Bouzid Menaa

Abstract: BACKGROUND: The formation of bacterial biofilms on urinary catheters is a leading cause of urinary tract infections in intensive care units. Cytobacteriological examination of urine from patients is often misleading, due to the formation of these biofilms. Therefore, characterizing these biofilms and identifying the bacterial species residing on the surface of catheters are of major importance. METHODS: We studied the formation of biofilms on the inner surface of urinary catheters using microbiological culture techniques, with the direct contact of catheter pieces with blood agar. The bacterial species on the surface were characterized by scanning electron microscopy, and the kinetic profile of biofilm formation on a silicone substrate for an imipenem-resistant Acinetobacter baumannii bacterium was evaluated with a crystal violet staining assay. RESULTS: The bacterial species that constituted these biofilms were identified as a variety of gram-negative bacilli, with a predominance of strains belonging to Pseudomonas aeruginosa. The other isolated strains belonged to A baumannii and Klebsiella ornithinolytica. Kinetic profiling of biofilm formation identified the transient behavior of A baumannii between its biofilm and planktonic state. This strain was highly resistant to all of the antibiotics tested except colistin. Scanning electron microscopy images showed that the identified isolated species formed a dense and interconnected network of cellular multilayers formed from either a single cell or from different species that were surrounded and enveloped by a protective matrix. CONCLUSIONS: Microbiological analysis of the intraluminal surface of the catheter is required for true identification of the causative agents of catheter-associated urinary tract infections. This approach, combined with a routine cytobacteriological examination of urine, allows for the complete characterization of biofilm-associated species, and also may help prevent biofilm formation in such devices and help guide optimum antibiotic treatment.

Abstract: Among the protein-based hydrogel-forming polymers, various salts of hyaluronic acid (HA), aka hyaluronan or sodium hyaluronate, are used to prepare tissue-engineering. HA is a natural occurring glycosaminoglycan, a polysaccharide of high molecular weight which displays interesting viscoelastic properties. Among other organisms, HA is omnipresent in the human body, occurring in almost all biological fluids and tissues, although the highest amounts of HA are found in the extracellular matrix of soft connective tissues. HA is synthesized in a unique manner by a family of hyaluronan syntheses and degraded by hyaluronidases and, exerts pleiotropic biological functions such as tissue repair and tissue regeneration. The excellent biocompatibility and biodegradability of HA derived hydrogels make them ideal materials for tissue engineering. Nevertheless, because of their hydrophilic nature, further modification with adhesion-mediating peptides is required to allow sufficient cell attachment. Hence, several methods of chemical cross-linking using different linkers have been investigated to improve the mechanical properties of those materials for long-term applications in the biomedical field. This manuscript provide an overview of HA and derivatives used as biomaterial scaffold for theranostic medicine.

Abstract: Carbon-Fluorine Spectroscopy (CFS(TM)), also known as Fluoro-Raman Spectroscopy (FRS(TM)), is a relatively new patented platform technology using a family of various methods and cost-effective devices called PLIRFATM (Pulsed Laser Isochronic Raman and Fluorescence Apparatus) developed by Fluorotronics, Inc. The key feature of this progressive and non-destructive technology is based on the discovery of a characteristic optical signature of carbon-fluorine bond(s) in the fingerprint spectral area of 500-800 cm(-1) allowing rapid, ultra-specific and sensitive detection, characterization, imaging, and measurement of any fluoroorganics. Interestingly, the C-F bond is unique in its character and so it can be used as a molecular label. Furthermore, the C-F label is efficient, soluble, cheaper, smaller, more stable and less toxic than fluorescent dyes, nanoparticles or quantum dot materials. Thereby, C-F bonds are often incorporated into pharmaceutical, agrochemical and biological molecules in addition to polymers and nano-materials to achieve special properties (e.g. molecular stability, molecular tracing). In this paper, we present some of our data obtained from FRS(TM) applied to pharmaceuticals and biologics, and provide perspectives of FRS applications for the pharmaceutical and biomedical fields.

Abstract: The role of fluorine and phosphonate groups on protein structure and biocompatibility has been probed by protein encapsulation in tetramethoxysilane (TMOS)-based sol-gel glass and assessed by circular dichroism spectroscopy (CD). Apomyoglobin (apoMb) is known as a model protein for the study of protein folding. Thus, we demonstrated the increase of apoMb helicity in phosphonate and fluorinated phosphonate-based sol-gel glasses via the addition of methane diphosphonic acid (MDPA) and difluoromethane diphosphonic acid (DFMDPA) during the hydrolysis/ polycondensation of TMOS precursor forming a nanoporous sol-gel glass host matrix for the protein. Alternatively to silica surface functionalisation using organosilane modifiers, functional organic molecules or nano-agents can be doped directly during the sol-gel process. Since TMOS is not functionalised, we can probe the role of some organic molecules as intermediates as well as their surface hydration effect contributing to the protein folding process. The presence of both fluorine and phosphonate groups in TMOS glass folded the protein to its native state as function of its molar content. The protein ellipticity has been enlightened by CD with signals observable at 222 nm characterising the secondary protein structure at the far UV. The incorporation of these groups to the sol-gel glass systems to mimic the behaviour and conformation of protein as function of its surrounding environment brings both steric and hydrophobic properties to enhance the protein folding. These results are important from the point of view of potential applications in bio-nanotechnology with the design of efficient biomaterials but also to probe the role of fluorine and phosphonate groups in protein folding for the human healthcare.

Abstract: MYOC encodes a secretary glycoprotein of 504 amino acids named myocilin. MYOC is the first gene to be linked to juvenile open-angle glaucoma (JOAG) and some forms of adult-onset primary open-angle glaucoma (POAG). The gene was identified as an up-regulated molecule in cultured trabecular meshwork (TM) cells after treatment with dexamethasone and was originally referred to as trabecular meshwork-inducible glucocorticoid response (TIGR). Elevated intraocular pressure (IOP), due to decreased aqueous outflow, is the strongest known risk factor for POAG. Increasing evidence showed that the modulation of the wild-type (wt) myocilin protein expression is not causative of glaucoma while some misfolded and self-assembly aggregates of mutated myocilin may be associated with POAG in related or unrelated populations. The etiology of the disease remains unclear. Consequently, a better understanding of the molecular mechanisms underlyingPOAG is required to obtain early diagnosis, avoid potential disease progression, and develop new therapeutic strategies. In the present study, we review and discuss the most relevant studies regarding structural characterizations, expressions, molecular interactions, putative functions of MYOC gene and/or its corresponding protein in POAG etiology.

