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Schoovaerts M, Ourak M, Borghesan G, Putzeys T, Poorten EV, Verhaert N. OCT-based intra-cochlear imaging and 3D reconstruction: ex vivo validation of a robotic platform. Int J Comput Assist Radiol Surg 2024:10.1007/s11548-024-03081-7. [PMID: 38436923 DOI: 10.1007/s11548-024-03081-7] [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: 08/17/2023] [Accepted: 02/15/2024] [Indexed: 03/05/2024]
Abstract
PURPOSE The small size of the cochlea, and its location deeply embedded in thick temporal bone, poses a challenge for intra-cochlear guidance and diagnostics. Current radiological imaging techniques are not able to visualize the cochlear microstructures in detail. Rotational optical coherence tomography (OCT) fibers show great potential for intra-cochlear guidance. The generated images could be used to map, and study, the tiny cochlear microstructures relevant for hearing. METHODS This work describes the design of a rotational OCT probe with an outer diameter of 0.9 mm. It further discusses a robotic system, which features a remote center of motion mechanism, dedicated to the probe's positioning, fine manipulation and stable insertion into the cochlear micro-spaces. Furthermore, the necessary calibration steps for 3D reconstruction are described, followed by a detailed quantitative analysis, comparing the 3D reconstructions using a synthetic, 2:1 scaled scala tympani model with a reconstruction from micro-CT, serving as the ground truth. Finally, the potential of the system is demonstrated by scanning a single ex vivo cadaveric human cochlea. RESULTS The study investigates five insertions in the same 2:1 scaled tympani model, along with their corresponding 3D reconstruction. The comparison with micro-CT results in an average root-mean-square error of 74.2 µm, a signed distance error of 38.1 µm and a standard deviation of 63.6 µm. The average F-score of the reconstructions, using a distance threshold of 100 and 74.2 µm, resulted in 83.0% and 71.8%, respectively. Insertion in the cadaveric human cochlea showed the challenges for straight insertion, i.e., navigating the hook region. CONCLUSION Overall, the system shows great potential for intra-cochlear guidance and diagnostics, due to the system's capability for precise and stable insertion into the basal turn in the scala tympani. The system, combined with the calibration procedure, results in detailed and precise 3D reconstructions.
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Affiliation(s)
- Maarten Schoovaerts
- Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300, 3001, Leuven, Belgium.
- Department of Neurosciences, KU Leuven, Herestraat 49, 3001, Leuven, Belgium.
| | - Mouloud Ourak
- Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300, 3001, Leuven, Belgium
| | - Gianni Borghesan
- Department of Mechanical Engineering, KU Leuven, Celestijnenlaan 300, 3001, Leuven, Belgium
- Flanders Make, KU Leuven, Celestijnenlaan 300, 3001, Leuven, Belgium
| | - Tristan Putzeys
- Department of Neurosciences, KU Leuven, Herestraat 49, 3001, Leuven, Belgium
- Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200, 3001, Leuven, Belgium
| | | | - Nicolas Verhaert
- Department of Neurosciences, KU Leuven, Herestraat 49, 3001, Leuven, Belgium
- Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital of Leuven, Herestraat 49, 3001, Leuven, Belgium
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Wils I, Geerardyn A, Putzeys T, Denis K, Verhaert N. Lumped element models of sound conduction in the human ear: A systematic review. J Acoust Soc Am 2023; 154:1696-1709. [PMID: 37712750 DOI: 10.1121/10.0020841] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 08/16/2023] [Indexed: 09/16/2023]
Abstract
Lumped element models facilitate investigating the fundamental mechanisms of human ear sound conduction. This systematic review aims to guide researchers to the optimal model for the investigated parameters. For this purpose, the literature was reviewed up to 12 July 2023, according to the PRISMA guidelines. Seven models are included via database searching, and another 19 via cross-referencing. The quality of the models is assessed by comparing the predicted middle ear transfer function, the tympanic membrane impedance, the energy reflectance, and the intracochlear pressures (ICPs) (scala vestibuli, scala tympani, and differential) with experimental data. Regarding air conduction (AC), the models characterize the pathway from the outer to the inner ear and accurately predict all six aforementioned parameters. This contrasts with the few existing bone conduction (BC) models that simulate only a part of the ear. In addition, these models excel at predicting one observable parameter, namely, ICP. Thus, a model that simulates BC from the coupling site to the inner ear is still lacking and would increase insights into the human ear sound conduction. Last, this review provides insights and recommendations to determine the appropriate model for AC and BC implants, which is highly relevant for future clinical applications.
