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Lopes PM, Fechete R, Minteuan F, Mare L, Moldovan D, Moldovan M, Cuc S, Saroși CL, Popescu V. The Influence of Lyophilization Pretreatment and Whey Content on Whey and Gelatin-Based Hydrogels. Gels 2024; 10:229. [PMID: 38667648 PMCID: PMC11048941 DOI: 10.3390/gels10040229] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/12/2024] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
Whey and gelatin, natural polymers within the protein category, find widespread use in hydrogel formulations applied across the food, medical, and pharmaceutical industries. This study presents new characteristics of hydrogels based on whey, gelatin, and copper sulfate as a consequence of the additional steps in the preparation method, specifically refrigeration and freezing storage followed by lyophilization. The water state in hydrogels prior to lyophilization impacts the morphological appearance, with refrigerated hydrogels exhibiting a more regular and dense pore distribution, as shown by the Scanning Electron Microscopy (SEM) images. This observation aligns with the higher mobility of polymer chains indicated by T2 distributions in 1H nuclear magnetic resonance (RMN) relaxometry measurements. Changes in the intensity and amide-specific wavenumbers of the FTIR spectra of whey and gelatin proteins are evident in the Fourier Transformed Infrared (FTIR) spectra of crosslinked and frozen hydrogels before lyophilization. Moreover, the reinforcing effect in the hydrogel matrix, noted in mechanical tests, is attributed to increased polymer chain content and copper sulfate crosslinking.
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Affiliation(s)
- Pompilia Mioara Lopes
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
- “SAMUS” Special Vocational School, 17 Ialomiței Street, 400574 Cluj-Napoca, Romania
| | - Radu Fechete
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
| | - Felicia Minteuan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
| | - Liviu Mare
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
| | - Dumitrița Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
| | - Marioara Moldovan
- Polymeric Composite Laboratory, Institute of Chemistry “Raluca Ripan”, Babeș-Bolyai University, 30 Fântânele Street, 400294 Cluj-Napoca, Romania; (M.M.); (S.C.); (C.L.S.)
| | - Stanca Cuc
- Polymeric Composite Laboratory, Institute of Chemistry “Raluca Ripan”, Babeș-Bolyai University, 30 Fântânele Street, 400294 Cluj-Napoca, Romania; (M.M.); (S.C.); (C.L.S.)
| | - Codruța Liana Saroși
- Polymeric Composite Laboratory, Institute of Chemistry “Raluca Ripan”, Babeș-Bolyai University, 30 Fântânele Street, 400294 Cluj-Napoca, Romania; (M.M.); (S.C.); (C.L.S.)
| | - Violeta Popescu
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, 400114 Cluj-Napoca, Romania; (P.M.L.); (R.F.); (F.M.); (L.M.); (D.M.)
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Purcea Lopes PM, Moldovan D, Fechete R, Mare L, Barbu-Tudoran L, Sechel N, Popescu V. Characterization of a Graphene Oxide-Reinforced Whey Hydrogel as an Eco-Friendly Absorbent for Food Packaging. Gels 2023; 9:gels9040298. [PMID: 37102911 PMCID: PMC10138084 DOI: 10.3390/gels9040298] [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: 02/24/2023] [Revised: 03/21/2023] [Accepted: 03/28/2023] [Indexed: 04/05/2023] Open
Abstract
This study presents a structural analysis of a whey and gelatin-based hydrogel reinforced with graphene oxide (GO) by ultraviolet and visible (UV-VIS) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The results revealed barrier properties in the UV range for the reference sample (containing no graphene oxide) and the samples with minimal GO content of 0.66×10−3% and 3.33×10−3%, respectively, in the UV-VIS and near-IR range; for the samples with higher GO content, this was 6.67×10−3% and 33.33×10−3% as an effect of the introduction of GO into the hydrogel composite. The changes in the position of diffraction angles 2θ from the X-ray diffraction patterns of GO-reinforced hydrogels indicated a decrease in the distances between the turns of the protein helix structure due to the GO cross-linking effect. Transmission electron spectroscopy (TEM) was used for GO, whilst scanning electron microscopy (SEM) was used for the composite characterization. A novel technique for investigating the swelling rate was presented by performing electrical conductivity measurements, the results of which led to the identification of a potential hydrogel with sensor properties.
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Affiliation(s)
- Pompilia Mioara Purcea Lopes
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Dumitrita Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Radu Fechete
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Liviu Mare
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Lucian Barbu-Tudoran
- Electron Microscopy Center, Faculty of Biology and Geology, Babes-Bolyai University of Cluj-Napoca, 1 M. Kogalniceanu Street, 400347 Cluj-Napoca, Romania
| | - Niculina Sechel
- Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105 Muncii Avenue, 400641 Cluj-Napoca, Romania
| | - Violeta Popescu
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
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Lopes PMP, Moldovan D, Fechete R, Prodan D, Pop CR, Rotar AM, Popescu V. Swelling and Antimicrobial Activity Characterization of a GO-Reinforced Gelatin-Whey Hydrogel. Gels 2022; 9:gels9010018. [PMID: 36661786 PMCID: PMC9857670 DOI: 10.3390/gels9010018] [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] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/21/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022] Open
Abstract
Whey-based hydrogel samples with increasing concentrations of graphene oxide (GO) were studied, against a control sample (M), for swelling behavior in light of nuclear magnetic resonance (NMR) and mathematical models of the diffusion process and for antibacterial activity. Graphene oxide (GO) is an optimal filler for whey-based hydrogels, giving them improved mechanical and swelling properties at low concentrations. Crosslinking induces a certain stiffness of the hydrogels, which is why only the first part of the swelling process (<60%) follows the first-order model, while during the whole time interval, the swelling process follows the second-order diffusion model. The NMR relaxometry results are consistent with the swelling behavior of GO-reinforced whey−gelatin composite hydrogels, showing that higher GO concentrations induce a higher degree of cross-linking and, therefore, lower swelling capacity. Only hydrogel samples with higher GO concentrations demonstrated antibacterial activity.
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Affiliation(s)
- Pompilia Mioara Purcea Lopes
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
- Correspondence: (P.M.P.L.); (V.P.)
| | - Dumitriţa Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Radu Fechete
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
| | - Doina Prodan
- Composite Materials Department, Chemistry Research Institute “Raluca Ripan”, “Babes-Bolyai” University, 30 Fantanele Str., 400294 Cluj-Napoca, Romania
| | - Carmen Rodica Pop
- Department of Food Science, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 64 Calea Floresti Str., 400509 Cluj-Napoca, Romania
| | - Ancuța M. Rotar
- Department of Food Science, Faculty of Food Science and Technology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 64 Calea Floresti Str., 400509 Cluj-Napoca, Romania
| | - Violeta Popescu
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania
- Correspondence: (P.M.P.L.); (V.P.)
