Limitations of Label-Free Sensors in Serum Based Molecular Diagnostics

Immunoassay formats applicable for clinical or point-of-care diagnostics fall into two broad classes. One which uses labeled secondary antibodies for signal transduction and the other which does not require the use of any labels. Comparison of the limits of detection (LoD) reported by these two sensing approaches over a wide range of detection techniques and target molecules in serum revealed that labeled techniques achieve 2-3 orders of magnitude better LoDs. Further, a vast majority of commercial tests and recent examples of technology translations are based on labeled assay formats. In light of this data, it is argued that extension of traditional labeled approaches and enhancing their functionality may have better clinical impact than the development of newer label-free techniques.