title: Aptamer-based electrochemical sensors that are not based on the target binding-induced conformational change of aptamers.
abstract: This study describes a new kind of aptamer-based electrochemical sensor that is not based on the target binding-induced conformational change of the aptamers by using a 15-mer thrombin-binding aptamer (5'-GGTTGGTGTGGTTGG-3') as the model oligonucleotide. The sensors are developed by first self-assembling the aptamer (i.e. a thrombin-binding aptamer) onto an Au electrode and then hybridizing the assembled aptamer with a ferrocene (Fc)-labeled short aptamer-complementary DNA oligonucleotide to form an electroactive double-stranded DNA (ds-DNA) oligonucleotide onto the Au electrode. The binding of the target (i.e. thrombin) towards the aptamer essentially destroys the Watson-Crick helix structure of the ds-DNA oligonucleotide assembled onto the electrode and leads to the dissociation of the Fc-labeled short complementary DNA oligonucleotide from the electrode surface to the solution, resulting in a decrease in the current signal obtained at the electrode, which can be used for the determination of the target. With the thrombin-binding aptamer as the model oligonucleotide, the current decrease obtained with the aptamer-based electrochemical sensors is linear with the concentration of thrombin within the concentration range from 0 to 10 nM (DeltaI/nA = 6.7C(thrombin)/nM + 2.8, gamma = 0.975). Unlike most kinds of existing aptamer-based electrochemical sensor, the electrochemical aptasensors demonstrated here are not based on the conformational change of the aptamers induced by the specific target binding. Moreover, the aptasensors are essentially label-free and are very responsive toward the targets. This study may pave a facile and general way to the development of aptamer-based electrochemical sensors.
authors: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, the Chinese Academy of Sciences (CAS), Beijing 100080, China.
authors: Ying
authors: Y
authors: Lu
authors: Ningning
authors: N
authors: Zhu
authors: Ping
authors: P
authors: Yu
authors: Lanqun
authors: L
authors: Mao
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D004247:DNA; D018076:DNA, Complementary; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D006046:Gold; D008839:Microelectrodes; D009841:Oligonucleotides; D013917:Thrombin / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D018076:DNA, Complementary; D009841:Oligonucleotides; C081676:thrombin aptamer; D006046:Gold; D004247:DNA; D013917:Thrombin