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Chopped optical biosensing enables temporal background subtraction for high-sensitivity fluorescence immunoassays
Shmuel Burg1, Yossi Yossef Teboul1, Meir Cohen1
1Faculty of Engineering, The Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Max and Anna Webb Street, Ramat Gan, 5290002, Israel.
Talanta
|March 15, 2026
Summary
Chopped Optical Biosensing (COB) enhances fluorescence immunoassay sensitivity by temporally separating background and target signals. This novel method achieves low detection limits for biomarkers and improves diagnostic accuracy, offering a practical foundation for streamlined workflows.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Biosensing Technology
Background:
- Fluorescence immunoassays are crucial for biomarker detection but suffer from background noise limiting sensitivity.
- Sources of background noise include unbound fluorophores, Raman scattering, and sample autofluorescence.
- Existing methods often require complex steps like washing or dynamic optical modulation.
Purpose of the Study:
- To introduce Chopped Optical Biosensing (COB), a novel analytical framework to enhance fluorescence immunoassay sensitivity.
- To demonstrate COB's ability to suppress background signals and improve detection limits.
- To validate COB's performance using clinically relevant biomarkers and serum samples.
Main Methods:
- COB utilizes magnetic beads to capture targets and concentrates them in a detection region.
- An optical chopper gates the excitation beam, enabling sequential background and target+background fluorescence measurements.
- Signal subtraction isolates target fluorescence, suppressing background noise and reducing photobleaching.
Main Results:
- Achieved low detection limits: 61 fM for Atto 532 dye, 0.05 ng/L for interleukin-8 (IL-8), and 3 ng/mL for anti-dengue virus NS1 IgG.
- Demonstrated high reproducibility below 15% and a total assay time of approximately 90 minutes.
- Successfully classified all 64 serum samples in a feasibility study for anti-DENV-2 NS1 IgG detection.
Conclusions:
- COB effectively suppresses background noise, significantly enhancing fluorescence immunoassay sensitivity and accuracy.
- The method offers a low-complexity, energy-efficient, and practical solution for biomarker detection.
- COB is well-suited for streamlined workflows and future portable diagnostic applications.
