Preliminary Development of a DNA Aptamer-Magnetic Bead Capture Electrochemiluminescence Sandwich Assay for Brain Natriuretic Peptide.

Fifty-two candidate DNA aptamer sequences were selected for binding to the cardiovascular biomarker B-type or brain natriuretic peptide (BNP). Candidate aptamers were screened to rank their relative affinities against BNP by an aptamer-based ELISA-like aptamer microplate assay (ELASA). The highest affinity aptamers from ELASA screening were also paired in all possible combinations and screened for electrochemiluminescence (ECL) assay potential in capture aptamer-magnetic bead and ruthenium trisbipyridine (Ru(bpy)32+)-reporter aptamer sandwich formats. The top ECL sandwich combinations utilized the same aptamer pair in either capture or reporting roles with nanogram to low picogram per mL levels of detection even in 50% human serum. ECL assay sensitivity and linearity even in 50% human serum suggest that the aptamer-based assay is at least comparable to other reported immunoassays for BNP.