Sensitive ctDNA detection by a novel zinc(II) complex with two-photon absorption based on electrochemiluminescence

Here we report that a novel zinc(II) complex with an intramolecular 'push-pull' structure was synthesized and fully characterized. For the zinc(II) complex, the photoluminescence (PL) emission wavelength is at 460 nm and the excitation wavelength is at 380 nm. The two-photon absorption cross-section (sigma) of the zinc(II) complex reached 140 GM (1 GM = 1 x 10(-50) cm(4) s photon(-1)). An electrochemiluminescence (ECL) sensor could be built with a glass carbon disk electrode (GCE, Phi 4 mm) modified with the zinc(II) complex, and this exhibited an enhanced ECL intensity, good biocompatibility and long-term stability to detect ctDNA. Meanwhile, the reliability of the extracted signal was demonstrated in solutions of different pH values.