Highly sensitive electrochemical assay for Nosema bombycis gene DNA PTP1 via conformational switch of DNA nanostructures regulated by H+ from LAMP

Publication date: 30 May 2018
Source:Biosensors and Bioelectronics, Volume 106
Author(s): Jianmin Zhao, Jiaxi Gao, Ting Zheng, Zhehan Yang, Yaqin Chai, Shihong Chen, Ruo Yuan, Wenju Xu
The portable and rapid detection of biomolecules via pH meters to monitor the concentration of hydrogen ions (H⁺) from biological reactions (e.g. loop-mediated isothermal amplification, LAMP) has attracted research interest. However, this assay strategy suffered from inherent drawback of low sensitivity, resulting in great limitations in practical applications. Herein, a novel electrochemical biosensor was constructed for highly sensitive detection of Nosema bombycis gene DNA (PTP1) through transducing chemical stimuli H⁺ from PTP1-based LAMP into electrochemical output signal of electroactive ferrocene (Fc). With use of target PTP1 as the template, the H⁺ from LAMP induced the conformational switch of pH-responsive DNA nanostructures (DNA NSs, Fc-Sp@Ts) that was assembled by the hybridization of Fc-labeled signal probe (Fc-Sp) with DNA-based receptor (Ts). Due to the folding of Ts into stable triplex structure at decreased pH, the configuration change of Fc-Sp@Ts led to the releasing of Fc-Sp, which was subsequently immobilized in the electrode interface through the hybridization with the capture probe modified with -SH (SH-Cp), generating amplified electrochemical signal from Fc. The developed biosensor for PTP1 exhibited a reliable linear range of 1 fg µL⁻¹ to 50 ng µL⁻¹ with the limit of detection of 0.31 fg µL⁻¹. Thus, by the regulation of H⁺ from LAMP reaction on DNA NSs allostery, this novel and simple transduction scheme would be interesting and promising to open up a novel analytical route for sensitive monitoring of different target DNAs in related disease diagnosis.



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