Conjugated Polyelectrolyte and Aptamer Based Potassium Assay via Single- and Two-Step Fluorescence Energy Transfer with a Tunable Dynamic Detection Range

Authors

  • Bao Lam Nguyen,

    1. Department of Nanofusion Engineering and Department of Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang, Republic of Korea
    2. Institute of Applied Materials Science, Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam
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  • Ji-Eun Jeong,

    1. Department of Nanofusion Engineering and Department of Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang, Republic of Korea
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  • In Hwan Jung,

    1. Department of Chemistry, University of Chicago, Chicago, IL, USA
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  • Boram Kim,

    1. Department of Nanofusion Engineering and Department of Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang, Republic of Korea
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  • Van Sang Le,

    1. Department of Nanofusion Engineering and Department of Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang, Republic of Korea
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  • Inhong Kim,

    1. Department of Cogno-Mechatronics Engineering, Physics Education and Physics, Pusan National University, Busan, Republic of Korea
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  • Kwangseuk Kyhm,

    1. Department of Cogno-Mechatronics Engineering, Physics Education and Physics, Pusan National University, Busan, Republic of Korea
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  • Han Young Woo

    Corresponding author
    1. Department of Nanofusion Engineering and Department of Cogno-Mechatronics Engineering (WCU), Pusan National University, Miryang, Republic of Korea
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Abstract

A new potassium ion detection assay was developed using a dye-labeled aptamer and conjugated polyelectrolyte (CPE) as a signaling platform via 1-step and 2-step fluorescence resonance energy transfer. Guanine-rich K+-specific aptamers were designed as K+ ion recognition species with 6-carboxyfluorescein (6-FAM) and 6-carboxytetramethylrhodamine (6-TAMRA) at both termini. In the presence of K+ ions, the aptamers undergo a conformational change from an unfolded to folded form by forming a G-quadruplex with K+, bringing two dyes in proximity. FRET-induced 6-TAMRA emission was proportional to [K+] in a range of 22.5 μm–100 mm in water without interference by the presence of excess Na+ ions (100 mm). Upon the addition of CPE, a two-step FRET process from CPE to 6-TAMRA via 6-FAM was enabled, showing an intensified 6-TAMRA signal with K+ ions. The dynamic detection range and limit of detection (LOD) was fine-tuned from ∼millimolar to ∼nanomolar concentrations of K+ by modulating the signal amplification effect of CPE. The LOD was determined to be ≈3.0 nm. This detection assay also showed high selectivity against other metal ions. This sensing scheme can be extended to the detection of a wide range of target materials by simply modifying the recognition aptamer sequence.

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