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Orban E, Pap Z, Micu AM, Sipos RS, Fechete R. Callus formation in albino Wistar rats after femur fracture assessed by visible spectroscopy. Biochem Biophys Res Commun 2022; 634:168-174. [DOI: 10.1016/j.bbrc.2022.09.114] [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] [Received: 09/20/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 11/02/2022]
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Chelcea RI, Daniș D, Fechete R. Structural and Kinetic Characterization of Unexpired and Expired Drugs by Proton Nuclear Magnetic Resonance ( 1H NMR) Relaxometry and Fourier Transform Infrared (FT-IR) Spectroscopy. ANAL LETT 2022. [DOI: 10.1080/00032719.2022.2080838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Ramona Ioana Chelcea
- Faculty of Material and Environmental Engineering, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | - Diana Daniș
- Faculty of Material and Environmental Engineering, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | - Radu Fechete
- Faculty of Material and Environmental Engineering, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
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Drăgan LR, Andras D, Fechete R. Fourier Transform Infrared (FT-IR) Spectroscopy and Proton Nuclear Magnetic Resonance ( 1H NMR) Relaxometry and Diffusometry for the Identification of Colorectal Cancer in Blood Plasma. ANAL LETT 2022. [DOI: 10.1080/00032719.2022.2065497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- Lavinia Raluca Drăgan
- Faculty of Physics, Doctoral School, Babeş-Bolyai University, Cluj-Napoca, Romania
- Surgical Department, County Emergency Hospital, Cluj-Napoca, Romania
| | - David Andras
- Surgical Department, County Emergency Hospital, Cluj-Napoca, Romania
- Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Radu Fechete
- Faculty of Physics, Doctoral School, Babeş-Bolyai University, Cluj-Napoca, Romania
- Faculty of Material and Environmental Engineering, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
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Purcea Lopes PM, Moldovan D, Moldovan M, Carpa R, Saroşi C, Păşcuţă P, Mazilu Moldovan A, Fechete R, Popescu V. New Composite Hydrogel Based on Whey and Gelatin Crosslinked with Copper Sulphate. Materials (Basel) 2022; 15:ma15072611. [PMID: 35407945 PMCID: PMC9000359 DOI: 10.3390/ma15072611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/26/2022] [Accepted: 03/28/2022] [Indexed: 01/15/2023]
Abstract
By-products from the meat and dairy industries are important sources of high biological value proteins. This paper explores possibilities for improving the swelling and integrity of a cross-linked whey and gelatin hydrogel with different amounts of CuSO4 × 5H2O. Overall, swelling tests demonstrate that cross-linked samples show a better hydration capacity and stability in the hydration medium, but different copper concentrations lead to different swelling behavior. At concentrations smaller than 0.39%, the sample lasts for 75 h in a water environment before beginning to disintegrate. At a concentration of copper sulphate higher than 0.55%, the stability of the sample increased substantially. The swelling kinetics has been investigated. The diffusion constant values increased with the increase in copper concentration, but, at the highest concentration of copper (0.86%), its value has decreased. Spectroscopy analyses such as Fourier transform infrared (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-VIS), and nuclear magnetic resonance (NMR) relaxometry analyses revealed changes in the secondary and tertiary structure of proteins as a result of the interaction of Cu2+ ions with functional groups of protein chains. In addition to its cross-linking ability, CuSO4 × 5H2O has also shown excellent antibacterial properties over common bacterial strains responsible for food spoilage. The result of this research demonstrates the potential of this hydrogel system as a unique material for food packaging.
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Affiliation(s)
- Pompilia Mioara Purcea Lopes
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
| | - Dumitriţa Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
| | - Marioara Moldovan
- Polymeric Composite Laboratory, Institute of Chemistry Raluca Ripan, Babeş-Bolyai University, 30 Fȃntȃnele Str., 400294 Cluj-Napoca, Romania; (M.M.); (C.S.)
| | - Rahela Carpa
- Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babeș Bolyai University, M. Kogălniceanu Street, 400084 Cluj-Napoca, Romania;
| | - Codruţa Saroşi
- Polymeric Composite Laboratory, Institute of Chemistry Raluca Ripan, Babeş-Bolyai University, 30 Fȃntȃnele Str., 400294 Cluj-Napoca, Romania; (M.M.); (C.S.)
| | - Petru Păşcuţă
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
| | - Amalia Mazilu Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
| | - Radu Fechete
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
| | - Violeta Popescu
- Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Str., 400114 Cluj-Napoca, Romania; (P.M.P.L.); (D.M.); (P.P.); (A.M.M.); (R.F.)
- Correspondence: ; Tel.: +40-74-317-41-95
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Hussmann L, Belthle T, Demco DE, Fechete R, Pich A. Stimuli-responsive microgels with cationic moieties: characterization and interaction with E. coli cells. Soft Matter 2021; 17:8678-8692. [PMID: 34518865 DOI: 10.1039/d1sm01007g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Stimuli-responsive microgel copolymer networks with ionizable functional groups have important applications for encapsulation of drugs, peptides, enzymes, proteins, or cells. Rational design of such networks can be based on characterization of stimuli-induced volume phase transition and spatial distribution of neutral and charged monomer units in crosslinked polymer chains. In this work we successfully synthesized poly(N-vinylcaprolactam-co-1-vinyl-3-methylimidazolium) (poly(VCL-VIM+)) microgels carrying permanent positive charges and demonstrate that 1H high-resolution NMR spectroscopy in combination with transverse (T2) magnetization relaxometry allows investigating separately the behavior of each functional group in the microgel network. The information about comonomer transition temperatures, width of transition, and change in transition entropy were reported and correlated with the concentration of charged functional groups and resulting electrophoretic mobility. A two-state approach was used to describe the temperature-induced volume phase transition separately for neutral and charged polymer segments. The core-corona architecture specific to each functional group was detected revealing that the charged methylated vinylimidazolium groups (VIM+) are concentrated mainly in the corona of the microgel. These biocompatible PVCL-based microgels functionalized with permanent positive charges are shown to serve as an antibacterial system against Gram-negative E. coli strains, due to the positive charge of the incorporated VIM+ comonomer in the polymer network.
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Affiliation(s)
- Larissa Hussmann
- DWI-Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
- Functional and Interactive Polymers, Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| | - Thomke Belthle
- DWI-Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
- Functional and Interactive Polymers, Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
| | - Dan E Demco
- DWI-Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
- Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca, Romania
| | - Radu Fechete
- Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca, Romania
| | - Andrij Pich
- DWI-Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
- Functional and Interactive Polymers, Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074 Aachen, Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
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Fechete R, Morar IA, Moldovan D, Chelcea RI, Crainic R, Nicoară SC. Fourier and Laplace-like low-field NMR spectroscopy: The perspectives of multivariate and artificial neural networks analyses. J Magn Reson 2021; 324:106915. [PMID: 33648679 DOI: 10.1016/j.jmr.2021.106915] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 12/20/2020] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Abstract
Low field Nuclear Magnetic Resonance (LF-NMR) is a rich source of information for a wide range of samples types. These can be hard or soft solids, such as plastics or elastomers; bulk liquids or liquids absorbed in porous materials, and can come from biomaterials, biological tissues, archaeological artifacts, cultural heritage objects. LF-NMR instruments present a significant advance especially for in situ, ex situ and in vivo measurement of relaxation and diffusion. Moreover, high resolution 1D and 2D spectroscopy, as well as magnetic resonance (MR) imaging are available in these fields. In this work we discuss the advanced analysis of the data measured in LF-NMR from the perspectives of tertiary level that implies the analysis on principal components (PCA), and on the quaternary analysis that uses an artificial neural network (ANN). The principles of PCA and ANN are largely discussed. For the PCA analysis, a series of 52 spectra were analyzed, having been recorded in vivo by LF-NMR. Of these spectra, 38 were generated from normal uterus, 7 by uterus tissue with endometrial cancer, and another 7 were obtained from tissues of women with uterine cervical cancer. The PC1 vs PC2 plot was further analyzed using an artificial neural network, and the results are presented as 2D maps of probability. Furthermore, the perspectives of applying an ANN to solve the problem of Laplace-like inversion are discussed. An example of such ANN was presented and the performance was discussed. Finally, a model of complex ANN, capable to sequentially solve this kind of problems specific to LF-NMR is proposed and discussed.
