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Biomedical subjects

Thierry Livache

Publications and source records attributed to Thierry Livache.

7 recordsLinked to original sources
PubMed2005

Clinically related protein-peptide interactions monitored in real time on novel peptide chips by surface plasmon resonance imaging.

BACKGROUND: Developing rapid, high-throughput assays for detecting and characterizing protein-protein interactions is a great challenge in the postgenomic era. We have developed a new method that allows parallel analysis of multiple analytes in biological fluids and is suitable for biological and medical studies. METHODS: This technology for studying peptide-antibody interactions is based on polypyrrole-peptide chips and surface plasmon resonance imaging (SPRi). We generated a chip bearing a large panel of peptide probes by successive electro-directed copolymerizations of pyrrole-peptide conjugates on a gold surface. RESULTS: We provide evidence that (a) the signal produced by antibody binding is highly specific; (b) the detected signal specifically reflects the antibody concentration of the tested solution in a dose-dependent manner; (c) this technique is appropriate for analyzing complex media such as undiluted sera, a novelty with respect to previous techniques; and (d) correlation between classic ELISA results and the SPRi signal is good (P = 0.008). We also validated this system in a medical model by detecting anti-hepatitis C antibodies in patient-derived sera. CONCLUSION: Because of its characteristics (easy preparation of the peptide chip; high-throughput, label-free, real-time detection; high specificity; and low background), this technology is suitable for screening biological samples and for large-scale studies.

Binding Sites, Antibody↗
PubMed2005

A polypyrrole protein microarray for antibody-antigen interaction studies using a label-free detection process.

Protein microarray is a promising technology that should combine rapidity and easy use with high throughput and versatility. This article describes a method in which an electrocopolymerization process is employed to graft biological molecules on to a chip so that surface plasmon resonance imaging may be used to detect molecular interactions. Copolymerization of pyrrole-modified protein and pyrrole is an efficient grafting process which immobilizes molecules at defined positions on a gold surface. Surface plasmon resonance imaging is an optical technique that allows real-time simultaneous detection of molecular interactions on a large number of spots without labeling. This method was successfully used to analyze antibody-antigen interactions. This illustrates its high specificity and good sensitivity and demonstrates its suitability for biological studies.

Animals↗
PubMed2004

New approach to writing and simultaneous reading of micropatterns: combining surface plasmon resonance imaging with scanning electrochemical microscopy (SECM).

This work establishes the compatibility of surface plasmon resonance imaging (SPR-i) with the visualization of localized electropolymerization. The "writing" of polypyrrole and polypyrrole-oligonucleotide patterns onto thin gold films is demonstrated using scanning electrochemical microcopy (SECM), while an optical method, SPR-i, simultaneously detected the formed micropatterns. The combination of these two methods, SECM/SPR-i, has the advantage of not only controlling the patterning process but also providing unique information on the micropattern formation. The influence of the pulsing time and the monomer concentration on the spot size and its characteristics has been investigated in detail using SPR-i. Fluorescence microscopy and atomic force microscopy have also been used to support the data obtained by SPR-i.

Gold↗
PubMed2004

Versatile analysis of multiple macromolecular interactions by SPR imaging: application to p53 and DNA interaction.

The greatest challenge in the postgenomic era is the description of proteome interactions, such as protein-protein or protein-DNA interactions. Surface plasmon resonance (SPR) is an optical technique in which binding of an analyte to the surface changes the refractive index at the surface/solution interface. Molecular interactions are analysed in real time without a labeling step. Currently, the limit to SPR imaging is the small number of reactions that can be simultaneously analysed. Using a novel grafting technology and a new imaging system, we increased the throughput of SPR imaging. The interaction between p53 and DNA was chosen as a paradigm for validation of this assay. Using a tagged DNA methodology, we simultaneously targeted multiple DNA sequences on a single chip. The interaction between p53 and these DNA sequences was monitored by SPR imaging. Qualitative and quantitative analysis provides results similar to those obtained with conventional technologies.

DNA↗
PubMed2003

Biotin grafting on boron-doped diamond.

Grafting of biotin on top of a polycrystalline boron-doped diamond layer was achieved by surface oxidation followed by an esterification reaction and revealed by fluorescently labelled streptavidin.

Journal Article↗
PubMed2003

Polypyrrole based DNA hybridization assays: study of label free detection processes versus fluorescence on microchips.

In this paper, we present different ways to detect DNA hybridization on a solid support. The grafting chemistry is based on the electro-controlled copolymerization of a pyrrole-modified oligonucleotide and pyrrole. This process allows an easy functionalization of conducting materials. Three kind of devices were studied: silicon chips bearing an array of addressable 50 or 4 microm microelectrodes, quartz crystal microbalance (QCM) and a non patterned gold/glass slide bearing 500 microm spots. Each device is compatible with a specific detection process: a classical indirect fluorescence detection for the microchips, a microgravimetric measurement for the QCM and a surface plasmon resonance imaging process (SPRi) for the gold slides. Both QCM and SPRi are a label-free real time detection process whereas the fluorescence methodology gives end-point data but only the fluorescence and the SPRi give multiparametric results. Although the hybridization experiments show that the detection limit for an oligonucleotide is better for the fluorescence (1-10 pM) than that found for SPRi (10 nM) and QCM (250 nM), the information content of real time measurement techniques such as SPRi is of interest for many biological studies.

DNA↗