
- Achieved subnanomolar detection limits, indicating high sensitivity.
- Demonstrated rapid detection with equilibration time constants of approximately 8 minutes.
- Confirmed high specificity, with no significant cross-reactivity between sensors and non-target antibodies.
- Successfully arrayed sensors for multiplexed antibody detection in small serum volumes.
Conclusions:
- The developed sensor platform provides a generalizable approach for rapid and specific antibody quantification.
- This technology has the potential to significantly advance point-of-care diagnostics for a range of diseases.
- The wash-free, direct detection method simplifies sample processing and analysis.
Abstract:
The diagnosis, prevention, and treatment of many illnesses, including infectious and autoimmune diseases, would benefit from the ability to measure specific antibodies directly at the point of care. Thus motivated, we designed a wash-free, electrochemical method for the rapid, quantitative detection of specific antibodies directly in undiluted, unprocessed blood serum. Our approach employs short, contiguous polypeptide epitopes coupled to the distal end of an electrode-bound nucleic acid "scaffold" modified with a reporting methylene blue. The binding of the relevant antibody to the epitope reduces the efficiency with which the redox reporter approaches, and thus exchanges electrons with, the underlying sensor electrode, producing readily measurable change in current. To demonstrate the versatility of the approach, we fabricated a set of six such sensors, each aimed at the detection of a different monoclonal antibody. All six sensors are sensitive (subnanomolar detection limits), rapid (equilibration time constants ∼8 min), and specific (no appreciable cross reactivity with the targets of the other five). When deployed in a millimeter-scale, an 18-pixel array with each of the six sensors in triplicate support the simultaneous measurement of the concentrations of multiple antibodies in a single, submilliliter sample volume. The described sensor platform thus appears be a relatively general approach to the rapid and specific quantification of antibodies in clinical materials.