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Affiliation(s)
- Radu Fechete
- Technical University of Cluj-Napoca, 28 Memorandumului str. 400114, Cluj-Napoca, Romania; Babeş-Bolyai University, Faculty of Physics, Doctoral School, 1 Kogălniceanu str., 400084 Cluj-Napoca, Romania.
| | - Iris Adina Morar
- Babeş-Bolyai University, Faculty of Physics, Doctoral School, 1 Kogălniceanu str., 400084 Cluj-Napoca, Romania; IMOGEN, County Emergency Hospital, Cluj-Napoca, Romania
| | - Dumitrița Moldovan
- Technical University of Cluj-Napoca, 28 Memorandumului str. 400114, Cluj-Napoca, Romania
| | - Ramona Ioana Chelcea
- Technical University of Cluj-Napoca, 28 Memorandumului str. 400114, Cluj-Napoca, Romania
| | - Ramona Crainic
- Technical University of Cluj-Napoca, 28 Memorandumului str. 400114, Cluj-Napoca, Romania; Babeş-Bolyai University, Faculty of Physics, Doctoral School, 1 Kogălniceanu str., 400084 Cluj-Napoca, Romania
| | - Simona Cornelia Nicoară
- Technical University of Cluj-Napoca, 28 Memorandumului str. 400114, Cluj-Napoca, Romania; STEM Faculty, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
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Chiorean A, Pintican RM, Duma MM, Fechete R, Feier D, Szep M, Dudea S. Visualization of the shear wave on gray-scale ultrasound: experience with a complex breast cyst. Med Ultrason 2020; 22:492-494. [PMID: 32190862 DOI: 10.11152/mu-2264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Shear wave elastography (SWE) is the newer of the two methods of measuring tissue stiffness using ultrasound. We present the case of a 39-year-old patient with fibrocystic breast disease who presented with a left painful breast lump. The patient underwent a breast ultrasound that depicted a complicated cyst with a "pseudo-solid" content. When the SWE mode was turned on, the ultrasound share wave was observed on the gray-scale image, as surface undulations of the "pseudo-solid" component. To the best of our knowledge, this is the first report of the share wave visualization on a gray-scale image. The impact on patient management is discussed.
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Affiliation(s)
- Angelica Chiorean
- Department of Medical Imaging and Radiology, "Iuliu Hatieganu" University Of Medicine and Pharmacy, Cluj-Napoca, Romania Medimages Breast Center, 400458, Cluj-Napoca, Romania.
| | - Roxana Maria Pintican
- Department of Medical Imaging and Radiology, "Iuliu Hatieganu" University Of Medicine and Pharmacy, Cluj-Napoca, Romania.
| | | | - Radu Fechete
- Department of Physics, Technical University, Cluj-Napoca, Romania.
| | - Diana Feier
- Department of Radiology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania Medimages Breast Center, 400458, Cluj-Napoca, Romania.
| | - Madalina Szep
- Medimages Breast Center, 400458, Cluj-Napoca, Romania.
| | - Sorin Dudea
- Department of Radiology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania.
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Fischer T, Demco DE, Fechete R, Möller M, Singh S. Poly(vinylamine-co-N-isopropylacrylamide) linear polymer and hydrogels with tuned thermoresponsivity. Soft Matter 2020; 16:6549-6562. [PMID: 32617537 DOI: 10.1039/d0sm00408a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The fabrication of functional hydrogels with tuned thermoresponsivity is a major challenge. To meet this challenge we copolymerize N-isopropylacrylamide (NIPAm) with N-vinylformamide (NVF) in different ratios with the formamide group being subsequently selectively hydrolyzed to the corresponding amine (VAm). The copolymers are crosslinked with phenylcarbonate telechelic glycol. The influence of the NIPAm : VAm ratio on the thermoresponsitiviy is investigated in terms of absorbance, rheology, NMR spectroscopy, relaxometry, and diffusometry. Phase transition temperatures, change in the entropy of the polymer-water system, and width of the transition in the process of coil-to-globule and swollen-to-collapsed network transitions were evaluated by a two state model and Boltzmann sigmoidal function.
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Affiliation(s)
- Thorsten Fischer
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
| | - Dan E Demco
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany. and Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania
| | - Radu Fechete
- Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania
| | - Martin Möller
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
| | - Smriti Singh
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
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Bumbu AV, Perian M, Fechete R, Dan C, Radu I, Brinzaniuc K. The Role of Muscle Cells and Fat Cells in Nerve Regeneration Evaluated by in vivo Electric Conductivity. Rev Chim 2019. [DOI: 10.37358/rc.19.8.7463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peripheral nerve reconstruction is a much debated subject nowadays that is why new surgical techniques are being performed. It has been demonstrated that after a complete section of a peripheral nerve, the healing process takes time, and most frequently the recovery is not complete. Muscle cells and fat cells due to their chemical components, can contribute in the healing process of the peripheral nerves. The purpose of this study is to evaluate the effect of wrapping a muscle flap or an adipose flap around the primary suture of a cuted nerve in order to improve the motor nerve regeneration in a rat model by using in vivo electric conductivity measurements.
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13
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Tan KH, Demco DE, Fechete R, Pich A. Functional selenium modified microgels: temperature-induced phase transitions and network morphology. Soft Matter 2019; 15:3227-3240. [PMID: 30916678 DOI: 10.1039/c8sm02646g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Microgels that host selenium and mimic the structure of the enzyme glutathione peroxidase are of great interest for biotechnological and catalytic applications. For this purpose selenium-functionalized thermoresponsive poly(N-vinylcaprolactam) (PVCL) microgels with cleavable diselenide crosslinks have been investigated. Thermodynamic and morphological parameters characterizing the temperature-induced phase transitions of dual crosslinked PVCL microgels were obtained using dynamic light scattering (DLS), 1H high-resolution magic-angle sample-spinning (MAS) NMR spectroscopy, and transverse magnetization (T2) NMR relaxometry. Quantities obtained from Flory-Rehner theory, a two-state model and Boltzmann sigmoidal function were used to relate the phase transitions of the dual crosslinked microgels to the transition temperature, entropy, temperature width of the phase transition, Flory interaction parameters, average number of strands, polymer volume fraction of the collapsed microgels, core-corona fractions and chain dynamics. The morphology of the selenium modified microgels after the oxidation and reduction processes was investigated by 1H T2 NMR and further correlated with the crosslink density.