Abstract: We report an original solventless thermal crystallisation method to grow large needle-like salicylic acid (SA) crystals of 10-12 mm in length. The method is based on the utilization of nitrogen gaz flow on salicylic acid powder during heating just below melting point temperature for 24 h. Salicylic acid provides one of the best examples of a pharmaceutical substance used for cosmetics whose physical and chemical properties indicate hydrogen-bond formation between the hydroxyl group and an adjacent oxygen atom of the same molecule. The structure of the crystals is confirmed by single crystal X-ray diffraction; it is monoclinic, a = 4.93(2) ��, b = 11.23(5) ��, c = 11.56(6) ��, beta = 90.77(4)�° with the space group P 21/c. The macrocrystals formation using this method is new and represents an interesting finding for a wide range of applications to be developed in the fields of biotechnology and photonics (�© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Abstract: Organic-inorganic nanoporous silica sol-gel glasses constitute the ideal support for protein bio-encapsulation and to study the different factors influencing the protein folding process in a crowded environment. Due to the facile silica surface modifications with desired Si-substituted organic groups from organosilanes precursors, organically modified 'wet-aged' silica-based glasses obtained via the sol-gel process, can be used as host materials to mimic the crowded environment of the proteins and cells that can be found in the cytoplasm for instance. Numerous studies to date showed that silica-based nanoporous glasses can stabilise bioactive proteins. However, it is important to know about the different factors affecting the protein stability and therefore its properly-folded state. In this review, we report the recent results on the influence of different parameters (such as surface hydration, hydrophobicity, solute effects, thermal stability, porosity, macromolecular crowding) on the protein conformation based on the design and the characterisation of nanoporous silica-based materials containing different functional groups (e.g., hydrophobic alkyl, phosphate and fluorinated groups). The enhancement of the protein folding owing to the physical properties and microstructure of the host matrix induced by the nature of the functional groups and the siloxane network play a major role on the protein biological activity and therefore to the development efficient bionanodevices such as biocatalysts, sensors, drug delivery systems or implanted devices. It is also the opportunity to understand the different factors influencing the protein misfolding that are the cause of devastating diseases such as Alzheimer or Huntington.

Abstract: The development of facile and rapid quantification of biologically active biomolecules such as isotretitoin in therapeutic drugs contained in many generic formulations is necessary for determining their efficiency and their quality to improve the human health care. Isotretritoin finds its applications in the maintenance of epithelial tissues. Different processes to date such as normal phase HPLC, or gas chromatrography among others are able to separate and quantify isotetroin. However, the extraction is quite complex and in the case of HPLC, the analysis requires long retention times. In such context, an isocratic reversed-phase high-performance liquid chromatography (HPLC) technique coupled with an UV-vis detector is described here for easy separation and quantification of 13-cis-retinoic (isotretinoin) from soft gelatin capsule formulations. The isotretinoin was extracted from three different commercial drug samples with tetrahydrofuran (THF) solvent by a procedure that can be completed in less than 10 minutes. Subsequent separation and quantification were accomplished in less than 5 minutes under isocratic reversed-phase conditions on a Lichrospher RP18 column and a mobile phase consisting of 0.01% TFA/acetonitrile (15/85, v/v) at a flow rate of 1.0 ml/min. Isotretoin was detected for the three samples via its UV-vis absorbance at 342 nm. The method was validated and the results showed good linearity, precision and accuracy for sensitive and selective quantitative determination of isotretinoin in the different pharmaceutical formulations. We found that the average isotretinoin content in two of the three commercial products fell outside the 90-110% United States Pharmacopeia specifications. Consequently, the facile extraction and the precise method for the biomolecule quantification open up tremendous possibilities in improving the quality control of drugs which can exist as different generic brands.

Abstract: Isotretinoin is the drug of choice for the management of severe recalcitrant nodular acne. Nevertheless, some of its physical-chemical properties are still poorly known. Hence, the aim of our study consisted to comparatively evaluate the particle size distribution (PSD) and characterize the thermal behavior of the three encapsulated isotretinoin products in oil suspension (one reference and two generics) commercialized in Brazil. Here, we show that the PSD, estimated by laser diffraction and by polarized light microscopy, differed between the generics and the reference product. However, the thermal behavior of the three products, determined by thermogravimetry (TGA), differential thermal (DTA) analyses and differential scanning calorimetry (DSC), displayed no significant changes and were more thermo-stable than the isotretinoin standard used as internal control. Thus, our study suggests that PSD analyses in isotretinoin lipid-based formulations should be routinely performed in order to improve their quality and bioavailability.

Abstract: Nanoporous sol-gel glasses were used as host materials for the encapsulation of apomyoglobin, a model protein employed to probe in a rational manner the important factors that influence the protein conformation and stability in silica-based materials. The transparent glasses were prepared from tetramethoxysilane (TMOS) and modified with a series of mono-, di- and tri-substituted alkoxysilanes, RnSi(OCH3)4-n (R = methyl-, n = 1; 2; 3) of different molar content (5, 10, 15%) to obtain the decrease of the siloxane linkage (&bond;Si&bond;O&bond;Si&bond;). The conformation and thermal stability of apomyoglobin characterized by circular dichroism spectroscopy (CD) was related to the structure of the silica host matrix characterized by 29Si MAS NMR and N2 adsorption. We observed that the protein transits from an unfolded state in unmodified glass (TMOS) to a native-like helical state in the organically modified glasses, but also that the secondary structure of the protein was enhanced by the decrease of the siloxane network with the methyl modification (n = 0 < n = 1 < n = 2 < n = 3; 0 < 5 < 10 < 15 mol %). In 15% trimethyl-modified glass, the protein even reached a maximum molar helicity (-24,000 deg. cm2 mol-1) comparable to the stable folded heme-bound holoprotein in solution. The protein conformation and stability induced by the change of its microlocal environment (surface hydration, crowding effects, microstructure of the host matrix) were discussed owing to this trend dependency. These results can have an important impact for the design of new efficient biomaterials (sensors or implanted devices) in which properly folded protein is necessary. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 895-906, 2009.This article was originally published online as an accepted preprint. The ldquoPublished Onlinerdquo date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Abstract:

Abstract: The secondary structures of two proteins were examined by circular dichroism spectroscopy after adsorption onto a series of organically modified silica glasses. The glasses were prepared by the sol-gel technique and were varied in hydrophobicity by incorporation of 5% methyl, propyl, trifluoropropyl, or n-hexyl silane. Both cytochrome c and apomyoglobin were found to lose secondary structure after adsorption onto the modified glasses. In the case of apomyoglobin, the{alpha} -helical content of the adsorbed protein ranged from 21% to 28%, well below the 62% helix found in solution. In contrast, these same glasses led to a striking increase in apomyoglobin structure when the protein was encapsulated within the pores during sol-gel processing: the helical content of apomyoglobin increased with increasing hydrophobicity from 18% in an unmodified glass to 67% in a 5% hexyl-modified glass. We propose that proteins preferentially adsorb onto unmodified regions of the silica surface, whereas encapsulated proteins are more susceptible to changes in surface hydration due to the proximity of the alkyl chain groups.

Abstract: The optical absorption and photoluminescence of metal-free phtalocyanine (H2Pc) in a glassy matrix were discussed regarding the preparation method used. We show that fluorescent monodisperse free metal phtalocyanine can be doped in polyphenylsiloxane glass films using a non-aqueous sol-gel derived method. No fluorescence study of metal-free phtalocyanine doped in polysiloxane sol-gel materials has been reported so far due to the miscibility problem of the dye and its aggregation behavior in aqueous sols.

Abstract: Organically-modified siloxanes were used as host materials to examine the influence of surface chemistry on protein conformation in a crowded environment. The sol-gel materials were prepared from tetramethoxysilane and a series of monosubstituted alkoxysilanes, RSi(OR')3, featuring alkyl groups of increasing chain length in the R-position. Using circular dichroism spectroscopy in the far-UV region, apomyoglobin was found to transit from an unfolded state to a native-like helical state as the content of the hydrophobic precursor increased from 0 to 15%. At a fixed molar content of 5% RSi(OR')3, the helical structure of apomyoglobin increased with the chain length of the R-group, i.e. methyl < ethyl < n-propyl < n-butyl < n-hexyl. This trend also was observed for the tertiary structure of ribonuclease A, suggesting that protein folding and biological activity are sensitive to the hydrophilic/hydrophobic balance of neighboring surfaces. The observed changes in protein structure did not correlate with total surface area or the average pore size of the modified glasses, but scanning electron microscopy images revealed an interesting relationship between surface morphology and alkyl chain length. The unexpected benefit of incorporating a low content of hydrophobic groups into a hydrophilic surface may lead to materials with improved biocompatibility for use in biosensors and implanted devices.

Abstract: A facile and simple route to obtain organic-inorganic hybrid glass films based on polyphenylsiloxane (1 - x)PhSiO3/2-(x)Ph2SiO2/2 (x = 0, 0.1, 0.2 and 0.3) has been proposed. The method involves the preparation of a non-aqueous coating sol composed of the polysiloxane in acetone. The films from 1 to 17 [mu]m thick were coated on silica substrate via a single-step dip-coating at room temperature prior to further heat-treatment. As the hybrid matrix remains stable in the solvent, the desired film thickness (H) can easily be obtained as a function of the viscosity ([eta]) of the sol with H [is proportional to] [eta]0.76, or as a function of the withdrawal speed (v) with H [is proportional to] v0.5. Homogeneous films (average surface roughness less than 20 � 10-4 [mu]m) of high optical quality (optical propagation loss estimated to be less than 1 dB cm-1 at the telecommunication wavelength) with refractive indices comprise between 1.5 and 1.6, stable against the ambient atmosphere were successfully obtained.

Abstract: Abstract: Hybrid organic-inorganic crystalline materials have been obtained from a simple solvent-free synthesis in highly basic conditions. The formation of an organized hybrid structure has been achieved for the first time via sol-gel without employing bridged organosilica precursors. 3-glycidoxypropyltrimethoxysilane, which is an organically modified alkoxide bearing a terminal epoxy group, has been used for the synthesis. The opening of the epoxy has been observed to produce poly/oligo(ethylene oxide) chains or p-dioxane species. In the second case crystalline hybrids have been formed by self-organization during gelation. Analysis performed by wide-angle X-ray scattering and X-ray diffraction have confirmed the crystalline nature of the aggregates, epoxy ring opening/self-condensation which resulted in a pillared-type organic-inorganic hybrid structure with Si-substituted 2,5-bis(propoxymethyl)-1,4-dioxane organic spacer as pillar.

Abstract: We investigated the water durability of the inorganic-organic hybrid tin-silico-phosphate glasses Me2SiO-SnO-P2O5 (Me designs the organic methyl group) doped with organic acids (salicylic acid (SA), tartaric acid (TA), citric acid (CA) and butane tetracarboxylic acid (BTCA)) containing one or more of carboxylic groups per molecule. The structure, thermal properties and durability of the final glasses obtained via a non-aqueous acid-base reaction were discussed owing to the nature and the concentration of the acid added. 29Si magic angle spinning (MAS) NMR and 31P MAS NMR spectra, respectively, showed clearly a modification of the network in the host glass matrix of the Me2SiO-SnO-P2O5 system. The polycondensation enhancement to form -P-O-Si-O-P- linkages (PSP) and the increase of the Q2 unit (two bridging oxygens per phosphorus atom) over the Q3 unit (three bridging oxygens per phosphorus atom) as a function of the acid in the order SA<TA<CA<BTCA, suggest the formation of a chain-like structure which contrasts with the high cross-linkage in the Me2SiO-SnO-P2O5 matrix. In addition, this structural change is accompanied by a decrease of the coefficient of thermal expansion and an increase of the water durability of the glasses with the acids containing a large number of carboxylic groups per molecule. The presence of carboxylic groups of the acid acting as network modifier may retard the movement of water molecules through the glasses due to the steric hindrance strengthening the PSP connections in a chain-like structure.

