Hydrophobic/Oleophilic Structures Based on MacroPorous Silicon: Effect of Topography and Fluoroalkyl Silane Functionalization on Wettability.

The effect of the morphology and chemical composition of a surface on the wettability of porous silicon structures is analyzed in the present work. Hydrophobic and superhydrophobic macroporous substrates are attractive for different potential applications. Herein, different hydrophobic macroporous silicon structures were fabricated by the chemical etching of p-type silicon wafers in a solution based on hydrofluoric acid and coated with a fluoro silane self-assembled monolayer.

Silicon microgrooves for contact guidance of human aortic endothelial cells.

Micro- and nanoscale substrates have been fabricated in order to study the influence of the topography on the cellular response. The aim of this work was to prepare different collagen-coated silicon substrates displaying grooves and ridges to mimic the aligned and elongated endothelium found in linear vessels, and to use them as substrates to study cell growth and behaviour. The influence of groove-shaped substrates on cell adhesion, morphology and proliferation were assessed, by comparing them to flat silicon substrates, used as control condition.

Effects of SiO micropillar arrays on endothelial cells' morphology.

Native tissues are highly organised at the microscale, so that modulating scaffold microarchitecture is a potent tool to mimic natural tissue structures. Moreover, three-dimensional microtopographical features are now being used to elucidate how extracellular physical cues can directly modulate cell behaviour and organise complex cellular processes such as cell differentiation and tissue organisation. Recent advances in microtechnology have allowed the development of platforms that can be used to further understand and control the complex interactions occurring between biointerfaces and living cells.

Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte.

Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells.

Silica Nanopills for Targeted Anticancer Drug Delivery.

Multifunctional SiO2 microtubes for targeted drug delivery are produced with precise control over shape and size by combining lithography and electrochemical etching. The hollow core is loaded with a lipophilic anticancer drug generating nanopills and an antibody is conjugated to the external surface for cancer cell targeting. Results demonstrate selective killing of neuroblastoma cells that express the cognate receptor.

Human aortic endothelial cell morphology influenced by topography of porous silicon substrates.

Porous silicon has received much attention because of its optical properties and for its usefulness in cell-based biosensing, drug delivery, and tissue engineering applications. Surface properties of the biomaterial are associated with cell adhesion and with proliferation, migration, and differentiation. The present article analyzes the behavior of human aortic endothelial cells in macro- and nanoporous collagen-modified porous silicon samples.

Protein attachment to silane-functionalized porous silicon: A comparison of electrostatic and covalent attachment.

Porous silicon (pSi) is a prosperous biomaterial, biocompatible, and biodegradable. Obtaining regularly functionalized pSi surfaces is required in many biotechnology applications. Silane-PEG-NHS (triethoxysilane-polyethylene-glycol-N-hydroxysuccinimide) is useful for single-molecule studies due to its ability to attach to only one biomolecule.

Effects of macro- versus nanoporous silicon substrates on human aortic endothelial cell behavior.

Human aortic endothelial cells play a key role in the pathogenesis of atherosclerosis, which is a common, progressive, and multifactorial disease that is the clinical endpoint of an inflammatory process and endothelial dysfunction. Study and development of new therapies against cardiovascular disease must be tested in vitro cell models, prior to be evaluated in vivo. To this aim, new cell culture platforms are developed that allow cells to grow and respond to their environment in a realistic manner.

pH-responsive drug delivery system based on hollow silicon dioxide micropillars coated with polyelectrolyte multilayers.

We report on the fabrication of polyelectrolyte multilayer-coated hollow silicon dioxide micropillars as pH-responsive drug delivery systems. Silicon dioxide micropillars are based on macroporous silicon formed by electrochemical etching. Due to their hollow core capable of being loaded with chemically active agents, silicon dioxide micropillars provide additional function such as drug delivery system.

New microarchitectures of (Er,Yb):Lu2O3 nanocrystals embedded in PMMA: synthesis, structural characterization, and luminescent properties.

We report the formation of two-dimensional disordered arrays of poly(methyl)methacrylate (PMMA) microcolumns with embedded single size distribution of Lu0.990Er0.520Yb0.

Tunable Fabry-Pérot interferometer based on nanoporous anodic alumina for optical biosensing purposes.

Here, we present a systematic study about the effect of the pore length and its diameter on the specular reflection in nanoporous anodic alumina. As we demonstrate, the specular reflection can be controlled at will by structural tuning (i.e.

Effect of thermal annealing on the kinetics of rehydroxylation of Eu3+:La2O3 nanocrystals.

Europium-doped lanthanum oxide (5 mol % Eu(3+):La(2)O(3)) was prepared by calcining europium-doped lanthanum hydroxide (5 mol % Eu(3+):La(OH)(3)) previously synthesized by a simple hydrothermal method. Interestingly, we observed different emission Eu(3+) signatures depending on the phase of the host (lanthanum oxide or hydroxide) by cathodoluminescence. Taking into account that lanthanum oxide easily rehydroxylates in air, for the first time, we report the use of cathodoluminiscence as a novel characterization technique to follow the lanthanum oxide rehydroxylation reaction versus time according to different annealing procedures.

Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids.

We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e.

Nanoporous anodic alumina barcodes: toward smart optical biosensors.

Toward a smart optical biosensor based on nanoporous anodic alumina (NAA): by modifying the pore geometry in nanoporous anodic alumina we are able to change the effective medium at will and tune the photoluminescence of NAA. The oscillations in the PL spectrum are converted into exclusive barcodes, which are useful for developing optical biomedical sensors in the UV-Visible region.

Understanding pore rearrangement during mild to hard transition in bilayered porous anodic alumina membranes.

We present a systematic study about the influence of the main anodization parameters (i.e., anodization voltage ramp and hard anodization voltage) on the pore rearrangement in nanoporous anodic alumina during mild to hard anodization regime transition.

Reactivity of Grubbs' catalysts with urea- and amide-substituted olefins. Metathesis and isomerization.

[Chemical reaction: see text] The reactions of a series of urea- and amide-substituted olefins with Grubbs' catalysts are presented. Depending on the substrate's nature, the formation of either cross-metathesis or isomerization products is observed. To favor the cross-metathesis products, the reactions have been carried out using a wide range of experimental conditions.

Chiral N-alkyl-2,4,6-triphenylpyridiniums as enantioselective triplet photosensitizers. laser flash photolysis and preparative studies.

Three N-alkylpyridinium photosensitizers having chiral alkyl groups have been prepared by reacting 2,4,6-triphenylpyrylium tetrafluoroborate ion with (1R,2S)-(-)-norephedrine, (S)-(+)-2-(aminomethyl)pyrrolidine, and (R)-(-)-1-cyclohexylethylamine. Laser flash photolysis allows detection of the corresponding triplet excited states that are quenched by hydrogen atom donors and electron donors. Asymmetric quenching of the chiral triplet excited state was observed using enantiomerically pure 1,2-diamino cyclohexane as quencher.