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Affiliation(s)
- Kok H Tan
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
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14
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Emma Dávid R, Fechete R, Sfrângeu S, Moldovan D, Chelcea RI, Morar IA, Stamatian F, Kovacs T, Popoi P. In Vivo 1H Nuclear Magnetic Resonance Spectroscopy and Relaxometry Maps of the Human Female Pelvis. ANAL LETT 2019. [DOI: 10.1080/00032719.2018.1437169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Réka Emma Dávid
- County Emergency Hospital Radiology Department, University of Medicine and Pharmacy “Iuliu Haţieganu”, Cluj-Napoca, Romania
| | - Radu Fechete
- Physics and Chemistry Department, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | | | - Dumitriţa Moldovan
- Physics and Chemistry Department, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | - Ramona Ioana Chelcea
- Physics and Chemistry Department, Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | | | | | - Tunde Kovacs
- IMOGEN, County Emergency Hospital, Cluj-Napoca, Romania
| | - Paula Popoi
- Leon Daniello Pneumophthisiology Clinical Hospital, Cluj-Napoca, Romania
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15
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Schweizerhof S, Demco DE, Mourran A, Fechete R, Möller M. Diffusion of Gold Nanorods Functionalized with Thermoresponsive Polymer Brushes. Langmuir 2018; 34:8031-8041. [PMID: 29897767 PMCID: PMC7434011 DOI: 10.1021/acs.langmuir.8b01289] [Citation(s) in RCA: 8] [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: 04/19/2018] [Revised: 06/12/2018] [Indexed: 05/19/2023]
Abstract
Understanding the diffusion of gold nanorods (AuNRs) and their composites in dispersion is important at fundamental level and in fields as diverse as material science, nanobiotechnology to drug delivery. The translational and rotational diffusion of AuNRs decorated with thermoresponsive poly( N-isopropylacrylamide) brushes having hydrophilic and hydrophobic end groups was investigated in the dilute regime by dynamic light scattering. The same series of functionalized AuNRs were studied in the isotropic concentrated dispersions by high-resolution NMR diffusometry. The dependence of translational and rotational diffusivity upon molecular weight and polymer end group were measured as a function of temperature in the region of the brush phase transition. The effective hydrodynamic radius of AuNR composites proved to be the most sensitive quantity to the temperature-induced phase transition of brushes, allowing the evaluation of the brush thickness in the swollen and collapsed states.
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Affiliation(s)
- Sjören Schweizerhof
- DWI-Leibniz-Institute
for Interactive Materials, e.V., RWTH-Aachen
University, Forckenbeckstraße
50, D-52074 Aachen, Germany
| | - Dan Eugen Demco
- DWI-Leibniz-Institute
for Interactive Materials, e.V., RWTH-Aachen
University, Forckenbeckstraße
50, D-52074 Aachen, Germany
- Technical
University of Cluj-Napoca, Department of
Physics and Chemistry, 25 G. Baritiu Str., RO-400027 Cluj-Napoca, Romania
| | - Ahmed Mourran
- DWI-Leibniz-Institute
for Interactive Materials, e.V., RWTH-Aachen
University, Forckenbeckstraße
50, D-52074 Aachen, Germany
| | - Radu Fechete
- Technical
University of Cluj-Napoca, Department of
Physics and Chemistry, 25 G. Baritiu Str., RO-400027 Cluj-Napoca, Romania
| | - Martin Möller
- DWI-Leibniz-Institute
for Interactive Materials, e.V., RWTH-Aachen
University, Forckenbeckstraße
50, D-52074 Aachen, Germany
- Institute
of Technical and Macromolecular Chemistry, RWTH-Aachen University, Worringerweg 2, D-52074 Aachen, Germany
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16
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Schweizerhof S, Demco DE, Mourran A, Fechete R, Möller M. Polymers Diffusivity Encoded by Stimuli‐Induced Phase Transition: Theory and Application to Poly(
N
‐Isopropylacrylamide) with Hydrophilic and Hydrophobic End Groups. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201700587] [Citation(s) in RCA: 4] [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)
- Sjören Schweizerhof
- DWI‐Leibniz‐Institute for Interactive Materials, e.V.RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
| | - Dan Eugen Demco
- DWI‐Leibniz‐Institute for Interactive Materials, e.V.RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
- Department of Physics and ChemistryTechnical University of Cluj‐Napoca 25 G. Baritiu Str. RO‐400027 Cluj‐Napoca Romania
| | - Ahmed Mourran
- DWI‐Leibniz‐Institute for Interactive Materials, e.V.RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
| | - Radu Fechete
- Department of Physics and ChemistryTechnical University of Cluj‐Napoca 25 G. Baritiu Str. RO‐400027 Cluj‐Napoca Romania
| | - Martin Möller
- DWI‐Leibniz‐Institute for Interactive Materials, e.V.RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
- Institute of Technical and Macromolecular ChemistryRWTH‐Aachen University Worringerweg 2 D‐52074 Aachen Germany
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17
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Schweizerhof S, Demco DE, Mourran A, Keul H, Fechete R, Möller M. Temperature-Induced Phase Transition Characterization of Responsive Polymer Brushes Grafted onto Nanoparticles. MACROMOL CHEM PHYS 2018. [DOI: 10.1002/macp.201700525] [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: 11/07/2022]
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18
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Schweizerhof S, Demco DE, Mourran A, Keul H, Fechete R, Möller M. Thermodynamic Parameters of Temperature-Induced Phase Transition for Brushes onto Nanoparticles: Hydrophilic versus Hydrophobic End-Groups Functionalization. Macromol Rapid Commun 2017; 38. [PMID: 28833862 DOI: 10.1002/marc.201700362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 07/20/2017] [Indexed: 11/10/2022]
Abstract
Quantification of the stimuli-responsive phase transition in polymers is topical and important for the understanding and development of novel stimuli-responsive materials. The temperature-induced phase transition of poly(N-isopropylacrylamide) (PNIPAm) with one thiol end group depends on the confinement-free polymer or polymer brush-on the molecular weight and on the nature of the second end. This paper describes the synthesis of heterotelechelic PNIPAm of different molecular weights with a thiol end group-that specifically binds to gold nanorods and a hydrophilic NIPAm end group by reversible addition-fragmentation chain-transfer polymerization. Proton high-resolution magic angle sample spinning NMR spectra are used as an indicator of the polymer chain conformations. The characteristics of phase transition given by the transition temperature, entropy, and width of transition are obtained by a two-state model. The dependence of thermodynamic parameters on molecular weight is compared for hydrophilic and hydrophobic end functional-free polymers and brushes.
