Novel Ternary System for Electrochemiluminescence Biosensor and Application toward Pb Assay.

This study constructed an electrochemiluminescence (ECL) biosensor for ultrasensitive detection of Pb in a ternary system by employing DNAzyme. The ternary system is composed of a potassium-neutralized perylene derivative (KPTC) as the ECL emitter, KSO as the coreactant, and neodymium metal-organic frameworks (Nd-MOFs) as the coreaction accelerators. Nd-MOFs immobilize DNAzymes and enhance the luminescence intensity of the KPTC/KSO system. As part of this system, KPTC enhances the ECL signal in solution and supports Pb detection. The sequence of ferrocene (Fc)-linked DNA (DNA-Fc) is catalytically cleaved by DNAzymes in the presence of Pb. This causes the removal of DNA1-Fc from the electrode surface to recover the ECL signal. As a result, the as-prepared ECL biosensor can quantify Pb with a detection limit (LOD) of 4.1 fM in the range of 1 μM to 10 fM. The ECL biosensor displays high specificity, good stability, excellent reproducibility, and desirable practicality for Pb detection in tap water. Moreover, by simply changing the sequence of the DNAzyme, new biosensors can be designed for ultrasensitive detection of different heavy metal ions, offering an excellent approach for monitoring water quality safety.