Publications by authors named "Guillaume Laurent"

42 Publications

Baicalein-modified hydroxyapatite nanoparticles and coatings with antibacterial and antioxidant properties.

Mater Sci Eng C Mater Biol Appl 2021 Jan 22;118:111537. Epub 2020 Sep 22.

Sorbonne Université, CNRS, Laboratoire de Réactivité de Surface (LRS), 4 place Jussieu, 75005 Paris, France. Electronic address:

Aseptic loosening and bacterial infections are the two main causes of failure for metallic implants used for joint replacement. A coating that is both bioactive and possesses antimicrobial properties may address such shortcomings and improve the performance of the implant. We have sought to study the properties of combining hydroxyapatite-based nanoparticles or coatings with baicalein, a plant-extracted molecule with both antibacterial and antioxidant properties. (B-type) carbonated hydroxyapatite nanoparticles prepared by a chemical wet method could subsequently adsorbed by soaking in a baicalein solution. The amount of adsorbed baicalein was determined to be 63 mg.g by thermogravimetric measurements. In a second approach, baicalein was adsorbed on a biomimetic calcium-deficient hydroxyapatite planar coating (12 μm thick) deposited on Ti6Al4V alloy from an aqueous solution of calcium, phosphate, sodium and magnesium salts. Soaking of the hydroxyapatite coated on titanium alloy in a baicalein solution induced partial dissolution/remodeling of the upper surface of the coating. However, the observed remodeling of the surface was much more pronounced in the presence of a baicalein solution, compared to pure water. The presence of adsorbed baicalein on the HAp layer, although it could not be precisely quantified, was assessed by XPS and fluorescence analysis. Planar coatings exhibited significant antibacterial properties against Staphylococcus epidermidis. Baicalein-modified nanoparticles exhibited significant antioxidant properties. These results illustrate the potential of hydroxyapatite used as a carrier for natural biologically-active molecules and also discuss the challenges associated with their applications as antibacterial agents.
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http://dx.doi.org/10.1016/j.msec.2020.111537DOI Listing
January 2021

Presacral Myelolipoma: The Usefulness of a 99mTc-Albumin Nanocolloid Scintigraphy.

Clin Nucl Med 2021 Jan;46(1):38-39

From the Departments of Nuclear Medicine.

Myelolipoma is a rare mesenchymal tumor consisting of adipose tissue and hematopoietic cells. Found usually in the adrenal region, however, few cases have been reported in extra-adrenal regions, most frequently in the presacral region. It is important to recognize such tumor, as it can attain massive size and causes pressure symptoms, and needs to be differentiated from malignant tumors, including liposarcomas. Although CT and MRI can suggest a diagnosis of myelolipoma, these are not conclusive. The hematopoietic cells are enhanced by a Tc-albumin nanocolloid scintigraphy and help to distinguish myolipoma from other entities.
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http://dx.doi.org/10.1097/RLU.0000000000003348DOI Listing
January 2021

Solid-State Phase Transformation and Self-Assembly of Amorphous Nanoparticles into Higher-Order Mineral Structures.

J Am Chem Soc 2020 07 7;142(29):12811-12825. Epub 2020 Jul 7.

Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, United States.

Materials science has been informed by nonclassical pathways to crystallization, based on biological processes, about the fabrication of damage-tolerant composite materials. Various biomineralizing taxa, such as stony corals, deposit metastable, magnesium-rich, amorphous calcium carbonate nanoparticles that further assemble and transform into higher-order mineral structures. Here, we examine a similar process in abiogenic conditions using synthetic, amorphous calcium magnesium carbonate nanoparticles. Applying a combination of high-resolution imaging and solid-state nuclear magnetic resonance spectroscopy, we reveal the underlying mechanism of the solid-state phase transformation of these amorphous nanoparticles into crystals under aqueous conditions. These amorphous nanoparticles are covered by a hydration shell of bound water molecules. Fast chemical exchanges occur: the hydrogens present within the nanoparticles exchange with the hydrogens from the surface-bound HO molecules which, in turn, exchange with the hydrogens of the free HO molecule of the surrounding aqueous medium. This cascade of chemical exchanges is associated with an enhanced mobility of the ions/molecules that compose the nanoparticles which, in turn, allow for their rearrangement into crystalline domains via solid-state transformation. Concurrently, the starting amorphous nanoparticles aggregate and form ordered mineral structures through crystal growth by particle attachment. Sphere-like aggregates and spindle-shaped structures were, respectively, formed from relatively high or low weights per volume of the same starting amorphous nanoparticles. These results offer promising prospects for exerting control over such a nonclassical pathway to crystallization to design mineral structures that could not be achieved through classical ion-by-ion growth.
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http://dx.doi.org/10.1021/jacs.0c05591DOI Listing
July 2020

Unveiling the Interstitial Pressure between Growing Ice Crystals during Ice-Templating Using a Lipid Lamellar Probe.

J Phys Chem Lett 2020 Mar 26;11(6):1989-1997. Epub 2020 Feb 26.

Sorbonne Université, Centre National de la Recherche Scientifique, Laboratoire de Chimie de la Matière Condensée de Paris, LCMCP, F-75005 Paris, France.

What is the pressure generated by ice crystals during ice-templating? This work addresses this crucial question by estimating the pressure exerted by oriented ice columns on a supramolecular probe composed of a lipid lamellar hydrogel during directional freezing. This process, also known as freeze-casting, has emerged as a unique processing technique for a broad class of organic, inorganic, soft, and biological materials. Nonetheless, the pressure exerted during and after crystallization between two ice columns is not known, despite its importance with respect to the fragility of the frozen material, especially for biological samples. By using the lamellar period of a glycolipid lamellar hydrogel as a common probe, we couple data obtained from ice-templated-resolved synchrotron small-angle X-ray scattering (SAXS) with data obtained from controlled adiabatic desiccation experiments. We estimate the pressure to vary between 1 ± 10% kbar at -15 °C and 3.5 ± 20% kbar at -60 °C.
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http://dx.doi.org/10.1021/acs.jpclett.9b03347DOI Listing
March 2020

A soft-chemistry approach to the synthesis of amorphous calcium ortho/pyrophosphate biomaterials of tunable composition.