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Affiliation(s)
- Sjören Schweizerhof
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074, Aachen, Germany
| | - Dan Eugen Demco
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074, Aachen, Germany.,Department of Physics and Chemistry, Technical University of Cluj-Napoca, 25 G. Baritiu Str, RO-400027, Cluj-Napoca, Romania
| | - Ahmed Mourran
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074, Aachen, Germany
| | - Helmut Keul
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074, Aachen, Germany
| | - Radu Fechete
- Department of Physics and Chemistry, Technical University of Cluj-Napoca, 25 G. Baritiu Str, RO-400027, Cluj-Napoca, Romania
| | - Martin Möller
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074, Aachen, Germany.,Institute for Technical and Macromolecular Chemistry, RWTH-Aachen University, Worringerweg 2, D-52074, Aachen, Germany
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19
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Schweizerhof S, Demco DE, Mourran A, Keul H, Fechete R, Möller M. Temperature-Induced Phase Transition Characterization of Responsive Polymer Brushes Grafted onto Nanoparticles. MACROMOL CHEM PHYS 2017. [DOI: 10.1002/macp.201600495] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Sjören Schweizerhof
- DWI-Leibniz-Institute for Interactive Materials, e.V.; RWTH-Aachen University; Forckenbeckstraße 50 52074 Aachen Germany
| | - Dan Eugen Demco
- DWI-Leibniz-Institute for Interactive Materials, e.V.; RWTH-Aachen University; Forckenbeckstraße 50 52074 Aachen Germany
- Technical University of Cluj-Napoca; Department of Physics and Chemistry; 25 G. Baritiu Str. 400027 Cluj-Napoca Romania
| | - Ahmed Mourran
- DWI-Leibniz-Institute for Interactive Materials, e.V.; RWTH-Aachen University; Forckenbeckstraße 50 52074 Aachen Germany
| | - Helmut Keul
- DWI-Leibniz-Institute for Interactive Materials, e.V.; RWTH-Aachen University; Forckenbeckstraße 50 52074 Aachen Germany
| | - Radu Fechete
- Technical University of Cluj-Napoca; Department of Physics and Chemistry; 25 G. Baritiu Str. 400027 Cluj-Napoca Romania
| | - Martin Möller
- DWI-Leibniz-Institute for Interactive Materials, e.V.; RWTH-Aachen University; Forckenbeckstraße 50 52074 Aachen Germany
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20
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Kensbock P, Demco DE, Singh S, Rahimi K, Fechete R, Walther A, Schmidt AM, Möller M. Peptizing Mechanism at the Molecular Level of Laponite Nanoclay Gels. Langmuir 2017; 33:66-74. [PMID: 27936777 DOI: 10.1021/acs.langmuir.6b03592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In the presence of additives such as etidronic acid (1-hydroxyethane-1,1-diphosphonic acid, HEDP), a process of peptizing of Laponite clay gels takes place. The peptizing process at the molecular level was directly revealed by 31P and 1H high-resolution magic-angle sample spinning (HRMAS) NMR spectroscopy. Two NMR spectral components were detected and assigned to free etidronic acid and bound to the Laponite disk edges. Furthermore, with increase of temperature the ratio of bound-to-free etidronic acid increases. This thermal activation process could be explained by the increase in electrical polarization of the hydroxyl group at the edges and by the exfoliation of the tactoids that leads to more access to the additive molecules to the electrical charges of platelet edges. 31P HRNMR spectroscopy on sodium fluorohectorite with an aspect ratio of ∼750 shows a reduction of the bound etidronic acid molecules. Transmission electron microscopy (TEM), field-emission scanning microscopy (FESEM), UV-vis spectrophotometry, dynamic light scattering (DLS), and zeta potential results support the proposed peptizing mechanisms.
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Affiliation(s)
- Philip Kensbock
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
| | - Dan Eugen Demco
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
- Institute of Physical Chemistry, University of Köln , Luxemburger Str. 116, D-50939 Köln, Germany
| | - Smriti Singh
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
| | - Khosrow Rahimi
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
| | - Radu Fechete
- Department of Physics and Chemistry, Technical University of Cluj-Napoca , 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania
| | - Andreas Walther
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
| | - Annette Monika Schmidt
- Institute of Physical Chemistry, University of Köln , Luxemburger Str. 116, D-50939 Köln, Germany
| | - Martin Möller
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany
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21
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Singh S, Demco DE, Rahimi K, Fechete R, Rodriguez-Cabello JC, Möller M. Aggregation behaviour of biohybrid microgels from elastin-like recombinamers. Soft Matter 2016; 12:6240-6252. [PMID: 27378252 DOI: 10.1039/c6sm00954a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Investigation of the aggregation behavior of biohybrid microgels, which can potentially be used as drug carriers, is an important topic, because aggregation not only causes loss of activity, but also toxicity and immunogenicity. To study this effect we synthesized microgels from elastin-like recombinamers (ELRs) using the miniemulsion technique. The existence of aggregation for such biohybrid microgels at different concentrations and temperatures was studied by different methods which include dynamic light scattering (DLS), (1)H high-resolution magic angle sample spinning (HRMAS) NMR spectroscopy, relaxometry and diffusometry. A hysteresis effect was detected in the process of aggregation by DLS as a function of temperature that strongly depends on ELR microgel concentration. The aggregation process was further quantitatively analyzed by the concentration dependence of the (1)H amino-acid residue chemical shifts and microgel diffusivity measured by NMR methods using the population balance kinetic aggregation model.
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Affiliation(s)
- Smriti Singh
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
| | - Dan Eugen Demco
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany. and Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania
| | - Khosrow Rahimi
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
| | - Radu Fechete
- Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania
| | | | - Martin Möller
- DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University, Forckenbeckstraße 50, D-52074 Aachen, Germany.
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22
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Singh S, Demco DE, Rahimi K, Fechete R, Rodriguez‐Cabello JC, Möller M. Coacervation of Elastin‐Like Recombinamer Microgels. Macromol Rapid Commun 2015; 37:181-6. [DOI: 10.1002/marc.201500457] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 09/16/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Smriti Singh
- DWI‐Leibniz‐Institute for Interactive Materials, e.V. RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
| | - Dan Eugen Demco
- DWI‐Leibniz‐Institute for Interactive Materials, e.V. RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
- Department of Physics and Chemistry Technical University of Cluj‐Napoca 25 G. Baritiu Str. RO‐400027 Cluj‐Napoca Romania
| | - Khosrow Rahimi
- DWI‐Leibniz‐Institute for Interactive Materials, e.V. RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
| | - Radu Fechete
- Department of Physics and Chemistry Technical University of Cluj‐Napoca 25 G. Baritiu Str. RO‐400027 Cluj‐Napoca Romania
| | | | - Martin Möller
- DWI‐Leibniz‐Institute for Interactive Materials, e.V. RWTH‐Aachen University Forckenbeckstraße 50 D‐52074 Aachen Germany
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23
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Şipos RS, Fechete R, Moldovan D, Şuş I, Szasz S, Pávai Z. Assessment of femoral bone osteoporosis in rats treated with simvastatin or fenofibrate. Open Life Sci 2015. [DOI: 10.1515/biol-2015-0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AbstractBackground: The effects of two lipidlowering drugs, simvastatin and fenofibrate on osteoporosis in the femurs of healthy and ovariectomized female rats were investigated quantitatively by histological images and
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Şipoş RS, Fechete R, Chelcea RI, Moldovan D, Pap Z, Pávai Z, Demco DE. Ovariectomized rats' femur treated with fibrates and statins. Assessment of pore-size distribution by ¹H-NMR relaxometry. Rom J Morphol Embryol 2015; 56:743-752. [PMID: 26429167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The effects of two wonder drugs, simvastatins and fenofibrates on the proximal part of the femoris of a series of ovariectomized and non-ovariectomized Wistar albino rats was estimated qualitatively and semi-quantitatively by the modern method of 1D 1H-NMR T2-distribution. The 72 rats subjected to this study were divided in six groups and were sacrificed at two, four, six and eight weeks after ovariectomy and the proximal part of femoris was harvested. The CPMG (Carr-Purcell-Meiboom-Gill) echoes train curves were measured for the bones fully saturated with water during two months after two months of natural drying. These decays were analyzed by Laplace inversion and an average of normalized T2-distributions was considered for all rat's groups. The 1D averaged T2-distributions present four peaks, which were associated with protons in four major environments, from which the free water protons are used as spy molecules to explore the boundaries of cavities. In the approximation of spherical pores, the averaged T2-distributions were transformed in distributions of pores diameters. These were found in the range from 2 μm up to 2 mm. The relative amplitudes, widths and position of deconvoluted distributions of small, medium and large cavities are used for a qualitatively analysis of the effect of our lipid-lowering drugs. For a semi-quantitatively analysis, we chose the diameter d of proximal part of femoris' trabecular cavities. We show that the positive or negative effects of treatments with simvastatins and fenofibrates are strongly dependent on the duration of treatment. Moreover, the treatment of healthy bone is generally counter-indicated.