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Affiliation(s)
- Irina Wils
- Department of Neurosciences, KU Leuven, B-3000 Leuven, Belgium
| | | | - Tristan Putzeys
- Department of Neurosciences, KU Leuven, B-3000 Leuven, Belgium
| | - Kathleen Denis
- Department of Mechanical Engineering, KU Leuven, B-3000 Leuven, Belgium
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Wellens J, Deschaume O, Putzeys T, Eyley S, Thielemans W, Verhaert N, Bartic C. Sulfobetaine-based ultrathin coatings as effective antifouling layers for implantable neuroprosthetic devices. Biosens Bioelectron 2023; 226:115121. [PMID: 36774733 DOI: 10.1016/j.bios.2023.115121] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/30/2023] [Accepted: 02/02/2023] [Indexed: 02/05/2023]
Abstract
Foreign body response (FBR), inflammation, and fibrotic encapsulation of neural implants remain major problems affecting the impedance of the electrode-tissue interface and altering the device performance. Adhesion of proteins and cells (e.g., pro-inflammatory macrophages, and fibroblasts) triggers the FBR cascade and can be diminished by applying antifouling coatings onto the implanted devices. In this paper, we report the deposition and characterization of a thin (±6 nm) sulfobetaine-based coating onto microfabricated platinum electrodes and cochlear implant (CI) electrode arrays. We found that this coating has stable cell and protein-repellent properties, for at least 31 days in vitro, not affected by electrical stimulation protocols. Additionally, its effect on the electrochemical properties relevant to stimulation (i.e., impedance, charge injection capacity) was negligible. When applied to clinical CI electrode arrays, the film was successful at inhibiting fibroblast adhesion on both the silicone packaging and the platinum/iridium electrodes. In vitro, in fibroblast cultures, coated CI electrode arrays maintained impedance values up to five times lower compared to non-coated devices. Our studies demonstrate that such thin sulfobetaine containing layers are stable and prevent protein and cell adhesion in vitro and are compatible for use on CI electrode arrays. Future in vivo studies should be conducted to investigate its ability to mitigate biofouling, fibrosis, and the resulting impedance changes upon long-term implantation in vivo.
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Affiliation(s)
- Jolan Wellens
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Olivier Deschaume
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium
| | - Tristan Putzeys
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium; Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Samuel Eyley
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Wim Thielemans
- Sustainable Materials Lab, Department of Chemical Engineering, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Nicolas Verhaert
- Experimental Oto-rhino-laryngology Research Group, Dept. Neuroscience, KU Leuven, Herestraat 49, 3000, Leuven, Belgium; Department of Otorhinolaryngology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - Carmen Bartic
- Laboratory for Soft Matter and Biophysics, Dept. Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium.
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Starovoyt A, Shaheen E, Putzeys T, Kerckhofs G, Politis C, Wouters J, Verhaert N. Anatomically and mechanically accurate scala tympani model for electrode insertion studies. Hear Res 2023; 430:108707. [PMID: 36773540 DOI: 10.1016/j.heares.2023.108707] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 11/25/2022] [Accepted: 01/24/2023] [Indexed: 01/26/2023]
Abstract
The risk of insertion trauma in cochlear implantation is determined by the interplay between individual cochlear anatomy and electrode insertion mechanics. Whereas patient anatomy cannot be changed, new surgical techniques, devices for cochlear monitoring, drugs, and electrode array designs are continuously being developed and tested, to optimize the insertion mechanics and prevent trauma. Preclinical testing of these developments is a crucial step in feasibility testing and optimization for clinical application. Human cadaveric specimens allow for the best simulation of an intraoperative setting. However, their availability is limited and it is not possible to conduct repeated, controlled experiments on the same sample. A variety of artificial cochlear models have been developed for electrode insertion studies, but none of them were both anatomically and mechanically representative for surgical insertion into an individual cochlea. In this study, we developed anatomically representative models of the scala tympani for surgical insertion through the round window, based on microCT images of individual human cochleae. The models were produced in transparent material using commonly-available 3D printing technology at a desired scale. The anatomical and mechanical accuracy of the produced models was validated by comparison with human cadaveric cochleae. Mechanical evaluation was performed by recording insertion forces, counting the number of inserted electrodes and grading tactile feedback during manual insertion of a straight electrode by experienced cochlear implant surgeons. Our results demonstrated that the developed models were highly representative for the anatomy of the original cochleae and for the insertion mechanics in human cadaveric cochleae. The individual anatomy of the produced models had a significant impact on the insertion mechanics. The described models have a promising potential to accelerate preclinical development and testing of atraumatic insertion techniques, reducing the need for human cadaveric material. In addition, realistic models of the cochlea can be used for surgical training and preoperative planning of patient-tailored cochlear implantation surgery.
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Affiliation(s)
- Anastasiya Starovoyt
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Eman Shaheen
- OMFS IMPATH Research Group, Department of Imaging and Pathology, KU Leuven, University of Leuven, Leuven, Belgium; Department of Oral and Maxillofacial Surgery, UZ Leuven, University Hospitals Leuven, Leuven, Belgium
| | - Tristan Putzeys
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, University of Leuven, Leuven, Belgium
| | - Greet Kerckhofs
- Biomechanics lab, Institute of Mechanics, Materials, and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Department of Materials Engineering, KU Leuven, University of Leuven, Leuven, Belgium; IREC, Institute of Experimental and Clinical Research, UCLouvain, Woluwé-Saint-Lambert, Belgium; Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, University of Leuven, Leuven, Belgium
| | - Constantinus Politis
- OMFS IMPATH Research Group, Department of Imaging and Pathology, KU Leuven, University of Leuven, Leuven, Belgium; Department of Oral and Maxillofacial Surgery, UZ Leuven, University Hospitals Leuven, Leuven, Belgium
| | - Jan Wouters
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Nicolas Verhaert
- Research Group Experimental Oto-Rhino-Laryngology, Department of Neurosciences, KU Leuven, University of Leuven, Leuven, Belgium; Leuven Brain Institute, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Department of Otorhinolaryngology, Head and Neck Surgery, UZ Leuven, University Hospitals of Leuven, Leuven, Belgium.
