The electrochemical detection of cadmium using surface-immobilized DNA

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• 作者：Elicia L.S. Wong ; Edith Chow ; J. Justin Gooding
• 关键词：Underpotential deposition ; Cadmium detection ; DNA modified surface ; Electrochemical assay ; Heavy metals
• 刊名：Electrochemistry Communications
• 出版年：2007
• 出版时间：April 2007
• 年：2007
• 卷：9
• 期：4
• 页码：845-849
• 全文大小：231 K

文摘

An electrochemical assay based on underpotential deposition (UPD) of metal has been utilised for the detection of Cd²⁺ using surface immobilized single-stranded DNA (ss-DNA). Since Cd²⁺ is able to undergo UPD on gold surface, this allows the opportunity to detect the amount of Cd²⁺ accumulated by immobilized ss-DNA directly via voltammetry. This is evidenced by the appearance of Cd²⁺/Cd⁰ electrochemistry at E^0′ of 92 mV (rather than E^0′ of −795 mV in bulk solution) at the ss-DNA modified gold electrode only after an exposure to Cd²⁺ solution. An association constant of 8.33 × 10⁵ M⁻¹ was determined from a Cd²⁺ calibration curve assuming a Langmuir-binding model for Cd²⁺ with surface-immobilized DNA. The high association constant is reflected in a low detectable concentration of 10 pM. The sensing layer can also be regenerated to metal-free status and can be reused up to 18 times without significant signal degradation.