Aptamer Conformation Cooperated Enzyme-assisted SERS (ACCESS) Enabling Ultrasensitive Detection of Cell Surface Protein Biomarkers in Blood Samples.

It is an active research field to develop novel strategies for sensitive and specific detection of protein biomarkers. Here we report an ultrasensitive biosensor to detect PTK7, an important protein biomarker on the cell surface, by aptamer conformation cooperated enzyme-assisted SERS (ACCESS) technology. Our approach features a synergistic combination of the conformational alteration of the anglerfish aptamer triggered by the recognition of the membrane protein (PTK7), and Exo III enzyme-assisted nucleic acid amplification. It transduces the specific binding events between the aptamer and PTK7 protein into dramatically improved SERS signals. Sensitive and specific detection of PTK7 protein has been demonstrated both in the solution and directly on the surface of live CCRF-CEM cells, with limit of detection (LOD) better than the commercial ELISA method by nearly 5 orders of magnitude. As a flexible, ultrasensitive, and specific approach, ACCESS promises important applications in clinical diagnostics where only a very limited amount of the biological sample is available.