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Issue 23, 2019
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Single droplet detection of immune checkpoints on a multiplexed electrohydrodynamic biosensor

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Abstract

Monitoring soluble immune checkpoints in circulating fluids has the potential for minimally-invasive diagnostics and personalised therapy in precision medicine. Yet, the sensitive detection of multiple immune checkpoints from small volumes of liquid biopsy samples is challenging. In this study, we develop a multiplexed immune checkpoint biosensor (MICB) for parallel detection of soluble immune checkpoints PD-1, PD-L1, and LAG-3. MICB integrates a microfluidic sandwich immunoassay using engineered single chain variable fragments and alternating current electrohydrodynamic in situ nanofluidic mixing for promoting biosensor–target interaction and reducing non-specific non-target binding. MICB provides advantages of simultaneous analysis of up to 28 samples in <2 h, requires as little as a single sample drop (i.e., 20 μL) per target immune checkpoint, and applies high-affinity yeast cell-derived single chain variable fragments as a cost-effective alternative to monoclonal antibodies. We investigate the assay performance of MICB and demonstrate its capability for accurate immune checkpoint detection in simulated patient serum samples at clinically-relevant levels. MICB provides a dynamic range of 5 to 200 pg mL−1 for PD-1 and PD-L1, and 50 to 1000 pg mL−1 for LAG-3 with a coefficient of variation <13.8%. Sensitive immune checkpoint detection was achieved with limits of detection values of 5 pg mL−1 for PD-1, 5 pg mL−1 for PD-L1, and 50 pg mL−1 for LAG-3. The multiplexing capability, sensitivity, and relative assay simplicity of MICB make it capable of serving as a bioanalytical tool for immune checkpoint therapy monitoring.

Graphical abstract: Single droplet detection of immune checkpoints on a multiplexed electrohydrodynamic biosensor

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Publication details

The article was received on 31 Jul 2019, accepted on 15 Oct 2019 and first published on 16 Oct 2019


Article type: Paper
DOI: 10.1039/C9AN01450K
Analyst, 2019,144, 6914-6921

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    Single droplet detection of immune checkpoints on a multiplexed electrohydrodynamic biosensor

    A. Wuethrich, A. R. Rajkumar, K. B. Shanmugasundaram, K. K. Reza, S. Dey, C. B. Howard, A. A. I. Sina and M. Trau, Analyst, 2019, 144, 6914
    DOI: 10.1039/C9AN01450K

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