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Starovoyt A, Quirk BC, Putzeys T, Kerckhofs G, Nuyts J, Wouters J, McLaughlin RA, Verhaert N. An optically-guided cochlear implant sheath for real-time monitoring of electrode insertion into the human cochlea. Sci Rep 2022; 12:19234. [PMID: 36357503 PMCID: PMC9649659 DOI: 10.1038/s41598-022-23653-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/03/2022] [Indexed: 11/12/2022] Open
Abstract
In cochlear implant surgery, insertion of perimodiolar electrode arrays into the scala tympani can be complicated by trauma or even accidental translocation of the electrode array within the cochlea. In patients with partial hearing loss, cochlear trauma can not only negatively affect implant performance, but also reduce residual hearing function. These events have been related to suboptimal positioning of the cochlear implant electrode array with respect to critical cochlear walls of the scala tympani (modiolar wall, osseous spiral lamina and basilar membrane). Currently, the position of the electrode array in relation to these walls cannot be assessed during the insertion and the surgeon depends on tactile feedback, which is unreliable and often comes too late. This study presents an image-guided cochlear implant device with an integrated, fiber-optic imaging probe that provides real-time feedback using optical coherence tomography during insertion into the human cochlea. This novel device enables the surgeon to accurately detect and identify the cochlear walls ahead and to adjust the insertion trajectory, avoiding collision and trauma. The functionality of this prototype has been demonstrated in a series of insertion experiments, conducted by experienced cochlear implant surgeons on fresh-frozen human cadaveric cochleae.
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Affiliation(s)
- Anastasiya Starovoyt
- grid.5596.f0000 0001 0668 7884Department of Neurosciences, ExpORL, KU Leuven, 3000 Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Department of Neurosciences, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Bryden C. Quirk
- grid.1010.00000 0004 1936 7304Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5005 Australia ,grid.1010.00000 0004 1936 7304Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA 5005 Australia
| | - Tristan Putzeys
- grid.5596.f0000 0001 0668 7884Department of Neurosciences, ExpORL, KU Leuven, 3000 Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Department of Neurosciences, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, 3000 Leuven, Belgium
| | - Greet Kerckhofs
- grid.7942.80000 0001 2294 713XBiomechanics Laboratory, Institute of Mechanics, Materials, and Civil Engineering, UCLouvain, 1348 Louvain-La-Neuve, Belgium ,grid.5596.f0000 0001 0668 7884Department of Materials Science and Engineering, KU Leuven, 3000 Leuven, Belgium ,grid.7942.80000 0001 2294 713XInstitute of Experimental and Clinical Research, UCLouvain, 1200 Woluwé-Saint-Lambert, Belgium ,grid.5596.f0000 0001 0668 7884Prometheus, Division of Skeletal Tissue Engineering, KU Leuven, 3000 Leuven, Belgium
| | - Johan Nuyts
- grid.5596.f0000 0001 0668 7884Department of Imaging and Pathology, Division of Nuclear Medicine, KU Leuven, 3000 Leuven, Belgium ,Nuclear Medicine and Molecular Imaging, Medical Imaging Research Center, 3000 Leuven, Belgium
| | - Jan Wouters
- grid.5596.f0000 0001 0668 7884Department of Neurosciences, ExpORL, KU Leuven, 3000 Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Department of Neurosciences, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
| | - Robert A. McLaughlin
- grid.1010.00000 0004 1936 7304Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA 5005 Australia ,grid.1010.00000 0004 1936 7304Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA 5005 Australia ,grid.1012.20000 0004 1936 7910School of Engineering, University of Western Australia, Perth, WA 6009 Australia
| | - Nicolas Verhaert
- grid.5596.f0000 0001 0668 7884Department of Neurosciences, ExpORL, KU Leuven, 3000 Leuven, Belgium ,grid.5596.f0000 0001 0668 7884Department of Neurosciences, Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium ,grid.410569.f0000 0004 0626 3338Department of Otorhinolaryngology, Head and Neck Surgery, University Hospitals of Leuven, 3000 Leuven, Belgium
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Putzeys T, Borgers C, Fierens G, Walraevens J, Van Wieringen A, Verhaert N. Intracochlear pressure as an objective measure for perceived loudness with bone conduction implants. Hear Res 2022; 422:108550. [PMID: 35689853 DOI: 10.1016/j.heares.2022.108550] [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] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 05/25/2022] [Accepted: 05/28/2022] [Indexed: 01/18/2023]
Abstract
BACKGROUND The generally accepted method to assess the functionality of novel bone conduction implants in a preclinical stage is to experimentally measure the vibratory response of the cochlear promontory. Yet, bone conduction of sound is a complex propagation phenomenon, depending on both frequency and amplitude, involving different conduction pathways. OBJECTIVES The aim of this study is to validate the use of intracochlear sound pressure (ICP) as an objective indicator for perceived loudness for bone conduction stimulation. It is investigated whether a correlation exists between intracochlear sound pressure measurements in cadaveric temporal bones and clinically obtained results using the outcome of a loudness balancing experiment. METHODS Ten normal hearing subjects were asked to balance the perceived loudness between air conducted (AC) sound and bone conducted (BC) sound by changing the AC stimulus. Mean balanced thresholds were calculated and used as stimulation levels in a cadaver trial (N = 4) where intracochlear sound pressure was measured during AC and BC stimulation to assess the correlation with the measured clinical data. The intracochlear pressure was measured at the relatively low stimulation amplitude of 80 dBHL using a lock-in amplification technique. RESULTS Applying AC and BC stimulation at equal perceived loudness on cadaveric heads yield a similar differential intracochlear pressure, with differences between AC and BC falling within the range of variability of normal hearing test subjects. CONCLUSION Comparing the perceived loudness at 80 dB HL for both AC and BC validates intracochlear pressure as an objective indicator of the cochlear drive. The measurement setup is more time-intensive than measuring the vibratory response of the cochlear promontory, yet it provides direct information on the level of the cochlear scalae.