Acta Biomater 2020 02 24;103:333-345. Epub 2019 Dec 24.

CIRIMAT, Université de Toulouse, CNRS, INPT-ENSIACET, Toulouse, France. Electronic address:

The development of amorphous phosphate-based materials is of major interest in the field of biomaterials science, and especially for bone substitution applications. In this context, we herein report the synthesis of gel-derived hydrated amorphous calcium/sodium ortho/pyrophosphate materials at ambient temperature and in water. For the first time, such materials have been obtained in a large range of tunable orthophosphate/pyrophosphate molar ratios. Multi-scale characterization was carried out thanks to various techniques, including advanced multinuclear solid state NMR. It allowed the quantification of each ionic/molecular species leading to a general formula for these materials: [(Ca Na H)(PO)(PO)](HO). Beyond this formula, the analyses suggest that these amorphous solids are formed by the aggregation of colloids and that surface water and sodium could play a role in the cohesion of the whole material. Although the full comprehension of mechanisms of formation and structure is still to be investigated in detail, the straightforward synthesis of these new amorphous materials opens up many perspectives in the field of materials for bone substitution and regeneration. STATEMENT OF SIGNIFICANCE: The metastability of amorphous phosphate-based materials with various chain length often improves their (bio)chemical reactivity. However, the control of the ratio of the different phosphate entities has not been yet described especially for small ions (pyrophosphate/orthophosphate) and using soft chemistry, whereas it opens the way for the tuning of enzyme- and/or pH-driven degradation and biological properties. Our study focuses on elaboration of amorphous gel-derived hydrated calcium/sodium ortho/pyrophosphate solids at 70 °C with a large range of orthophosphate/pyrophosphate ratios. Multi-scale characterization was carried out using various techniques such as advanced multinuclear SSNMR (P, Na, H, Ca). Analyses suggest that these solids are formed by colloids aggregation and that the location of mobile water and sodium could play a role in the material cohesion.
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http://dx.doi.org/10.1016/j.actbio.2019.12.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7286349PMC
February 2020

Design of an optically-locked interferometer for attosecond pump-probe setups.

Opt Express 2019 Oct;27(21):30989-31000

We present the design and performance of an active stabilization system for attosecond pump-probe setups based on a Mach-Zehnder interferometer configuration. The system employs a CW laser propagating coaxially with the pump and probe beams in the interferometer. The stabilization is achieved with a standalone feedback controller that adjusts the length of one of its arms to maintain a constant relative phase between the CW beams. With this system, the time delay between the pump and probe beams is stabilized within 10 as rms over several hours. The system is easy to operate and only requires a few minutes to set up before any pump/probe measurements.
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http://dx.doi.org/10.1364/OE.27.030989DOI Listing
October 2019

Bone mineral: new insights into its chemical composition.

Sci Rep 2019 06 11;9(1):8456. Epub 2019 Jun 11.

Sorbonne Université, CNRS, Collège de France, Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), 4, place Jussieu, F-75005, Paris, France.

Some compositional and structural features of mature bone mineral particles remain unclear. They have been described as calcium-deficient and hydroxyl-deficient carbonated hydroxyapatite particles in which a fraction of the PO lattice sites are occupied by HPO ions. The time has come to revise this description since it has now been proven that the surface of mature bone mineral particles is not in the form of hydroxyapatite but rather in the form of hydrated amorphous calcium phosphate. Using a combination of dedicated solid-state nuclear magnetic resonance techniques, the hydrogen-bearing species present in bone mineral and especially the HPO ions were closely scrutinized. We show that these HPO ions are concentrated at the surface of bone mineral particles in the so-called amorphous surface layer whose thickness was estimated here to be about 0.8 nm for a 4-nm thick particle. We also show that their molar proportion is much higher than previously estimated since they stand for about half of the overall amount of inorganic phosphate ions that compose bone mineral. As such, the mineral-mineral and mineral-biomolecule interfaces in bone tissue must be driven by metastable hydrated amorphous environments rich in HPO ions rather than by stable crystalline environments of hydroxyapatite structure.
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http://dx.doi.org/10.1038/s41598-019-44620-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6560110PMC
June 2019

Variables linked to hepatitis B vaccination success in non-dialyzed chronic kidney disease patients: Use of a bayesian model.

Nephrol Ther 2019 Jul 23;15(4):215-219. Epub 2019 May 23.

Hospices civils de Lyon, université Claude-Bernard Lyon 1, 69000 Lyon, France.

Background: Hepatitis B vaccination is recommended for chronic kidney disease (CKD) patients before starting dialysis. We performed an analyis aimed to describe the clinical and biological parameters related to the success of vaccination in CKD patients before starting dialysis.

Methods: We extracted data of 170 non-dialyzed patients who were offered hepatitis B vaccination from a register. They received a first vaccination of 40μg followed by boosters after one, two and six months. Patients were considered protected if their hepatitis B antibody level was >10IU/L, three months apart. A logistic regression and a Bayesian model were used to describe the relationships between variables and the success of vaccination.

