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Franck Thétiot

Bio: Franck Thétiot is an academic researcher from University of Western Brittany. The author has contributed to research in topics: Bridging ligand & Coordination polymer. The author has an hindex of 13, co-authored 19 publications receiving 599 citations. Previous affiliations of Franck Thétiot include Foundation for Research & Technology – Hellas.

Papers
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Journal ArticleDOI
TL;DR: In this article, a novel antimicrobial composite materials incorporating zinc oxide nanoparticles (ZnO NP) into biocompatible poly( N -isopropylacrylamide) (PNIPAAm) hydrogel layers are prepared by mixing the PNIPaam prepolymer with ZnO nanoparticles, followed by spin-coating and photocrosslinking.
Abstract: Despite multiple research approaches to prevent bacterial colonization on surfaces, device-associated infections are currently responsible for about 50% of nosocomial infections in Europe and signifi cantly increase health care costs, which demands development of advanced antibacterial surface coatings. Here, novel antimicrobial composite materials incorporating zinc oxide nanoparticles (ZnO NP) into biocompatible poly( N -isopropylacrylamide) (PNIPAAm) hydrogel layers are prepared by mixing the PNIPAAm prepolymer with ZnO NP, followed by spin-coating and photocrosslinking. Scanning electron microscopy (SEM) characterization of the composite fi lm morphology reveals a homogeneous distribution of the ZnO NP throughout the fi lm for every applied NP/polymer ratio. The optical properties of the embedded NP are not affected by the matrix as confi rmed by UV-vis spectroscopy. The nanocomposite fi lms exhibit bactericidal behavior towards Escherichia coli (E. coli) for a ZnO concentration as low as ≈ 0.74 μ g cm − 2 (1.33 mmol cm − 3 ), which is determined by inductively coupled plasma optical emission spectrometry. In contrast, the coatings are found to be non-cytotoxic towards a mammalian cell line (NIH/3T3) at bactericidal loadings of ZnO over an extended period of seven days. The differential toxicity of the ZnO/hydrogel nanocomposite thin fi lms between bacterial and cellular species qualifi es them as promising candidates for novel biomedical device coatings.

206 citations

Journal ArticleDOI
TL;DR: These new compounds are characterized by X-ray crystallography and magnetic measurements and show strong antiferromagnetic exchange interactions between the Cu(II) metal ions dominated by the magnetic exchange through the bis-chelating bpym.
Abstract: Reactions between CuCl2 and K2tcpd (tcpd2- = [C10N6]2- = (C[C(CN)2]3)2-) in the presence of neutral co-ligands (bpym = 2,2'-bipyrimidine, and tn = 1,3-diaminopropane) in aqueous solution yield the new compounds [Cu2(bpym)(tcpd)2(H2O)4] x 2H2O (1), [Cu(tn)(tcpd)] (2), and [Cu(tn)2(tcpd)] x H2O (3), which are characterized by X-ray crystallography and magnetic measurements. Compound 1 displays a one-dimensional structure in which the bpym ligand, acting with a bis-chelating coordination mode, leads to [Cu2(bpym)]4+ dinuclear units which are connected by two mu2-tcpd2- bridging ligands. Compound 2 consists of a three-dimensional structure generated by [Cu(tn)]2+ units connected by a mu4-tcpd2- ligand. The structure of 3 is made up of centrosymmetric planar [Cu(tn)]2+ units connected by a mu2-tcpd2- ligand leading to infinite zigzag chains. In compounds 1 and 3, the bridging coordination mode of the tcpd2- unit involves only two nitrogen atoms of one C(CN)2 wing, while in 2, this ligand acts via four nitrogen atoms of two C(CN)2 wings. Despite this difference, the structural features of the tcpd2- units in 1-3 are essentially similar. Magnetic measurements for compound 1 exhibit a maximum in the chi(m) vs T plot (at approximately 150 K) which is characteristic of strong antiferromagnetic exchange interactions between the Cu(II) metal ions dominated by the magnetic exchange through the bis-chelating bpym. The fit of the magnetic data to a dimer model gives J and g values of -90.0 cm(-1) and 2.12, respectively. For compounds 2 and 3 the thermal variations of the magnetic susceptibility show weak antiferromagnetic interactions between the Cu(II) metal ions that can be well reproduced with an antiferromagnetic regular S = 1/2 chain model that gives J values of -0.07(2) and -0.18(1) cm(-1) with g values of 2.12(1) and 2.13(1) for compounds 2 and 3, respectively (the Hamiltonian is written in all the cases as H = -2JS(a)S(b)).

