Peer-reviewed Publications |
Alchab, L., Dupuis, G., Balleyguier, C., Mathieu, M. - C., Fontaine-Aupart, M. - P., & Farcy, R. (2010). Towards an optical biopsy for the diagnosis of breast cancer in vivo by endogenous fluorescence spectroscopy. JOURNAL OF BIOPHOTONICS, 3(5-6), 373–384.
Résumé: The techniques of medical imaging allow the detection of suspect lesions in the breast, but they do not always evidence the malignant nature of these lesions. Breast biopsies and histological analyses are therefore implemented to establish a diagnosis. In order to reduce the number of these invasive procedures, a portable clinical system was designed based upon the excitation of Endogenous Fluorescence in vivo at 405 nm via a fiber-optics probe included in a disposable needle of small diameter (<1 mm). From the fluorescence signal, the authors are able to discriminate between diseased and healthy areas of human breast biopsies. Stronger fluorescence intensity and systematic spectral red shift of the tumor areas were observed. These results are confirmed by confocal microscopy. This new instrument is promising for the minimally invasive diagnosis of breast tumors in vivo with an appreciable limitation of patient trauma and of operational and financial cost. [GRAPHICS] Measurement of the endogenous fluorescence spectrum of a tissue sample via a fiber-optics probe included in a disposable needle of small diameter (<1 mm).
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Aubry, G., Meance, S., Haghiri-Gosnet, A. - M., & Kou, Q. (2010). Flow rate based control of wavelength emission in a multicolor microfluidic dye laser. MICROELECTRONIC ENGINEERING, 87(5-8), 765–768.
Résumé: An original method is investigated to monitor the emission of a microfluidic dye laser. It relies on the flow rate of a dye mixture solution. The two dyes are at the origin of laser effects at two distinct wavelengths. In function of the dye mixture flow rate, one wavelength or the other can be selected. The purpose is to achieve a wavelength on-demand system which would be of great interest for spectroscopic analysis of biochemical samples. (C) 2009 Elsevier B.V. All rights reserved.
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Guelluy, P. - H., Fontaine-Aupart, M. - P., Grammenos, A., Lecart, S., Piette, J., & Hoebeke, M. (2010). Optimizing photodynamic therapy by liposomal formulation of the photosensitizer pyropheophorbide-a methyl ester: In vitro and ex vivo comparative biophysical investigations in a colon carcinoma cell line. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES, 9(9), 1252–1260.
Résumé: Photodynamic therapy (PDT), induced by a photosensitizer (PS) encapsulated in a nanostructure, has emerged as an appropriate treatment to cure a multitude of oncological and non-oncological diseases. Pyropheophorbide-a methyl ester (PPME) is a second-generation PS tested in PDT, and is a potential candidate for future clinical applications. The present study, carried out in a human colon carcinoma cell line (HCT-116), evaluates the improvement resulting from a liposomal formulation of PPME versus free-PPME. Absorption and fluorescence spectroscopies, fluorescence lifetime measurements, subcellular imaging and co-localization analysis have been performed in order to analyze the properties of PPME for each delivery mode. The benefit of drug encapsulation in DMPC-liposomes is clear from our experiments, with a 5-fold higher intracellular drug delivery than that observed with free-PPME at similar concentrations. The reactive oxygen species (ROSs) produced after PPME-mediated photosensitization have been identified and quantified by using electron spin resonance spectroscopy. Our results demonstrate that PPME-PDT-mediated ROSs are composed of singlet oxygen and a hydroxyl radical. The small amounts of PPME inside mitochondria, as revealed by fluorescence co-localization analysis, could maybe explain the very low apoptotic cell death measured in HCT-116 cells.
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Kobayashi, K., Usami, N., Porcel, E., Lacombe, S., & Le Sech, C. (2010). Enhancement of radiation effect by heavy elements. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH, 704(1-3), 123–131.
Résumé: The enhancement of radiobiological effects by heavy elements is reviewed. As an underlying mechanism, Auger effects have been stressed which can be induced via inner-shell photoabsorption or via excitation and/or ionization by secondary electrons. Latter channel of Auger induction expands the applicability of Auger enhancing phenomena to electron and hadron therapy. After discussion on the required characteristics for radiosensitizers, possibility of nanoparticles of Au or Pt is mentioned since they could be synthesized or modified as ideal radiosensitizers. (C) 2010 Elsevier B.V. All rights reserved.
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Lacombe, S., Sabatier, L., Wien, F., & Gauduel, Y. A. (2010). Spatio-temporal radiation biology: new insights and biomedical perspectives. CELL DEATH & DISEASE, 1.
