Nanohole arrays

This review will discuss the possibility to control and improve the reactivity of Titania by design of new tailored nano-architecture. Specifically, analyses quasi-ID Ti02 nanostructures, e.g. nanorods, nanowires and nanofibres, nanotubes and nanopillars. 2D Titania nanostructures, e.g. columnar-type films, ordered arrays of nanotubes or nano-rods/-wires, nanobowl array, nanomembranes (called also nanohole array) and nanosponge, and Ti-based ordered mesoporous matrices will be instead discussed in a consecutive review paper. 

Alumina nanotubes have been prepared by the anodic oxidation of aluminum [41] the resulting tubes have one-dimensional channels with uniform diameters of 5nm and lengths of 50-100 nm. An alumina membrane with a highly ordered nanohole array in 50-100 nm diameter has also been synthesized by long-period anodization thus these local alumina nanotubes have been tried as a template for metal nanowire formation. 

A variety of nanomaterials have been synthesized by many researchers using anodic aluminum oxide film as either a template or a host material e.g., magnetic recording media (13,14), optical devices (15-18), metal nanohole arrays (19), and nanotubes or nanofibers of polymer, metal and metal oxide (20-24). No one, however, had tried to use anodic aluminum oxide film to produce carbon nanotubes before Kyotani et al. (9,12), Parthasarathy et al. (10) and Che et al. (25) prepared carbon tubes by either the pyrolytic carbon deposition on the film or the carbonization of organic polymer in the pore of the film. The following section describes the details of the template method for carbon nanotube production. 

H. Masuda and K. Fukuda, Ordered metal nanohole arrays made by a two-step replication of honeycomb structures of anodic alumina, Science 268 1466-1468 (1995). 

Nanohole Arrays in Metal Films as Integrated Chemical Sensors and Biosensors... 

Keywords Nanohole array Surface plasmon resonance Optical sensing Chemical sensing Biosensing Microfluidic Nanofluidic Extraordinary optical transmission... 

Fig. 12 Lab-on-chip integration and application of arrays of nanohole arrays (a) Schematic of device at range of relevant lengthscales (b) Schematic of optical and fluidic setup with an image of the device (c) Image showing six cross-stream nanohole sensors across a cross-stream microfluidic concentration gradient and (d) Results of on-chip biosensing test. Reprinted with permission from the American Chemical Society [67]...

A schematic of the flow-through nanohole array concept is shown in Fig. 13a. Figure 13b shows computationally predicted biomarker transport within the nanoholes for in-hole average fluid velocities of 1 pm/s and 1 cm/s (as indicated). Reaction rate constants characteristic of surface-based antibody-antigen reactions (with reaction rate constant k - 10 /M/s) [69] were applied at the nanohole walls. For the low average velocity, diffusion of the biomarker (with diffusivity D - 4x10 m s ) to the nanohole surface is effectively complete in one diameter. This result reflects the rapid diffusion characteristic of nanoconfinement. For the higher flow rate case, the absorption of the analyte stream is delayed however, over 90% bulk adsorption of analyte is attained with the flow rates and nanohole... 

Fig. 13 Integrated flow-through nanohole array concept (a) Schematic of the flow-through nanohole array in a chip-and-reader conflguration (b) Results of computational modeling showing predicted biomarker concentration profiles with through-hole fluid average velocities indicated...

Gao HW, Henzie J, Odom TW (2006) Direct evidence for surface plasmon-mediated enhanced light transmission through metallic nanohole arrays. Nano Lett 6 2104-2108... 

Gordon R, Hughes M, Leathern B, Kavanagh KL, Brolo AG (2005) Basis and lattice polarization mechanisms for light transmission through nanohole arrays in a metal film. Nano Lett 5 1243-1246... 

Lesuffleur A, Im H, Lindquist NC, Oh SH (2007) Periodic nanohole arrays with shape-enhanced plasmon resonance as real-time biosensors. Appl Phys Lett 90 261104... 

Pang L, Hwang GM, Slutsky B, Eainman Y (2007) Spectral sensitivity of two-dimensional nanohole array surface plasmon polariton resonance sensor. Appl Phys Lett 91 123112... 

Stark PRH, Halleck AE, Larson DN (2005) Short order nanohole arrays in metals for highly sensitive probing of local indices of refraction as the basis for a highly multiplexed biosensor technology. Methods 37 37 7... 

Tetz KA, Pang L, Fainman Y (2006) High-resolution surface plasmon resonance sensor based on linewidth-optimized nanohole array transmittance. Opt Lett 31 1528-1530... 

Ji J, O Connell JG, Carter DID, Larson DN (2008) High-throughput nanohole array based system to monitor multiple binding events in real time. Anal Chem 80 2491-2498... 

Sharpe JC, Mitchell JS, Lin L, Sedoglavich H, Blaikie RJ (2008) Gold nanohole array substrates as immunobiosensors. Anal Chem 80 2244-2249... 

Gordon R, Brolo AG, McKinnon A, Rajora A, Leathern B, Kavanagh KL (2004) Strong polarization in the optical transmission through elliptical nanohole arrays. Phys Rev Lett 92 037401... 

De Leebeeck A, Kumar LKS, de Lange V, Sinton D, Gordon R, Brolo AG (2007) On-chip surface-based detection with nanohole arrays. Anal Chem 79 4094-4100... 

Eftekhari F, Gordon R, Ferreira J, Brolo AG, Sinton D (2008) Polarization-dependent sensing of a self-assembled monolayer using biaxial nanohole arrays. Appl Phys Lett 92 253103... 

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