Results: Vaccination protected 50.6% of the patients. Model adjustment to the data was higher using the Bayesian model compared to the logistic regression (with area under the ROC curve of 0.955±0.007 vs 0.775±0.066 respectively). The Bayesian model's robustness studied using a 10 fold cross validation showed a percentage of misclassified subjects of 12.4±1.8%, a sensitivity of 87.7±0.3%, a specificity of 87.5±0.3%, a positive predictive value of 87.8±0.3% and negative predictive value of 87.4±0.2%. As classified by the Bayesian model, the variables most related to successful vaccination were, in descending order: age, eGFR, protidemia, albuminemia, cause of renal failure, gender, previous vaccination and weight.

Conclusion: The Bayesian network confirmed that both kidney function and nutritional status of patients are important factors to explain the success of vaccination against hepatitis B in CKD patients before dialysis. For research purposes, before an external validation, the network can be used online at www.hed.cc/?s=Bhepatitis&n=ReseauhepatiteBsup10.neta.
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http://dx.doi.org/10.1016/j.nephro.2019.02.010DOI Listing
July 2019

Digital Holography as Computer Vision Position Sensor with an Extended Range of Working Distances.

Sensors (Basel) 2018 Jun 22;18(7). Epub 2018 Jun 22.

FEMTO-ST Institute, Université Bourgogne Franche-Comté, CNRS, 25000 Besançon, France.

Standard computer vision methods are usually based on powerful contact-less measurement approaches but applications, especially at the micro-scale, are restricted by finite depth-of-field and fixed working distance of imaging devices. Digital holography is a lensless, indirect imaging method recording the optical wave diffracted by the object onto the image sensor. The object is reconstructed numerically by propagating the recorded wavefront backward. The object distance becomes a computation parameter that can be chosen arbitrarily and adjusted to match the object position. No refractive lens is used and usual depth-of-field and working distance limitations are replaced by less restrictive ones tied to the laser-source coherence-length and to the size and resolution of the camera sensor. This paper applies digital holography to artificial visual in-plane position sensing with an extra-large range-to-resolution ratio. The object is made of a pseudoperiodic pattern allowing a subpixel resolution as well as a supra field-of-observation displacement range. We demonstrate an in-plane resolution of 50 nm and 0.002deg. in , and θ respectively, over a working distance range of more than 15 cm. The allowed workspace extends over 12×10×150mm3. Digital holography extends the field of application of computer vision by allowing an extra-large range of working distances inaccessible to refractive imaging systems.
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http://dx.doi.org/10.3390/s18072005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6068586PMC
June 2018

High-Frequency Neuronavigated rTMS in Auditory Verbal Hallucinations: A Pilot Double-Blind Controlled Study in Patients With Schizophrenia.

Schizophr Bull 2018 04;44(3):505-514

Department of Psychiatry, CH Le Rouvray, Sotteville les Rouen, France.

Introduction: Despite extensive testing, the efficacy of low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) of temporo-parietal targets for the treatment of auditory verbal hallucinations (AVH) in patients with schizophrenia is still controversial, but promising results have been reported with both high-frequency and neuronavigated rTMS. Here, we report a double-blind sham-controlled study to assess the efficacy of high-frequency (20 Hz) rTMS applied over a precise anatomical site in the left temporal region using neuronavigation.

Methods: Fifty-nine of 74 randomized patients with schizophrenia or schizoaffective disorders (DSM-IV R) were treated with rTMS or sham treatment and fully evaluated over 4 weeks. The rTMS target was determined by morphological MRI at the crossing between the projection of the ascending branch of the left lateral sulcus and the superior temporal sulcus (STS).

Results: The primary outcome was response to treatment, defined as a 30% decrease of the Auditory Hallucinations Rating Scale (AHRS) frequency item, observed at 2 successive evaluations. While there was no difference in primary outcome between the treatment groups, the percentages of patients showing a decrease of more than 30% of AHRS score (secondary outcome) did differ between the active (34.6%) and sham groups (9.1%) (P = .016) at day 14.

Discussion: This controlled study reports negative results on the primary outcome but demonstrates a transient effect of 20 Hz rTMS guided by neuronavigation and targeted on an accurate anatomical site for the treatment of AVHs in schizophrenia patients.
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http://dx.doi.org/10.1093/schbul/sbx127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5890503PMC
April 2018

Oil shale powders and their interactions with ciprofloxacin, ofloxacin, and oxytetracycline antibiotics.

Environ Sci Pollut Res Int 2017 Nov 23;24(33):25977-25985. Epub 2017 Sep 23.

Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France, UMR 7574, Laboratoire de Chimie de la Matière Condensée de Paris, F-75005, Paris, France.

The interaction of oil shale, as a widespread sedimentary rock, with common antibiotics ofloxacine, oxytetracycline, and ciprofloxacine was studied. The selected Moroccan deposit and its thermally treated forms were fully characterized from a chemical and structural point of view, indicating the prevalence of quartz as a mineral component together with aluminum- and iron-rich phase that are converted into Al-doped iron oxide phases upon heating. The presence of 4 wt% organics was also detected, which was removed at 550 °C without significant loss of specific surface area. The pseudo-second-order kinetic model and Langmuir equation were found the most adequate to reproduce the kinetics and isothermal sorption experiments. These analyses enlighten the contribution of the organic matter on antibiotic retention as well as the key role of hydrophobic interactions on the molecule-mineral surface interactions. Our results emphasize the possible contribution of raw oil shale in the accumulation of antibiotics in soils and suggest that thermally treated oil shell powders can constitute cheap mineral sorbents for environmental cleaning.
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http://dx.doi.org/10.1007/s11356-017-0100-5DOI Listing
November 2017

Amorphous surface layer versus transient amorphous precursor phase in bone - A case study investigated by solid-state NMR spectroscopy.

Acta Biomater 2017 09 6;59:351-360. Epub 2017 Jul 6.

