(13e) Aptamers for Parallel Protein Measurements

Analytical technologies for parallel measurements of proteins are essential for systematic understanding of complex biological processes. These have the potential to provide economical diagnostic tools with greater accuracy and information content than single protein measurements. Proteomic methods based on electrophoresis, chromatography, and mass spectrometry are powerful for identifying new proteins and their functions but are limited in their flexibility. In contrast, affinity-based parallel analytical techniques that focus on analyzing small sets of proteins of interest are potentially less labor intensive and may provide better sensitivity and dynamic range for the proteins of interest. In this study, we use aptamers, in vitro selected single-stranded DNA or RNA molecules that bind to other molecules with high specificity and affinity, as affinity reagents to develop a new parallel protein analytical technology. Simultaneous and quantitative detection of a coagulation protein, thrombin, and an oncoprotein, platelet derived growth factor (PDGF), were achieved. The assay can sensitively detect both proteins at pico- to low nanomolar concentrations, and showed high specificity and reproducibility in both buffer and serum samples. Moreover, in vitro selection was used to generate new aptamers to acute phase proteins. The selected aptamers bind on the protein in a non-competitive fashion, and will be used in further development of dual aptamer-based protein biosensors.