Label-Free Dual Sensing of DNA Molecules Using GaN Nanowires

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• 作者：Chin-Pei Chen ; Abhijit Ganguly ; Chen-Hao Wang ; Chih-Wei Hsu ; Surojit Chattopadhyay ; Yu-Kuei Hsu ; Ying-Chih Chang ; Kuei-Hsien Chen ; Li-Chyong Chen
• 刊名：Analytical Chemistry
• 出版年：2009
• 出版时间：January 1, 2009
• 年：2009
• 卷：81
• 期：1
• 页码：36-42
• 全文大小：330K
• 年卷期：v.81,no.1(January 1, 2009)
• ISSN：1520-6882

文摘

We demonstrate a rationale for using GaN nanowires (GaNNWs) in label-free DNA-sensing using dual routes of electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) measurements, employing a popular target DNA with anthrax lethal factor (LF) sequence. The in situ EIS reveals that both high surface area and surface band-bending in the nanowires, providing more binding sites and surface-enhanced charge transfer, respectively, are responsible for the enhanced sensitivity to surface-immobilized DNA molecules. The net electron-transfer resistance can be readily deconvoluted into two components because of the coexistence of two interfaces, GaN/DNA and DNA/electrolyte interfaces, in series. Interestingly, the former, decreasing with LF concentration (C_LF), serves as a signature for the extent of hybridization, while the latter as a fingerprint for DNA modification. For PL-sensing, the band-edge emission of GaNNWs serves as a parameter for DNA modification, which quenches exponentially with C_LF as the incident light is increasingly blocked from reaching the core nanowire by rapidly developing a UV-absorbing DNA sheath at high C_LF. Furthermore, successful application for detection of “hotspot” mutations, related to the human p53 tumor-suppressor gene, revealed excellent selectivity and specificity, down to picomolar concentration, even in the current unoptimized sensor design/condition, and in the presence of mutations and noncomplementary strands, suggesting the potential pragmatic application in complex clinical samples.