1
|
Orfanidis S, Kosarli M, Karagianni M, Paipetis AS, Papavassiliou G, Fardis M. Structural integrity and healing efficiency study of micro-capsule based composite materials via 1H NMR relaxometry. Sci Rep 2023; 13:12189. [PMID: 37500804 PMCID: PMC10374639 DOI: 10.1038/s41598-023-39302-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 07/23/2023] [Indexed: 07/29/2023] Open
Abstract
In this work we present a novel approach utilizing nuclear magnetic resonance (NMR) relaxometry to assess the structural stability of microcapsules employed as self-healing agents in advanced aerospace composites both in ambient and harsh environmental conditions. We successfully correlate the amount of the encapsulated self-healing agent with the signal intensity and confirm non-destructively the quantity of the encapsulated self-healing agent mass for the first time in the literature using 1H NMR spin-spin relaxation techniques on urea-formaldehyde (UF) microcapsules of different diameters containing an epoxy healing agent. The amount of self-healing agent is shown to increase by reducing the capsule diameter; however, the reduced shell mass renders the capsules more fragile and prone to failure. Most notably, via NMR experiments conducted during thermal cycling simulating flight conditions, we demonstrate that the microcapsule integrity under thermal fatigue varies according to their size. Especially we experimentally verify that the microcapsules with the most sensitive shells are the 147 nm and 133 nm diameter microcapsules, which are the most commonly used in self-healing systems. Finally, we were able to retrieve the same results using a portable NMR spectrometer developed in-house for in situ microcapsule testing, thus demonstrating the potential of NMR relaxometry as a powerful non-destructive evaluation tool for the microcapsule production line.
Collapse
Affiliation(s)
- S Orfanidis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
- Department of Materials Science and Engineering, University of Ioannina, 45110, Ioannina, Greece
| | - M Kosarli
- Department of Materials Science and Engineering, University of Ioannina, 45110, Ioannina, Greece
| | - M Karagianni
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | - A S Paipetis
- Department of Materials Science and Engineering, University of Ioannina, 45110, Ioannina, Greece
| | - G Papavassiliou
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | - M Fardis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece.
| |
Collapse
|
2
|
Gkoura L, Panopoulos N, Karagianni M, Romanos G, Chatzichristos A, Papavassiliou G, Hassan J, Fardis M. Investigation of Dynamic Behavior of Confined Ionic Liquid [BMIM] +[TCM] - in Silica Material SBA-15 Using NMR. Int J Mol Sci 2023; 24:6739. [PMID: 37047711 PMCID: PMC10095388 DOI: 10.3390/ijms24076739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/19/2023] [Accepted: 03/20/2023] [Indexed: 04/08/2023] Open
Abstract
The molecular dynamics of 1-butyl-3-methyl imidazolium tricyanomethanide ionic liquid [BMIM]+[TCM]- confined in SBA-15 mesoporous silica were examined using 1H NMR spin-lattice (T1) relaxation and diffusion measurements. An extensive temperature range (100 K-400 K) was considered in order to study both the liquid and glassy states. The hydrogen dynamics in the two states and the self-diffusion coefficients of the cation [BMIM]+ above the glass transition temperature were extracted from the experimental data. The results were then compared to the corresponding bulk substance. The effects of confinement on the dynamic properties of the ionic liquid clearly manifest themselves in both temperature regimes. In the high-temperature liquid state, the mobility of the confined cations reduces significantly compared to the bulk; interestingly, confinement drives the ionic liquid to the glassy state at a higher temperature Tg than the bulk ionic liquid, whereas an unusual T1 temperature dependence is observed in the high-temperature regime, assigned to the interaction of the ionic liquid with the silica-OH species.
Collapse
Affiliation(s)
- Lydia Gkoura
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
- Division of Science, New York University Abu Dhabi, Abu Dhabi 129188, United Arab Emirates
| | - Nikolaos Panopoulos
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| | - Marina Karagianni
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| | - George Romanos
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| | - Aris Chatzichristos
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
- Department of Physics, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates
| | - George Papavassiliou
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| | - Jamal Hassan
- Department of Physics, Khalifa University of Science and Technology, Abu Dhabi 127788, United Arab Emirates
| | - Michael Fardis
- Institute of Nanoscience & Nanotechnology, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| |
Collapse
|
3
|
Fardis M, Karagianni M, Gkoura L, Papavassiliou G. Self-Diffusion in Confined Water: A Comparison between the Dynamics of Supercooled Water in Hydrophobic Carbon Nanotubes and Hydrophilic Porous Silica. Int J Mol Sci 2022; 23:ijms232214432. [PMID: 36430907 PMCID: PMC9697084 DOI: 10.3390/ijms232214432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
Confined liquids are model systems for the study of the metastable supercooled state, especially for bulk water, in which the onset of crystallization below 230 K hinders the application of experimental techniques. Nevertheless, in addition to suppressing crystallization, confinement at the nanoscale drastically alters the properties of water. Evidently, the behavior of confined water depends critically on the nature of the confining environment and the interactions of confined water molecules with the confining matrix. A comparative study of the dynamics of water under hydrophobic and hydrophilic confinement could therefore help to clarify the underlying interactions. As we demonstrate in this work using a few representative results from the relevant literature, the accurate assessment of the translational mobility of water molecules, especially in the supercooled state, can unmistakably distinguish between the hydrophilic and hydrophobic nature of the confining environments. Among the numerous experimental methods currently available, we selected nuclear magnetic resonance (NMR) in a field gradient, which directly measures the macroscopic translational self-diffusion coefficient, and quasi-elastic neutron scattering (QENS), which can determine the microscopic translational dynamics of the water molecules. Dielectric relaxation, which probes the re-orientational degrees of freedom, are also discussed.
