Papers by Karine Steenkeste
Photochemical & Photobiological Sciences
Photophysical studies on a BODIPY-fullerene-distyryl BODIPY triad (BDP-C 60-DSBDP) and its refere... more Photophysical studies on a BODIPY-fullerene-distyryl BODIPY triad (BDP-C 60-DSBDP) and its reference dyads (BODIPYfullerene; BDP-C 60 and distyryl BODIPY-fullerene; DSBDP-C 60) are presented herein. In the triad, the association of the two chromophore units linked by a fullerene moiety leads to strong near UV-Visible light absorption from 300 to 700 nm. The triplet-excited state was observed upon visible excitation in all these assemblies, and shown to be localized on the C 60 or BODIPY moieties. Using quantitative nanosecond transient absorption, we provide a complete investigation on the lifetime and formation quantum yield of the triplet-excited state. In the BDP-C 60 dyad, the triplet excited state of C 60 (τ = 7 ± 1 μs) was obtained with a quantum yield of 40 ± 8%. For the DSBDP-C 60 dyad and BDP-C 60-DSBDP triad, a longer-lived triplet excited state with a lifetime of around 250 ± 20 μs centered on the DSBDP moiety was formed, with respective quantum yields of 37 ± 8 and 20 ± 4%. Triplet-triplet annihilation up-conversion is characterized in the BDP-C 60 dyad and the bichromophoric triad in the presence of perylene and DSBDP-monomer as respective annihilators. The photo-induced formation of a longlived 3 DSBDP* in the triad coupled with panchromatic light absorption offers potential applications as a heavy-atom-free organic triplet photosensitizer.
MOESM2 of Food-grade TiO2 is trapped by intestinal mucus in vitro but does not impair mucin O-glycosylation and short-chain fatty acid synthesis in vivo: implications for gut barrier protection
Additional file 2. Movie sequence showing the fluorescence distribution inside HT29-MTX structure... more Additional file 2. Movie sequence showing the fluorescence distribution inside HT29-MTX structures from the substratum to the top 1 hour after the addition of food-grade TiO2 (E171).
MOESM1 of Food-grade TiO2 is trapped by intestinal mucus in vitro but does not impair mucin O-glycosylation and short-chain fatty acid synthesis in vivo: implications for gut barrier protection
Additional file 1. Movie sequence showing the fluorescence distribution inside HT29-MTX structure... more Additional file 1. Movie sequence showing the fluorescence distribution inside HT29-MTX structures from the substratum to the top before the addition of food-grade TiO2 (E171).
Je remercie tout d'abord M. Philippe Bréchignac, directeur de l'ISMO, de m'avoir accueillie dans ... more Je remercie tout d'abord M. Philippe Bréchignac, directeur de l'ISMO, de m'avoir accueillie dans son unité de recherche. Je suis très reconnaissante à mes trois directeurs de thèse, Marie-Pierre Fontaine-Aupart, Karine Steenkeste et Romain Briandet pour m'avoir encadrée durant les trois années de thèse. Je les remercie pour leur disponibilité, leur aide à améliorer mon manuscrit de thèse et leurs encouragements à présenter les résultats de mon travail dans des congrès et des journées scientifiques. Merci Karine de m'avoir formée à l'utilisation des techniques de microscopie de fluorescence multimodale. Je tiens à remercier François Waharte de l'Institut Curie qui nous a fait bénéficier de son expérience pour traiter les données de FRAP. Mes remerciements vont à toute l'équipe du CPBM, de l'
The Journal of antimicrobial chemotherapy, Jan 6, 2016
Prosthetic vascular graft infection (PVGI) is an emerging disease, mostly caused by staphylococci... more Prosthetic vascular graft infection (PVGI) is an emerging disease, mostly caused by staphylococci, with limited data regarding efficacy of current antistaphylococcal agents. We aimed to assess the efficacy of different antibiotic regimens. Six different strains of MSSA and MRSA were used. We compared results of minimal biofilm inhibitory and eradicating concentrations (MBICs and MBECs) obtained with a Calgary Biofilm Pin Lid Device (CBPD) with those yielded by an original Dacron(®)-related minimal inhibitory and eradicating concentration measure model. We then used a murine model of Staphylococcus aureus vascular prosthetic material infection to evaluate efficacy of different antibiotic regimens: vancomycin and daptomycin combined or not with rifampicin for MRSA and the same groups with cloxacillin and cloxacillin combined with rifampicin for MSSA. We demonstrated that classical measures of MBICs and MBECs obtained with a CPBD could overestimate the decrease in antibiotic susceptibi...
La photonique pour l'étude du milieu biologique: De la réactivité au diagnostic
Photonics for the study of biological systems: from the reactivity to the diagnostic Fluorescence... more Photonics for the study of biological systems: from the reactivity to the diagnostic Fluorescence microscopy under two photon excitation is a recent biophotonic development aiming at original fluorescence analysis by intensity and fluorescence lifetime imaging. After a brief description of the performance of the instrumental set up, its utilization for studies of pharmacological and biomedical interest is presented.
Surface functionalization strategy to enhance the antibacterial effect of nisin Z peptide
Surfaces and Interfaces, 2022
Applied and Environmental Microbiology, 2011
ABSTRACTDiffusion of entities inside biofilm triggers most mechanisms involved in biofilm-specifi... more ABSTRACTDiffusion of entities inside biofilm triggers most mechanisms involved in biofilm-specific phenotypes. Using genetically engineered hydrophilic and hydrophobic cells ofLactococcus lactisyielding similar biofilm architectures, we demonstrated by fluorescence correlation spectroscopy that bacterial surface properties affect diffusion of nanoparticles through the biofilm matrix.