Sorbonne Universités, UPMC Univ Paris 06, CNRS, Collège de France, Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), 4 place Jussieu, F-75005 Paris, France. Electronic address:

The presence of an amorphous surface layer that coats a crystalline core has been proposed for many biominerals, including bone mineral. In parallel, transient amorphous precursor phases have been proposed in various biomineralization processes, including bone biomineralization. Here we propose a methodology to investigate the origin of these amorphous environments taking the bone tissue as a key example. This study relies on the investigation of a bone tissue sample and its comparison with synthetic calcium phosphate samples, including a stoichiometric apatite, an amorphous calcium phosphate sample, and two different biomimetic apatites. To reveal if the amorphous environments in bone originate from an amorphous surface layer or a transient amorphous precursor phase, a combined solid-state nuclear magnetic resonance (NMR) experiment has been used. The latter consists of a double cross polarization H→P→H pulse sequence followed by a H magnetization exchange pulse sequence. The presence of an amorphous surface layer has been investigated through the study of the biomimetic apatites; while the presence of a transient amorphous precursor phase in the form of amorphous calcium phosphate particles has been mimicked with the help of a physical mixture of stoichiometric apatite and amorphous calcium phosphate. The NMR results show that the amorphous and the crystalline environments detected in our bone tissue sample belong to the same particle. The presence of an amorphous surface layer that coats the apatitic core of bone apatite particles has been unambiguously confirmed, and it is certain that this amorphous surface layer has strong implication on bone tissue biogenesis and regeneration.

Statement Of Significance: Questions still persist on the structural organization of bone and biomimetic apatites. The existing model proposes a core/shell structure, with an amorphous surface layer coating a crystalline bulk. The accuracy of this model is still debated because amorphous calcium phosphate (ACP) environments could also arise from a transient amorphous precursor phase of apatite. Here, we provide an NMR spectroscopy methodology to reveal the origin of these ACP environments in bone mineral or in biomimetic apatite. The H magnetization exchange between protons arising from amorphous and crystalline domains shows unambiguously that an ACP layer coats the apatitic crystalline core of bone et biomimetic apatite platelets.
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http://dx.doi.org/10.1016/j.actbio.2017.06.040DOI Listing
September 2017

Optical microalgal biosensors for aqueous contaminants using organically doped silica as cellular hosts.

Anal Bioanal Chem 2018 Feb 2;410(4):1205-1216. Epub 2017 Jun 2.

Sorbonne Universités, Université Pierre et Marie Curie, CNRS, Collège de France, UMR 7574, Laboratoire de Chimie de la Matière Condensée de Paris, 4 place Jussieu, 75005, Paris, France.

Optical biosensors for the detection of toxic species in aqueous media were developed via the encapsulation of microalgae in sol-gel matrices. In a first step, the effect of cadmium(II), lead(II), and anthracene on the chlorophyll a fluorescence intensity of Anabaena flos-aquae, Chlorella vulgaris, and Euglena gracilis microalgae in suspension was studied. Complementary ATP-metry measurements demonstrated a direct relationship between optical response and pollutant toxicity, in a cell- and dose-dependent manner. In a second step, microalgae were successfully encapsulated in silicate-colloidal silica nanocomposite matrices. However, a complete loss of cell response to pollutant addition was observed, despite the preservation of cell viability. Introduction of a low amount (5 mol%) of amine- or ethyl-bearing silanes in the matrix formulation allowed the recovery of the sensing capacity of the immobilized microalgae, without impacting on the response time (30 s). Porosimetry and Si solid-state NMR spectroscopy showed that the organic moieties are fully integrated into the inorganic network, tuning the ability of the target pollutant to diffuse and reach the encapsulated algae. This versatile strategy could be useful for the easy and fast assessment of contamination levels in polluted waters. Graphical Abstract Microalgal biosensors for aqueous contaminants using organically doped silica as cellular hosts.
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http://dx.doi.org/10.1007/s00216-017-0405-8DOI Listing
February 2018

How High Concentrations of Proteins Stabilize the Amorphous State of Calcium Orthophosphate: A Solid-State Nuclear Magnetic Resonance (NMR) Study of the Casein Case.

Langmuir 2017 02 30;33(5):1256-1264. Epub 2017 Jan 30.

Science et Technologie du Lait et de l'Œuf, INRA, UMR1253 , 65 rue de saint Brieuc, 35000 Rennes, France.

Understanding how proteins stabilize amorphous calcium ortho-phosphate (ACP) phases is of great importance in biology and for pharmaceutical or food applications. Until now, most of the former investigations about ACP-protein stability and equilibrium were performed under conditions where ACP colloidal nanoclusters are surrounded by low to moderate concentrations of peptides or proteins (15-30 g L). As a result, the question of ACP-protein interactions in highly concentrated protein systems has clearly been overlooked, whereas it corresponds to actual industrial conditions such as drying or membrane filtration in the dairy industry for instance. In this study, the structure of an ACP phase is monitored in association with one model phosphorylated protein (casein) using solid-state nuclear magnetic resonance (ssNMR) under two conditions of high protein concentration (300 and 400 g L). At both concentrations and at 25 °C, it is found that the caseins maintain the mineral phase in an amorphous form with no detectable influence on its structure or size. Interestingly, and in both cases, a significant amount of the nonphosphorylated side chains interacts with ACP through hydrogen bonds. The number of these interacting side chains is found to be higher at the highest casein concentration. At 45 °C, which is a destabilizing temperature of ACP under protein-free conditions, the amorphous structure of the mineral phase is partially transformed at a casein concentration of 300 g L, while it remains almost intact at a casein concentration of 400 g L. Therefore, these results clearly indicate that increasing the concentration of proteins favors ACP-protein interactions and stabilizes the ACP clusters more efficiently.
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http://dx.doi.org/10.1021/acs.langmuir.6b04235DOI Listing
February 2017

Photoluminescence spectra and quantum yields of gold nanosphere monomers and dimers in aqueous suspension.