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Affiliation(s)
- Remus Sebastian Şipoş
- Department of Morphological Sciences, University of Medicine and Pharmacy of Tirgu Mures, Romania; ; Department of Physics and Chemistry, Technical University of Cluj-Napoca, Romania;
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25
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Fechete R, Demco DE, Zhu X, Tillmann W, Möller M. Water states and dynamics in perfluorinated ionomer membranes by 1H one- and two-dimensional NMR spectroscopy, relaxometry, and diffusometry. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.02.024] [Citation(s) in RCA: 9] [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] [Indexed: 10/25/2022]
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Demco DE, Filipoi C, Zhu X, Fechete R, Möller M. Morphological Heterogeneity by Diffusional Kurtosis NMR Spectroscopy in Perfluorosulfonic Acid/SiO2
Composite Proton-Exchange Membranes. MACROMOL CHEM PHYS 2013. [DOI: 10.1002/macp.201300039] [Citation(s) in RCA: 5] [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: 11/07/2022]
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27
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Ritchie J, Bevins A, Assi L, Hoefield R, Cockwell P, Kalra P, Airoldi A, Canavese C, Izzo C, Radin E, Quaglia M, Rossi D, Crespi I, Stratta P, Lv LL, Cao YH, Xu M, Liu BC, Rudnicki M, Perco P, D'haene B, Leierer J, Sunzenauer J, Fechete R, Heinzel A, Mestdagh P, Vandesompele J, Mayer B, Mayer G, Kretschmer A, Kukuk S, Brandt AS, Burkhardt-Soares S, Bruck H, Roth S, de Borst M, Humalda J, Vervloet M, Kwakernaak A, ter Wee P, Navis G. Biomarkers. Nephrol Dial Transplant 2013. [DOI: 10.1093/ndt/gft152] [Citation(s) in RCA: 2] [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
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28
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Demco DE, Oros-Peusquens AM, Utiu L, Fechete R, Blümich B, Shah NJ. Molecular dynamics parameter maps by 1H Hahn echo and mixed-echo phase-encoding MRI. J Magn Reson 2013; 227:1-8. [PMID: 23220231 DOI: 10.1016/j.jmr.2012.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 10/29/2012] [Accepted: 11/08/2012] [Indexed: 06/01/2023]
Abstract
Residual dipolar couplings and averaged correlation time maps in soft matter were obtained by mixed echo phase-encoding solid imaging (MIPSI). Use of the mixed echo in soft matter NMR imaging experiments has two crucial advantages: the signal intensity is recovered with a weak incoherence losses, and second, the intervals during which the phase-encoding evolution due to the magnetic field gradients takes place can be chosen to be much larger than with all other spin echo experiments and hence, a higher special resolution can be achieved. The parameter maps are compared to those obtained by the Hahn-echo phase-frequency encoding method. For both MRI methods the density operator formalism is applied in the average Hamiltonian approximation to describe the encoding of the spin echoes by the molecular motions. The results of preliminary experiments are presented.
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Affiliation(s)
- Dan E Demco
- Institute of Neuroscience and Medicine, Research Centre Jülich, Juelich, Germany.
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29
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Filipoi C, Demco DE, Zhu X, Vinokur R, Conradi O, Fechete R, Möller M. Water self-diffusion anisotropy and electrical conductivity of perfluorosulfonic acid/SiO2 composite proton exchange membranes. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.10.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Utiu L, Demco DE, Fechete R, Möller M, Popescu C. Morphology and molecular dynamics of hard α-keratin based micro-tubes by 1H and 13C solid-state NMR. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.10.036] [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: 10/15/2022]
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Filipoi C, Demco DE, Zhu X, Vinokur R, Conradi O, Fechete R, Möller M. Channel orientation anisotropy in perfluorosulfonic acid/SiO2 composite proton exchange membranes: Water self-diffusion study using NMR. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Moldovan D, Fechete R, Demco DE, Culea E, Blümich B, Herrmann V, Heinz M. The heterogeneity of segmental dynamics of filled EPDM by (1)H transverse relaxation NMR. J Magn Reson 2011; 208:156-162. [PMID: 21106419 DOI: 10.1016/j.jmr.2010.10.019] [Citation(s) in RCA: 9] [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] [Received: 07/21/2010] [Revised: 10/29/2010] [Accepted: 10/31/2010] [Indexed: 05/30/2023]
Abstract
Residual second moment of dipolar interactions M(2) and correlation time segmental dynamics distributions were measured by Hahn-echo decays in combination with inverse Laplace transform for a series of unfilled and filled EPDM samples as functions of carbon-black N683 filler content. The fillers-polymer chain interactions which dramatically restrict the mobility of bound rubber modify the dynamics of mobile chains. These changes depend on the filler content and can be evaluated from distributions of M(2). A dipolar filter was applied to eliminate the contribution of bound rubber. In the first approach the Hahn-echo decays were fitted with a theoretical relationship to obtain the average values of the (1)H residual second moment <M(2)> and correlation time <τ(c)>. For the mobile EPDM segments the power-law distribution of correlation function was compared to the exponential correlation function and found inadequate in the long-time regime. In the second approach a log-Gauss distribution for the correlation time was assumed. Furthermore, using an averaged value of the correlation time, the distributions of the residual second moment were determined using an inverse Laplace transform for the entire series of measured samples. The unfilled EPDM sample shows a bimodal distribution of residual second moments, which can be associated to the mobile polymer sub-chains (M(2) ≅ 6.1 rad (2) s(-2)) and the second one associated to the dangling chains M(2) ≅ 5.4 rad(2) s(-2)). By restraining the mobility of bound rubber, the carbon-black fillers induce diversity in the segmental dynamics like the apparition of a distinct mobile component and changes in the distribution of mobile and free-end polymer segments.
