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This paper describes a nanoporous substrate for applications in biomedical diagnostics. A photolithographic microstructuring technique for an ordered nanopore array fabrication is reported. The process uses a negative resist with hydrophobic properties increasing specificity to biomolecule linking. Nanoporous alumina is formed by an anodic process and yields straight holes with high aspect ratio: its use as substrates for DNA-microarray or protein-chip application offers several advantages over conventional supports, making them very attractive to use as supports for biological sample microarray application.

Multi-walled carbon nanotubes (MWNTs) were functionalized via oxidative polymerization of 3-3'(vinylcarbazole) (PVK). Thin films of PVK-functionalized MWNTs (PVK-MWNTs) were fabricated by the Langmuir-Schaefer (LS) technique and characterized by spectroscopic, microscopic, electrical and electrochemical techniques before and after doping with iodine. I/V characterization showed an increase in the conductivity of the PVK-MWNTs and I-2-doped PVK-MWNTs compared with the PVK and I-2-doped PVK, respectively. The electrochemical characterization showed the formation of an I-2-doped PVK-MWNT complex. These nanostructured PVK-MWNT films revealed an increase in the current density under illumination of about 500 nA cm(-2).

A new method of protein crystallization based on a homologous Langmuir-Schaefer (LS) protein thin-film template proves to successfully stimulate crystal nucleation and growth of the four different proteins being studied, under different crystallization conditions including those failing to lead to crystal formation in solution. Protein microcrystals were obtained by a modified vapour diffusion hanging drop method. This report is focused on recombinant bovine cytochrome P-450scc crystallization and subsequent crystal characterization by atomic force microscopy in an appropriate chamber. The results are discussed in terms of a possible transition in protein crystallization from art to science by means of LS thin-film nanotechnology.

An in situ self-assembly technique with nanometre control over thicknesses and multilayered structures was used to manufacture the ultrathin films of polypyrrole (PPY). The PPY film was deposited on a polyanion, poly(styrene sulfonate) (PSS) modified surface as a function of time, previously PSS had been deposited on various substrates (glass, mica, indium-tin-oxide coated glass plates). Later, alternate PPY and PSS films were fabricated on such substrates using a layer-by-layer (LBL) technique. The glucose oxidase (GOD) molecules were also deposited on such self-assembled PPY films by the LBL technique. The PSS/PPY/GOD, PPY/PPY/GOD/poly(ethylene imine) (PEI)/GOD etc, film configurations were fabricated, and functionally as well as structurally characterized by UV-visible, electrochemical and scanning probe microscopy techniques, respectively. The results of a scanning probe microscopic study on the films were analysed to understand the molecular orientation of GOD on the PPY surface, and the dependence of the enzyme concentration for the depositing solutions. Moreover, the electrochemical studies performed provided information with respect to the electron transfer processes on the spatial arrangement of GOD molecules on the PPY surfaces. The immobilization of GOD on a conductive PPY represented a crucial and important step, and allowed us to construct the glucose-responsive biosensors.

Nanoscale science and technology is today mainly focused on the fabrication of nanodevices. Our approach makes use of lithography processes to build the desired nanostructures directly. The fabrication process involves an electron-beam lithography technique to define metallic microstructures onto which nanometre scale patterning is performed using an atomic force microscope (AFM) as a mechanical modification tool. Both direct material removal and AFM-assisted mask patterning are applied in order to achieve the smallest possible separation between electrode pairs. The sample preparation involves a polymer deposition process that results in conformal growth and in surface roughness comparable to that of the substrate. The results of the application of this technique show that the process is reproducible and exhibits a good operation control during the lithographic steps, both ensured by the imaging facilities of the AFM. The nanolithography technique has been used to fabricate nanogap electrodes to be used for molecular devices. The study reported here can be considered as a reliable starting point for the development of more complex nanodevices, such as single-electron transistors.

Langmuir-Schaefer (LS) films of poly(o-anisidine) (POAS) were fabricated and characterized by means of Brewster-angle microscopy, ellipsometry and electrochemical techniques. The studied optical, cyclic voltammetric and ellipsometric properties of films underlined a regular deposition up to at least 40 monolayers of POAS conducting polymer. The development of surface irregularities beyond 40 monolayers in LS films showed an electrochemical kinetic similar to electrodeposited films. More importantly, the electrochemical kinetic in a small number of monolayers was indicative of the fast transfer process of the electrons. The nature of anions caused meaningful changes in the redox properties of POAS LS films. The electrochromic switching response time and diffusion coefficient of the LS films were estimated through electrochemical surveying. Later, POAS LS films were used as a sensing element for a survey of 0.1 ppm of acid in water through conductimetric measurement.

Semiconductor nanoparticles were synthesized by exposing fatty acid salt Langmuir-Blodgett films to the atmosphere of . The particle sizes were characterized by small-angle x-ray scattering of their solutions using synchrotron radiation source at higher resolution, as it was impossible previously to study it with usual laboratory x-ray sources. The particle sizes were found to correspond with the demands of single-electron and quantum junctions. Semiconductor heterostructures were grown by self-aggregation of these particles of different types. Electrical properties of these nanostructures were studied by using STM. Voltage-current characteristics revealed the presence of differential negative resistance. Measurements confirmed the formation of semiconductor superlattices directed towards a development of new nanodevices, such as tunnelling diodes and semiconductor lasers.