Collapse
|
4
|
Massarelli E, Schoenfeld A, Chesney J, Hong Y, Lammers P, Nieva J, Wise-Draper T, Goldberg Z, Cacovean A, Yadav B, Chen G, Jagasia M, Finckenstein FG, Fardis M, Sukari A. P14.04 A Phase 2 Multicenter Study of Iovance Autologous Tumor Infiltrating Lymphocytes (TIL, LN-145) Cell Therapy in Patients With Metastatic NSCLC. J Thorac Oncol 2021. [DOI: 10.1016/j.jtho.2021.08.334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
5
|
Massarelli E, Goldberg Z, Cacovean A, Yadav B, Chen G, Jagasia M, Finckenstein FG, Fardis M, Sukari A. 188TiP A phase II multicenter study of autologous tumor infiltrating lymphocytes (TIL, LN-145) cell therapy in patients with metastatic non-small cell lung cancer (mNSCLC). J Thorac Oncol 2021. [DOI: 10.1016/s1556-0864(21)02030-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
6
|
Gettinger S, Kluger H, Schoenfeld A, Warner AB, He K, Sukari A, Thomas S, de Spéville BD, Lee S, Haefliger S, Goldberg Z, Cacovean A, Fiaz R, Chen G, Jagasia M, Finckenstein FG, Fardis M, Jimeno A. 187TiP Phase II, multicenter study of autologous tumor infiltrating lymphocytes (TIL, LN 144/LN-145/LN-145-S1) in patients with solid tumours. J Thorac Oncol 2021. [DOI: 10.1016/s1556-0864(21)02029-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
7
|
Ritthipichai K, Machin M, Juillerat A, Poirot L, Fardis M, Chartier C. 1052P Genetic modification of Iovance’s TIL through TALEN-mediated knockout of PD-1 as a strategy to empower TIL therapy for cancer. Ann Oncol 2020. [DOI: 10.1016/j.annonc.2020.08.1172] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
8
|
Jazaeri A, Gontcharova V, Blaskovich M, Kunkalla K, Masteller E, Fardis M, Chartier C. 873P In vivo persistence of Iovance tumour-infiltrating lymphocytes LN-145 in cervical cancer patients. Ann Oncol 2020. [DOI: 10.1016/j.annonc.2020.08.1012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
|
9
|
Gkoura L, Diamantopoulos G, Fardis M, Homouz D, Alhassan S, Beazi-Katsioti M, Karagianni M, Anastasiou A, Romanos G, Hassan J, Papavassiliou G. The peculiar size and temperature dependence of water diffusion in carbon nanotubes studied with 2D NMR diffusion-relaxation D - T 2eff spectroscopy. Biomicrofluidics 2020; 14:034114. [PMID: 32595817 PMCID: PMC7305942 DOI: 10.1063/5.0005398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
It is well known that water inside hydrophobic nano-channels diffuses faster than bulk water. Recent theoretical studies have shown that this enhancement depends on the size of the hydrophobic nanochannels. However, experimental evidence of this dependence is lacking. Here, by combining two-dimensional nuclear magnetic resonance diffusion-relaxation ( D - T 2 e f f ) spectroscopy in the stray field of a superconducting magnet and molecular dynamics simulations, we analyze the size dependence of water dynamics inside Carbon Nanotubes (CNTs) of different diameters ( 1.1 - 6.0 nm), in the temperature range of 265 - 305 K. Depending on the CNT diameter, the nanotube water is shown to resolve in two or more tubular components acquiring different self-diffusion coefficients. Most notably, a favorable CNT diameter range ( 3.0 - 4.5 nm) is experimentally verified for the first time, in which water molecule dynamics at the center of the CNTs exhibits distinctly non-Arrhenius behavior, characterized by ultrafast diffusion and extraordinary fragility, a result of significant importance in the efforts to understand water behavior in hydrophobic nanochannels.
Collapse
Affiliation(s)
- L. Gkoura
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | | | - M. Fardis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | | | - S. Alhassan
- Department of Chemical Engineering, Khalifa University of Science and Technology, 127788 Abu Dhabi, UAE
| | - M. Beazi-Katsioti
- School of Chemical Engineering, National Technical University of Athens, 15780 Zografou, Athens, Greece
| | - M. Karagianni
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | - A. Anastasiou
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | - G. Romanos
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| | - J. Hassan
- Department of Physics, Khalifa University of Science and Technology, 127788 Abu Dhabi, UAE
| | - G. Papavassiliou
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15310 Aghia Paraskevi, Attiki, Greece
| |
Collapse
|
10
|
Subrati A, Kim Y, Al Wahedi Y, Tzitzios V, Alhassan S, Kim HJ, Lee S, Sakellis E, Boukos N, Stephen S, Lee SM, Lee JB, Fardis M, Papavassiliou G. Monitoring the multiphasic evolution of bismuth telluride nanoplatelets. CrystEngComm 2020. [DOI: 10.1039/d0ce00719f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bismuth telluride hexagonal nanoplatelets originate from electronically distinct thicker Bi-rich triangular nanoplatelets while being centrally knitted by Te nanorods.
