Aptamer-Based Electric-Double -Layer (EDL) Extended-Gated FET Biosensor for Detection of Cadmium Ion

Abstract

Cadmium ion (Cd2+) is a highly toxic heavy metal pollutant. It causes irreversible damage to human health even at low doses due to a long biological half-life and strong bioaccumulation. Common heavy metal detection includes Inductively Coupled Plasma with Atomic Emission, Spectroscopy (ICP-AES), Inductively coupled plasma mass spectrometry (ICP-MS), Flame Atomic Absorption Spectrophotometry (FAAS), and Graphite Furnace Atomic Absorption Spectrometry (GFAAS), and. However, these technologies are high-cost, time-consuming, complicated operations, and can't be detected immediately and accurately.In this study, we developed an electric double-layer (EDL) extended-gate field effect transistor sensor based on aptamers to detect cadmium ions (Cd2+). Use N-channel enhanced-mode MOSFETs to connect the extended-gate array chips with aptamer modified. The aptamers were self-assembled on the gold electrode surface through Au-S bonds. Since the aptamer has a specific binding ability to cadmium ions, it will bind to the aptamer to form a stem-loop structure. The gate voltage changes caused by the structure change and then amplify the electrical signal through the transconductance of the field effect transistor. The linear detection range of this sensor for cadmium ions is from 1nM to 10uM. The Cd2+ calibration curve is shown a high correlation coefficient (R2 = 0.99001) and an excellent detection limit as low as 99.5 nＭ. Importantly, it responds to Cd2+ within 10 seconds. The sensor exhibits high selectivity in the presence of other heavy metals such as arsenic, chromium, lead, and mercury for electrical signal measurements. It also can be reused without significant signal attenuation.The advantages of this method are convenient portability, short detection time, high sensitivity, and simple operation. It has a good prospect for detection in the daily life of cadmium environmental pollution. Figure 1