Abstract: We report a facile route for the preparation of polyphenylsiloxane ((1 - x)PhSiO3/2-(x)Ph2SiO2/2 (x = 0, 0.1, 0.2, 0.3)) glass films from 50 to 150 [mu]m thick. The films were obtained via a multi-step spin-coating process at room temperature using a non-aqueous coating sol where the preformed polyphenylsiloxane is homogeneously dissolved in acetone. The different stages of the spinning process have been described and optimised, and represent an important issue to the preparation of homogeneous films. The thickness of the films (H) coated on silica and polyethyleneterephtalate substrates showed a trend dependency with the sol viscosity ([eta]), H [is proportional to] [eta]0.37 and H [is proportional to] [eta]0.41, respectively, making the thickness of the films easy to control. The average surface roughness evaluated to be less than 5 nm and the high optical transmittance (99%) demonstrated the high quality coatings. In addition, the stability of the glass matrix in the solvent makes this method of practical interest for tremendous possibilities in a wide range of applications such as the development microfluidic channels, protective coatings and optical components.

Abstract: Abstract&nbsp;&nbsp;Phenylsilsesquioxane-diphenylsiloxane glass thick films doped with anthracene were prepared from homogeneous coating sols obtained from two different approaches. One approach consisted in incorporating the dye during the glass preparation (which implies the incorporation of the dye in an aqueous media). The doped-glass was further dissolved in the solvents mixture composed of cyclohexane and acetone. The other approach which is non-aqueous consisted simply in dissolving directly the preformed non-doped polyphenylsiloxane glass in the dye solutions. The stability of the organic-inorganic hybrid glass matrix in most organic solvents makes possible the incorporation of the dye without problems of miscibility and dispersion in the hybrid matrix. The coating was performed at room temperature using spin-coating technique prior to further heat-treatment. Crack-free and homogeneous films of high optical quality were obtained. The optical properties of the doped films based on their absorption and emission spectra were discussed owing the incorporation route of the dye. The results showed that the non-aqueous approach used to incorporate the dye minimizes the dye aggregation. This property associated to the preparation route permits to obtain optically active hybrid films loaded with high concentrations of anthracene (in the order of 10�2&nbsp;M) which enhance the fluorescence of the doped films. The hybrid doped-films obtained represent therefore a tremendous potential for applications in the field of optics and photonics including the development of new nonlinear optical materials.

Abstract: Copper vinylphosphonate monohydrate, Cu(O3PC2H3)[middle dot]H2O, and zinc vinylphosphonate monohydrate, Zn(O3PC2H3)[middle dot]H2O, materials have been prepared using vinylphosphonic acid, and copper and zinc oxide, respectively, as precursors. Their crystal structures have been solved by single crystal X-ray diffraction and show that in copper vinylphosphonate, the Cu atoms are five-coordinate, whereas in zinc vinylphosphonate, the Zn atoms are in a distorted octahedral environment. In both structures, closest neighbour vinyl groups are separated by short contacts of ca. 4.15-4.3 [Angstrom]. However, due to the different coordination environments of the metal centres, the orientation of the vinyl groups in these two structures is not the same, which is expected to lead to different solid state reactivity with respect to the possibility of dimerisation or polymerisation reactions.

Abstract: New layered mixed divalent metal vinylphosphonates CuII1-xZnIIx(O3PC2H3)

Abstract: Layered mixed divalent metal phosphonates Mg1[space]-[space]xZnx(O3PR)[middle dot]H2O [with R[space]=[space]CH3, C2H3, C6H5] and Ni1[space]-[space]xZnx(O3PR)[middle dot]H2O [with R[space]=[space]CH3, C2H3, C6H5, (CH2)2COOH] have been prepared by heating, respectively, mixed divalent magnesium-zinc hydroxides and nickel-zinc hydroxides above the melting point of the phosphonic acid being used. A range of pre-formed mixed divalent metal hydroxides Mg1[space]-[space]xZnx(OH)2 and Ni1[space]-[space]xZnx(OH)2 with different ratios of Zn content (x[space]=[space]0, 0.1, 0.25, 0.5) are obtained by isomorphous substitution of zinc into the, respective, Mg(OH)2 and Ni(OH)2 brucite-type structure: space group P3m1; a[space]=[space]3.13-3.15[space]A, c[space]=[space]4.63-4.77[space]A). The phosphonate materials have been characterized by X-ray powder diffraction, IR, TGA, and 31P MAS NMR. Mg1[space]-[space]xZnx(O3PR)[middle dot]H2O and Ni1[space]-[space]xZnx(O3PR)[middle dot]H2O crystallize in an orthorhombic system with space group Pmn21 with b[space]=[space]5.55-5.69[space]A, c[space]=[space]4.71-4.86[space]A and a varying according to the size of the organic group R.

Abstract: Book Description: The authors of this book discuss the use of organosilanes as anchoring layers for biomolecules on different materials. The biofunctionalization of organosilanes and their applications are also examined. Moreover, heterogenizing of organocatalysts is one of the big issues during this decade and mesoporous silica seems to be the best candidate in viewpoint of easy catalyst preparation and support stability. The synthesis pathways of organofunctionalized mesoporous materials are analyzed. In addition, sol-gel derived hybrid organic/inorganic (O/I) nanocomposites are largely exploited in materials technology, due to the synergic merge at the molecular scale of the components characteristics through a large extent of phase interaction. A review of the main results are reported here on the preparation. In other chapters, the authors explore the bioapplications of silica-based glasses prepared from functionalized organosilane precursses and provide some examples of newly developed Si-Si or Si-H bond containing compounds, which exhibit a high reactivity both in Free Radical Polymerization (FRP) and in Free Radical Promoted Cationic Polymerization (FRPCP) under air.