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Affiliation(s)
- D Moldovan
- Technical University of Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
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Moldovan D, Fechete R, Demco DE, Culea E, Blümich B, Herrmann V, Heinz M. Heterogeneity of Nanofilled EPDM Elastomers Investigated by Inverse Laplace Transform 1
H NMR Relaxometry and Rheometry. MACROMOL CHEM PHYS 2010. [DOI: 10.1002/macp.201000086] [Citation(s) in RCA: 16] [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: 11/10/2022]
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Melian C, Demco DE, Istrate M, Balaceanu A, Moldovan D, Fechete R, Popescu C, Möller M. Morphology and side-chain dynamics in hydrated hard α-keratin fibres by 1H solid-state NMR. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.09.013] [Citation(s) in RCA: 8] [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: 11/27/2022]
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Chelcea RI, Fechete R, Culea E, Demco DE, Blümich B. Distributions of transverse relaxation times for soft-solids measured in strongly inhomogeneous magnetic fields. J Magn Reson 2009; 196:178-190. [PMID: 19083248 DOI: 10.1016/j.jmr.2008.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 11/09/2008] [Accepted: 11/12/2008] [Indexed: 05/27/2023]
Abstract
The single-sided NMR-MOUSE sensor that operates in highly inhomogeneous magnetic fields is used to record a CPMG (1)H transverse relaxation decay by CPMG echo trains for a series of cross-linked natural rubber samples. Effective transverse relaxation rates 1/T(2,short) and 1/T(2,long) were determined by a bi-exponential fit. A linear dependence of transverse relaxation rates on cross-link density is observed for medium to large values of cross-link density. As an alternative to multi-exponential fits the possibility to analyze the dynamics of soft polymer network in terms of multi-exponential decays via the inverse Laplace transformation was studied. The transient regime and the effect of the T(1)/T(2) ratio in inhomogeneous static and radiofrequency magnetic fields on the CPMG decays were studied numerically using a dedicated C++ program to simulate the temporal and spatial dependence of the CPMG response. A correction factor T(2)/T(2,eff) is derived as a function of the T(1)/T(2) ratio from numerical simulations and compared with earlier results from two different well logging devices. High-resolution T(1)-T(2) correlations maps are obtained by two-dimensional Laplace inversion of CPMG detected saturation recovery curves. The T(1)-T(2) experimental correlations maps were corrected for the T(1)/T(2) effect using the derived T(2)/T(2,eff) correction factor.
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Affiliation(s)
- R I Chelcea
- Technical University of Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
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Baias M, Demco DE, Popescu C, Fechete R, Melian C, Blümich B, Möller M. Thermal Denaturation of Hydrated Wool Keratin by 1H Solid-State NMR. J Phys Chem B 2009; 113:2184-92. [DOI: 10.1021/jp8094616] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Baias
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Dan E. Demco
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Crisan Popescu
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Radu Fechete
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Claudiu Melian
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Bernhard Blümich
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
| | - Martin Möller
- DWI an der RWTH-Aachen University, Pauwelsstrasse 8, D-52056 Aachen, Germany, Institut für Technische and Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 1, D-52074 Aachen, Germany, Department of Physics, Technical University Cluj-Napoca, RO-400020 Cluj-Napoca, Romania, and University “Aurel Vlaicu” Arad, Bd. Revolutiei 77, RO-310130 Arad, Romania
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Bertmer M, Demco DE, Wang M, Melian C, Marcean-Chelcea RI, Fechete R, Baias M, Blümich B. Segmental dynamic heterogeneity of short-chain grafted-poly(dimethylsiloxane) by 1H spin-diffusion NMR. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.09.092] [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: 11/29/2022]
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Abstract
The principal values of the diffusion tensor of free water in the pores of sheep Achilles tendon were determined. For this purpose, the azimuthally angular dependence of the self-diffusion coefficient was measured using a radiofrequency tilt coil and pulsed-field-gradient stimulated-echo (PFGSE) NMR. Combining the PFGSE with multiple acquisitions of Hahn echoes using the Carr-Purcell-Meiboom-Gill pulse sequence reduced the measuring time. The diffusion measurements revealed two diffusion process characterized by a fast and a slow effective diffusion coefficient. A model which describes the stimulated-echo amplitude, encoded by the water diffusion and magnetization transfer, was used for evaluation of the fast diffusion coefficients. The fast diffusion process characterizes the water molecules in pores surrounding the collagen fibrils. The diffusion coefficients characterizing the fast process show a well-defined anisotropy. The principal values of the diffusion tensors were determined assuming the elongated pores to be oriented parallel to the tendon fibrils and thus the orientation distribution function of the pores followed that of the collagen fibrils. The average aspect ratio of pores was estimated from the principal values of the water diffusion tensor and is suitable to characterize quantitatively the changes in tendon morphology due to healing or aging. The methods in this investigation can also be applied to measurements of the diffusion anisotropy using ex situ NMR sensors.
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Affiliation(s)
- R Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany
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Affiliation(s)
- D. E. Demco
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany, and Technical University Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
| | - G. Rata
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany, and Technical University Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
| | - R. Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany, and Technical University Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
| | - B. Blümich
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany, and Technical University Cluj-Napoca, Daicoviciu 1, R-400020 Cluj-Napoca, Romania
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Fechete R, Demco DE, Blümich B. Enhanced sensitivity to residual dipolar couplings of elastomers by higher-order multiple-quantum NMR. J Magn Reson 2004; 169:19-26. [PMID: 15183352 DOI: 10.1016/j.jmr.2004.03.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 03/29/2004] [Indexed: 05/24/2023]
Abstract
The homonuclear and heteronuclear residual dipolar couplings in elastomers reflect changes in the cross-link density, temperature, the uniaxial and biaxial extension or compression as well as the presence of penetrant molecules. It is shown theoretically that for an isolated methyl group the relative changes in the intensity of the homonuclear double-quantum buildup curves in the initial time regime due to variation of the residual dipolar coupling strength is less sensitive than the changes in the triple-quantum filtered NMR signal when considering the same excitation/reconversion time. For a quadrupolar nucleus with spin I=2 the sensitivity enhancement was simulated for four-quantum, triple-quantum, and double-quantum buildup curves. In this case the four-quantum build-up curve shows the highest sensitivity to changes of spin couplings. This enhanced sensitivity to the residual dipolar couplings was tested experimentally by measuring 1H double-quantum, triple-quantum, and four-quantum buildup curves of differently cross-linked natural rubber samples. In the initial excitation/reconversion time regime, where the residual dipolar couplings can be measured model free, the relative changes in the intensity of the four-quantum buildup curves are about five times higher than those of the double-quantum coherences. For the first time proton four-quantum coherences were recorded for cross-linked elastomers.
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Affiliation(s)
- R Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany
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Fechete R, Demco DE, Blümich B. Order parameters of the orientation distribution of collagen fibers in Achilles tendon by 1H NMR of multipolar spin states. NMR Biomed 2003; 16:479-483. [PMID: 14696005 DOI: 10.1002/nbm.854] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The angular distribution function of collagen fibrils in a sheep Achilles tendon was investigated by (1)H NMR of multipolar spin states represented by dipolar-encoded longitudinal magnetization and double-quantum filtered signals. For the first time the angular distribution function based on the Legendre moment expansion is used. Order parameters were obtained from the anisotropy of (1)H residual dipolar couplings of bond water, which were determined model-free from the excitation efficiency of the multipolar spin states and from double-quantum filtered line splitting. The orientation distribution function of collagen fibrils in Achilles tendon measured from the anisotropy of the residual dipolar couplings is characterized by the average values of beta0 = 1.8+/-0.2 degrees and order parameters [P2] = 0.93+/-0.04, [P4] = 0.78+/-0.04 and [P6] = 0.58+/-0.04. The order of many biological tissues in the presence of ageing, injuries or regeneration can be quantified by the order parameters of the angular distribution function.
