Fluorescent aptasensor based on target-induced hairpin conformation switch coupled with nicking enzyme-assisted signal amplification for detection of beta-amyloid oligomers in cerebrospinal fluid.

A fluorescent aptasensor was developed based on target-induced hairpin conformation switch coupled with nicking enzyme-assisted signal amplification (NESA) to detect the oligomeric form of ß-amyolid peptide (AβO) in cerebrospinal fluid. The hairpin DNA probe (HP) was specifically designed to recognize AβO. When AβO is present in the sensing system, it induces an HP conformational switch and triggers the NESA reaction. After evaluating the parameters of the aptasensor system, we selected Hairpin10, which has a 10-nucleotide extended sequence, as the hairpin sequence that interacts with AβO. The quantitative linear range of the proposed aptasensor is from 11.3 to 113 ng mL in artificial cerebrospinal fluid (aCSF), and the detection limit was 7.29 ng mL. The present work realized the assay of AβO in aCSF with satisfactory quantitative results.