Abstract: In the present time most researchers believe that progress in medicine is connected with the development of drug delivery systems using nanoparticles. Very important drugs are immune-modulators which are natural or synthetic compounds. They often have protein nature. The efficiency of immune-modulator delivery into cells using nanocarriers will depend on both physical-chemical and biological properties of the drug, and the properties of nanocarriers themselves. Silica materials with different surface functionalities have been synthesized by sol-gel method. Physical properties of the silica materials in general have been studied to date to enlighten the molecular interactions and biocompatibility between host matrices and biomolecules (enzymes, proteins). These properties will be reported in this Chapter. We will also mainly report the work that is a part of original study concerning with the potential application of silica particles as nanocarriers of immune-modulator. For instance, for drug delivery applications, the adsorption ability of the silica materials has been studied and will be also described specifically using human serum albumin as a model compound of the drug. The studies of physical and adsorption properties of the silica materials as well as their interactions with immune cells in vitro is in the forefront of the research in the field as it will allow designing and selecting the most promising, and efficient silica carrier of immune-modulator proteins for drug delivery.

Abstract:

Abstract: Carbon-Fluorine Spectroscopy (CFS) aka Fluoro-Raman Spectroscopy (FRS), is a relatively new patented platform technology using a family of various methods and cost-effective devices called PLIRFA� (Pulsed Laser Isochronic Raman and Fluorescence Apparatus) developed by Fluorotronics, Inc. The key feature of this progressive and non-destructive technology is based on the discovery of a characteristic optical signature of carbon-fluorine bond(s) in the fingerprint spectral area of 500�800 cm-1 allowing rapid, ultra-specific and sensitive detection, characterization, imaging, and measurement of any fluoroorganics. Interestingly, the C-F bond, unique in its character, can be used as a molecular label. Indeed, the C-F label is efficient, soluble, cheaper, smaller, more stable and less toxic than fluorescent dyes, nanoparticles or quantum dot materials. Thereby, C-F bonds are often incorporated into molecules, compounds in addition to nano-materials to achieve special properties (e.g. molecular stability, molecular tracing). In this study, we present some of our key data obtained from the promising CFS.

Abstract: Organic-inorganic nanoporous silica sol-gel glasses constitute the ideal support for protein bio-encapsulation and adsorption to study the different factors influencing the protein folding process in a crowded environment. Due to the facile silica surface modifications with desired Si-substituted organic groups from organosilanes precursors, organically modified �wet-aged� silica-based glasses obtained via the sol-gel process, can be used as host materials to mimic the crowded environment of the proteins and cells that can be found in the cytoplasm for instance. Numerous studies to date showed that silica-based nanoporous glasses can stabilize bioactive proteins. However, it is important to know about the different factors affecting the protein stability and therefore its properly-folded state. We report the recent results on the influence of different parameters (such as surface hydration, hydrophobicity, solute effects, thermal stability, porosity, macromolecular crowding) on the protein conformation based on the design and the characterization of nanoporous silica-based materials containing different functional groups (e.g., hydrophobic alkyl, phosphate and fluorinated groups). The enhancement of the protein folding owing to the physical properties and microstructure of the host matrix induced by the nature of the functional groups and the siloxane network play a major role on the protein biological activity and therefore to the development efficient bionanodevices such as biocatalysts, sensors, drug delivery systems or implanted devices. It is also the opportunity to understand the different factors influencing the protein misfolding that are the cause of devastating diseases such as Alzheimer or Huntington.

Abstract:

Abstract: Detection of low-expressed proteins from biological samples is possible by our patented FRS (Fluoro-RAMAN spectroscopy) technology and its associated device PLIRFATM (Pulsed Laser Isochronic Raman and Fluorescence Apparatus) (www. Fluorotronics.com). The goal of our study was to detect specifically important biomarkers involved in the cell cycle checkpoints (i.e., p53-downstream target p21) using human tumour cells (i.e., colon carcinoma cells HCT116) and a new simple three steps method. Indeed, a single type of Fluoro-modified-amino acid (4-fluoro-L-phenyalanine or 5-fluoro-DL-tyrosine or 5-fluoro-DL-tryptophane) was added to the medium-containing cells. The corresponding non-modified amino-acid (DL-tyrosine, DL-tryptophane, L-phenylalanine), which is present in the sequence of the protein of interest, was used as control. The cells incorporated naturally the amino-acid for protein synthesis process without interfering with the activity or the conformation of the protein. After Carbone-Fluor (C-F) labelling, the protein of interest was isolated and enriched by immunoprecipitation using a specific antibody. Eventually, the enriched Fluoro-labelled protein and the non-Fluoro-labelled protein were comparatively analysed, by FRS. A 532 nm DPSS Q-switched laser (Sierra, General Atomics, USA) with 20 kHz repetition rate and 10 ns pulse duration was used to deliver 10 mW of average power to a small amount of the sample. The RAMAN spectra of the F-protein were detected specifically due to the unique characteristic of the C-F bond label. In the meantime, the vibrational assignment of the other main spectral regions were reported. Furthermore, the F-protein was more sensitively detected than the non-labeled protein, which allowed us to clearly differentiate the two states of proteins. Thus, we showed for the first time, that the non-destructive Fluoro-Raman spectroscopy technology can be routinely used to selectively, sensitively and rapidly detect/screen fluorinated molecules (i.e., amino-acids, proteins and nucleic acids) in biological samples (i.e., cells or tissues). In addition to the potential use of the FRS technology in Fluoro-diagnostic, our emerging and challenging Fluoro-imaging approach coupled to FRS which use stable non-fluorescent and non-radioactive labelling would offer obvious advantages in terms of safety and cost-effectiveness.