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Laffon, C., Lasne, J., Bournel, F., Schulte, K., Lacombe, S., & Parent, P. (2010). Photochemistry of carbon monoxide and methanol in water and nitric acid hydrate ices: A NEXAFS study. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 12(36), 10865–10870.
Résumé: Soft X-ray induced chemistry of H(2)O, CO and CH(3)OH and the effects of the water and nitric acid hydrate (HNO(3)center dot 1.65H(2)O) matrix on the photochemistry of CO and CH(3)OH have been investigated using NEXAFS spectroscopy. For pure H(2)O, CO and CH(3)OH ices, we show that the destruction rates are strongly limited by back reactions, leading to strikingly high survival rates of these molecules upon the harsh irradiation conditions to which they are submitted. We also evidence the interplay between the photochemical reactions of CO and CH(3)OH and those of the matrix. The OH and O radicals released by the photolysis of H(2)O and HNO(3) react with the CO and CH(3)OH and their fragments, considerably reducing the survival rates compared to pure CO and pure CH(3)OH ices, especially in presence of nitric acid, and dramatically enhancing the formation of CO(2) at the expense of CO. Because NEXAFS spectroscopy allows identifying which reactions are important among those possible, it emerges a simple picture of the photochemical routes of CO and CH(3)OH in the H(2)O and HNO(3)/H(2)O environments.
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Porcel, E., Liehn, S., Remita, H., Usami, N., Kobayashi, K., Furusawa, Y., Le Sech, C., & Lacombe, S. (2010). Platinum nanoparticles: a promising material for future cancer therapy? Nanotechnology, 21(8), 85103.
Résumé: Recently, the use of gold nanoparticles as potential tumor selective radiosensitizers has been proposed as a breakthrough in radiotherapy. Experiments in living cells and in vivo have demonstrated the efficiency of the metal nanoparticles when combined with low energy x-ray radiations (below conventional 1 MeV Linac radiation). Further studies on DNA have been performed in order to better understand the fundamental processes of sensitization and to further improve the method. In this work, we propose a new strategy based on the combination of platinum nanoparticles with irradiation by fast ions effectively used in hadron therapy. It is observed in particular that nanoparticles enhance strongly lethal damage in DNA, with an efficiency factor close to 2 for double strand breaks. In order to disentangle the effect of the nano-design architecture, a comparison with the effects of dispersed metal atoms at the same concentration has been performed. It is thus shown that the sensitization in nanoparticles is enhanced due to auto-amplified electronic cascades inside the nanoparticles, which reinforces the energy deposition in the close vicinity of the metal. Finally, the combination of fast ion radiation (hadron therapy) with platinum nanoparticles should strongly improve cancer therapy protocols.
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Steenkeste, K., Tfibel, F., Perree-Fauvet, M., Briandet, R., & Fontaine-Aupart, M. - P. (2010). Tracking the Photosensitizing Antibacterial Activity of Mono(acridyl)bis(arginyl)porphyrin (MABAP) by Time-Resolved Spectroscopy. JOURNAL OF PHYSICAL CHEMISTRY A, 114(9), 3334–3339.
Résumé: Photodynamic inactivation (PDI) is currently receiving interest for its potential as an antimicrobial treatment. Although photosensitizing agents and light have been used for medical purposes for a very long time, only a little information is available about the mechanism of PDI for bacteria. Pseudomonas aeruginosa is a Gram negative bacteria involved in chronic infections in cystic fibrosis patients and also one of the commonest agents of hospital acquired infections. In the present study the sensitivity of Pseudomonas aeruginosa to the phototoxic effects of the mono(acridyl)bis(arginyl)porphyrin (MABAP) has been investigated as well as the photophysical and photochemical properties of this cationic porphyrin complexed to [poly(dG-dC)](2) to investigate the mechanisms that lead to bacteria inactivation. Both picosecond time-resolved fluorescence and femtosecond to nanosecond transient absorption measurements give evidence that while MABAP can react through its triplet state and/or an ultrafast electron transfer with guanine, its intercalation between GC base pairs is not the main target of MABAP photoactivity. The analysis of both fluorescence emission and excitation spectra reveals the occurrence of an energy transfer through the DNA double helix between the acridine and porphyrin chromophores of MABAP, as previously observed for the stacked free molecule in solution. This efficient process may lead to the excitation of twice more porphyrin chromophores in MABAP by comparison to other cationic porphyrins.