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Affiliation(s)
- Tristan Putzeys
- KU Leuven - University of Leuven, Department of Neurosciences, ExpORL, B-3000 Leuven, Belgium; KU Leuven - University of Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, Heverlee, Belgium.
| | - Charlotte Borgers
- KU Leuven - University of Leuven, Department of Neurosciences, ExpORL, B-3000 Leuven, Belgium
| | - Guy Fierens
- KU Leuven - University of Leuven, Department of Neurosciences, ExpORL, B-3000 Leuven, Belgium; KU Leuven - University of Leuven, Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, Heverlee, Belgium; Cochlear Technology Centre, Mechelen, Belgium
| | | | - Astrid Van Wieringen
- KU Leuven - University of Leuven, Department of Neurosciences, ExpORL, B-3000 Leuven, Belgium
| | - Nicolas Verhaert
- KU Leuven - University of Leuven, Department of Neurosciences, ExpORL, B-3000 Leuven, Belgium; University Hospitals Leuven, Department of Otorhinolaryngology, Head and Neck Surgery, Leuven, Belgium
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Wackers G, Cornelis P, Putzeys T, Peeters M, Tack J, Troost F, Doll T, Verhaert N, Wagner P. Electropolymerized Receptor Coatings for the Quantitative Detection of Histamine with a Catheter-Based, Diagnostic Sensor. ACS Sens 2021; 6:100-110. [PMID: 33337133 DOI: 10.1021/acssensors.0c01844] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this article, we report on the development of a catheter-based, biomimetic sensor as a step toward a minimally invasive diagnostic instrument in the context of functional bowel disorders. Histamine is a key mediator in allergic and inflammatory processes in the small intestines; however, it is a challenge to determine histamine levels at the duodenal mucosa, and classical bioreceptors are unsuitable for use in the digestive medium of bowel fluid. Therefore, we have developed molecularly imprinted polypyrrole coatings for impedimetric sensing electrodes, which enable the quantification of histamine in nondiluted, human bowel fluid in a broad concentration range from 25 nM to 1 μM. The electrodes show negligible cross-sensitivity to histidine as a competitor molecule and, for comparison, we also evaluated the response of nonimprinted and taurine-imprinted polypyrrole to histamine. Furthermore, using equivalent-circuit modeling, we found that the molecular recognition of histamine by polypyrrole primarily increases the resistive component of the electrode-liquid interface while capacitive effects are negligible. The sensor, integrated into a catheter, measures differentially to correct for nonspecific adsorption effects in the complex matrix of bowel fluids, and a single triggering frequency is sufficient to determine histamine concentrations. Together, these features are beneficial for real-time diagnostic tests.
