The Fabrication of High-Performance Flexible Mercury Aptasensor Based on Graphene
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The Fabrication of High-Performance Flexible Mercury Aptasensor Based on Graphene Ji Hyun An1 and Jyongsik Jang1 1 School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul, Korea. ABSTRACT Liquid-ion gated FET-type flexible graphene-based aptasensor was fabricated for Hg detection in real world samples. Single-layer graphene was grown and transferred onto a flexible substrate and integrated into the liquid-ion gated FET system via surface engineerging process. Field-induced responses to Hg2+ ions in real world samples were highly rapid, sensitive and selective, leading to the high-perfromance graphene aptasensor. The aptasensor also displayed excellent flexibility and mechanical durability. INTRODUCTION Mercury (Hg) has been used as chemical additive and energy source in industrial development for decades [1] Hg can be extremely toxic, both to human health and to the environment [2]. Hg has been implicated in a number of fatal diseases such as Minamata disease, pulmonary edema, cyanosis and nephrotic syndrome. Therefore, the use and manufacture of Hg is regulated in many countries. To improve safety, various analytical devices have been developed to detect Hg2+ ions, including photoelectrochemical methods, colorimetric analysis, and oligonucleotide-based sensors [3, 4]. Other conventional Hg sensors have significant drawbacks, including a slow time response, low sensitivity and/or poor selectivity. Graphene has superb thermally conducting property, excellent mechanical stability, and an extraordinarily high electrical charge carrier mobility. Graphene has been investigated as a transducer in analytical methodologies, showing high sensitivity, selectivity, and rapid response/recovery times owing to extraordinary carrier mobility and high conductivity [5]. Transistor-based sensors, which are the combination of a sensor and amplifier, have potential for the development of miniaturized and portable sensor systems with effective interfacing transfer. Graphene transistor can be integrated with liquid-ion gated field-effect transistor (FET) geometry, which can operate in the solution state via the gate dielectric. The liquid-ion gated FET system with a graphene transistor has shown excellent stability in the liquid state, as well as low-voltage operation, leading to biosensors [6]. Herein, we report a straightforward fabrication methodology for flexible graphene-based aptasensors and demonstrate devices with high sensitivity and selectivity for Hg detection. Chemical vapor deposition (CVD)-grown single-layer graphene was successfully transferred onto a flexible substrate and integrated into the liquid-ion gated FET system via surface engineering. The graphene-based aptasensor had a response time of < 1 s and a strong fieldinduced response through the binding between Hg2+ ions and the aptamer, leading to a high sensitivity toward Hg2+ ions, with a detection limit of 10 pM, which is 2–3 orders of magnitude more sensitive than previously reported Hg sensors based on electri
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