Tetrahedral DNA nanostructure enhanced toehold-mediated strand displacement for highly sensitive electrochemiluminescence assay of CA125

Cancer antigen 125 (CA125) is a typical tumor marker of ovarian cancer. Here, a multi-amplified electro-chemiluminescence (ECL) aptasensor was developed for efficient recognition of CA125 using tetrahedral DNA nanostructure (TDN) enhanced toehold-mediated strand displacement (TMSD) coupled with gold nanoparticles/ Ru(bpy)32+/metal-organic framework (AuNPs/Ru/ZIF-MOF) signal probe. AuNPs and Ru(bpy)32+ modified ZIF-MOF acted as initial ECL signal and further used for the immobilization of TDN, the activated DNA templates on the surface of TDN were firstly hybridized with ferrocene labeled DNA probe (S6) and S5, in which, S6 acted as the energy acceptor of ECL signal from Ru(bpy)32+, making the sensor in a signal-off state. After the specific recognition of aptamer (AP) with CA125, DNA initiator (S7) was freed to induce the happen of TMSD by using S8 as the helper DNA, accompanying with the release of S6 from the electrode surface and the recovery of Ru (bpy)32+ ECL signal, making the sensor in a signal-on state. Then, S7 was recycled for the next TMSD, making the sensor highly sensitive with a detection limit of 6 x 10-3 pg/mL. Moreover, the proposed aptasensor achieved high performance for CA125 detection in human serum samples, illustrating the reliability of the sensor in clinical analysis.

Automated summary

A multi-amplified electro-chemiluminescence aptasensor was developed for efficient recognition of the tumor marker CA125 in ovarian cancer. The sensor utilizes a tetrahedral DNA nanostructure and gold nanoparticles/Ru(bpy)32+/metal-organic framework signal probe for enhanced detection. The aptasensor shows high sensitivity and reliability, making it suitable for clinical analysis of CA125 detection.