An electrochemical method based on CRISPR-Cas12a and enzymatic reaction for the highly sensitive detection of tumor marker MUC1 mucin

Abstract

Anti-cancer therapy is crucial in cancer prevention and anti-cancer, and thus, highly sensitive methods for detecting cancer biomarkers are essential for cancer early diagnosis. Herein, an electrochemical aptamer biosensor based on the CRISPR-Cas12a system was constructed for the detection of cancer tumor biomarker MUC1 mucin. The sensitivity was significantly prompted by enzyme-catalyzed signal amplification, and the selectivity was improved by the dual recognition of the aptamer to MUC1 and crRNA-Cas12a system to the aptamer. Glucose oxidase (GOD) was loaded on the surface of magnetic Fe₃O₄@Au (MGNP) via probe single-stranded DNA (pDNA) with the terminal modification of mercapto (–SH) to form GOD-pDNA/MGNP. The corresponding aptamer of MUC1 (MUC1 Apt) binds to its complementary ssDNA (cDNA) to form the activator Apt/cDNA, which is specifically recognized by crRNA-Cas12a and excites the trans-cleavage function of Cas12a, thus in turn trans-cleaves pDNA and detaches GOD from the magnetic particles. The magnetic beads were separated and transferred into a glucose solution, and the oxidation current of H₂O₂ produced by the catalytic reaction of GOD was measured on a Pt-modified magnetically-controlled glassy carbon electrode, resulting in an indirect determination of MUC1. The current change was linear with the logarithm of MUC1 concentration in the range from 1.0 × 10⁻¹⁷ g mL⁻¹ to 1.0 × 10⁻¹⁰ g mL⁻¹. The detection limit was as low as 7.01 × 10⁻¹⁸ g mL⁻¹. The method was applied for the detection of MUC1 in medical samples.