title: A sensitive, label-free electrochemical detection of telomerase activity without modification or immobilization.
abstract: Telomerase has become one of the most typical tumor marker because it is closely related to cancers. In this paper, a simple label-free electrochemical detection of telomerase activity by using methylene blue (MB) as a G-quadruplex binding probe was proposed, avoiding commonly used complex label procedures, nano-probe synthesis, complicated electrode modification, probe immobilization or signal amplification. In the presence of telomerase substrate (TS) primer, the binding of MB on primer was weak. When repeats of (TTAGGG) were extended on the TS primer under the action of telomerase, they formed multiple G-quadruplexes with the help of K+. As a result, a large amount of MB bounded to multiple G-quadruplexes because they have more strong interaction with G-quadruplexes than TS primer. As a result, the diffusion current of MB decreased sharply, which was strongly dependent on the telomerase activity. The DPV current change has a linear correlation with the logarithm of HeLa cell number in the range of 10-10,000 cells, with the detection limit of 3 cells. The high sensitivity was due to the formed multiple G-quadruplexes. Using indium tin oxide (ITO) as working electrode without modification ensured the good reproducibility of the method. The method was also simple, rapid, and has been successfully applied in the telomerase activity detection in urine with good selectivity and reproducibility, which is significant for cancer diagnosis, anticancer drugs screening, and cancer therapy evaluation.
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wei
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
authors.forename: Ensheng
authors.initials: E
authors.lastname: Xu
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
authors.forename: Haitang
authors.initials: H
authors.lastname: Yang
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China. Electronic address: weiw@seu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Wei
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
authors.forename: Yuanjian
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Jiangsu Engineering Laboratory of Smart Carbon-Rich Materials and Device, Jiangsu Province Hi-Tech Key Laboratory for Bio-medical Research, School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
authors.forename: Songqin
authors.initials: S
authors.lastname: Liu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D057075:Enzyme Assays / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D054856:G-Quadruplexes; D006367:HeLa Cells; D006801:Humans; D057230:Limit of Detection; D008751:Methylene Blue / Q000378:metabolism; D015203:Reproducibility of Results; D019098:Telomerase / Q000032:analysis / Q000378:metabolism* / Q000652:urine*; D017971:Tin Compounds / Q000737:chemistry; D001749:Urinary Bladder Neoplasms / Q000201:enzymology / Q000652:urine
chemical_list: D017971:Tin Compounds; C109984:indium tin oxide; D004247:DNA; D019098:Telomerase; D008751:Methylene Blue
keywords: Electrochemistry; G-quadruplex; Indium tin oxide; Label-free; Methylene blue; Telomerase activity