55 citations

Journal ArticleDOI
TL;DR: One-pot reactions in aqueous solutions of the polynitrile anion dcne− {2,2-dicyano-1-ethoxyethenolate = [(CN)2CC(O)OEt)]−] with the MII ions (M = Mn, Fe, Co, Cu) in the presence of bis(bidentate) 2,2′-bipyrimidine) afford the first mixed dcne/bpym compounds [M2(bpym)(dcne)4(H2O)2] (1
Abstract: One-pot reactions in aqueous solutions of the polynitrile anion dcne− {2,2-dicyano-1-ethoxyethenolate = [(CN)2CC(O)OEt)]−] with the MII ions (M = Mn, Fe, Co, Cu) in the presence of bpym (2,2′-bipyrimidine) afford the first mixed dcne/bpym compounds [M2(bpym)(dcne)4(H2O)2] (1: M = Mn; 2: M = Co) and [M2(bpym)(dcne)4(H2O)4]·2H2O (3: M = Fe; 4: M = Cu). The new compounds have been characterized by IR spectroscopy and X-ray crystallography. Compounds 1 and 2 are isostructural, with each metal ion being located in an MN5O pseudo-octahedral environment with three N atoms coming from three dcne− ligands, two nitrogen atoms from bpym and one oxygen atom from a water molecule. The extended structures of 1 and 2 are best described as dcne-bridged zigzag chains of MII ions running along the [100] direction; connections of these chains in the [010] direction, by the bis(chelating) bpym ligand, afford 2D structures. Compounds 3 and 4 are isostructural, and consist of discrete dinuclear units involving MN4O2 octahedrally coordinated MII ions bridged by bis(bidentate) 2,2′-bipyrimidine and terminal dcne ligands. Magnetic measurements for the 2D compounds 1 and 2 exhibit maxima in the χm vs. T plots (at about 4.5 K for 1 and about 20 K for 2) which are characteristic of weak antiferromagnetic exchange interactions between the high-spin metal centres. While the dinuclear iron complex 3 presents a similar behaviour (maximum in χm vs. T plot at 12 K), the antiferromagnetic exchange interactions are stronger in the copper complex 4. Fits of magnetic data for compounds 1, 3 and 4 with appropriate models led to J values of −0.6, −1.5 and −99.0 cm−1 respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

42 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe a monodimensional chain of a ladder-like structure in which the Cu⋯Cu distance through the tcm − ligand forming the sides is significantly shorter than the corresponding distance observed through that providing the rung (7.5157(4) A).

36 citations

Journal ArticleDOI
TL;DR: In this article, a bridging-mode polymeric materials of formula [M(tcnp)2(H2O)2] (MnII, 1; FeII, 2; CoII, 3 and CuII, 4; tcnp−=[(NC)2CC(OEt)C(CN)2 ]−=1, 1,1,3,3-tetracyano-2-ethoxypropenide anion) have been synthesized and characterized by infrared spectroscopy and X-ray crystallography.

34 citations


Cited by
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Journal ArticleDOI
TL;DR: This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination,ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration.
Abstract: Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH− (hydroxyl radicals), and O2 −2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.

2,627 citations

Journal ArticleDOI
TL;DR: Comparing Magnetic Metals and Semiconductors with Halometalate Anions and Chain Anions: Maleonitriledithiolates 5439 4.1.
Abstract: 2.2. BETS Salts with Halometalate Anions 5424 3. Magnetic Metals and Semiconductors 5426 3.1. Mononuclear Metal Complexes 5427 3.1.1. Tetrahalometalates 5427 3.1.2. Hexahalo Anions 5431 3.1.3. Pseudohalide-Containing Anions 5431 3.2. Polynuclear Metal Complexes 5433 3.2.1. Dimeric Anions 5433 3.2.2. Polyoxometalate Clusters 5434 3.3. Chain Anions: Maleonitriledithiolates 5439 4. Ferromagnetic Conductors 5441 5. Ferrimagnetic Insulators 5443 6. Conclusions 5445 7. Acknowledgment 5446 8. References 5446

