Journal
BIOSENSORS & BIOELECTRONICS
Volume 87, Issue -, Pages 495-500Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2016.08.056
Keywords
Signal amplification; Electrochemical biosensor; Catalytic hairpin assembly; Thrombin; Terminal deoxynucleotidyl transferase
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Funding
- National Natural Science Foundation of China [21275004, 21275119]
- New Century Excellent Talent Program of MOE of China [NCET-12-0932]
- Fundamental Research Funds for the Central Universities [XDJK2014A012, XDJK2015A002]
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Specific and sensitive detection of protein biomarkers is of great importance in biomedical and bioanalytical applications. In this work, a dual amplified signal enhancement approach based on the integration of catalytic hairpin assembly (CHA) and terminal deoxynucleotidyl transferase (TdT)-mediated in situ DNA polymerization has been developed for highly sensitive and label-free electrochemical detection of thrombin in human serums. The presence of the target thrombin leads to the unfolding and capture of a significant number of hairpin signal probes with free 3'-OH termini on the sensor electrode. Subsequently, TdT can catalyze the elongation of the signal probes and formation of many G-quadruplex sequence replicates with the presence of dGTP and dATP at a molar ratio of 6:4. These G-quadruplex sequences bind hemin and generate drastically amplified current response for sensitive detection of thrombin in a completely label-free fashion. The sensor shows a linear range of 0.5 pM-10.0 nM and a detection limit of 0.12 pM for thrombin. Moreover, the developed sensor can selectively discriminate the target thrombin against other non-target proteins and can be employed to monitor thrombin in human serum samples. (C) 2016 Elsevier B.V. All rights reserved.
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