Phys Chem Chem Phys 2016 Dec;18(48):33264-33273

Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS-Cachan, Université Paris-Saclay, 91405 Orsay Cedex, France. and PPSM, ENS-Cachan, CNRS, Université Paris-Saclay, 94235 Cachan cedex, France.

The intrinsic one-photon excited photoluminescence (PL) of dimers and monomers of gold spheres suspended in water was studied by combining photon time-of-flight spectroscopy (PTOFS) and light scattering fluctuation correlation spectroscopy (LS-FCS). The samples are obtained by precisely controlling the dimerization of aqueous colloidal systems based on 50 and 80 nm gold nanospheres. The combination of PTOFS and LS-FCS enables the separate spectroscopic study of monomers and dimers even though they exist as a mixture in the samples. PL emission spectra and diffusional dynamics are obtained simultaneously through measurement at the single particle level. The PL spectra resemble the light scattering spectra, indicating the plasmon-assisted character of the photoluminescence process. We determine the intrinsic PL quantum yields of the dimers and the monomers. It is often not possible to measure such very low quantum yields in solution using conventional techniques, and we show here that PTOFS provides access to this information. The quantum yield of the dimers was found to be of same order of magnitude as that of the monomers, of the order of 10, which indicates that the interparticle 'electromagnetic hot-spots' do not play a major role in the luminescence emission mechanism in such plasmonic molecules.
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http://dx.doi.org/10.1039/c6cp04032bDOI Listing
December 2016

Impact of Polyethylenimine Conjugation Mode on the Cell Transfection Efficiency of Silica Nanovectors.

Langmuir 2015 Oct 29;31(40):11078-85. Epub 2015 Sep 29.

Sorbonne Universités , UPMC Univ Paris 06, CNRS, UMR 7574, Laboratoire de Chimie de la Matière Condensée de Paris, F-75005 Paris, France.

The conjugation of polyethylenimine (PEI) to silica nanoparticles has emerged as a useful strategy in gene delivery. Here we investigate the influence of the PEI conjugation mode on the transfection ability of plain silica nanoparticles. Surface functionalization with sulfonate- and chloride-bearing silanes modulates the amount and conformation of PEI and therefore the particles' affinity for the plasmid, without impacting on cytotoxicity. However, transfection efficiency in both immortalized and primary cells is more directly correlated to the nature and strength of the particle-PEI interactions. It suggests that PEI detachment from the particle surface at the stage of endosomal escape is a key event in the plasmid delivery process. These data should provide fruitful guidelines for the fine tuning of colloidal surfaces intended for intracellular delivery of bioactive molecules.
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http://dx.doi.org/10.1021/acs.langmuir.5b02616DOI Listing
October 2015

First acidic macro-mesocellular aluminosilicate monolithic foams "SiAl(HIPE)" and their catalytic properties.

Chem Commun (Camb) 2015 Sep;51(74):14018-21

Institute of Condensed Matter and Nanoscience - Molecules, Solids and reactiviTy (IMCN/MOST), Université catholique de Louvain, Croix du Sud 2/17, 1348 Louvain-La-Neuve, Belgium.

A new type of acidic macrocellular and mesoporous silica-alumina foam is obtained via a one pot alkaline sol-gel route coupled with a concentrated emulsion-based templating technique. The mixed oxide monolith exhibits high surface acidity, translating into excellent performance in the acid-catalyzed dehydration of bioethanol to ethene.
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http://dx.doi.org/10.1039/c5cc05328eDOI Listing
September 2015

High-energy, kHz, picosecond hybrid Yb-doped chirped-pulse amplifier.

Opt Express 2015 Apr;23(8):10132-44

We report on a diode-pumped, hybrid Yb-doped chirped-pulse amplification (CPA) laser system with a compact pulse stretcher and compressor, consisting of Yb-doped fiber preamplifiers, a room-temperature Yb:KYW regenerative amplifier (RGA), and cryogenic Yb:YAG multi-pass amplifiers. The RGA provides a relatively broad amplification bandwidth and thereby a long pulse duration to mitigate B-integral in the CPA chain. The ~1030-nm laser pulses are amplified up to 70 mJ at 1-kHz repetition rate, currently limited by available optics apertures, and then compressed to ~6 ps with high efficiency. The near-diffraction-limited beam focusing quality is demonstrated with M(x)(2) = 1.1 and M(y)(2) = 1.2. The shot-to-shot energy fluctuation is as low as ~1% (rms), and the long-term energy drift and beam pointing stability for over 8 hours measurement are ~3.5% and <6 μrad (rms), respectively. To the best of our knowledge, this hybrid laser system produces the most energetic picosecond pulses at kHz repetition rates among rod-type laser amplifiers. With an optically synchronized Ti:sapphire seed laser, it provides a versatile platform optimized for pumping optical parametric chirped-pulse amplification systems as well as driving inverse Compton scattered X-rays.
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http://dx.doi.org/10.1364/OE.23.010132DOI Listing
April 2015

Identification of a previously unobserved dissociative ionization pathway in time-resolved photospectroscopy of the deuterium molecule.

Phys Rev Lett 2015 Mar 16;114(11):113001. Epub 2015 Mar 16.

J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA.