Collapse
|
11
|
Chesney J, Cacovean A, Li H, Barton D, Fardis M. A phase II study of autologous tumor infiltrating lymphocytes (TIL; LN-144/LN-145) in patients with solid tumors. Ann Oncol 2018. [DOI: 10.1093/annonc/mdy485.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
12
|
Shankarayya Wadi V, Jena KK, Khawaja SZ, Yannakopoulou K, Fardis M, Mitrikas G, Karagianni M, Papavassiliou G, Alhassan SM. NMR and EPR Structural Analysis and Stability Study of Inverse Vulcanized Sulfur Copolymers. ACS Omega 2018; 3:3330-3339. [PMID: 31458588 PMCID: PMC6641320 DOI: 10.1021/acsomega.8b00031] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 03/07/2018] [Indexed: 05/31/2023]
Abstract
Sulfur copolymers with high sulfur content find a broad range of applications from Li-S batteries to catalytic processes, self-healing materials, and the synthesis of nanoparticles. Synthesis of sulfur-containing polymers via the inverse vulcanization technique gained a lot of attention due to the feasibility of the reaction to produce copolymers with high sulfur content (up to 90 wt %). However, the interplay between the cross-linker and the structure of the copolymers has not yet been fully explored. In the present work, the effect of the amount of 1,3-diisopropenyl benzene (DIB) cross-linker on the structural stability of the copolymer was thoroughly investigated. Combining X-ray diffraction and differential scanning calorimetry, we demonstrated the partial depolymerization of sulfur in the copolymer containing low amount of cross-linker (<30 wt % DIB). On the other hand, by applying NMR and electron paramagnetic resonance techniques, we have shown that increasing the cross-linker content above 50 wt % leads to the formation of radicals, which may severely degrade the structural stability of the copolymer. Thus, an optimum amount of cross-linker is essential to obtain a stable copolymer. Moreover, we were able to detect the release of H2S gas during the cross-linking reaction as predicted based on the abstraction of hydrogen by the sulfur radicals and therefore we emphasize the need to take appropriate precautions while implementing the inverse vulcanization reaction.
Collapse
Affiliation(s)
- Vijay
Kumar Shankarayya Wadi
- Department
of Chemical Engineering, Khalifa University
of Science and Technology, P.O. Box 2533, Abu Dhabi, United Arab Emirates
| | - Kishore K. Jena
- Department
of Chemical Engineering, Khalifa University
of Science and Technology, P.O. Box 2533, Abu Dhabi, United Arab Emirates
| | - Shahrukh Z. Khawaja
- Department
of Chemical Engineering, Khalifa University
of Science and Technology, P.O. Box 2533, Abu Dhabi, United Arab Emirates
| | - Konstantina Yannakopoulou
- National
Center for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Patr. Gregoriou and 27 Neapoleos
Street, Agia Paraskevi Attikis 15341, Greece
| | - Michael Fardis
- National
Center for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Patr. Gregoriou and 27 Neapoleos
Street, Agia Paraskevi Attikis 15341, Greece
| | - George Mitrikas
- National
Center for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Patr. Gregoriou and 27 Neapoleos
Street, Agia Paraskevi Attikis 15341, Greece
| | - Marina Karagianni
- National
Center for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Patr. Gregoriou and 27 Neapoleos
Street, Agia Paraskevi Attikis 15341, Greece
| | - Georgios Papavassiliou
- National
Center for Scientific Research “Demokritos”, Institute of Nanoscience and Nanotechnology, Patr. Gregoriou and 27 Neapoleos
Street, Agia Paraskevi Attikis 15341, Greece
| | - Saeed M. Alhassan
- Department
of Chemical Engineering, Khalifa University
of Science and Technology, P.O. Box 2533, Abu Dhabi, United Arab Emirates
| |
Collapse
|
13
|
Karyampudi L, Gokuldass A, Blaskovich M, Fardis M, Lotze M. Phenotypic and functional characterization of tumor infiltrating lymphocytes (TIL) grown from non-hodgkin lymphoma tumors: Implications for the development of novel therapies for lymphoma. Ann Oncol 2017. [DOI: 10.1093/annonc/mdx373.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
14
|
Rabias I, Fardis M, Kehagias T, Kletsas D, Pratsinis H, Tsitrouli D, Maris TG, Papavassiliou G. Novel Synthesis of Ultra-Small Dextran Coated Maghemite Nanoparticles for MRI and CT Contrast Agents via a Low Temperature Co-Precipitation Reaction. J Nanosci Nanotechnol 2015; 15:205-210. [PMID: 26328331 DOI: 10.1166/jnn.2015.8996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ultra-small dextran coated maghemite nanoparticles are synthesized via a low temperature modified co-precipitation method. A monoethylene glycol/water solution of 1:1 molar ratios and a fixed apparatus is used at a constant temperature of 5-10 degrees C. The growth of nanoparticles is prohibited due to low temperature synthesis and differs from usual thermal decomposition methods via Ostwald ripening. Strict temperature control and reaction timing of less than 20 minutes are essential to maintain narrow distribution in particle size. These nanoparticles are water-dispersible and biocompatible by capping with polyethylene glycol ligands. The aqueous suspensions are tested for cytotoxic activity on normal human skin fibroblasts. There is no reduction of the cells' viability at any concentration tested, the highest being 1% v/v of the suspension in culture medium, corresponding to the highest concentrations to be administered in vivo. Initial comparison with a T1 MRI contrast agent in sale shows that maghemite nanoparticles exhibit high r1 and r2 relaxivities in MRI tomography and strong contrast in computed tomography, demonstrating that these nanoparticles can be efficient T1, T2 and CT contrast agents.