Abstract:

Abstract: The binary glass systems MIIO-P2O5 (with M = Zn, Sn) were prepared via a non-aqueous acid-base reaction using orthophosphoric acid and the relevant metal chloride as starting materials. We investigated their glass-forming regions, thermal, and structural properties with different compositions and different heat-treatment temperatures. Transparent glasses with high chemical durability and low softening temperatures ranging from 50��C to 250��C were obtained at low temperature process. The X-ray fluorescence measurements results showed that no chlorine remained in the glasses after heat-treatment, making the method suitable for obtaining durable and environmental-friendly low-melting glasses.

Abstract:

Abstract: (EN) Disclosed is a lead-free low-melting glass having excellent water resistance. Also disclosed is a method for production of a lead-free low-melting glass, comprising thermally treating a mixture comprising an oxide microparticle, an acid component and a metal chloride.

Abstract: PROBLEM TO BE SOLVED: To solve the problems that it is very difficult to form a film having thickness of ?3 ��m by one time of processing, and the processing in multiple stages is needed for forming a film having thickness of ?3��m, thereby resulting in the ...

Abstract: Thesis (Ph.D.)--University of Birmingham, 2002.

Abstract: Introduction: Malignant melanoma is associated with genetic heterogeneity and a complex etiology. In contrast to other skin cancers, melanoma affects a younger population and has a strong tendency to metastasize with a consequently extremely poor overall survival. Oncogenic B-RAF and N-RAS mutations are respectively the most frequent genetic alterations, which are responsible for melanoma malignancy and maintenance. The new model of carcinogenesis involving cancer stem cell is believed to be responsible for initiation and progression of melanoma to metastasis as well as for recurrence after cytoreductive therapy. Here, we explored the possible relationship between the mutational status of tumor genes B-RAF and N-RAS and the presence or absence of putative melanoma stem cells (aka melanoma initiating cells or melanoma propagating cells) in a cohort control-case genome association study which involved patients diagnosed with metastatic melanoma. Material and Methods: Patients with primary ocular melanomas were excluded. All tumor samples (metastatic melanoma stage IV biopsies) and clinical data were collected with Institutional Review Board approval and patient�s informed consent. A part of the frozen solid tumor tissue samples was used for genomic DNA isolation by RNase and proteinase K digestion and subsequent phenol/chloroform extraction. Established cell lines derived from another part of a biopsy, were maintained in RPMI 1640 supplemented with 10% fetal calf serum, 5 mM L-glutamine, 100 U/ml penicillin and 100 mg/ml streptomycin at 37 degrees Celcius in a humidified 5% CO2 atmosphere. Detection of mutation(s) has been performed by single strand conformation polymorphism (SSCP). Fluorescent capillary SSCP technique was used to detect mutations the B-RAF and the N-RAS genes. Direct DNA sequencing was used to identify and confirm mutations detected in the B-RAF and N-RAS genes by SSCP. Identification of a side population of stem-like melanoma cells, previously isolated and characterized, was assessed routinely by Hoechst exclusion assay. Statistical analyses were performed using a combination of statistical packages. Differences with a p value equal to 0.05 were considered statistically significant. Results: Interestingly and for the first time, we found that it does exist, in melanoma, an inverse correlation between the presence of B-RAF mutations and the presence of a cancer cell sub-population (SP) defined as putative melanoma stem cells. Conclusion: Eventually, our results strongly suggest that the systematic determination of a side population of stem-like melanoma cells within a given tumor could provide precious information for a more reliable diagnosis, predict the clinical outcome of melanoma patients, and opt for a more efficient personalized therapy.

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Abstract: AFM-based single molecule force spectroscopy is a powerful tool employed to investigate inter- and intra-molecular interactions at the level of single molecules. The extension of selected molecules trapped between the cantilever and a surface is measured as a function of the applied force and can provide detailed information on the structure and function of many molecular systems. The methodology has been applied to molecular recognition of biomolecules (such as antigens and antibodies) and to probe DNA-interactions with tremendous applications in biotechnology. We report here on the measurement of the forces that hold complementary strands of DNA and on the effect induced by the binding of a DNA minor groove ligand binder (Hoechst 33258). This study is critical to understand the role and the function of therapeutic agents such the anti-filarial Hoechst 33258 via the determination of the DNA-ligand interactions. In that context, a thiol-derivatized single stranded DNA constituted of 24-base oligonucleotide containing 33% CG-base was grafted onto the AFM-tip and its complementary strand to a gold-coated mica substrate. Both DNA strands were designed to correspond to the formation of a DNA-duplex long enough to be detected by force spectroscopy. The DNA hybridization obtained via the contact of the AFM-tip with the substrate was successfully detected by the force curves showing a rupture corresponding to an extension similar to the length of the DNA-duplex formed. In addition, the force curves obtained for different loading rates revealed that the force necessary to rupture the duplex into single strands increases in presence of the minor groove ligand binder. For instance, the rupture force at a loading rate of 36 nN s-1 increases from 34 pN when no ligand is present in the solution to 84 pN in presence of the ligand. These results confirm the ligand complexation with the DNA duplex and its tendency to stabilize it. These promising results have an important impact for the utilization of atomic force spectroscopy on short DNA-duplexes to probe the role and mimic the effects of ligand binders having therapeutic properties.

