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Biomedical subjects

Andrea Valsesia

Publications and source records attributed to Andrea Valsesia.

5 recordsLinked to original sources
PubMed2006

Electrogenerated indium tin oxide-coated glass surface with photosensitive interfaces: surface analysis.

We present herein a photo-immobilization technique for the localized and specific conjugation of biochip platforms with different proteinaceous bioreceptors, such as antigen or antibodies. This methodology based on a photoactivable electrogenerated polymer film, pyrrole-benzophenone, allows the covalent immobilization of biomolecules through light mediation. The surface-conductive glass platform electropolymerized with poly(pyrrole-benzophenone) thin film may then be used to affinity-coat the chip with molecular recognition probes. This glass chip electroconductive surface modification is done by the deposition of a thin layer of indium tin oxide (ITO). Thereafter, pyrrole-benzophenone monomers are electropolymerized onto the conductive metal oxide surface and then exposed to an antigen Staphylococcal Enterotoxin B (SEB)) solution and illuminated with UV light (wavelength approximately 345 nm) through a mask. As a result of the photochemical reaction, a pattern thin layer of the antigen was covalently bound to the benzophenone-modified surface. Then the sample to be analyzed, along with its specific target antibody (anti-SEB antibodies), is introduced onto the glass surface and left to react with the previously photo-immobilized antigen. When the immuno-reaction is completed, the specifically attached immunoglobulin analytes are detected by using secondary antibodies conjugated with Fluorescein isothiocyanate (FITC). The fluorescence signal emanating from the biochip surface is then quantified by two methods, using a filtered intensified charge-coupled device (CCD) camera and a grating spectrometer.

Antibodies↗
PubMed2006

Fabrication of polypyrrole-based nanoelectrode arrays by colloidal lithography.

This paper describes a novel technique to produce polypyrrole-based nanoelectrodes for electrochemical detection purpose. The fabrication process relies on the creation of patterned nanotemplates i.e., nanometric gold spots surrounded by an electrically insulating material (SiO(x)). From these templates, polypyrrole nanopillars are grown by classical electrochemical methods. Atomic force microscopy demonstrates that polypyrrole grows selectively inside the gold nanotemplates. The electrochemical characterization by cyclic voltammetry showed a sigmoidal-shaped voltammogram characterizing the typical nanoelectrode array behavior.

Colloids↗
PubMed2006

Plasma-based processes for surface wettability modification.

In this article, we describe a method to create rough features on silicon surfaces by reactive etching of a photoresist layer. The roughness and, consequently, the wettability of the surfaces can be modified by modifying the duration of plasma etching. Hydrophobic materials deposited on the rough silicon surface can be modified until a superhydrophobic behavior is obtained, whereas hydrophilic materials become more hydrophilic. The elaboration technique described herein offers an inexpensive and rapid method for the creation of tunable roughness on silicon surfaces with large areas.

Hydrophobic and Hydrophilic Interactions↗
PubMed2006

Immobilization of antibodies on biosensing devices by nanoarrayed self-assembled monolayers.

This work presents an original and straightforward technique for antibody immobilization onto a surface, keeping the antibody in a biologically reactive configuration. Self-assembly of molecular monolayers and plasma-based colloidal lithography were combined to create chemical nanopatterns on the surface of a biosensing device. This technique was employed to create an array of 100 nm wide motifs having a hexagonal 2-D crystalline structure, characterized by COOH-terminated nanospots in a CH3-terminated matrix. The quality control of the chemical nanopattern was carried out by combining atomic force microscopy, ellipsometry, and contact angle measurements. Enzyme-linked immunosorbent assay experiments were set up showing that the COOH/CH3 nanopatterned surface constrains the immobilization of the antibodies in a biologically reactive configuration, thus significantly improving the device performances as compared to those of more conventional nonpatterned COOH-terminated or CH3-terminated surfaces.

Adsorption↗