Electrochemiluminescence of Supramolecular Nanorods and Their Application in the "On-Off-On" Detection of Copper Ions.

In this work, an "on-off-on" switch system has been successfully applied through the construction of an electrochemiluminscent biosensor for copper ion (Cu(2+) ) detection based on a new electrochemiluminescence (ECL) emitter of supramolecular nanorods, which was achieved through supramolecular interactions between 3,4,9,10-perylenetetracarboxylic acid (PTCA) and aniline. The initial "signal-on" state with strong and stable ECL emission was obtained by use of the supramolecular nanorods with a new signal amplification strategy involving a co-reaction accelerator. In addition, ECL quencher probes (Fc-NH2 /Cu-Sub/nano-Au) were fabricated by immobilizing aminoferrocene (Fc-NH2 ) on Cu-substrate strand modified Au nanoparticles. The quencher probes were hybridized with the immobilized Cu-enzyme strand to form Cu(2+) -specific DNAzyme. Similarly, the "signal-off" state was obtained by the high quenching effect of Fc-NH2 on the ECL of the excited-state PTCA ((1) PTCA*). As expected, the second "switch-on" state could achieved by incubating with the target Cu(2+) , owing to the Cu(2+) -specific DNAzyme, which was irreversibly cleaved, resulting in the release of the quencher probes from the sensor interface. Herein, on the basis of the ECL intensity changes (ΔIECL ) before and after incubating with the target Cu(2+) , the prepared Cu(2+) -specific DNAzyme-based biosensor was used for the determination of Cu(2+) concentrations with high sensitivity, excellent selectivity, and good regeneration.