Highly Sensitive Flow Cytometry Biosensor with a High Signal-to-Background Ratio for FEN1 Analysis via Solid-Phase Interface-Mediated Primer Exchange Reaction Amplification

Flap endonuclease 1 (FEN1) is a specific enzyme capable of recognizing and cleaving triplex DNA structures and releasing 5'-flap fragments. It plays a crucial role in the DNA metabolism of cells, participating in DNA replication and the repair of damaged DNA. Additionally, FEN1 is overexpressed in various tumor tissues, promoting tumor progression and drug resistance through different regulatory mechanisms. However, few significant advancements have been made in sensitive analytical methods for detecting FEN1. Herein, in this study, we present a highly sensitive flow cytometry biosensor with solid-phase interface-mediated primer exchange reaction amplification (FCsperA) for FEN1 analysis. By comparing homogeneous PER amplification (h-PER), we found that solid-phase interface-mediated PER amplification (s-PER) effectively suppressed background signals, leading to a higher signal-to-background (S/B) ratio exceeding ∼46-fold when FEN1 was at 1 × 10