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Affiliation(s)
- R Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany
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Abstract
Proton multipolar spin states associated with dipolar encoded longitudinal magnetization (DELM) and double-quantum (DQ) coherences of bound water are investigated for bovine and sheep Achilles tendon under mechanical load. DELM decay curves and DQ buildup and decay curves reveal changes of the 1H residual dipolar couplings for tendon at rest and under local compression forces. The multipolar spin states are used to design dipolar contrast filters for NMR 1H images of heterogeneous tendon. Heterogeneities in tendon samples were artificially generated by local compression parallel and perpendicular to the tendon plug axis. Quotient images obtained from DQ-filtered images by matched and mismatched excitation/reconversion periods are encoded only by the residual dipolar couplings. Semi-quantitative parameter maps of the residual dipolar couplings of bound water were obtained from these quotient images using a reference elastomer sample. This method can be used to quantify NMR imaging of injured ordered tissues.
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Affiliation(s)
- R Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056, Aachen, Germany
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Abstract
The NMR-MOUSE is a unilateral and mobile NMR sensor which operates with highly inhomogeneous magnetic fields. To produce a mobile NMR unit, RF excitation is sought, which can be produced with the most simple equipment, in particular nonlinear, low-power amplifiers, and to observe a free induction decay in strongly inhomogeneous fields, the excitation needs to be selective. The possibility to produce selective excitation by sequences of hard low-power radiofrequency pulses in the strongly inhomogeneous magnetic fields of the NMR-MOUSE is explored. The use of the DANTE sequence for selection of magnetization from parts of the sensitive volume was investigated for longitudinal and transverse magnetization by computer simulations and experiments. The spectra of the recorded FIDs and echo signals are in good agreement with those simulated for the excitation, which verifies the concept of the DANTE excitation. The results obtained are an important step towards a low-power operation of the NMR-MOUSE to improve its mobility.
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Affiliation(s)
- M Todica
- Institute of Technical Chemistry and Macromolecular Chemistry, University of Aachen, RWTH, Worringerweg 1, Aachen D-52056, Germany
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Klein M, Fechete R, Demco DE, Blümich B. Self-diffusion measurements by a constant-relaxation method in strongly inhomogeneous magnetic fields. J Magn Reson 2003; 164:310-320. [PMID: 14511599 DOI: 10.1016/s1090-7807(03)00237-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The simple pulse sequence thetax-tau1-2thetay-tau1+tau2-2thetay-tau2-Hahn echo used to measure the self-diffusion coefficient D under constant-relaxation condition, i.e., for tau1+tau2=const. was investigated in the presence of strongly inhomogeneous static as well as radiofrequency magnetic fields. The encoding of the Hahn-echo amplitude by the pulse flip angle and diffusion was evaluated by taking into account the spatial distribution of the off-resonance field, the strength and orientation of the local field gradients, and the pulse flip angles by a computer simulation program. As input files, this program uses maps of static and radiofrequency fields, and the D coefficient can be evaluated from the time dependence of the Hahn-echo amplitude. The method was applied to a mobile one-sided NMR sensor, NMR-MOUSE with a bar magnet by measuring D for a series of liquids with different viscosities. The method was shown to be particularly useful for measuring D of solvents in elastomers without the need for measurements of the transverse relaxation rates. The self-diffusion coefficient of toluene in a series of crosslinked natural rubber samples was measured and correlated with the crosslink density. Finally, the method was applied to measure the diffusion anisotropy of free water in bovine Achilles tendon.
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Affiliation(s)
- M Klein
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, Aachen D-52056, Germany
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Fechete R, Demco DE, Blümich B, Eliav U, Navon G. Anisotropy of collagen fiber orientation in sheep tendon by 1H double-quantum-filtered NMR signals. J Magn Reson 2003; 162:166-175. [PMID: 12762993 DOI: 10.1016/s1090-7807(02)00200-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The anisotropy of the angular distribution of collagen fibrils in a sheep tendon was investigated by 1H double-quantum (DQ) filtered NMR signals. Double-quantum build-up curves generated by the five-pulse sequence were measured for different angles between the direction of the static magnetic field and the axis of the tendon plug. Proton residual dipolar couplings determined from the DQ build-up curves in the initial excitation/reconversion time regime which mainly represent the bound water are interpreted in terms of a model of spin-1/2 pairs with their internuclear axes oriented on average along the fibril direction in the presence of proton exchange. The angular distribution of collagen fibrils around the symmetry axis of the tendon measured by the anisotropy of the residual dipolar couplings was described by a Gaussian function with a standard deviation of 12 degrees +/-1 degrees and with the center of the distribution at 4 degrees +/-1 degrees. The existence of this distribution is directly reflected in the finite value of the residual dipolar couplings at the magic angle, the value of the angular contrast, and the oscillatory behavior of the DQ build-up curves. The 1H residual dipolar couplings were also measured from the doublets recorded by the DQ-filtered signals. From the angular dependence of the normalized splitting the angular distribution of the collagen fibrils was evaluated using a Gaussian function with a standard deviation of 19 degrees +/-1 degrees and with the center of distribution at 2 degrees +/-1 degrees. The advantages and disadvantages of these approaches are discussed.
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Affiliation(s)
- R Fechete
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Worringerweg 1, D-52056, Aachen, Germany
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Hailu K, Fechete R, Demco DE, Blümich B. Segmental anisotropy in strained elastomers detected with a portable NMR scanner. Solid State Nucl Magn Reson 2002; 22:327-343. [PMID: 12469818 DOI: 10.1006/snmr.2002.0067] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Single-side NMR is particularly suitable for measurements of segmental anisotropy induced in elastomers by uniaxial forces or local strain. Proton transverse nuclear magnetic relaxation was investigated with the NMR-MOUSE by recording the Hahn-echo decay in cross-linked natural rubber bands. This provided information on the dependence of the Hahn-echo decay on the angle between the direction of the uniaxial stretching force and the axis Z defined direction perpendicular to the magnet pole faces of the NMR-scanner. The anisotropy effect on the Hahn-echo decay is correlated with the extension ratio, and it is more evident in the liquid-like regime of the decay. A weaker segmental anisotropy is detected by 1H solid- and Hahn-echo decays recorded by multi-pulse sequences. A qualitative understanding of the angular dependence is obtained by an analytical theory of the Hahn-echo decay adapted to the case of stretched elastomers and to strongly inhomogeneous magnetic fields. Using angular-dependent 1H residual second van Vleck moments and correlation times reported previously [P.T. Callaghan and E.T. Samulski, Macromolecules 30, 113 (1997)] from stretched natural rubber bands the segmental anisotropy measured in inhomogeneous magnetic fields by the Hahn-echo decay was numerically simulated. As an example of a macroscopic distribution of local segmental anisotropy, 1H Hahn-echo decays were measured by the NMR-MOUSE sensor in a stretched cross-linked natural rubber plate with a circular cut in the center.
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Affiliation(s)
- K Hailu
- Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfalische, Technische Hochschule, Worringerweg 1, D-52056 Aachen, Germany
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