785 citations

Journal ArticleDOI
TL;DR: It has been confirmed from SEM and TEM images of the bacterial cells that zinc oxide nanoparticles disintegrate the cell membrane and accumulate in the cytoplasm where they interact with biomolecules causing cell apoptosis leading to cell death.
Abstract: Zinc oxide is an essential ingredient of many enzymes, sun screens, and ointments for pain and itch relief. Its microcrystals are very efficient light absorbers in the UVA and UVB region of spectra due to wide bandgap. Impact of zinc oxide on biological functions depends on its morphology, particle size, exposure time, concentration, pH, and biocompatibility. They are more effective against microorganisms such as Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Sarcina lutea, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Pseudomonas vulgaris, Candida albicans, and Aspergillus niger. Mechanism of action has been ascribed to the activation of zinc oxide nanoparticles by light, which penetrate the bacterial cell wall via diffusion. It has been confirmed from SEM and TEM images of the bacterial cells that zinc oxide nanoparticles disintegrate the cell membrane and accumulate in the cytoplasm where they interact with biomolecules causing cell apoptosis leading to cell death.

600 citations

Journal ArticleDOI
25 May 2017-ACS Nano
TL;DR: An in vivo bacteria-infected wound-healing experiment indicates that the APA-modified AuNPs (Au_APA) has a striking ability to remedy a MDR bacteria wound infection and can assist the wound care for bacterial infections.
Abstract: Remedying a multidrug-resistant (MDR) bacteria wound infection is a major challenge due to the inability of conventional antibiotics to treat such infections against MDR bacteria. Thus, developing wound dressings for wound care, particularly against MDR bacteria, is in huge demand. Here, we present a strategy in designing wound dressings: we use a small molecule (6-aminopenicillanic acid, APA)-coated gold nanoparticles (AuNPs) to inhibit MDR bacteria. We dope the AuNPs into electrospun fibers of poly(e-caprolactone) (PCL)/gelatin to yield materials that guard against wound infection by MDR bacteria. We systematically evaluate the bactericidal activity of the AuNPs and wound-healing capability via the electrospun scaffold. APA-modified AuNPs (Au_APA) exhibit remarkable antibacterial activity even when confronted with MDR bacteria. Meanwhile, Au_APA has outstanding biocompatibility. Moreover, an in vivo bacteria-infected wound-healing experiment indicates that it has a striking ability to remedy a MDR bacte...

285 citations

Journal ArticleDOI
TL;DR: The inherent antibacterial activity of graphene-family and recent advances that have been made on graphene-based antibacterial materials covering the functionalization with silver nanoparticles, other metal ions/oxides nanoparticles , polymers, antibiotics, and enzymes along with their multicomponent functionalization are described.
Abstract: Bacteria mediated infections may cause various acute or chronic illnesses and antibiotic resistance in pathogenic bacteria has become a serious health problem around the world due to their excessive use or misuse. Replacement of existing antibacterial agents with a novel and efficient alternative is the immediate demand to alleviate this problem. Graphene-based materials have been exquisitely studied because of their remarkable bactericidal activity on a wide range of bacteria. Graphene-based materials provide advantages of easy preparation, renewable, unique catalytic properties, and exceptional physical properties such as a large specific surface area and mechanical strength. However, several queries related to the mechanism of action, significance of size and composition toward bacterial activity, toxicity criteria, and other issues are needed to be addressed. This review summarizes the recent efforts that have been made so far toward the development of graphene-based antibacterial materials to face current challenges to combat against the bacterial targets. This review describes the inherent antibacterial activity of graphene-family and recent advances that have been made on graphene-based antibacterial materials covering the functionalization with silver nanoparticles, other metal ions/oxides nanoparticles, polymers, antibiotics, and enzymes along with their multicomponent functionalization. Furthermore, the review describes the biosafety of the graphene-based antibacterial materials. It is hoped that this review will provide valuable current insight and excite new ideas for the further development of safe and efficient graphene-based antibacterial materials.

260 citations