An electrochemical biosensor integrating self-propelled nanocarriers with DNA cascade amplification strategy for ultrasensitive PPIA detection.

Abstract

Peptidylprolyl isomerase A (PPIA) catalyzes cis-trans isomerization of proline residues, a key process regulating protein folding and signal transduction. Its aberrant secretion is closely associated with tumor metastasis and progression, making it a promising biomarker. However, currently available immunoassays often suffer from insufficient sensitivity for low-abundance PPIA detection. Herein, we present an electrochemical biosensor that integrates self-propelled nanocarriers with DNA cascade amplification strategy for ultrasensitive PPIA detection. The biosensor employs PtNPs@COF particles that catalyze H2O2 decomposition to generate O2. This autonomous propulsion accelerates target binding in homogeneous solution and helps mitigate diffusion-limited binding kinetics. After PPIA binding, the liberated DNAzyme catalytically cleaves the co-immobilized substrate strands, generating numerous triggers for the catalytic hairpin assembly (CHA) reaction. The biosensor achieves a wide linear range from 1 pg/mL to 10 μg/mL with a detection limit of 0.330 pg/mL. It also exhibits excellent specificity and performs reliably in clinical lung adenocarcinoma serum specimens, demonstrating its promising applicability for early diagnosis of this malignancy.