Disease Detection by Ultrasensitive Quantification of Microdosed Synthetic Urinary Biomarkers

The delivery of exogenous agents can enable noninvasive disease monitoring, but existing low-dose approaches require complex infrastructure. In this paper, we describe a microdose-scale injectable formulation of nanoparticles that interrogate the activity of thrombin, a key regulator of clotting, and produce urinary reporters of disease state. We establish a customized single molecule detection assay that enables urinary discrimination of thromboembolic disease in mice using doses of the nanoparticulate diagnostic agents that fall under regulatory guidelines for “microdosing.”National Science Foundation (U.S.). Graduate Research FellowshipNational Institutes of Health (U.S.) (Ruth L. Kirschstein National Research Service Award F32CA159496-02)Burroughs Wellcome Fund (Career Award at the Scientific Interface)National Cancer Institute (U.S.) (Koch Institute Support (Core) Grant P30-CA14051)David H. Koch Institute for Integrative Cancer Research at MIT (Frontier Research Program

Incorporation of Slow Off-Rate Modified Aptamers Reagents in Single Molecule Array Assays for Cytokine Detection with Ultrahigh Sensitivity

Slow off-rate modified aptamers (SOMAmers) are attractive protein recognition reagents due to their high binding affinities, stable chemical structures, easy production, and established selection process. Here, biotinylated SOMAmer reagents were incorporated into single molecule array (Simoa)-based assays in place of traditional detection antibodies for six cytokine targets. Optimization and validation were conducted for TNF-α as a demonstration using a capture antibody/detection-SOMAmer detection scheme to highlight the performance of this approach. The optimized assay has a broad dynamic range (>4 log₁₀ units) and an ultralow detection limit of 0.67 fM (0.012 pg/mL). These results show comparable sensitivity to our antibody pair-based Simoa assays, and tens to thousands-fold enhancement in sensitivity compared with conventional ELISAs. High recovery percentages were observed in a spike-recovery test using human sera, demonstrating the feasibility of this novel Simoa assay in detecting TNF-α in clinically relevant samples. Detection SOMAmers were also used to detect other cytokines, such as IFN-γ, IL-1β, IL-2, IL-6, and IL-10, in human samples. Although not yet demonstrated, in principle it should be possible to eventually replace both the capture and detector antibodies with corresponding SOMAmer pairs in sandwich immunoassays. The combination of the ultrasensitive Simoa platform with the higher reliability of SOMAmer binding reagents will greatly benefit both biomarker discovery and disease diagnostic fields