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Affiliation(s)
- Gideon Wackers
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
| | - Peter Cornelis
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
| | - Tristan Putzeys
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
- Research Group Experimental Oto-rhino-laryngology, KU Leuven, O&N II, Herestraat 49, Leuven B-3001, Belgium
| | - Marloes Peeters
- School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K
| | - Jan Tack
- Translational Research in Gastrointestinal Disorders TARGID, KU Leuven, O&N I, Herestraat 49, Leuven B-3000, Belgium
| | - Freddy Troost
- NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Universiteitsingel 40, ER Maastricht NL-6229, The Netherlands
| | - Theodor Doll
- Institute of AudioNeuroTechnology VIANNA, Hannover Medical School, Stadtfelddamm 34, Hannover D-30625, Germany
| | - Nicolas Verhaert
- Research Group Experimental Oto-rhino-laryngology, KU Leuven, O&N II, Herestraat 49, Leuven B-3001, Belgium
| | - Patrick Wagner
- Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, Leuven B-3001, Belgium
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Grigoriadi K, Wübbenhorst M, Breemen LCA, Putzeys T, Gennaro A, Anderson PD, Hütter M. Transient dynamics of cold‐rolled and subsequently thermally rejuvenated atactic‐polystyrene using broadband dielectric spectroscopy. Journal of Polymer Science 2020. [DOI: 10.1002/pol.20190068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kalouda Grigoriadi
- Polymer Technology, Department of Mechanical EngineeringEindhoven University of Technology Eindhoven The Netherlands
- Dutch Polymer Institute Eindhoven The Netherlands
| | | | - Lambèrt C. A. Breemen
- Polymer Technology, Department of Mechanical EngineeringEindhoven University of Technology Eindhoven The Netherlands
| | | | | | - Patrick D. Anderson
- Polymer Technology, Department of Mechanical EngineeringEindhoven University of Technology Eindhoven The Netherlands
| | - Markus Hütter
- Polymer Technology, Department of Mechanical EngineeringEindhoven University of Technology Eindhoven The Netherlands
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Pan H, Geysens P, Putzeys T, Gennaro A, Yi Y, Li H, Atkin R, Binnemans K, Luo J, Wübbenhorst M. Physicochemical study of diethylmethylammonium methanesulfonate under anhydrous conditions. J Chem Phys 2020; 152:234504. [PMID: 32571054 DOI: 10.1063/5.0011756] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The protic ionic liquid diethylmethylammonium methanesulfonate ([DEMA][OMs]) was analyzed in depth by differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and broadband dielectric spectroscopy (BDS) under anhydrous conditions. Karl Fischer titration, NMR, and FT-IR spectra confirmed the high purity of [DEMA][OMs]. The melting point (37.7 °C) and the freezing point (14.0 °C) obtained by DSC agree well with the values determined by BDS (40.0 °C and 14.0 °C). The dc conductivity (σdc) above the melting/freezing point obeys the Vogel-Fulcher-Tammann (VFT) equation well, and thus, the proton conduction in [DEMA][OMs] is assumed to be dominated by the vehicle mechanism. In contrast, the σdc below the melting/freezing point can be fitted by the Arrhenius equation separately, and therefore, the proton conduction is most likely governed by the proton hopping mechanism. The non-negligible influence of previously reported low water content on the physicochemical properties of [DEMA][OMs] is found, indicating the importance of reducing water content as much as possible for the study of "intrinsic" properties of protic ionic liquids.
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Affiliation(s)
- Hailong Pan
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
| | - Pieter Geysens
- Department of Chemistry, KU Leuven, 3001 Leuven, Belgium
| | - Tristan Putzeys
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
| | - Alessia Gennaro
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
| | - Yingting Yi
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
| | - Hua Li
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Rob Atkin
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Koen Binnemans
- Department of Chemistry, KU Leuven, 3001 Leuven, Belgium
| | - Jiangshui Luo
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
| | - Michael Wübbenhorst
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Leuven 3001, Belgium
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10
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Wackers G, Putzeys T, Peeters M, Van de Cauter L, Cornelis P, Wübbenhorst M, Tack J, Troost F, Verhaert N, Doll T, Wagner P. Towards a catheter-based impedimetric sensor for the assessment of intestinal histamine levels in IBS patients. Biosens Bioelectron 2020; 158:112152. [PMID: 32275205 DOI: 10.1016/j.bios.2020.112152] [Citation(s) in RCA: 8] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 12/18/2022]
Abstract
In this work, we report on the development of a catheter-based sensor designed for measuring the concentration of histamine in the human duodenum. Certain gut disorders, such as the irritable bowel syndrome (IBS), are associated with elevated levels of intestinal histamine due to chronic immune activation. As it is still impossible to determine histamine concentrations in vivo, a nasointestinal catheter with histamine-sensing capabilities has the potential to become a valuable diagnostic instrument. Regarding the sensing principle, we selected impedance spectroscopy using voltages that are compatible with intra-body applications with molecularly imprinted polymers (MIPs) as recognition elements. MIPs are synthetic receptors that offer the advantages of robustness, high specificity and selectivity for histamine as a target. In this specific case, the MIPs were synthesized from acryclic acid monomers, which guarantees a uniform binding capacity within the pH range of intestinal fluid. We have validated the catheter sensor on human intestinal liquids spiked with histamine in a testing setup that mimics the environment inside the duodenum. The dose-response curves show an analytical range between 5 and 200 nM of histamine, corresponding to physiologically normal conditions while higher concentrations correlate with disease. The key output signal of the sensor is the resistive component of the MIP-functionalized titanium electrodes as derived from the equivalent-circuit modelling of full-range impedance spectra. Future applications could be catheters tailored to cardiovascular, urological, gastrointestinal, and neurovascular applications. This, in combination with the versatility of the MIPs, will make this sensor platform a versatile diagnostic tool.