A femtosecond vacuum ultraviolet (VUV) pulse with high spectral resolution (<200  meV) is selected from the laser-driven high order harmonics. This ultrafast VUV pulse is synchronized with an infrared (IR) laser pulse to study dissociative ionization in deuterium molecules. At a VUV photon energy of 16.95 eV, a previously unobserved bond-breaking pathway is found in which the dissociation direction does not follow the IR polarization. We interpret it as corresponding to molecules predissociating into two separated atoms, one of which is photoionized by the following IR pulse. A time resolved study allows us to determine the lifetime of the intermediate predissociation process to be about 1 ps. Additionally, the dissociative ionization pathways show high sensitivity to the VUV photon energy. As the VUV photon energy is blueshifted to 17.45 eV, the more familiar bond-softening channel is opened to compete with the newly discovered pathway. The interpretation of different pathways is supported by the energy sharing between the electron and nuclei.
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http://dx.doi.org/10.1103/PhysRevLett.114.113001DOI Listing
March 2015

Stabilization of ribofuranose by a mineral surface.

Carbohydr Res 2015 Jan 1;402:241-4. Epub 2014 Aug 1.

Laboratoire de Réactivité de Surface, CNRS UMR-7197, UPMC Univ Paris 06, 3 Rue Galilée, 94200 Ivry sur Seine, France. Electronic address:

The existence of the ribose moiety in biomolecules poses two problems for prebiotic chemistry. First, the exclusive presence of the furanose isomer in RNA has to be accounted for since furanose is a minor form in solution and does not exist in crystals. Second, all D-ribose polymorphs are unstable in aqueous medium so that a stabilization mechanism has to be invoked. We observed that the adsorption on mineral surfaces as amorphous silica protects the sugar from degradation processes. Moreover, this silica surface, used as realistic chert model, is able to increase significantly the proportion of ribofuranose compared to ribopyranose forms. The interaction between surface and sugar was analyzed by 13C NMR. Our results show a very significant chemical and thermal stabilization of the adsorbed sugar by a silica surface and an almost twofold increase of ribofuranose compared to ribose in solution.
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http://dx.doi.org/10.1016/j.carres.2014.07.018DOI Listing
January 2015

Nanostructured ultrafast silicon-tip optical field-emitter arrays.

Nano Lett 2014 Sep 7;14(9):5035-43. Epub 2014 Aug 7.

Microsystems Technology Laboratories and ‡Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.

Femtosecond ultrabright electron sources with spatially structured emission are an enabling technology for free-electron lasers, compact coherent X-ray sources, electron diffractive imaging, and attosecond science. In this work, we report the design, modeling, fabrication, and experimental characterization of a novel ultrafast optical field emission cathode comprised of a large (>100,000 tips), dense (4.6 million tips·cm(-2)), and highly uniform (<1 nm tip radius deviation) array of nanosharp high-aspect-ratio silicon columns. Such field emitters offer an attractive alternative to UV photocathodes while providing a direct means of structuring the emitted electron beam. Detailed measurements and simulations show pC electron bunches can be generated in the multiphoton and tunneling regime within a single optical cycle, enabling significant advances in electron diffractive imaging and coherent X-ray sources on a subfemtosecond time scale, not possible before. At high charge emission yields, a slow rollover in charge is explained as a combination of the onset of tunneling emission and the formation of a virtual cathode.
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http://dx.doi.org/10.1021/nl501589jDOI Listing
September 2014

Subpixelic measurement of large 1D displacements: principle, processing algorithms, performances and software.

Sensors (Basel) 2014 Mar 12;14(3):5056-73. Epub 2014 Mar 12.

Automation and Micro-Mechatronics Systems Department, FEMTO-ST Institute, UMR CNRS 6174, ENSMM, Université de Franche-Comté, 25000 Besançon, France.

This paper presents a visual measurement method able to sense 1D rigid body displacements with very high resolutions, large ranges and high processing rates. Sub-pixelic resolution is obtained thanks to a structured pattern placed on the target. The pattern is made of twin periodic grids with slightly different periods. The periodic frames are suited for Fourier-like phase calculations-leading to high resolution-while the period difference allows the removal of phase ambiguity and thus a high range-to-resolution ratio. The paper presents the measurement principle as well as the processing algorithms (source files are provided as supplementary materials). The theoretical and experimental performances are also discussed. The processing time is around 3 µs for a line of 780 pixels, which means that the measurement rate is mostly limited by the image acquisition frame rate. A 3-σ repeatability of 5 nm is experimentally demonstrated which has to be compared with the 168 µm measurement range.
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http://dx.doi.org/10.3390/s140305056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4003981PMC
March 2014

Water-mediated structuring of bone apatite.

Nat Mater 2013 Dec 10;12(12):1144-53. Epub 2013 Nov 10.

1] Laboratoire Chimie de la Matière Condensée de Paris, UMR 7574 CNRS, UPMC Univ Paris 06, Collège de France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France [2].

It is well known that organic molecules from the vertebrate extracellular matrix of calcifying tissues are essential in structuring the apatite mineral. Here, we show that water also plays a structuring role. By using solid-state nuclear magnetic resonance, wide-angle X-ray scattering and cryogenic transmission electron microscopy to characterize the structure and organization of crystalline and biomimetic apatite nanoparticles as well as intact bone samples, we demonstrate that water orients apatite crystals through an amorphous calcium phosphate-like layer that coats the crystalline core of bone apatite. This disordered layer is reminiscent of those found around the crystalline core of calcified biominerals in various natural composite materials in vivo. This work provides an extended local model of bone biomineralization.
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http://dx.doi.org/10.1038/nmat3787DOI Listing
December 2013

Insights from the use in clinical practice of eculizumab in adult patients with atypical hemolytic uremic syndrome affecting the native kidneys: an analysis of 19 cases.

Am J Kidney Dis 2014 Jan 8;63(1):40-8. Epub 2013 Sep 8.

Department of Immunology, Assistance Publique-Hôpitaux de Paris Hôpital Européen Georges Pompidou, Paris, France.