Abstract: Purpose: Specific detection of markers of disease from biological samples by our patented Carbon-Fluorine Spectroscopy aka Fluoro-Raman Spectroscopy (www.fluorotronics.com). Material and Methods: A single type of fluoro-modified-amino acid (4-Fluoro-L-phenyalanine or 5-Fluoro-DL-tyrosine or 5-Fluoro-DL-tryptophane) was added to the medium-containing cells at the final concentration of 10 mM. The corresponding non-modified amino-acid (L-phenylalanine, DL-tyrosine, DL-tryptophane) was used as control. The cells (e.g., colon cancer cells HCT116) incorporated naturally the amino-acid during the natural occurring protein synthesis process without interfering with the activity or the conformation of the proteins of interest. After C-F labelling, the biomarker (e.g., p21) was isolated and enriched by immunoprecipitation using a specific antibody. Eventually, the enriched fluoro-labelled protein and the corresponding non-fluoro-labelled protein were comparatively analysed by FRS. A 532 nm DPSS Q-switched laser (Sierra, General Atomics, USA) with 20 kHz repetition rate and 10 ns pulse duration was used to deliver 10 mW of average power to a small amount of the sample. Discussion: The Raman spectra of the F-protein and the non F-protein were detected specifically due to the unique characteristic of the C-F bond label. The vibrational assignment of the others main spectral regions were identified. Furthermore, the F-protein was more sensitively detected than the non-labeled protein, which allowed us to clearly differentiate the two profiles of a same protein before and after fluorination. Because the C-F signal is directly proportional to the concentration of the analyte, it was also possible to quantify the protein amount in a cell population. Conclusion: Thus, we showed for the first time, that the non-destructive Fluoro-Raman spectroscopy technology can be routinely used to selectively, sensitively and rapidly detect/screen fluorinated molecules (e.g., amino-acids, peptides, proteins and nucleic acids) in vitro, ex-vivo in biological samples (e.g., cells and tissues) or even, in vivo (e.g., animals). Perspective: Our emerging and challenging fluoro-imaging approach coupled to the patented FRS, which use stable non-fluorescent and non-radioactive labelling, will offer additional advantages in terms of safety, health care (e.g., diagnostics and therapeutics) and cost-effectiveness.

Abstract: Abstract: Carbon-Fluorine Spectroscopy aka Fluoro-Raman Spectroscopy (FRS) is a patented platform technology using various methods and a family of devices called PLIRFATM (�Pulsed Laser Isochronic Raman and Fluorescence Apparatus�) developed by Fluorotronics, Inc., (www.fluorotronics.com). The key feature of this technology is based on the discovery of a characteristic optical signature of carbon-fluorine bond(s) (-C-F, =CF2, -CF3) in the fingerprint spectral area of 550 cm-1 and 950 cm-1 allowing detection, characterization, imaging, and measurement of fluoroorganic compounds and fluoro-molecules. The FRS method is ultra-specific and ultra-sensitive for C-F bonds, is non-destructive, allows rapid data acquisition in ns-level and real-time analysis, require little or no sample preparation, is easy to use and the data are simple to interprete, leading therefore, to cost effectiveness. Furthermore, the C-F bond signal is directly proportional to the concentration of the analyte, allowing a quantitative determination of a fluorinated compounds, F-labelled materials and F-impurities. Since the C-F bond is unique and it does not exist in nature - with exception of being present in some rare plants -, it can be used as an external or internal chemical tag, molecular marker or label. Furthermore, the C-F label is efficient, soluble, cheaper than those known in the market, smaller, more stable and less toxic than fluorescent dyes, nanoparticles or quantum dot materials. Consequently, C-F bonds do not require maintenance and avoid logistical problems normally associated with radioactive labels. Consequently, FRS can be used for numerous applications. For instance, FRS is applicable for multiplexing, high throughput analysis of any type of fluoroorganic compounds and can also detect fluoroorganic impurities or fluoro-degradation products in matrices, in various media (pharmaceutical, chemical or biological solutions) and in any physical state (e.g. solids or surfaces (chips, beads, quantum dots)). Measurements can be done via glass and polymer containers, quartz vials and by the use of free standing, imaging and fiber optic devices. Indeed, using the PLIRFATM platform and corresponding specialized devices, we have successfully characterized both fluoroorganic and other molecules, compounds, cells and materials in different physical states such as solids, powders, nano-dispersed materials, liquids and solutions. C-F bonds are often incorporated into pharmaceutical, agrochemical and biological molecules as well as in polymers and nano-materials to achieve special properties (e.g. molecular stability, tracing a compound during the production or the synthesis cycle). Eventually, the patented broad Fluoro-Raman technology platform represents a powerful and flexible fluoro-analytical technology, allowing unification of the detection, measurement and characterization platforms in life sciences, pharmaceutical and diagnostic industries. We will present the results of the most recent projects and intended applications in different fields.

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Abstract: The improvement of chemical durability will stimulate the applications of phosphate glasses in several fields of materials science such as ionic conductors, photonic materials, hermetic seals, rare-earth-doped solid-state lasers and biomedical materials. In this context, we investigated the effects of polycarboxylic acids (salicylic acid, tartaric acid, citric acid and butane tetracarboxylic acid) incorporation on the chemical durability of phospho-silicate glasses in the Me2SiO-SnO-P2O5 system. The glasses obtained via a non-aqueous acid-base reaction were characterised by a variety of spectroscopic (Infra-red, 29Si & 31P MAS NMR) and thermoanalytical (TMA, DSC) techniques. The influence of the acid on the chemical durability of glass was discussed based on the molecular structure, the acidity and the concentration in the glass matrix.

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Abstract: The preparation of organic-inorganic hybrid polysiloxane-based �glasses� constitutes an important step in the development of new optical and photonic devices. Multifunctional hybrid materials present advantages of designing materials for optical applications (integrated optics, planar optical waveguides�). Phenylsilsesquioxane-diphenylsiloxane-based glasses obtained by gel-melting method are characterised by a combination of properties such as low-softening temperature (70-200 deg.C), transparency, stability against the ambient, tuneable refractive index and so on. One of the interesting features is also the large solubility and high stability in different organic solvents (acetone, acetonitrile, alcohols, dichloromethane, tetrahydrofuran, cyclohexane, chloronaphtalene and so on). Interesting properties of functionalised materials can be then obtained by incorporating dyes (rhodamine 6G, anthracene, phtalocyanine, coumarin 152 in hybrid glass matrices. We report the preparation of the doped-glass films by dip- or spin-coating (1 to 150 microns thick) using the miscibility of the dye solution with the polysiloxane-based glass. The process is simple and allows homogeneous and crack-free films of high optical quality coated on various substrates (PET, silica, silicon�). The functional hybrid doped-glass films obtained exhibits emission properties (such as solid state dye lasers) and their nonlinear optical properties have been studied. We think that these materials can be use for a large range of applications such as distributed feedback lasers, nonlinear optical materials and so on.