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Affiliation(s)
- Gideon Wackers
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium.
| | - Tristan Putzeys
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium; KU Leuven, Research Group Experimental Oto-rhino-laryngology, O&N II, Herestraat 49, B-3001, Leuven, Belgium
| | - Marloes Peeters
- Newcastle University, School of Engineering, Newcastle NE1 7RU, United Kingdom
| | - Lori Van de Cauter
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium
| | - Peter Cornelis
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium
| | - Michael Wübbenhorst
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium
| | - Jan Tack
- KU Leuven, Translational Research in Gastrointestinal Disorders, O&N I, Herestraat 49, B-3001, Leuven, Belgium
| | - Freddy Troost
- Food Innovation and Health, Centre for Healthy Eating and Food Innovation, Maastricht University, NUTRIM School of Nutrition and Translational Research in Metabolism, Universiteitssingel 40, NL-6229 ER, Maastricht, the Netherlands
| | - Nicolas Verhaert
- KU Leuven, Research Group Experimental Oto-rhino-laryngology, O&N II, Herestraat 49, B-3001, Leuven, Belgium
| | - Theodor Doll
- Hannover Medical School, Institute of AudioNeuroTechnology VIANNA, Stadtfelddamm 34, D-30625, Hannover, Germany
| | - Patrick Wagner
- KU Leuven, Laboratory for Soft Matter and Biophysics, Celestijnenlaan 200 D, B-3001, Leuven, Belgium
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11
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Gorbunov AV, Putzeys T, Urbanavičiūtė I, Janssen RAJ, Wübbenhorst M, Sijbesma RP, Kemerink M. True ferroelectric switching in thin films of trialkylbenzene-1,3,5-tricarboxamide (BTA). Phys Chem Chem Phys 2018; 18:23663-72. [PMID: 27510767 DOI: 10.1039/c6cp03835b] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [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
We have investigated the ferroelectric polarization switching properties of trialkylbenzene-1,3,5-tricarboxamide (BTA), which is a model system for a large class of novel organic ferroelectric materials. In the solid state BTAs form a liquid crystalline columnar hexagonal phase that provides long range order that was previously shown to give rise to hysteretic dipolar switching. In this work the nature of the polar switching process is investigated by a combination of dielectric relaxation spectroscopy, depth-resolved pyroelectric response measurements, and classical frequency- and time-dependent electrical switching. We show that BTAs, when brought in a homeotropically aligned hexagonal liquid crystalline phase, are truly ferroelectric. Analysis of the transient switching behavior suggests that the ferroelectric switching is limited by a highly dispersive nucleation process, giving rise to a wide distribution of switching times.
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Affiliation(s)
- A V Gorbunov
- Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
| | - T Putzeys
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | - I Urbanavičiūtė
- Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183 Linköping, Sweden.
| | - R A J Janssen
- Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
| | - M Wübbenhorst
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | - R P Sijbesma
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P. O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - M Kemerink
- Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands and Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183 Linköping, Sweden.
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12
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Munro T, Putzeys T, Copeland CG, Xing C, Lewis RV, Ban H, Glorieux C, Wubbenhorst M. Investigation of synthetic spider silk crystallinity and alignment via electrothermal, pyroelectric, literature XRD, and tensile techniques. Macromol Mater Eng 2017; 302:1600480. [PMID: 29430211 PMCID: PMC5804743 DOI: 10.1002/mame.201600480] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The processes used to create synthetic spider silk greatly affect the properties of the produced fibers. This paper investigates the effect of process variations during artificial spinning on the thermal and mechanical properties of the produced silk. Property values are also compared to the ones of the natural dragline silk of the N. clavipes spider, and to unprocessed (as-spun) synthetic silk. Structural characterization by scanning pyroelectric microscopy is employed to provide insight into the axial orientation of the crystalline regions of the fiber and is supported by XRD data. The results show that stretching and passage through liquid baths induce crystal formation and axial alignment in synthetic fibers, but with different structural organization than natural silks. Furthermore, an increase in thermal diffusivity and elastic modulus is observed with decreasing fiber diameter, trending towards properties of natural fiber. This effect seems to be related to silk fibers being subjected to a radial gradient during production.
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Affiliation(s)
- Troy Munro
- Mechanical Engineering Department, Brigham Young University, Provo, UT 84602, USA
| | - Tristan Putzeys
- Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, TU/e Eindhoven University of Technology, 5600 MB Eindhoven, the Netherlands Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
| | - Cameron G Copeland
- Synthetic Bioproducts Center, Biology Dept., Utah State University, North Logan, UT 84341, USA
| | - Changhu Xing
- Mechanical and Aerospace Engineering Department, Utah State University, Logan, UT 84322, USA
| | - Randolph V Lewis
- Synthetic Bioproducts Center, Biology Dept., Utah State University, North Logan, UT 84341, USA
| | - Heng Ban
- Mechanical and Aerospace Engineering Department, Utah State University, Logan, UT 84322, USA
| | - Christ Glorieux
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
| | - Michael Wubbenhorst
- Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Heverlee B-3001, Belgium
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13
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Gorbunov AV, Meng X, Urbanaviciute I, Putzeys T, Wübbenhorst M, Sijbesma RP, Kemerink M. Polarization loss in the organic ferroelectric trialkylbenzene-1,3,5-tricarboxamide (BTA). Phys Chem Chem Phys 2017; 19:3192-3200. [DOI: 10.1039/c6cp08015d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The depolarization mechanism for the archetypical molecular ferroelectric BTA is quantitatively understood as an activated collective reversal of molecular dipoles.
