Digital single-molecule detection and absolute quantification of biomarkers

In biochemical analysis, detecting biomarkers is like finding the needle in the haystack. The ultimate ambition of the field is to achieve the sensitivity of single-molecule detection. So far, this is not possible outside of some specific applications, e.g. PCR have us covered for nucleic acids. For majority of biomarkers (e.g., proteins) there is a trade-off between throughput and sensitivity. For example, typical fluorescence plate readers are not able to detect the analyte unless it is present in millions of molecules. Other methods such as ELISA, mass spectrometry, or western blotting, can only provide a generalised readout of population, and testing each assay takes hours or days. That makes them inapplicable to problems like an early detection of tumour growth, requiring much higher sensitivity.

In this talk, I will introduce the digital approach to specific, single-molecule detection and real-time quantification. I will discuss my work addressing this problem using a combination of statistics, fluorescence microscopy, 3D printing and microfluidics. Finally, I will outline the remaining challenges and future opportunities.