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Usami, N., Kobayashi, K., Hirayama, R., Furusawa, Y., Porcel, E., Lacombe, S., & Le Sech, C. (2010). Comparison of DNA Breaks at Entrance Channel and Bragg Peak Induced by Fast C6+ Ions-Influence of the Addition of Platinum Atoms on DNA. JOURNAL OF RADIATION RESEARCH, 51(1), 21–26.
Résumé: When energetic carbon ion beam (GeV range) goes through the matter, inelastic processes such as electronic ionization, molecular and nuclear fragmentation occur. For carbontherapy (hadrontherapy) purpose, it is of interest to compare the number of DNA breaks -single SSB or double DSB- for a given dose at the entrance channel and at the Bragg peak to look for a possible differential effect in the number of DNA breaks induced at these two locations. Samples of free plasmids DNA and complexes of plasmids DNA added with molecules containing platinum have been placed at different locations of an experimental setup simulating penetration depths of the ion beam in water and irradiated by carbon ions 290 MeV/amu. The DNA breaks have been quantified by subsequent electrophoresis on agarose gels. To disentangle the respective role of the direct and indirect effect, a free radical scavenger of hydroxyl radicals HO degrees -dimethyl sulfoxide DMSO- has been added in some of the experiments. In the range of Linear Energy Transfert -LET 13 – 110 keV/mu m-, the number of the DSB was found to be constant versus the LET for a given dose. Contrary, the number of the SSB decreases at the Bragg peak compared to the entrance channel. In the presence of platinum, the number of single and double breaks was considerably enhanced, and follows a similar behaviour than in the free-DNA experiments. Quantitative results on DNA damages do not show significant enhancement due to the nuclear or to the molecular fragmentation in the present experiments.
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Waharte, F., Steenkeste, K., Briandet, R., & Fontaine-Aupart, M. - P. (2010). Diffusion Measurements inside Biofilms by Image-Based Fluorescence Recovery after Photobleaching (FRAP) Analysis with a Commercial Confocal Laser Scanning Microscope. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 76(17), 5860–5869.
Résumé: Research about the reactional and structural dynamics of biofilms at the molecular level has made great strides, owing to efficient fluorescence imaging methods in terms of spatial resolution and fast acquisition time but also to noninvasive conditions of observation consistent with in situ biofilm studies. In addition to conventional fluorescence intensity imaging, the fluorescence recovery after photobleaching (FRAP) module can now be routinely implemented on commercial confocal laser scanning microscopes (CLSMs). This method allows measuring of local diffusion coefficients in biofilms and could become an alternative to fluorescence correlation spectroscopy (FCS). We present here an image-based FRAP protocol to improve the accuracy of FRAP measurements inside “live” biofilms and the corresponding analysis. An original kymogram representation allows control of the absence of perturbing bacterial movement during image acquisition. FRAP data analysis takes into account molecular diffusion during the bleach phase and uses the image information to extract molecular diffusion coefficients. The fluorescence spatial intensity profile analysis used here for the first time with biofilms is supported both by our own mathematical model and by a previously published one. This approach was validated to FRAP experiments on fluorescent-dextran diffusion inside Lactoccocus lactis and Stenotrophomonas maltophilia biofilms, and the results were compared to previously published FCS measurements.
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Actes de Conférences |
Delahaye, J., Gresillon, S., Leveque-Fort, S., Sojic, N., & Fort, E. (2010). Fluorescence Correlation Spectroscopy on Nano-fakir Surfaces. In SINGLE MOLECULE SPECTROSCOPY AND IMAGING III (Vol. 7571).
Résumé: Single biomolecule behaviour can reveal crucial information about processes not accessible by ensemble measurements. It thus represents a real biotechnological challenge. Common optical microscopy approaches require pico- to nano-molar concentrations in order to isolate an individual molecule in the observation volume. However, biologically relevant conditions often involve micromolar concentrations, which impose a drastic reduction of the conventional observation volume by at least three orders of magnitude. This confinement is also crucial for mapping sub-wavelength heterogeneities in cells, which play an important role in many biological processes. We propose an original approach, which couples Fluorescence Correlation Spectroscopy (FCS), a powerful tool to retrieve essential information on single molecular behaviour, and nano-fakir substrates with strong field enhancements and confinements at their surface. These electromagnetic singularities at nanometer scale, called “hotspots”, are the result of the unique optical properties of surface plasmons. They provide an elegant means for studying single-molecule dynamics at high concentrations by reducing dramatically the excitation volume and enhancing the fluorophore signal by several orders of magnitude. The nano-fakir substrates used are obtained from etching optical fiber bundles followed by sputtering of a gold thin-film. It allows one to design reproducible arrays of nanotips.
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