A Host-Guest-Recognition-Based Electrochemical Sensor for Sequence-Specific DNA Detection

We herein constructed a sensor that converts target DNA hybridation-induced conformational transformation of the probe DNA to electrochemical response based on host-guest recognition and nanoparticle label In the sensor, the hairpin DNA terminal-labeled with 4-((4-(dimethylamino)phenyl)azo)benzoic acid (dabcyl) and thiol group was immobilized on Au electrode surface as the probe DNA by Au-S bond, and the CdS nanoparticles surface-modified with fl-cyclodextrins (CdS-CDs) weie employed as electrochemical signal provider and host-guest recognition element Initially, the probe DNA immobilized on electrode kept the stem-loop configuration, which shielded dabcvl from docking with the CdS-CDs in solution due to the stem effect After taiget hybridization, the probe DNA underwent a significant confolmational change. which forced dabcyl away from the electrode As a iesult. foi mci lyshielded dabcyl became accessible to host-guest recognition between /3-cyclodextrin (fl-CD) and &hey!, thus the target hybridization event could he sensitively tiansduced to electrochemical signal provided by CdS-CDs This hostguest recognition-based electrochemical sensor has been able to detect as low as picomolai DNA taiget with excellent diffeientiation ability for even single misrmitch