Collapse
|
15
|
Fardis M, Douvalis AP, Tsitrouli D, Rabias I, Stamopoulos D, Kehagias T, Karakosta E, Diamantopoulos G, Bakas T, Papavassiliou G. Structural, static and dynamic magnetic properties of dextran coated γ-Fe(2)O(3) nanoparticles studied by (57)Fe NMR, Mössbauer, TEM and magnetization measurements. J Phys Condens Matter 2012; 24:156001. [PMID: 22418594 DOI: 10.1088/0953-8984/24/15/156001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The structural and magnetic properties and spin dynamics of dextran coated and uncoated γ-Fe(2)O(3) (maghemite) nanoparticles have been investigated using high resolution transmission electron microscopy (HRTEM), (57)Fe nuclear magnetic resonance (NMR), Mössbauer spectroscopy and dc magnetization measurements. The HRTEM observations indicated a well-crystallized system of ellipsoid-shaped nanoparticles, with an average size of 10 nm. The combined Mössbauer and magnetic study suggested the existence of significant interparticle interactions not only in the uncoated but also in the dextran coated nanoparticle assemblies. The zero-field NMR spectra of the nanoparticles at low temperatures are very similar to those of the bulk material, indicating the same hyperfine field values at saturation in accord with the performed Mössbauer measurements. The T(2) NMR spin-spin relaxation time of the nanoparticles has also been measured as a function of temperature and found to be two orders of magnitude shorter than that of the bulk material. It is shown that the thermal fluctuations in the longitudinal magnetization of the nanoparticles in the low temperature limit may account for the shortening and the temperature dependence of the T(2) relaxation time. Thus, the low temperature NMR results are in accord with the mechanism of collective magnetic excitations, due to the precession of the magnetization around the easy direction of the magnetization at an energy minimum, a mechanism originally proposed to interpret Mössbauer experiments in magnetic nanoparticles. The effect of the surface spins on the NMR relaxation mechanisms is also discussed.
Collapse
Affiliation(s)
- M Fardis
- Institute of Materials Science, National Centre for Scientific Research Demokritos, 153 10 Athens, Greece.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Papavassiliou G, Argyriou D, Panopoulos N, Koumoulis D, Boukos N, Fardis M, Pissas M, Kim HJ, Kim JG. MHz Broadline NMR and HRTEM in the Study of Novel Strongly Correlated Electron Materials. J Anal Sci Technol 2011. [DOI: 10.5355/jast.2011.a31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
17
|
Vasiliadou IA, Papoulis D, Chrysikopoulos CV, Panagiotaras D, Karakosta E, Fardis M, Papavassiliou G. Attachment of Pseudomonas putida onto differently structured kaolinite minerals: A combined ATR-FTIR and 1H NMR study. Colloids Surf B Biointerfaces 2011; 84:354-9. [DOI: 10.1016/j.colsurfb.2011.01.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Revised: 01/15/2011] [Accepted: 01/20/2011] [Indexed: 10/18/2022]
|
18
|
Sideratou Z, Tsiourvas D, Theodossiou T, Fardis M, Paleos CM. Synthesis and characterization of multifunctional hyperbranched polyesters as prospective contrast agents for targeted MRI. Bioorg Med Chem Lett 2010; 20:4177-81. [DOI: 10.1016/j.bmcl.2010.05.055] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 05/13/2010] [Accepted: 05/13/2010] [Indexed: 10/19/2022]
|
19
|
Rabias I, Tsitrouli D, Karakosta E, Kehagias T, Diamantopoulos G, Fardis M, Stamopoulos D, Maris TG, Falaras P, Zouridakis N, Diamantis N, Panayotou G, Verganelakis DA, Drossopoulou GI, Tsilibari EC, Papavassiliou G. Rapid magnetic heating treatment by highly charged maghemite nanoparticles on Wistar rats exocranial glioma tumors at microliter volume. Biomicrofluidics 2010; 4:024111. [PMID: 20697578 PMCID: PMC2917883 DOI: 10.1063/1.3449089] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 05/18/2010] [Indexed: 05/29/2023]
Abstract
One of the most significant challenges implementing colloidal magnetic nanoparticles in medicine is the efficient heating of microliter quantities by applying a low frequency alternating magnetic field. The ultimate goal is to accomplish nonsurgically the treatment of millimeter size tumors. Here, we demonstrate the synthesis, characterization, and the in vitro as well as in vivo efficiency of a dextran coated maghemite (gamma-Fe(2)O(3)) ferrofluid with an exceptional response to magnetic heating. The difference to previous synthetic attempts is the high charge of the dextran coating, which according to our study maintains the colloidal stability and good dispersion of the ferrofluid during the magnetic heating stage. Specifically, in vitro 2 mul of the ferrofluid gives an outstanding temperature rise of 33 degrees C within 10 min, while in vivo treatment, by infusing 150 mul of the ferrofluid in animal model (rat) glioma tumors, causes an impressive cancer tissue dissolution.