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Affiliation(s)
- A. V. Gorbunov
- Department of Applied Physics
- Eindhoven University of Technology
- 5600 MB Eindhoven
- The Netherlands
| | - X. Meng
- Laboratory of Macromolecular and Organic Chemistry
- Eindhoven University of Technology
- 5600 MB Eindhoven
- The Netherlands
| | - I. Urbanaviciute
- Complex Materials and Devices
- Department of Physics
- Chemistry and Biology (IFM)
- Linköping University
- 58183 Linköping
| | - T. Putzeys
- Department of Physics and Astronomy
- Laboratory for Soft Matter and Biophysics
- KU Leuven
- B-3001 Heverlee
- Belgium
| | - M. Wübbenhorst
- Department of Physics and Astronomy
- Laboratory for Soft Matter and Biophysics
- KU Leuven
- B-3001 Heverlee
- Belgium
| | - R. P. Sijbesma
- Laboratory of Macromolecular and Organic Chemistry
- Eindhoven University of Technology
- 5600 MB Eindhoven
- The Netherlands
| | - M. Kemerink
- Department of Applied Physics
- Eindhoven University of Technology
- 5600 MB Eindhoven
- The Netherlands
- Complex Materials and Devices
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14
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Gorbunov AV, Haedler AT, Putzeys T, Zha RH, Schmidt HW, Kivala M, Urbanavičiu̅tė I, Wübbenhorst M, Meijer EW, Kemerink M. Switchable Charge Injection Barrier in an Organic Supramolecular Semiconductor. ACS Appl Mater Interfaces 2016; 8:15535-15542. [PMID: 27246280 DOI: 10.1021/acsami.6b02988] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We disclose a supramolecular material that combines semiconducting and dipolar functionalities. The material consists of a discotic semiconducting carbonyl-bridged triarylamine core, which is surrounded by three dipolar amide groups. In thin films, the material self-organizes in a hexagonal columnar fashion through π-stacking of the molecular core and hydrogen bonding between the amide groups. Alignment by an electrical field in a simple metal/semiconductor/metal geometry induces a polar order in the interface layers near the metal contacts that can be reversibly switched, while the bulk material remains nonpolarized. On suitably chosen electrodes, the presence of an interfacial polarization field leads to a modulation of the barrier for charge injection into the semiconductor. Consequently, a reversible switching is possible between a high-resistance, injection-limited off-state and a low-resistance, space-charge-limited on-state. The resulting memory diode shows switchable rectification with on/off ratios of up to two orders of magnitude. This demonstrated multifunctionality of a single material is a promising concept toward possible application in low-cost, large-area, nonvolatile organic memories.
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Affiliation(s)
| | | | - Tristan Putzeys
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | | | - Hans-Werner Schmidt
- Makromolekuläre Chemie I, Bayreuther Institut für Makromolekülforschung (BIMF), and Bayreuther Zentrum für Kolloide und Grenzflächen (BZKG), Universität Bayreuth , 95440 Bayreuth, Germany
| | - Milan Kivala
- Lehrstuhl für Organische Chemie I, Department Chemie und Pharmazie, Friedrich-Alexander-Universität Erlangen-Nürnberg , 91054 Erlangen, Germany
| | - Indre Urbanavičiu̅tė
- Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University , 58183 Linköping, Sweden
| | - Michael Wübbenhorst
- Department of Physics and Astronomy, Laboratory for Soft Matter and Biophysics, KU Leuven , Celestijnenlaan 200D, B-3001 Heverlee, Belgium
| | | | - Martijn Kemerink
- Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping University , 58183 Linköping, Sweden
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15
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Markey K, Putzeys T, Horcajada P, Devic T, Guillou N, Wübbenhorst M, Van Cleuvenbergen S, Verbiest T, De Vos DE, van der Veen MA. Second harmonic generation microscopy reveals hidden polar organization in fluoride doped MIL-53(Fe). Dalton Trans 2016; 45:4401-6. [PMID: 26812223 DOI: 10.1039/c5dt04632g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [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
Polar metal-organic frameworks have potential applications as functional non-linear optical, piezoelectric, pyroelectric and ferroelectric materials. Using second harmonic generation microscopy we found that fluoride doping of the microporous iron(iii) terephthalate MOF MIL-53(Fe) induces a polar organization in its structure, which was not previously detected with XRD. The polar order is only observed when both fluoride and guest molecules are present, and may be related to a complex interplay between the adsorbates and the framework, leading to a modification of the positioning of fluoride in the inorganic Fe-chains. Combined polarized second harmonic generation microscopy and scanning pyroelectric microscopy show that the polar axis is unidirectional and of the same sense over the whole crystal, extending up to 100 micrometers. This finding shows how MOF materials can be endowed with useful properties by doping MOFs with fluoride.
