Moses Selina, Brewer Scott H, Lowe Lisa B, Lappi Simon E, Gilvey Lauren B G, Sauthier Marc, Tenent Robert C, Feldheim Daniel L, Franzen Stefan
Department of Chemistry, North Carolina State University, Raleigh, NC 27606, USA.
Langmuir. 2004 Dec 7;20(25):11134-40. doi: 10.1021/la0492815.
Single- and double-stranded deoxy ribonucleic acid (DNA) molecules attached to self-assembled monolayers (SAMs) on gold surfaces were characterized by a number of optical and electronic spectroscopic techniques. The DNA-modified gold surfaces were prepared through the self-assembly of 6-mercapto-1-hexanol and 5'-C(6)H(12)SH -modified single-stranded DNA (ssDNA). Upon hybridization of the surface-bound probe ssDNA with its complimentary target, formation of double-stranded DNA (dsDNA) on the gold surface is observed and in a competing process, probe ssDNA is desorbed from the gold surface. The competition between hybridization of ssDNA with its complimentary target and ssDNA probe desorption from the gold surface has been investigated in this paper using X-ray photoelectron spectroscopy, chronocoulometry, fluorescence, and polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS). The formation of dsDNA on the surface was identified by PM-IRRAS by a dsDNA IR signature at approximately 1678 cm(-)(1) that was confirmed by density functional theory calculations of the nucleotides and the nucleotides' base pairs. The presence of dsDNA through the specific DNA hybridization was additionally confirmed by atomic force microscopy through colloidal gold nanoparticle labeling of the target ssDNA. Using these methods, strand loss was observed even for DNA hybridization performed at 25 degrees C for the DNA monolayers studied here consisting of attachment to the gold surfaces by single Au-S bonds. This finding has significant consequence for the application of SAM technology in the detection of oligonucleotide hybridization on gold surfaces.
通过多种光学和电子光谱技术对附着在金表面自组装单分子层（SAMs）上的单链和双链脱氧核糖核酸（DNA）分子进行了表征。DNA修饰的金表面是通过6-巯基-1-己醇和5'-C(6)H(12)SH修饰的单链DNA（ssDNA）的自组装制备的。当表面结合的探针ssDNA与其互补靶标杂交时，观察到金表面双链DNA（dsDNA）的形成，并且在竞争过程中，探针ssDNA从金表面解吸。本文使用X射线光电子能谱、计时电量法、荧光和偏振调制红外反射吸收光谱（PM-IRRAS）研究了ssDNA与其互补靶标杂交和ssDNA探针从金表面解吸之间的竞争。通过PM-IRRAS在约1678 cm(-)(1)处的dsDNA红外特征峰鉴定了表面dsDNA的形成，该特征峰通过核苷酸及其碱基对的密度泛函理论计算得到证实。通过原子力显微镜对靶标ssDNA进行胶体金纳米颗粒标记，进一步证实了通过特异性DNA杂交存在dsDNA。使用这些方法，即使对于在此研究的由单个Au-S键附着在金表面的DNA单分子层在25摄氏度下进行的DNA杂交，也观察到了链损失。这一发现对SAM技术在金表面寡核苷酸杂交检测中的应用具有重要意义。