Abstract: Metal phosphate glasses find applications in several fields of materials science such as ionic conductors, photonic materials, hermetic seals, rare-earth-doped solid-state lasers and for the development of biomedical materials. Recent interest concerns with the preparation, characterisation, processing and manufacturing of new types of materials with interesting properties for larger range of applications. One of the important features of our work resides in the method employed for the preparation of these glasses. Low-melting glasses can be obtained by incorporation of elements such as Pb and F, which are not environmentally-friendly. Recently, we have developed an interesting new route for obtaining low-melting glass free of toxic elements based on the concept of acid-base pair reaction method, which is a non-aqueous method. In this work, we prepared glasses in the ZnO-P2O5 binary system using orthophosphoric acid and zinc chloride as starting materials. They were allowed to react with each other during a gradual heat-treatment to 200 deg.C for 5 hours and the transparent liquid phase obtained was subjected to heat-treatment maintained at this temperature for 6 hours. Finally, transparent glasses were obtained after cooling down to room temperature. We investigated their glass-forming region, the thermal, structural properties and the chemical durability of the glasses with different composition and different heat-treatment temperatures (from 200 deg.C up to 800 deg.C). Transparent glasses were obtained at low temperature process over a wide composition region, and with low softening temperatures of which ranged from 50 deg.C to 250 deg.C. The results show that the glass transition and softening temperatures increase with increasing heat-treatment time without the change in the composition. The glasses are found to be highly durable in water and other organic solvents. X-ray fluorescence measurements showed that no chlorine remained in the glasses after heat-treatment. The low temperature processing (100 deg.C-200 deg.C) of materials with low softening temperature will provide novel functionalities to our glasses by incorporation of various organic dyes of interest, and/or rare-earth ions.

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Abstract: Low-melting glass thick films of 10�m in thickness have been successfully deposited on silica substrate via a single dip-coating at room temperature. Inorganic-organic hybrid low-melting glasses of compositions (1-x)PhSiO3/2-(x)Ph2SiO2/2 (x = 0, 0.1, 0.2, 0.3) used for this purpose have been prepared using the sol-gel method. These low-melting glasses derived from two different organoalkoxysilanes showed interesting modulation of thermal and optical properties on account of the composition � the softening temperature decreases with the addition of diphenyl unit allowing with further heat-treatment a better transparency of the films and in addition, their refractive index can be controlled by varying the ratios of the organics present. Consequently, transparent, homogeneous, flat and chemically stable thick-films with high optical quality can be obtained and are promising candidates for optical and photonic devices.

Abstract: The synthesis and study of metal phosphonate materials M(O3P-R).nH2O represents an important step in the development of organic-inorganic hybrid compounds. The synthesis of tetravalent metal phosphonates to date, particularly of zirconium phenylphosphonate, and then of divalent and trivalent metal phosphonates showed that these compounds were composed of layered structures of alternating organic and inorganic layers. These materials have many potential applications due to their interesting structure and to the various organic species we can co-ordinate to the metal. They can be used as proton conductors for the development of fuel cells, as cation exchangers, and the selective adsorption to vacant sites on the different metal atoms within the structure opens up tremendous possibilities for shape-catalytic reactions to be carried out within the interlayer region . We have expanded the studies on phosphonate materials to systems containing two different divalent metals into the structure. Layered mixed divalent metal phosphonates M1-xM�x(O3P-R). H2O (x=M�/(M�+M)= 0 ; 0.1 ; 0.25 ; 0.5 ; 1) containing different pairs of metal such as (M, M�)= (Mg, Zn); (Ni, Zn); (Cu, Zn); (Cd, Cu) and different organic groups (R= -CH3, -C2H3, -C6H5, -(CH2)2COOH) have been prepared using the relevant mixed divalent hydroxides or mixed divalent oxides in the case of the synthesis of the copper-zinc vinylphosphonate monohydrate. Those phosphonates have been characterised by X-ray powder diffraction, FTIR, TGA and by MAS NMR 31P solid state for the magnesium-zinc ones. Intercalation with n-alkylamines have also been studied.

Abstract: The synthesis and study of metal phosphonate materials M(O3P-R). nH2O represents an important step in the development of organic-inorganic compounds. The synthesis of tetravalent metal phosphonates, particularly of zirconium phenylphosphonate, and then of divalent and trivalent metal phosphonates showed that these compounds were composed of layered structures of alternating organic and inorganic layers. These materials have many potential applications due to their interesting structure and to the various organic species we can co-ordinate to the metal. They can be used as proton conductors for the development of fuel cells, as cation exchangers, and the selective adsorption to vacant sites on the different metal atoms within the structure opens up tremendous possibilities for shape-catalytic reactions to be carried out within the interlayer region (intercalation with alkylamines). We have expanded the studies on phosphonate materials to systems containing two different divalent metals Ni1-xZnx(O3P-R). H2O (x=Zn/(Ni+Zn)), synthesised by using a range of the mixed divalent metal hydroxides precursors which have an Mg(OH)2 brucite structure type (Space group P-3m1) with similar cell parameters a=b=3.1-3.3, c= 4.6-4.8 and the desired phosphonic acid (ie: methyl, vinyl, 2-carboxyethyl, or phenylphosphonic acid) to obtain the corresponding mixed divalent phosphonate and study the properties of these materials with different amount of one of these metals. We showed in this work the success of the intercalation in the nickel-zinc phosphite phenylphosphonate material with n-hexylamine, whereas the nickel-zinc phenyl phosphonates do not intercalate with amines but give very stable dehydrated compounds. The dehydrated nickel-zinc carboxyethyl phosphonates has been used as Bronsted acid catalyst for a deprotection of an orthoester, and also react with an aqueous solution of cupric sulfate showing the ion exchange properties of these materials containing a mobile proton which can readily diffuse through the layers. Further studies on these different properties are still in progress using other metals and different organic groups.

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