A novel aptamer- metal ions- nanoscale MOF based electrochemical biocodes for multiple antibiotics detection and signal amplification

A novel kind of electrochemical biocodes based on nanoscale metal organic framework (NMOF) was developed for simultaneous detection of multiple antibiotics such as kanamycin (KANA) and chloramphenicol (CAP). Herein, amine-functionalized NMOF (UiO-66-NH2) was firstly employed as substrate to carry different metal ions (Pb2+ or Cd2+) respectively (M-NMOF). The adsorption capacities were 293.52 mg g(-1) for Pb2+ and 268.37 mg g(-1) for Cd2+. Secondly, the M-NMOFs were respectively labeled with the complementary DNA strands of aptamers toward KANA and CAP to obtain two signal tags. Finally, both of the tags were conjugated with aptamers functionalized magnetic beads (MB@Apt1/Apt2) to obtain the biocodes. Upon aptamers bound to targets (KANA and CAP) specifically, the corresponding M-NMOFs were released into supernatant after magnetic separation, which can be detected by square wave voltammetry (SWV). Results showed the high sensitivity with detection limits as low as 0.16 pM and 0.19 pM (S/N= 3) toward KANA and CAP respectively, which is 3 or 4 orders of magnitude lower than that of ELISA. Moreover, it exhibited excellent selectivity and more resistant to interference in food analysis. Furthermore, this NMOF based biocodes can be extended to other simultaneous detection system just by changing the aptamer and increasing the types of metal ions. (C) 2016 Elsevier B.V. All rights reserved.