title: A label-free optical sensor based on nanoporous gold arrays for the detection of oligodeoxynucleotides.
abstract: Interest in using nanoporous materials for sensing applications has increased. The present study reports a method of preparing well-ordered nanoporous gold arrays using a porous silicon (PSi) template. Gold nanolayer could be electrodeposited on the surface of the PSi template at low electrolysis currents in low concentration of chloroauric acid (HAuCl(4)) solution. Surface morphology characterizations and optical measurements revealed that a PSi-templated nanoporous gold (Au-PSi) array well replicated the nanoporous structure and retained the optical properties of PSi. Fourier transform reflectometric interference spectra showed that a characteristic blue-shifted effective optical thickness (EOT) was observed due to the low refractive index of the gold film. An optical DNA biosensor was then fabricated via the self-assembly of single-stranded DNA (ssDNA) with a specific sequence on the surface of Au-PSi. The attachment of ssDNA and its hybridization with target oligonucleotides (ODNs) persistently caused the blue shift of the EOT. Consequently, a relationship between the EOT shift and the ODN concentration was established. The mechanism of the optical response caused by DNA hybridization on the Au-PSi surface was qualitatively explained by the electromagnetic theory and electrochemical impedance spectroscopy (EIS). The lowest detection limit for target ODNs was estimated at around 10(-14) mol L(-1), when the baseline noise, a variation in the value of EOT is around 5 nm. The fabricated Au-PSi based optical biosensor has potential use in the discovery of new ODN drugs because it will be able to detect the binding event between ODNs and the target DNA.
authors.affiliation: Institute of Microanalytical System, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
authors.forename: Jiandong
authors.initials: J
authors.lastname: Feng
authors.forename: Weijie
authors.initials: W
authors.lastname: Zhao
authors.forename: Bin
authors.initials: B
authors.lastname: Su
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000295:instrumentation*; D009838:Oligodeoxyribonucleotides / Q000032:analysis*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D055096:Optical Devices; D016062:Porosity; D012031:Refractometry / Q000295:instrumentation*; D013194:Staining and Labeling; D014159:Transducers
chemical_list: D009838:Oligodeoxyribonucleotides; D006046:Gold