title: DNA detection using nanostructured SERS substrates with Rhodamine B as Raman label.
abstract: 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.
authors.affiliation: Institute of Microelectronics, A STAR (Agency for Science, Technology and Research), Singapore Science Park II, Singapore. fangc@ime.a-star.edu.sg
authors.forename: Cheng
authors.initials: C
authors.lastname: Fang
authors.forename: Ajay
authors.initials: A
authors.lastname: Agarwal
authors.forename: Kavitha Devi
authors.initials: KD
authors.lastname: Buddharaju
authors.forename: Nizamudin Mohamed
authors.initials: NM
authors.lastname: Khalid
authors.forename: Shaik Mohamed
authors.initials: SM
authors.lastname: Salim
authors.forename: Effendi
authors.initials: E
authors.lastname: Widjaja
authors.forename: Marc V
authors.initials: MV
authors.lastname: Garland
authors.forename: Narayanan
authors.initials: N
authors.lastname: Balasubramanian
authors.forename: Dim-Lee
authors.initials: DL
authors.lastname: Kwong
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004247:DNA / Q000032:analysis* / Q000737:chemistry* / Q000235:genetics; D004867:Equipment Design; D019544:Equipment Failure Analysis; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D015203:Reproducibility of Results; D012235:Rhodamines / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*; D013194:Staining and Labeling
chemical_list: D012235:Rhodamines; D004247:DNA; C029773:rhodamine B