An electrochemical aptasensor for multiplex antibiotics detection using Y-shaped DNA-based metal ions encoded probes with NMOF substrate and CSRP target-triggered amplification strategy

An effective electrochemical aptasensor has been developed for the detection of multiplex antibiotics using Y-shaped DNA probes. These probes-based metal ions encoded the nanoscale metal-organic frameworks (NMOF) as a substrate, and circular strand-replacement DNA polymerization (CSRP) target triggered the amplification strategy. The Y-DNA probes (Y-DNA) were assembled using an assisted DNA probe (assisted DNA labeled with magnetic gold nanoparticles) which can hybridize to the captured DNA probe (consisting of aptamer and primer recognition region), and signal tags (NMOF encapsulating signal DNAs and different metal ions such as Pb2+ or Cd2+). Notably, NMOF was employed as the developed platform with a large specific area to load abundant metal ions that can produce distinguishable signals. In the presence of targets, chloramphenicol (CAP) and oxytetracycline (OTC) as models, the conformational change of the captured DNA can disassemble the Y-DNA probes that can consequently release the signal tags in the supernatant due to the high affinity of targets towards the aptamer domain than its complementary sequences. Subsequently, the exposed sequences of captured DNA serve as the initiators for triggering the target cyclic-induced polymerization with the assistance of Bst DNA polymerase. Thus, numerous signal tags could be detected by square wave voltammetry in the supernatant after magnetic separation, thereby amplifying the electrochemical signals. The proposed strategy exhibited a high sensitivity to antibiotics with a detection limit of 33 and 48 fM (S/N = 3) towards CAP and OTC, respectively. Moreover, this aptasensor showed promising applications for the detection of other analytes.