Microfluidic Digital Nanobiosensors for Point-of-Care Detection of Analytes

Detection, identification and quantification of molecular biomarkers, such as proteins, peptides, exosomes, hormones, neurotransmitters, metabolites and nucleic acids, are critical to disease diagnosis, progression monitoring, and management. While there are numerous approaches for analyzing biomarkers, the most validated and well-established is ELISA. Although powerful, the limit of detection (LOD) and time required for testing in ELISA techniques are oftentimes insufficient for the majority of clinical applications. Digital immunoassay methods have been developed for single molecule analyses, however, improved detection limits come at the expense of test time (e.g., >1 hr) and dynamic range (e.g., <2 ng/mL), which are critical for timely diagnosis and treatment.

 

Researchers at the Biodesign Institute of Arizona State University and collaborators have developed time-resolved digital immunoassay nanobiosensors that utilize optical-based imaging of antibody-conjugated nanoparticles for rapid detection of biomarkers with a wide dynamic range. These nanobiosensors provide high contrast and fast imaging so that single molecule binding events can be detected. Real-time counting of the nanoparticles as they bind to the biomarkers enables accurate assessment of biomarker concentration without requiring lengthy incubation or additional sample processing. Further, super-localization tracking of each nanoparticle and real-time counting allows two binding events to be detected within a distance smaller than the diffraction limit, enhancing the dynamic range and minimizing counting error. These nanobiosensors have been utilized to detect and quantify NT-proBNP concentrations in whole blood samples, cardiac troponin in plasma and blood, procalcitonin in serum, and CAR T-cells and cytokines from a drop of blood.

 

These microfluidic digital nanobiosensors are sensitive and POC compatible to rapidly detect and quantify molecular biomarkers with a reduced test time and maximized precision. They would be highly valuable in diagnosing and monitoring diseases where rapid and precise biomarker quantification is needed.

 

Potential Applications

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Dr. Wang’s laboratory webpage