Analytical techniques for nucleic acid and protein detection with single-molecule sensitivity

Nucleic acids and proteins serve as crucial biomarkers used in the diagnosis, prognosis and therapy monitoring across various diseases. Traditionally, these biomarkers are identified at an ensemble level following the amplification of target or signaling molecules. However, these methods have limitations in addressing contemporary challenges in molecular diagnostics, such as low sensitivity, specificity, throughput and imprecise quantification. To overcome these limitations, various analytical techniques offering single-molecule sensitivity have been developed. Here we aim to provide a concise overview of historically notable and potentially promising analytical techniques to detect nucleic acids and proteins with single-molecule sensitivity. Our focus is on their potential in liquid biopsy, delineating their strengths and weaknesses, providing insights into their ability to revolutionize biomarker analysis and paving the way for more advanced technologies.