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Affiliation(s)
- Karen Markey
- Centre for Surface Chemistry and Catalysis, University of Leuven, Belgium
| | | | - Patricia Horcajada
- Institut Lavoisier, UMR 8180 CNRS - University of Versailles St-Quentin-en-Yvelines, France
| | - Thomas Devic
- Institut Lavoisier, UMR 8180 CNRS - University of Versailles St-Quentin-en-Yvelines, France
| | - Nathalie Guillou
- Institut Lavoisier, UMR 8180 CNRS - University of Versailles St-Quentin-en-Yvelines, France
| | | | | | - Thierry Verbiest
- Molecular Electronics and Photonics, University of Leuven, Belgium
| | - Dirk E De Vos
- Centre for Surface Chemistry and Catalysis, University of Leuven, Belgium
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16
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Abstract
Recently [S. Capponi, S. Napolitano, and M. Wübbenhorst, Nat. Commun. 3, 1233 (2012)], vapor deposited glasses of glycerol have been found to recover their super-cooled liquid state via a metastable, ordered liquid (MROL) state characterized by a tremendously enhanced dielectric strength along with a slow-down of the relaxation rate of the structural relaxation. To study the calorimetric signature of this phenomenon, we have implemented a chip-based, differential AC calorimeter in an organic molecular beam deposition setup, which allows the simultaneous measurement of dielectric relaxations via interdigitated comb electrodes and specific heat relaxation spectra during deposition and as function of the temperature. Heating of the as-deposited glass just above the bulk Tg and subsequent cooling/reheating revealed a step-wise increase in cp by in total 9%, indicating unambiguously that glycerol, through slow vapour deposition, forms a thermodynamically stable glass, which has a specific heat as low as that of crystalline glycerol. Moreover, these glasses were found to show excellent kinetic stability as well as evidenced by both a high onset-temperature and quasi-isothermal recovery measurements at -75 °C. The second goal of the study was to elucidate the impact of the MROL state on the specific heat and its relaxation to the super-cooled state. Conversion of "MROL glycerol" to its "normal" (ordinary liquid, OL) state revealed a second, small (∼2%) increase of the glassy cp, a little gain (<10%) in the relaxed specific heat, and no signs of deviations of τcal from that of normal "bulk" glycerol. These findings altogether suggest that the MROL state in glycerol comprises largely bulk-type glycerol that coexist with a minor volume fraction (<10%) of PVD-induced structural anomalies with a crystal-like calorimetric signature. Based on the new calorimetric findings, we have proposed a new physical picture that assumes the existence of rigid polar clusters (RPCs) and conclusively explains the extraordinary high kinetic stability of the MROL state, its specific calorimetric signature, the enhanced strength, and apparent slow-down of the dielectric α-relaxation. In this new picture, the incredibly slow and strengthened dielectric response is ascribed to driven rotational diffusion of whole RPCs, a mechanism that perfectly couples to the relaxation time of the "normal" glycerol fraction. First considerations based on the strength and the retardation of the dielectric RPCs' response yield independently a size estimate for the RPCs in the order of 4-5 nm. Finally, we have discussed possible crystallisation and reorganisation effects, which give rise to pronounced out-of phase components of the specific heat at higher temperatures.
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Affiliation(s)
- A Kasina
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
| | - T Putzeys
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
| | - M Wübbenhorst
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven, Leuven, Belgium
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17
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Burgener M, Putzeys T, Gashti MP, Busch S, Aboulfadl H, Wübbenhorst M, Kniep R, Hulliger J. Polar Nature of Biomimetic Fluorapatite/Gelatin Composites: A Comparison of Bipolar Objects and the Polar State of Natural Tissue. Biomacromolecules 2015; 16:2814-9. [PMID: 26252528 DOI: 10.1021/acs.biomac.5b00770] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The correspondence of the state of alignment of macromolecules in biomimetic materials and natural tissues is demonstrated by investigating a mechanism of electrical polarity formation: An in vitro grown biomimetic FAp/gelatin composite is investigated for its polar properties by second harmonic (SHGM) and scanning pyroelectric microscopy (SPEM). Hexagonal prismatic seed crystals formed in gelatin gels represent a monodomain polar state, due to aligned mineralized gelatin molecules. Later growth stages, showing dumbbell morphologies, develop into a bipolar state because of surface recognition by gelatin functionality: A reversal of the polar alignment of macromolecules, thus, takes place close to that basal plane of the seed. In natural hard tissues (teeth and bone investigated by SPEM) and the biomimetic FAp/gelatin composite, we find a surprising analogy in view of growth-induced states of polarity: The development of polarity in vivo and in vitro can be explained by a Markov-type mechanism of molecular recognition during the attachment of macromolecules.
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Affiliation(s)
- Matthias Burgener
- Department of Chemistry and Biochemistry, University of Berne , Freiestrasse 3, CH-3012 Berne, Switzerland
| | - Tristan Putzeys
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven , Celestijnenlaan 200d, B-3001 Leuven, Belgium
| | - Mazeyar Parvinzadeh Gashti
- Department of Chemistry and Biochemistry, University of Berne , Freiestrasse 3, CH-3012 Berne, Switzerland
| | - Susanne Busch
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
| | - Hanane Aboulfadl
- Department of Chemistry and Biochemistry, University of Berne , Freiestrasse 3, CH-3012 Berne, Switzerland
| | - Michael Wübbenhorst
- Department of Physics and Astronomy, Soft Matter and Biophysics Section, KU Leuven , Celestijnenlaan 200d, B-3001 Leuven, Belgium
| | - Rüdiger Kniep
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
| | - Jürg Hulliger
- Department of Chemistry and Biochemistry, University of Berne , Freiestrasse 3, CH-3012 Berne, Switzerland
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18
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Putzeys T, