Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: Analytical Chemistry
A novel probe for highly sensitive detection of microRNA, that enhanced the helix accessibility and yielded good assembling without backfilling, was developed using a tripod structure fabricated by triplex DNA. A layer of triplex DNA assembled on electrodeposited reduced graphene oxide was used as the capture probe and a subsequent hybridization chain reaction that promoted the efficient intercalation of the electrogenerated chemiluminescence(ECL) emitter [Ru(bpy)2(dppz)]2+ (bpy = 2,2'-bipyridine, dppz = dipyrido[3,2-a: 2',3'-c]phenazine) was used an analytical signal amplifier. The fabricated biosensor was examined with an anodic ECL mode using tri-n-propyl amine as the coreactant. The construction of the biosensor was systematically characterized with various techniques including atomic force microscopy, gel electrophoresis, cyclic voltammetry, and electrochemical impedance spectroscopy, and its performance was optimized under a variety of experimental conditions especially the concentration of each reagent as well as its incubation time. Under the optimal experimental conditions, the reported biosensor showed a very low limit of detection of 0.10 fM (S/N = 3) and a wide linear dynamic range covering from 0.50 fM to 100 pM towards microRNA-155, with excellent specificity, stability, and reproducibility. Finally, the biosensor was successfully applied to detect the amount of microRNA-155 extracted from the colon cancer cell line DLD1, demonstrating its potential applications in sensitive detection of biological samples in early diagnosis of diseases.