Ratiometric electrochemiluminescent aptasensor array for antibiotic based on internal standard method and spatial-resolved technique

A novel ratiometric electrochemiluminescent (R-ECL) aptasensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for antibiotic chloramphenicol (CAP) based on the ratio of working signal to internal reference signal. The SPCE substrate consists of a common Ag/AgCl reference electrode, carbon counter electrode and two spatial-resolved carbon working electrodes (WE1 and WE2). In the system, luminol-gold nanoparticles (L-Au NPs) as working signal tags were modified on WE1, and CdS quantum dots (QDs) were modified on WE2 as internal reference to provide a correction for avoiding the environmental effects. The L-Au NPs at WE1 were functionalized with a CAP aptamer's DNA complementary (DNA1) and then CAP aptamer (DNA2) that was tagged with chlorogenic acid (CA) as quenchers of L-Au NPs. Upon CAP adding to WE1, the DNA2-CAP complexes were formed due to the highly affinity of CAP towards DNA2. Meanwhile, it could release the CA, which recovered the ECL of L-Au NPs. This ratio of ECL signals for quantification between target probes (at WEI) to internal standard probes (at WE2) could reduce the matrix environmental interference to a certain degree. Moreover, the two probes immobilized on two working electrodes while not one electrode, could also reduce cross-talk interference between each other. Such R-ECL approach offers a selective and sensitive platform and shows a great utility for detection of CAP in the food analysis. (C) 2015 Elsevier B.V. All rights reserved.