Collapse
|
20
|
Koumoulis D, Panopoulos N, Reyes A, Fardis M, Pissas M, Douvalis A, Bakas T, Argyriou DN, Papavassiliou G. Direct NMR evidence of phase solitons in the spin ground state of overdoped manganites. Phys Rev Lett 2010; 104:077204. [PMID: 20366913 DOI: 10.1103/physrevlett.104.077204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Indexed: 05/29/2023]
Abstract
Charge ordering phenomena in overdoped La1-xCaxMnO3 (LCMO) manganites with x>or=0.5 are generally believed to be associated with the formation of charge stripes composed of alternating Mn3+ and Mn4+ charges. However, a number of recent experiments indicate that instead of stripes the charge in these systems is spatially organized in a uniform charge density wave. At the same time theory predicts that the ground state is modulated by an incommensurate (IC) orbital and charge soliton lattice. Here, by using nuclear magnetic resonance we provide the first direct evidence that the spin ground state in overdoped LCMO manganites is IC modulated with phase solitons. At higher temperatures the solitonic superstructure is replaced by a uniform spin-density wave, subjected to coherent slow fluctuations, showing a striking similarity with slow fluctuations in the striped phase of high T{c} cuprates and nickelates.
Collapse
Affiliation(s)
- D Koumoulis
- Institute of Materials Science, NCSR, Demokritos, 153 10 Aghia Paraskevi, Athens, Greece
| | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Maffeo D, Lampropoulou M, Fardis M, Lazarou YG, Mavridis IM, Mavridou DAI, Urso E, Pratsinis H, Kletsas D, Yannakopoulou K. Novel polycarboxylated EDTA-type cyclodextrins as ligands for lanthanide binding: study of their luminescence, relaxivity properties of Gd(iii) complexes, and PM3 theoretical calculations. Org Biomol Chem 2010; 8:1910-21. [DOI: 10.1039/b924980j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
22
|
Karakosta E, Diamantopoulos G, Katsiotis MS, Fardis M, Papavassiliou G, Pipilikaki P, Protopapas M, Panagiotaras D. In Situ Monitoring of Cement Gel Growth Dynamics. Use of a Miniaturized Permanent Halbach Magnet for Precise 1H NMR Studies. Ind Eng Chem Res 2009. [DOI: 10.1021/ie901255b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Eleni Karakosta
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - George Diamantopoulos
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Marios S. Katsiotis
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Michael Fardis
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Georgios Papavassiliou
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Panagiota Pipilikaki
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Maria Protopapas
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| | - Dionysios Panagiotaras
- Institute of Materials Science, NCSR Demokritos, 153 10 Aghia Paraskevi, Attiki, Greece, RD & Q Department, TITAN S.A., P.O. Box 18-19200, Elefsina, Greece, ENDITECH S.A., Technological Park Lefkippos, 153 10 Aghia Paraskevi, Attiki, Greece, and Department of Mechanical Engineering, Technological Educational Institute of Patras, 26334, Patras, Greece
| |
Collapse
|
23
|
Fardis M, Diamantopoulos G, Karakosta E, Rabias I, Papavassiliou G, Miller JS. Spin dynamics in the molecule-based ferromagnet decamethylferrocenium tetracyanoethanide [][TCNE], as probed by 1H NMR relaxation. Polyhedron 2009. [DOI: 10.1016/j.poly.2009.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
24
|
Papaefthymiou GC, Rabias I, Fardis M, Devlin E, Boukos N, Tsitrouli D, Papavassiliou G. Gummic acid stabilized γ-Fe2O3 aqueous suspensions for biomedical applications. ACTA ACUST UNITED AC 2009. [DOI: 10.1007/s10751-009-9922-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
25
|
Efthimiadou EK, Katsarou ME, Fardis M, Zikos C, Pitsinos EN, Kazantzis A, Leondiadis L, Sagnou M, Vourloumis D. Synthesis and characterization of novel natural product-Gd(III) MRI contrast agent conjugates. Bioorg Med Chem Lett 2008; 18:6058-61. [DOI: 10.1016/j.bmcl.2008.10.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 10/07/2008] [Accepted: 10/07/2008] [Indexed: 01/16/2023]
|
26
|
Rabias I, Fardis M, Devlin E, Boukos N, Tsitrouli D, Papavassiliou G. No aging phenomena in ferrofluids: the influence of coating on interparticle interactions of maghemite nanoparticles. ACS Nano 2008; 2:977-983. [PMID: 19206495 DOI: 10.1021/nn700414w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The influence of coating on interparticle interactions in ferrofluids has been investigated using various techniques such as Mossbauer spectroscopy, magnetometry, transmission electron microscopy, photon correlation spectroscopy, X-ray diffraction, X-ray photoelectron, and resonance micro-Raman spectroscopy. Aging and spin-glass-like behavior was investigated in frozen ferrofluids of various concentrations from dense, initial value of 40 mg of coated nanoparticles per 1 mL of water, to dilute 1:10 (4 mg/mL). The as-prepared nanoparticles, core size 7-8 nm, were subsequently coated with a gummic acid corona of 20 nm thickness, which was observed to prevent agglomeration and to delay aggregation even in dense ferrofluids. The resulting separation of magnetic cores due to the coating eliminated all magnetic interparticle interaction mechanisms, such as exchange and dipoledipole, thus ensuring no aging effects of the magnetic particle system, as manifested in particle agglomeration and precipitation.
