Detection and quantification of low-abundance biomarkers is essential to early disease detection, monitoring and treatment. While many techniques, have been developed for measuring single molecules, all require signal amplification, via enzyme amplification, or fluorescence or gold nanoparticle probes, which come with their own unique drawbacks, including matrix effects, photobleaching and autofluorescence interference. This makes it impossible to achieve single molecule detection of biomarkers directly in undiluted complex sample matrices, particularly in whole blood.
Researchers at the Biodesign Institute of Arizona State University have developed a real-time mass imaging-based, label-free, single-molecule immunoassay (LFSM-immunoassay). This immunoassay features plasmonic scattering microscopy based real-time mass imaging, a 2-step sandwich assay format-enabled background reduction, and minimization of matrix effect by dynamic tracking. This results in ultra-sensitive and direct protein detection at single-molecule resolution in neat blood sample matrices.
This label-free, single-molecule-immunoassay overcomes the limitation of existing single molecule immunoassays and enables specific, rapid and ultrasensitive detection in undiluted complex sample matrices.
Potential Applications
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Biomarker detection and quantification
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Disease detection, monitoring and treatment
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Benefits and Advantages
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Label free
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Reduces costs
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Eliminates the influence of labelling reagents such as matrix effects and photobleaching/autofluorescence interference
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Simple but with ultrasensitive and direct detection
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The 2-step sandwich assay format separates sample incubation from detection of antibody binding to reduce background signal
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Femtomolar detection sensitivity
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Strong linear correlation (r>0.99) with current technologies and their clinical lab reported value for biomarkers in serum samples
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Works on complex sample matrices including undiluted serum, plasma and whole blood
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Achieves a dynamic range of 8 logs
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Novel image processing algorithms
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