Background: Atypical hemolytic uremic syndrome (aHUS) is a devastating form of renal thrombotic microangiopathy. Despite plasma exchange, the standard treatment of aHUS for decades, the renal prognosis for patients with aHUS has remained poor. We assessed the off-trial use of eculizumab in adult patients with aHUS affecting the native kidneys.

Study Design: A retrospective study was conducted. aHUS was defined as the presence of 3 or more of the following: acute kidney injury (serum creatinine >1.4 mg/dL [120 μmol/L]), mechanical hemolytic anemia, thrombocytopenia, and the presence of thrombotic microangiopathy features in a kidney biopsy specimen. Patients who had received 4 or more weekly 900-mg infusions of eculizumab were included.

Setting & Participants: 19 patients were identified through a query sent to all French nephrology centers.

Outcomes & Measurements: Evolution of kidney function, hemolysis, and thrombocytopenia after the initiation of eculizumab therapy.

Results: All patients had acute kidney injury (serum creatinine range, 2.2-17.0 mg/dL) and 12 required hemodialysis. Thirteen patients carried a mutation in 1 complement gene and 1 had anti-factor H antibodies. For first-line therapy, 16 patients underwent plasma exchange and 3 patients received eculizumab. Median time between aHUS onset and eculizumab therapy initiation was 6 (range, 1-60) days and median time to platelet count normalization after eculizumab therapy initiation was 6 (range, 2-42) days. At the 3-month follow-up, 4 patients still required dialysis, 8 had non-dialysis-dependent chronic kidney disease, and 7 had normalized kidney function. At last follow-up (range, 4-22 months), 3 patients remained dialysis dependent, 7 had non-dialysis-dependent chronic kidney disease (estimated glomerular filtration rate, 17-55 mL/min/1.73 m(2)), and 9 had normal kidney function. Risks of reaching end-stage renal disease within 3 months and 1 year of aHUS onset were reduced by half in eculizumab-treated patients compared with recent historical controls.

Limitations: Retrospective study and use of historical controls.

Conclusions: Our data indicate that eculizumab improves kidney disease outcome in patients with aHUS.
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http://dx.doi.org/10.1053/j.ajkd.2013.07.011DOI Listing
January 2014

Introduction of disulfide bridges within silica nanoparticles to control their intra-cellular degradation.

Chem Commun (Camb) 2013 Apr;49(33):3410-2

UPMC Univ Paris 06, UMR 7574, Chimie de la Matière Condensée de Paris, Collège de France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.

Incorporation of disulfide bridges in the core structure of silica nanoparticles modifies their intracellular fate within dermal fibroblasts, especially influencing their degradation pathway.
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http://dx.doi.org/10.1039/c3cc41062eDOI Listing
April 2013

Solid-state NMR study reveals collagen I structural modifications of amino acid side chains upon fibrillogenesis.

J Biol Chem 2013 Mar 22;288(11):7528-7535. Epub 2013 Jan 22.

Laboratoire de Chimie de la Matière Condensée de Paris, UMR 7574 Université Pierre et Marie Curie (UPMC)/Centre National de La Recherche Scientifique (CNRS)/Collège de France, UPMC, 4 place Jussieu, 75005 Paris, France. Electronic address:

In vivo, collagen I, the major structural protein in human body, is found assembled into fibrils. In the present work, we study a high concentrated collagen sample in its soluble, fibrillar, and denatured states using one and two dimensional {(1)H}-(13)C solid-state NMR spectroscopy. We interpret (13)C chemical shift variations in terms of dihedral angle conformation changes. Our data show that fibrillogenesis increases the side chain and backbone structural complexity. Nevertheless, only three to five rotameric equilibria are found for each amino acid residue, indicating a relatively low structural heterogeneity of collagen upon fibrillogenesis. Using side chain statistical data, we calculate equilibrium constants for a great number of amino acid residues. Moreover, based on a (13)C quantitative spectrum, we estimate the percentage of residues implicated in each equilibrium. Our data indicate that fibril formation greatly affects hydroxyproline and proline prolyl pucker ring conformation. Finally, we discuss the implication of these structural data and propose a model in which the attractive force of fibrillogenesis comes from a structural reorganization of 10 to 15% of the amino acids. These results allow us to further understand the self-assembling process and fibrillar structure of collagen.
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http://dx.doi.org/10.1074/jbc.M112.390146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3597793PMC
March 2013

High dynamics and precision optical measurement using a position sensitive detector (PSD) in reflection-mode: application to 2D object tracking over a Smart Surface.

Sensors (Basel) 2012 Dec 6;12(12):16771-84. Epub 2012 Dec 6.

FIE&FIMMR, University Valahia of Targoviste, B-dul Unirii Nr.18-20, 130082 Targoviste, Romania.

When related to a single and good contrast object or a laser spot, position sensing, or sensitive, detectors (PSDs) have a series of advantages over the classical camera sensors, including a good positioning accuracy for a fast response time and very simple signal conditioning circuits. To test the performance of this kind of sensor for microrobotics, we have made a comparative analysis between a precise but slow video camera and a custom-made fast PSD system applied to the tracking of a diffuse-reflectivity object transported by a pneumatic microconveyor called Smart-Surface. Until now, the fast system dynamics prevented the full control of the smart surface by visual servoing, unless using a very expensive high frame rate camera. We have built and tested a custom and low cost PSD-based embedded circuit, optically connected with a camera to a single objective by means of a beam splitter. A stroboscopic light source enhanced the resolution. The obtained results showed a good linearity and a fast (over 500 frames per second) response time which will enable future closed-loop control by using PSD.
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http://dx.doi.org/10.3390/s121216771DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3571810PMC
December 2012

Ultrasound-assisted synthesis of mesoporous zirconia-hydroxyapatite nanocomposites and their dual surface affinity for Cr3+/Cr2O7(2-) ions.

