A high density array of free standing alumina nanotubes aligned vertically on solid substrates in a large area

We report an innovative fabrication of a high density array of free standing alumina nanotubes (ANTs) aligned vertically on substrates. A nanoporous polyimide (PI) template was first prepared by dry etching with the aid of an anodized aluminum oxide (AAO) membrane mask followed by atomic layer deposition (ALD) of alumina. ANTs with various diameters, lengths, and wall thicknesses were obtained by controlling the pore size, the thickness of the nanoporous PI template, and the deposition thickness of alumina through ALD, respectively. Optical properties of an ANT array were also tuned by changing the wall thickness of ANTs, and an ANT array on a glass showed excellent antireflectance with less than 0.1% reflectance at a visible wavelength. The nanoporous polymer template fabricated in this study could also be used to obtain a high density array of various inorganic nanotubes with uniform wall thickness and length in a large area. It also enables on-demand patterning of the nanotube array.open112021sciescopu

Functional nanoporous membranes for drug delivery

This feature article reviews controlled drug release based on nanoporous membranes for potential medical applications. First, we describe the preparations of nanoporous membranes by top-down and bottom-up methods, and the combination of the two. Then, sustained long-term drug delivery and stimuli-responsive drug delivery by utilizing the nanoporous membranes are explained. The drug delivery system using nanoporous membranes can be used for a new therapy of various diseases through patient-customized medical treatment.open118484sciescopu

Nanoporous membranes based on hard and soft templates for biomedical applications

11Nsci

Enhanced adhesion of osteoblastic cells on polystyrene films by independent control of surface topography and wettability

We independently controlled surface topography and wettability of polystyrene (PS) films by CF4 and oxygen plasma treatments, respectively, to evaluate the adhesion and proliferation of human fetal osteoblastic (hFOB) cells on the films. Among the CF4 plasma-treated PS films with the average surface roughness ranging from 0.9 to 70 nm, the highest adhesion of hFOB cells was observed on a PS film with roughness of similar to 11 nm. When this film was additionally treated by oxygen plasma to provide a hydrophilic surface with a contact angle less than 10 degrees, the proliferation of bone-forming cell was further enhanced. Thus, the plasma-based independent modification of PS film into an optimum nanotexture for human osteoblast cells could be appplied to materials used in bone tissue engineering. (C) 2012 Elsevier B.V. All rights reserved.X1119sciescopu

Hierarchically Well-Ordered Array of Concentric Silver Nanorings for Highly Sensitive Surface -Enhanced Raman Scattering Substrate

We fabricated a high density array of concentric silver nanorings in a large area (over in.(2)) with uniform gap distance by utilizing half onion-shaped micro domains prepared by symmetric polystyrene-block-poly(methyl methacrylate) copolymers (PS-b-PMMA) confined within hemispherical cavities in anodized aluminum oxide (AAO) template. Silver nanoparticles with 6 nm height were selectively deposited only on the PS microdomains by thermal evaporation. The gap distance of two neighboring silver nanorings was controlled from 12 to 24 nm by changing the total molecular weight of PS-b-PMMAs. The substrate showed high surface-enhanced Raman scattering (SERS) enhancement factor as high as 4.3 x 10(7) with good reproducibility (+/-7%). It could be used for biosensing, detection of trace-level explosive and hazardous chemicals, and reaction monitoring.X11109sciescopu

Highly Ordered Nanoporous Alumina on Conducting Substrates with Adhesion Enhanced by Surface Modification: Universal Templates for Ultrahigh-Density Arrays of Nanorods

A highly ordered nanoporous anodized aluminum oxide template with excellent adhesion is fabricated on various conducting substrates by surface modification of the substrates. This template can be universally utilized to fabricate laterally long-range-ordered and hexagonally packed arrays of freestanding and vertically aligned metal, semiconductor, and conducting polymer nanorods on various substrates, including flexible substrates (see image).X115054sciescopu

Ultrahigh Density Array of Free-Standing Poly(3-hexylthiophene) Nanotubes on Conducting Substrates via Solution Wetting

An ultrahigh density array of vertically and laterally aligned poly(3-hexylthiophene) (P3HT) nanotubes on conducting substrates was successfully fabricated by solution wetting in the anodized aluminum oxide (AAO) template. After solvent annealing, the conductivity of P3HT nanotubes was significantly increased due to highly aligned P3HT chains along the nanotube direction (or perpendicular to the substrate). This approach also provides a facile route for the preparation of ultrahigh density array of various conjugated polymer nanotubes. The conducting polymer nanotube array could be used for high performance organic devices, such as sensors, organic photovoltaic cells, and electrochromic devices

High aspect ratio cylindrical microdomains oriented vertically on the substrate using block copolymer micelles and temperature-programmed solvent vapor annealing

We report a novel, yet simple, method for the preparation of high aspect ratio cylindrical microdomains oriented vertically on a substrate by using block copolymer micelles and temperature-programmed solvent vapor annealing. Multilayered spherical micelles were first prepared by spin-coating of polystyrene-block-poly(4-vinylpyridine) copolymer (PS-b-P4VP) in toluene solution on a silicon wafer. When temperature-programmed solvent vapor annealing was performed, the spherical micelle cores consisting of P4VP chains were transformed into vertically oriented cylindrical microdomains spanning the entire film thickness up to 550 nm corresponding to the aspect ratio of 15.2. Since nitrogen in the P4VP block could be easily coordinated with many metal precursors, we also fabricated a high density array of gold nanoparticle/polymer nanocomposite nanorods oriented vertically on the substrate.X111310sciescopu

Hierarchically Well-Ordered Array of Concentric Silver Nanorings for Highly Sensitive Surface-Enhanced Raman Scattering Substrate

We fabricated a high density array of concentric silver nanorings in a large area (over in.²) with uniform gap distance by utilizing half onion-shaped microdomains prepared by symmetric polystyrene-<i>block</i>-poly­(methyl methacrylate) copolymers (PS-<i>b</i>-PMMA) confined within hemispherical cavities in anodized aluminum oxide (AAO) template. Silver nanoparticles with 6 nm height were selectively deposited only on the PS microdomains by thermal evaporation. The gap distance of two neighboring silver nanorings was controlled from 12 to 24 nm by changing the total molecular weight of PS-<i>b</i>-PMMAs. The substrate showed high surface-enhanced Raman scattering (SERS) enhancement factor as high as 4.3 × 10⁷ with good reproducibility (±7%). It could be used for biosensing, detection of trace-level explosive and hazardous chemicals, and reaction monitoring