Abstract
<jats:p>Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disease associated with repetitive head trauma, for which there is currently no well-established antemortem diagnostic biomarker. In this report, a proof-of-concept experiment is described for conditions optimized for the selection and detection of aptamers against S100B, a biomarker for blood-brain barrier disruption that is elevated following traumatic brain injury, as a potential improvement to the wave-mixing CTE biomarker detector conceptualized in Chapter 5. A fast three-round systematic evolution of ligands by exponential enrichment (SELEX) procedure was established using a FAM-labeled random 40-nucleotide ssDNA library targeting pure biotinylated S100B immobilized on streptavidin magnetic beads. The stringency of selection was gradually increased over the rounds by increasing the number of wash steps from 3 to 7 and reducing the target protein concentration by half in Round 3. The inter-round Polymerase Chain Reaction (PCR) amplification using REDTaq ReadyMix and 15, 12, and 10 cycles for Rounds 1, 2, and the final Round (Round 3) generated high-affinity binding sequences. The enriched aptamer exhibited intense absorbance at 494 nm and a strong wave-mixing signal at 532 nm. Capillary electrophoresis (CE) was employed to characterize the enriched aptamer pool, and binding parameters, including KD values (dissociation constants), were determined using a onesite binding model. The technical principle of an enriched aptamer wave-mixing CE integrated platform for antibody-free, label-free CTE biomarker detection has been demonstrated, and the results provide a direction for further improvement and the establishment of an optimized clinical detection system.</jats:p>