title: Label-free dual sensing of DNA molecules using GaN nanowires.
abstract: 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.
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Chin-Pei
authors.initials: CP
authors.lastname: Chen
authors.forename: Abhijit
authors.initials: A
authors.lastname: Ganguly
authors.forename: Chen-Hao
authors.initials: CH
authors.lastname: Wang
authors.forename: Chih-Wei
authors.initials: CW
authors.lastname: Hsu
authors.forename: Surojit
authors.initials: S
authors.lastname: Chattopadhyay
authors.forename: Yu-Kuei
authors.initials: YK
authors.lastname: Hsu
authors.forename: Ying-Chih
authors.initials: YC
authors.lastname: Chang
authors.forename: Kuei-Hsien
authors.initials: KH
authors.lastname: Chen
authors.forename: Li-Chyong
authors.initials: LC
authors.lastname: Chen
mesh_terms: D000942:Antigens, Bacterial / Q000235:genetics*; D001408:Bacillus anthracis / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D001672:Biocompatible Materials / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D017097:Electric Impedance; D005708:Gallium / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods; D053770:Nanowires / Q000737:chemistry*; D015345:Oligonucleotide Probes; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D001672:Biocompatible Materials; D004269:DNA, Bacterial; D015345:Oligonucleotide Probes; C030325:anthrax toxin; C473348:gallium nitride; D005708:Gallium