Cytokeratin fragment antigen 21-1 (CYFRA 21-1) DNA is perceived as sensitive tumor marker for the diagnosis of non-small cell lung cancer and other tumor. Herein, linear chain poly(ε-caprolactone) (PCL) synthesized by ring-opening polymerization is applied to ultrasensitive label-free electrochemical impedance detection system for CYFRA 21-1 DNA. First, thiolated peptide nucleic acid (PNA) is self-assembled into the Au electrode surface through the formation of Au–S bonds, allowing the PNA to act as biomolecular probe and form PNA/DNA heteroduplex with the target DNA via specific hybridization. Then, PCL is conjugated to the immobilized DNA on the electrode via “carboxylate–Zr⁴⁺–phosphate” bridges. Finally, the electrochemical response of modified PNA/DNA/Zr⁴⁺/PCL electrode is determined by electrochemical impedance method to quantify of CYFRA 21-1 DNA. Under optimal conditions, this method exhibits highly sensitivity with a broad linear range (0.1 fM – 1 nM) (R² = 0.995) and the limit of detection (LOD) is as low as 10.73 aM, which is equivalent to just 64 molecules in a 10 μL sample. What's more, the high selectivity, good anti-interference, label-free operation, and real-time monitoring in complex samples of the proposed strategy demonstrate its broad application for the early diagnosis and clinical monitoring.

细胞角蛋白片段抗原21-1（CYFRA 21-1）DNA被认为是诊断非小细胞肺癌和其他肿瘤的敏感肿瘤标志物。在此，将通过开环聚合合成的线性链聚（ε-己内酯）（PCL）应用于CYFRA 21-1 DNA的超灵敏无标记电化学阻抗检测系统。首先，通过形成Au–S键将硫醇化的肽核酸（PNA）自组装到Au电极表面，使PNA可以充当生物分子探针并通过特异性杂交与目标DNA形成PNA / DNA异源双链体。然后，PCL通过“羧酸盐-Zr ⁴⁺ -磷酸盐”桥与电极上固定的DNA结合。最后，修饰的PNA / DNA / Zr ⁴⁺的电化学响应通过电化学阻抗法测定/ PCL电极以定量CYFRA 21-1 DNA。在最佳条件下，该方法具有高灵敏度，线性范围宽（0.1 fM – 1 nM）（R ²  = 0.995），检测限（LOD）低至10.73 aM，仅相当于64种分子。 10μL样品。此外，所提出策略的高选择性，良好的抗干扰性，无标签操作以及对复杂样品的实时监测证明了其在早期诊断和临床监测中的广泛应用。