Fang Cheng, Agarwal Ajay, Buddharaju Kavitha Devi, Khalid Nizamudin Mohamed, Salim Shaik Mohamed, Widjaja Effendi, Garland Marc V, Balasubramanian Narayanan, Kwong Dim-Lee
Institute of Microelectronics, A STAR (Agency for Science, Technology and Research), Singapore Science Park II, Singapore.
Biosens Bioelectron. 2008 Oct 15;24(2):216-21. doi: 10.1016/j.bios.2008.03.032. Epub 2008 Apr 4.
A technique is demonstrated to detect DNA hybridization at low concentrations, based on Surface-Enhanced Raman Scattering (SERS) using silicon nanostructures coated with gold-silver as substrate. Standard silicon process technologies were employed to fabricate the SERS substrates featuring nanogaps with a characteristic distance of 15+/-10nm. Target DNA was hybridized with cysteine-modified Peptide Nucleic Acids (PNA), which was previously fixed into the nanogaps as the capture sites. After hybridization, the introduced phosphate groups from the backbone of the target DNA showed strong affinity to an inorganic linker, Zr(4+), so that resulting in the assembly substrate-PNA-DNA-Zr. Since PNA does not possess phosphate groups, the linker is avoided when there is no hybridization from the complimentary DNA. Subsequently, the assembly of substrate-PNA-DNA-Zr was incubated with a Raman label, Rhodamine B (RB). The carboxylic acid group in RB reacted with the linker Zr(4+) allowing this Raman Label to be attached to the assembly substrate-PNA-DNA-Zr. The Raman peaks corresponding to RB were selected to detect the target DNA, with a detection limit of 1 x 10(-12)M.
展示了一种基于表面增强拉曼散射（SERS）检测低浓度DNA杂交的技术，该技术使用涂有金银的硅纳米结构作为底物。采用标准的硅工艺技术制造具有特征距离为15±10nm纳米间隙的SERS底物。将目标DNA与半胱氨酸修饰的肽核酸（PNA）杂交，PNA先前已作为捕获位点固定在纳米间隙中。杂交后，目标DNA主链引入的磷酸基团对无机连接体Zr(4+)表现出很强的亲和力，从而形成底物-PNA-DNA-Zr组装体。由于PNA不具有磷酸基团，当不存在互补DNA杂交时，可避免连接体的存在。随后，将底物-PNA-DNA-Zr组装体与拉曼标记罗丹明B（RB）一起孵育。RB中的羧酸基团与连接体Zr(4+)反应，使该拉曼标记附着到底物-PNA-DNA-Zr组装体上。选择与RB对应的拉曼峰来检测目标DNA，检测限为1×10(-12)M。