Langmuir 2011 Dec 28;27(24):15176-84. Epub 2011 Nov 28.

UPMC-P6, CNRS, Chimie de la Matière Condensée de Paris, Collège de France, 75005 Paris, France.

Zirconia-hydroxyapatite nanocomposites were prepared by sol-gel deposition of zirconium oxide from a zirconium alkoxide in the presence of apatite colloidal suspension under ultrasonication. The material porosity evolves from mainly microporous zirconia to mesoporous hydroxyapatite, with decreasing surface area and increasing pore volume. XRD studies indicate that the apatite phase is well-preserved within the composite materials. The homogeneous dispersion of apatite colloids within the zirconia network was supported by TEM observations and nitrogen sorption measurements. (31)P solid-state NMR studies suggest that partial dissolution of apatite may have occurred during the preparation, leading to the adsorption of phosphate species on zirconia particles. This is confirmed by XRD studies of nanocomposites after thermal treatment that demonstrate the preferred formation of tetragonal over monoclinic ZrO(2) in the presence of hydroxyapatite. In order to investigate the surface properties of these novel materials, the adsorption of Pb(2+), Cr(3+), and Cr(2)O(7)(2-) was evaluated. Metal cations were preferentially adsorbed on apatite-rich composites, whereas Cr(2)O(7)(2-) shows a good affinity for the zirconia-rich phases. Zirconia-apatite materials showed the most promising performance in terms of recyclability. These nanocomposites that combine microporosity, mesoporosity and dual sorption properties for these species appear as interesting materials for metal ion remediation and may also find applications as biomaterials.
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http://dx.doi.org/10.1021/la2029643DOI Listing
December 2011

Hydrothermal carbon from biomass: structural differences between hydrothermal and pyrolyzed carbons via 13C solid state NMR.

Langmuir 2011 Dec 3;27(23):14460-71. Epub 2011 Nov 3.

Max-Planck Institute for Colloids, Research Campus Golm, D-14424 Potsdam, Germany.

The objective of this paper is to better describe the structure of the hydrothermal carbon (HTC) process and put it in relationship with the more classical pyrolytic carbons. Indeed, despite the low energetic impact and the number of applications described so far for HTC, very little is known about the structure, reaction mechanism, and the way these materials relate to coals. Are HTC and calcination processes equivalent? Are the structures of the processed materials related to each other in any way? Which is the extent of polyaromatic hydrocarbons (PAH) inside HTC? In this work, the effect of hydrothermal treatment and pyrolysis are compared on glucose, a good model carbohydrate; a detailed single-quantum double-quantum (SQ-DQ) solid state (13)C NMR study of the HTC and calcined HTC is used to interpret the spectral region corresponding to the signal of furanic and arene groups. These data are compared to the spectroscopic signatures of calcined glucose, starch, and xylose. A semiquantitative analysis of the (13)C NMR spectra provides an estimation of the furanic-to-arene ratio which varies from 1:1 to 4:1 according to the processing conditions and carbohydrate employed. In addition, we formulate some hypothesis, validated by DFT (density functional theory) modeling associated with (13)C NMR chemical shifts calculations, about the possible furan-rich structural intermediates that occur in the coalification process leading to condensed polyaromatic structures. In combination with a broad parallel study on the HTC processing conditions effect on glucose, cellulose, and raw biomass (Falco, C.; Baccile, N.; Titirici, M.-M. Green Chem., 2011, DOI: 10.1039/C1GC15742F), we propose a broad reaction scheme and in which we show that, through HTC, it is possible to tune the furan-to-arene ratio composing the aromatic core of the produced HTC carbons, which is not possible if calcination is used alone, in the temperature range below 350 °C.
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http://dx.doi.org/10.1021/la202361pDOI Listing
December 2011

Investigation of the interface in silica-encapsulated liposomes by combining solid state NMR and first principles calculations.

J Am Chem Soc 2011 Oct 4;133(42):16815-27. Epub 2011 Oct 4.

UPMC Univ Paris 06 & CNRS, UMR 7574, Chimie de la Matière Condensée de Paris, Collège de France, 11, place Marcelin Berthelot, F-75005, Paris, France.

In the context of nanomedicine, liposils (liposomes and silica) have a strong potential for drug storage and release schemes: such materials combine the intrinsic properties of liposome (encapsulation) and silica (increased rigidity, protective coating, pH degradability). In this work, an original approach combining solid state NMR, molecular dynamics, first principles geometry optimization, and NMR parameters calculation allows the building of a precise representation of the organic/inorganic interface in liposils. {(1)H-(29)Si}(1)H and {(1)H-(31)P}(1)H Double Cross-Polarization (CP) MAS NMR experiments were implemented in order to explore the proton chemical environments around the silica and the phospholipids, respectively. Using VASP (Vienna Ab Initio Simulation Package), DFT calculations including molecular dynamics, and geometry optimization lead to the determination of energetically favorable configurations of a DPPC (dipalmitoylphosphatidylcholine) headgroup adsorbed onto a hydroxylated silica surface that corresponds to a realistic model of an amorphous silica slab. These data combined with first principles NMR parameters calculations by GIPAW (Gauge Included Projected Augmented Wave) show that the phosphate moieties are not directly interacting with silanols. The stabilization of the interface is achieved through the presence of water molecules located in-between the head groups of the phospholipids and the silica surface forming an interfacial H-bonded water layer. A detailed study of the (31)P chemical shift anisotropy (CSA) parameters allows us to interpret the local dynamics of DPPC in liposils. Finally, the VASP/solid state NMR/GIPAW combined approach can be extended to a large variety of organic-inorganic hybrid interfaces.
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http://dx.doi.org/10.1021/ja201002rDOI Listing
October 2011