Taking Advantage of Fluorescent‐Based Tools to Puzzle out Successes and Failures of Antibiotics to Inactivate Infectious Bacteria
The Journal of Physical Chemistry C, 2016
To an early diagnosis of cancers by cellular autofluorescence imaging
Biomedical Optics, 2006
We developed a method for early diagnosis of cancers based on spectrally- and time-resolved endog... more We developed a method for early diagnosis of cancers based on spectrally- and time-resolved endogenous fluorescence as a contrast factor. Promising results have already been obtained for bladder cancers. A detailed clinical study is presented.
Nanostructural Evolution of Natural Rubber/Silica Nanoparticle Coagulation from Binary Colloidal Suspensions to Composites: Implications for Tire Materials
ACS Applied Nano Materials
Time‐Resolved Spectroscopy and High Efficiency Light‐driven Hydrogen Evolution of a {Mo3S4}‐Containing Polyoxometalate‐Based System
Chemistry – A European Journal
Fluorescence Emitted by Papanicolaou-Stained Urothelial Cells Improves Sensitivity of Urinary Conventional Cytology for Detection of Urothelial Tumors
World Journal of Oncology
Cover Image, Volume 138, Issue 8
Journal of Applied Polymer Science
Natural rubber‐carbon black coagulation: Following the nanostructure evolution from a colloidal suspension to a composite
Journal of Applied Polymer Science
Self-assembled multifunctional core–shell highly porous metal–organic framework nanoparticles
International Journal of Pharmaceutics
Journal of Antimicrobial Chemotherapy
Objectives: To evaluate the significant role played by biofilms during prosthetic vascular materi... more Objectives: To evaluate the significant role played by biofilms during prosthetic vascular material infections (PVMIs). Methods: We developed an in vivo mouse model of Staphylococcus aureus PVMI allowing its direct observation by confocal microscopy to describe: (i) the structure of biofilms developed on Dacron V R vascular material; (ii) the localization and effect of antibiotics on these biostructures; and (iii) the interaction between bacteria and host tissues and cells during PVMI. Results: In this model we demonstrated that the biofilm structures are correlated to the activity of antibiotics. Furthermore, live S. aureus bacteria were visualized inside the macrophages present at the biofilm sites, which is significant as antibiotics do not penetrate these immune cells. Conclusions: This intracellular situation may explain the limited effect of antibiotics and also why PVMIs can relapse after antibiotic therapy.
ACS Omega
Fast and selective detection of pathogens represents high challenges given the considerably high ... more Fast and selective detection of pathogens represents high challenges given the considerably high proliferation rate and mutation potential of bacteria against antibiotics. With this aim, anionic red-orangeemitting fluorescent organic nanoparticles (FONs), characterized by high brightness and photostability, are developed to selectively stain Staphylococcus aureus after only 5 min of exposure. No cytotoxicity effects are observed as a result of the negatively charge surface of the employed FONs. By contrast, no staining can be observed with Pseudomonas aeruginosa strains. The exclusive labeling of Gram-positive bacteria is ascribed to originate from the phosphonic acid moieties incorporated in the FON-constituting fluorophores because model FONs, devoid of phosphonic acids, show no adhesion under the same experimental conditions. Tight hydrogen bonding between the FON acidic units and the peptidoglycan (PG) layers comprising the outer wall of S. aureus is suspected to be the prevailing factor for the encountered selective interactions. PG layers from S. aureus are employed to apprehend the interactions developed between FONs and the bacteria membrane. Correlative light electron microscopy using confocal fluorescence microscopy and SEM reveal FONs mainly located at extensively reorganized or "dented" PG areas. Such privileged localizations tend to suggest multivalent physicochemical interactions to aggregate a multifold of nanoparticles. Finally, spectral follow-up of the FON-stained bacteria membrane shows significant hypsochromic shift of the fluorescence emission, signaling progressive disassembly of FONs and a change of the surrounding polarity. This feature offers promising perspectives to use doped FONs as theranostic agents to liberate encapsulated antibiotics upon FON disintegration inside the bacteria membrane.
The Cell Surface
We took benefit from Atomic Force Microscopy (AFM) in the force spectroscopy mode to describe the... more We took benefit from Atomic Force Microscopy (AFM) in the force spectroscopy mode to describe the time evolutionover 24 hof the surface nanotopography and mechanical properties of the strain Staphylococcus aureus 27217 from bacterial adhesion to the first stage of biofilm genesis. In addition, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) experiments allowed identifying two types of selfadhering subpopulations (the so-called "bald" and "hairy" cells) and revealed changes in their relative populations with the bacterial culture age and the protocol of preparation. We indeed observed a dramatic evanescing of the "hairy" subpopulation for samples that underwent centrifugation and resuspension processes. When examined by AFM, the "hairy" cell surface resembled to a herringbone structure characterized by upper structural units with lateral dimensions of ∼70 nm and a high Young modulus value (∼2.3 MPa), a mean depth of the trough between them of ∼15 nm and a resulting roughness of ∼5 nm. By contrast, the "bald" cells appeared much softer (∼0.35 MPa) with a roughness one order of magnitude lower. We observed too the gradual detachment of the herringbone patterns from the "hairy" bacterial envelope of cell harvested from a 16 h old culture and their progressive accumulation between the bacteria in the form of globular clusters. The secretion of a soft extracellular polymeric substance was also identified that, in addition to the globular clusters, may contribute to the initiation of the biofilm spatial organization.
Uploads
Papers by Karine Steenkeste