A novel "on-off-on" electrochemiluminescence strategy based on RNA cleavage propelled signal amplification and resonance energy transfer for Pb²⁺ detection

Background: Lead (Pb) is one of the most toxic heavy-metal pollutants. Additionally, lead ions (Pb2+) can accumulate in the human body through the food chain, causing irreversible damage through organ damage and system disorders. In the past few years, the detection of Pb2+ has mainly relied on instrumental methods such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). Nonetheless, these techniques are complicated in terms of equipment and procedures, along with being time -intensive and expensive in terms of detection. These drawbacks have limited their wide application. Hence, there is a pressing need to develop detection techniques for Pb2+ that are not only cost-efficient but also highly sensitive and specific. Results: A novel "on -off -on" electrochemiluminescence (ECL) sensor for detecting Pb2+ was developed based on the resonance energy transfer (RET) effect between AuNPs and boron nitride quantum dots (BN QDs) and the recognition of Pb2+ by DNAzyme along with the cleavage reaction of the substrate chain. Poly(6-carboxyindole)/ stannic sulfide (P6ICA/SnS2) nanocomposite was employed as a co -reaction accelerator to consequently facilitate the production of intermediate SO4 center dot- . This effective enhancement of the reaction led to an improved ECL intensity of BN QDs and enabled the sensor platform to exhibit a higher original ECL response. Benefiting from the combination of the DNAzyme signal amplification strategy with the "on -off -on" design, the ECL sensor showed satisfactory selectivity, good stability, and high sensitivity. This ECL sensor exhibited a linear detection range (LDR) of 10-12-10-5 M and a limit of detection (LOD) of 2.6 x 10-13 M. Significance: In the present work, an "on -off -on" ECL sensor is constructed based on RET effect for ultrasensitive detection of Pb2+. P6ICA/SnS2 was investigated as the co -reaction accelerator in this sensor. Moreover, this ECL sensor exhibited excellent analytical capability for detecting Pb2+ in actual water samples, providing a method for detecting other heavy metal ions as well.