Electrochemiluminescence biosensor for determination of lead(II) ions using signal amplification by Au@SiO2 and tripropylamine-endonuclease assisted cycling process

MXene@Au as the base and Au@SiO 2 as signal amplification factor were used for constructing an ultrasensitive “on–off” electrochemiluminescence (ECL) biosensor for the detection of Pb 2+ in water. The use of MXene@Au composite provided a good interface environment for the loading of tris(2,2-bipyridyl)ruthenium(II) (Ru(bpy) 3 2+ ) on the electrode. Based on resonance energy transfer, the Au (core) SiO 2 (shell) (Au@SiO 2 ) nanoparticles stimulate electron transport and promote tripropylamine (TPrA) oxidation. The luminescence effect of Au@SiO 2 was five times that of AuNPs and SiO 2 nanomaterials alone, and the ECL intensity was greatly improved. In addition, Pb 2+ activated the aptamer to exert its endonuclease activity, which realized the signal cycle amplification in the process of Pb 2+ detection. When Pb 2+ was added, the ECL signal weakened, and the Pb 2+ concentration was detected according to the decreased ECL intensity. Under optimized experimental conditions, this aptamer sensor for Pb 2+ has a wide detection range (0.1 to 1 × 10 6  ng L −1 ) and a low detection limit (0.059 ng L −1 ). The relative standard deviation (RSD) of the sensor is 0.39–0.99%, and the recovery of spiked standard is between 90.00 and 125.70%. The sensor shows good selectivity and high sensitivity in actual water sample analysis. This signal amplification strategy possibly provides a new method for the detection of other heavy metal ions and small molecules. Graphical abstract