Collapse
Affiliation(s)
- Ioannis Rabias
- Institute of Materials Science, NCSR Demokritos, 15310 Aghia Paraskeui, Athens, Greece.
| | | | | | | | | | | |
Collapse
|
27
|
Rabias I, Pratsinis H, Drossopoulou G, Fardis M, Maris T, Boukos N, Tsotakos N, Kletsas D, Tsilibary E, Papavassiliou G. In vitro studies on ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid for T2 MRI contrast agent. Biomicrofluidics 2007; 1:44104. [PMID: 19693403 PMCID: PMC2717733 DOI: 10.1063/1.2821757] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Accepted: 11/14/2007] [Indexed: 05/28/2023]
Abstract
Ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid have been investigated as possible constituents of aqueous ferrofluids for biomedical applications and especially for MRI contrast agent. The structural characteristics and the size of the nanoparticles have been analyzed as well as the magnetic properties. In order to evaluate any possible capabilities as a contrast agent, the relaxation time, T2, of hydrogen protons in the colloidal solutions of nanoparticles have been measured in order to gain information on the relaxation behavior compared to other MRI contrast agents. The in vitro cytotoxicity of the obtained magnetic nanoparticles of iron oxide coated with gummic acid was investigated by two separate methods (MTT and FACS analysis) and by using three different normal and transformed cell lines. Our results showed that the synthesized nanoparticles had no toxic effect on any of the cell lines used.
Collapse
Affiliation(s)
- I Rabias
- Institute of Materials Science, National Centre for Scientific Research 'Demokritos', 153 10 Aghia Paraskevi, Athens, Greece
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Raptopoulou CP, Boudalis AK, Sanakis Y, Psycharis V, Clemente-Juan JM, Fardis M, Diamantopoulos G, Papavassiliou G. Hexanuclear iron(III) salicylaldoximato complexes presenting the [Fe6(mu3-O)2(mu2-OR)2]12+ core: syntheses, crystal structures, and spectroscopic and magnetic characterization. Inorg Chem 2007; 45:2317-26. [PMID: 16499398 DOI: 10.1021/ic051945q] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The use of salicylaldehyde oxime (H2salox) in iron(III) carboxylate chemistry has yielded two new hexanuclear compounds [Fe6(mu3-O)2(O2CPh)10(salox)2(L)2].xMeCN.yH2O [L = MeCONH2, x = 6, y = 0 (1); L = H2O, x = 2, y = 3 (2)]. Compound 1 crystallizes in the triclinic space group P with (at 25 degrees C) a = 13.210(8) A, b = 13.87(1) A, c = 17.04(1) A, alpha = 105.79(2) degrees , beta = 96.72(2) degrees , gamma = 116.69(2) degrees , V = 2578.17(2) A(3), and Z = 1. Compound 2 crystallizes in the monoclinic space group C2/c with (at 25 degrees C) a = 21.81(1) A, b = 17.93(1) A, c = 27.72(1) A, beta = 111.70(2) degrees , V = 10070(10) A(3), and Z = 4. Complexes 1 and 2 contain the [Fe6(mu3-O)2(mu2-OR)2]12+ core and can be considered as two [Fe3(mu3-O)] triangular subunits linked by two mu2-oximato O atoms of the salox2- ligands, which show the less common mu3:eta1:eta2:eta1 coordination mode. The benzoato ligands are coordinated through the usual syn,syn-mu2:eta1:eta1 mode. The terminal MeCONH2 ligand in 1 is the hydrolysis product of the acetonitrile solvent in the presence of the metal ions. Mössbauer spectra from powdered samples of 2 give rise to two well-resolved doublets with an average isomer shift consistent with that of high-spin Fe(III) ions. The two doublets, at an approximate 1:2 ratio, are characterized by different quadrupole splittings and are assigned to the nonequivalent Fe(III) ions of the cluster. Magnetic measurements of 2 in the 2-300 K temperature range reveal antiferromagnetic interactions between the Fe(III) ions, stabilizing an S = 0 ground state. NMR relaxation data have been used to investigate the energy separation between the low-lying states, and the results are in agreement with the susceptibility data.
Collapse
|
29
|
Psycharis V, Raptopoulou CP, Boudalis AK, Sanakis Y, Fardis M, Diamantopoulos G, Papavassiliou G. Syntheses, Structural, and Physical Studies of Basic CrIII and FeIII Benzilates and Benzoates: Evidence of Antisymmetric Exchange and Distributions of Isotropic and Antisymmetric Exchange Parameters. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600306] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
30
|
Papavassiliou G, Pissas M, Diamantopoulos G, Belesi M, Fardis M, Stamopoulos D, Kontos AG, Hennion M, Dolinsek J, Ansermet JP, Dimitropoulos C. Low temperature charge and orbital textures in La0.875Sr0.125MnO3. Phys Rev Lett 2006; 96:097201. [PMID: 16606306 DOI: 10.1103/physrevlett.96.097201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Indexed: 05/08/2023]
Abstract
By using nuclear magnetic resonance techniques we show that for T<30 K the La0.875Sr0.125MnO3 compound displays a nonuniform charge distribution, comprised of two interconnected Mn ion subsystems with different spin, orbital, and charge couplings. The NMR results agree very well with the two spin wave stiffness constants observed at small q values in the spin wave dispersion curves [Phys. Rev. B 67, 214430 (2003)]. This picture is probably related to a yet undetermined charge and orbital superstructure occurring in the ferromagnetic insulating state of the La0.875Sr0.125MnO3 compound.
