Enhanced electrochemiluminescence of RuSi nanoparticles for ultrasensitive detection of ochratoxin A by energy transfer with CdTe quantum dots

This paper develops a new approach to enhance the electrochemiluminescence (ECL) emission of the Ru(bpy)32+-tripropyl amine (TPrA) system for ultrasensitive determination of ochratoxin A (OTA). Ru(bpy)32+-doped silica nanoparticles (RuSi NPs) act as ECL materials, which are immobilized on the surface of electrode by chitosan to fabricate a solid-state ECL sensor. CdTe quantum dots (QDs) can enhance the ECL emission of the Ru(bpy)32+-TPrA ECL system by energy transfer. This strategy can improve the sensitivity of the sensor. In this assay, we combine the ECL with molecular imprinting technique to improve the selectivity of this sensor. The template molecule could be eluted from the molecularly imprinted polymer (MIP), and the formed cavities could then selectively recognize the target. The cavities could also work as the tunnel for the transfer of coreactant TPrA to produce responsive signal. With the increase of the concentration of OTA in samples, more cavities were filled because of the rebinding of OTA to the MIP surface, resulting in a gradual decrease in ECL intensity. The results showed that the ECL decrease value depended linearly on the logarithm of the OTA concentration in the range from 1.00×10−5 to 11.13 ng mL−1 with lower detection limit of 3.0 fg mL−1 (S/N=3). This ECL sensor has also been applied to detect OTA concentration in the real samples with satisfied results, and the recoveries range from 85.1% to 107.9%.