An intramolecular self-catalysis-boosted electrochemiluminescence biosensor for alpha fetoprotein detection in serum samples from liver cancer patients.

Constructing a highly boosted biosensor is critical for sensitive detection of trace targets in biological matrices with enhanced signal intensity and anti-interference capacity. Herein, an intramolecular self-catalysis-boosted electrochemiluminescence (ECL) biosensor is designed for alpha fetoprotein (AFP) detection, accompanying with entropy-driven strand displacement reaction (ESDR). Due to the synergistic catalytic self-supply of •OH by CoP and Ni dopant, CoP@Ni-CdS nanocomposites accelerate electron transfer and charge separation, and promote excited-state generation, thus yielding an enhanced ECL response. The integration of magnetic separation and aptamer recognition endows the sensing system with high specificity and target enrichment, realizing reliable signal transduction from AFP to DNA strands (M). Impressively, the introduction of ESDR enables rapid and enzyme-free signal amplification, leading to enhanced sensing sensitivity and a lower background signal. After activation of ESDR by the AFP-determined M strands, gold nanoparticles labelled F strands (F-Au NPs) are assembled to the surface of CoP@Ni-CdS modified electrode. Relying on ECL signal quenching via resonance energy transfer (RET), this proposed method exhibits favourable performance for AFP detection with a linear range from 10 fg/mL to 1000 ng/mL. This sensing system achieves accurate detection of AFP in clinical serum samples from liver cancer patients, illuminating the reliability in practical applications.