Collapse
Affiliation(s)
- G Papavassiliou
- Institute of Materials Science, NCSR, Demokritos, 153 10 Aghia Paraskevi, Athens, Greece
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Kontos AG, Fardis M, Prodromidis MI, Stergiopoulos T, Chatzivasiloglou E, Papavassiliou G, Falaras P. Morphology, ionic diffusion and applicability of novel polymer gel electrolytes with LiI/I2. Phys Chem Chem Phys 2006; 8:767-76. [PMID: 16482318 DOI: 10.1039/b515113a] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel polymer gel electrolytes have been prepared by incorporating LiI-I(2) solutions into a polyethylene oxide matrix supported by a TiO(2) filler. The gel electrolytes, based on either acetonitrile or propylene carbonate solvents are compared with liquid standard ones and are examined by (7)Li solid state nuclear magnetic resonance relaxometry and diffusion measurements. In parallel, the triiodide apparent diffusion coefficient has been determined by linear sweep voltammetry. The results are correlated with atomic force microscopic images of the electrolytes and give insight of the dynamic properties of the ions in the constrained polymer medium. Furthermore, the dissociation of the ions is estimated by relating the ionic conductivity to the ionic diffusion. As a prime application, the polymer gel electrolytes were incorporated in dye sensitized solar cells and the measured energy conversion efficiencies were successfully correlated with their morphological, diffusive and conducting properties.
Collapse
Affiliation(s)
- A G Kontos
- Institute of Physical Chemistry, NCSR Demokritos, Aghia Paraskevi, 15310 Athens, Greece
| | | | | | | | | | | | | |
Collapse
|
32
|
Vlachos A, Psycharis V, Raptopoulou CP, Lalioti N, Sanakis Y, Diamantopoulos G, Fardis M, Karayanni M, Papavassiliou G, Terzis A. A nearly symmetric trinuclear chromium(III) oxo carboxylate assembly: preparation, molecular and crystal structure, and magnetic properties of [Cr3O(O2CPh)6(MeOH)3](NO3)·2MeOH. Inorganica Chim Acta 2004. [DOI: 10.1016/j.ica.2004.04.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
33
|
Papavassiliou G, Pissas M, Belesi M, Fardis M, Dolinsek J, Dimitropoulos C, Ansermet JP. Orbital domain state and finite size scaling in ferromagnetic insulating manganites. Phys Rev Lett 2003; 91:147205. [PMID: 14611553 DOI: 10.1103/physrevlett.91.147205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2002] [Indexed: 05/24/2023]
Abstract
55Mn and 139La NMR measurements on a high quality single crystal of ferromagnetic (FM) La0.80Ca0.20MnO3 demonstrate the formation of localized Mn(3+,4+) states below 70 K, accompanied by a strong cooling-rate dependent increase of certain FM neutron Bragg peaks. (55,139)(1/T(1)) spin-lattice and (139)(1/T(2)) spin-spin relaxation rates are strongly enhanced on approaching this temperature from below, signaling a genuine phase transition at T(tr) approximately 70 K. The disappearance of the FM metallic signal by applying a weak external magnetic field, the different NMR radio-frequency enhancement of the FM metallic and insulating states, and the observed finite size scaling of T(tr) with Ca (hole) doping, as observed in powder La(1-x)CaxMnO3 samples, are suggestive of freezing into an inhomogeneous FM insulating and orbitally ordered state embodying "metallic" hole-rich walls.
Collapse
Affiliation(s)
- G Papavassiliou
- Institute of Materials Science, NCSR, Demokritos, 153 10 Aghia Paraskevi, Athens, Greece
| | | | | | | | | | | | | |
Collapse
|
34
|
Revill WP, Voda J, Reeves CR, Chung L, Schirmer A, Ashley G, Carney JR, Fardis M, Carreras CW, Zhou Y, Feng L, Tucker E, Robinson D, Gold BG. Genetically engineered analogs of ascomycin for nerve regeneration. J Pharmacol Exp Ther 2002; 302:1278-85. [PMID: 12183690 DOI: 10.1124/jpet.102.034264] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The polyketides FK506 (tacrolimus) and FK520 (ascomycin) are potent immunosuppressants that function by inhibiting calcineurin phosphatase through formation of an FKBP12-FK506/520-calcineurin ternary complex. They also have calcineurin-independent neuroregenerative properties in cell culture and animal models of nervous system disorders. Based on the crystal structure of the FKBP12-FK506-calcineurin complex, we deduced that the 13- and 15-methoxy groups of FK506 or FK520 are important for inhibition of calcineurin phosphatase but not for binding to FKBP12. By genetic modification of the FK520 gene cluster, we generated 13- and 15-desmethoxy analogs of FK520 that contain hydrogen, methyl, or ethyl instead of methoxy at one or both of these positions. These analogs bind FKBP12 tightly, have decreased calcineurin phosphatase inhibition and immunosuppressive properties, and enhance neurite outgrowth in cell cultures. A representative compound was also shown to accelerate nerve regeneration and functional recovery in the rat sciatic nerve crush model.
Collapse
Affiliation(s)
- W P Revill
- Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, CA 94545, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Papavassiliou G, Belesi M, Fardis M, Dimitropoulos C. (139)La NMR investigation of quasistatic orbital ordering in La(1-x)Ca(x)MnO(3). Phys Rev Lett 2001; 87:177204. [PMID: 11690307 DOI: 10.1103/physrevlett.87.177204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2001] [Indexed: 05/23/2023]
Abstract
We report (139)La nuclear magnetic resonance in ferromagnetic and insulating (FMI) La(1-x)Ca(x)MnO(3), 0.10< or =x< or =0.20, which at low temperatures shows the formation of Mn octants with enhanced Mn-O wave function overlapping and electron-spin alignment. The rapid increase of the relaxation rates and the "wipeout" of the (139)La NMR signal intensity on heating, imply a quasistatic character for the Mn octant cells in the FMI phase, which freeze below a transition temperature T(f).
Collapse
Affiliation(s)
- G Papavassiliou
- Institute of Materials Science, National Center for Scientific Research Demokritos, 153 10 Athens, Greece
| | | | | | | |
Collapse
|
36
|
Fardis M, Ashley GW, Carney JR, Chu DT. Synthesis of 14,15-dehydroerythromycin A ketolides: effects of the 13-substituent on erythromycin tautomerism. J Antibiot (Tokyo) 2001; 54:278-84. [PMID: 11372784 DOI: 10.7164/antibiotics.54.278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A ketolide was prepared from 14,15-dehydroerythromycin A by two different routes. The first approach involving oxidation of the 3-OH of 3-descladinosyl-14,15-dehydroerythromycin A 2'-O-acetate gave unexpectedly high levels of 3,11-double oxidation. This may be due to greater formation of the 9,12-hemiketal in 14,15-dehydroerythromycin A and concomitant exposure of the 11-OH group for oxidation. NMR studies of 14,15-dehydroerythromycin A support this hypothesis, revealing a 9:1 ratio of 9-ketone to 9,12-hemiketal in CDCl3 and a 1:1 ratio in CD3OD as contrasted with the corresponding tautomer ratios of 30:1 in CDCl3, and 6: 1 in CD3OD with erythromycin A. Alteration of the 13-substituent on the erythronolide A ring from ethyl to vinyl thus favors formation of the 9,12-hemiketal. A second route to the ketolides was developed based on these findings, in which the 11-OH is eliminated prior to oxidation of the 3-OH.
Collapse
Affiliation(s)
- M Fardis
- Department of Chemistry, Kosan Biosciences, Inc, Hayward, CA 94545, USA
| | | | | | | |
Collapse
|
37
|
Leventis A, Papavassiliou G, Fardis M, Milia F, Chaniotakis E, Dolinsek J, Apih T. 1H NMR study of the local magnetic field gradients in evoluting porous structures. An application to cement gels. J Chem Phys 2000. [DOI: 10.1063/1.1311973] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
38
|
Papavassiliou G, Fardis M, Belesi M, Maris TG, Kallias G, Pissas M, Niarchos D, Dimitropoulos C, Dolinsek J. 55Mn NMR investigation of electronic phase separation in La1-xCaxMnO3 for 0.2 < or = x < or = 0.5. Phys Rev Lett 2000; 84:761-764. [PMID: 11017366 DOI: 10.1103/physrevlett.84.761] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/1999] [Indexed: 05/23/2023]
Abstract
55Mn NMR line shape measurements in La1-xCaxMnO3 for 0.20< or =x< or =0.50 provide experimental evidence about the existence of two distinct regions in the T-x magnetic phase diagram, where the homogeneous ferromagnetic (FM) metallic state is separated into FM metallic and FM insulating regions. These results are in agreement with recent theoretical predictions, which reveal a novel electronic phase separation in two FM states, providing orbital ordering and Jahn-Teller phonons are taken into consideration.
Collapse
Affiliation(s)
- G Papavassiliou
- Institute of Materials Science, National Center for Scientific Research "Demokritos," 153 10 Athens, Greece
| | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
Nuclear magnetic resonance (NMR) was used to determine the pore size distribution of hardened Portland cement pastes. The method is based on the well-known freezing point depression of water when confined inside the pore matrix of a material. It is demonstrated how this technique can be applied in cementitious materials to probe the microstructure of the main hydration product: the cement gel.
Collapse
Affiliation(s)
- F Milia
- Institute of Materials Science, National Centre for Scientific Research, Demokritos, Athens, Greece.
| | | | | | | |
Collapse
|
40
|
Abstract
Different synthetic strategies are required for the two kinds of libraries being developed for combinatoral chemistry. Preparation of a 'focused' library involves conversion of a known synthetic route to the solid-phase or automated format, whereas generation of a 'prospecting' library is driven more by availability of input materials and considerations of structural novelty. While both types can be identified over the history of combinatorial chemistry, elaborating syntheses of novel, nonoligomeric, 'drug-like' molecules for use in prospecting libraries is a relatively recent development.
Collapse
Affiliation(s)
- M R Spaller
- Department of Chemistry, University of California, Berkeley, California, 94720-1460, USA
| | | | | | | |
Collapse
|
41
|
Fardis M, Papavassiliou G, Abulnasr L, Miljkovic L, Rumm R, Milia F, Chaniotakis E, Frangoulis D. Effect of clay minerals on the hydration of cement An NMR study. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/1065-7355(94)90032-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
42
|
Cowan B, Fardis M. Direct measurement of spin diffusion from spin relaxation times in solid 3He. Phys Rev B Condens Matter 1991; 44:4304-4313. [PMID: 10000079 DOI: 10.1103/physrevb.44.4304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
|
43
|
|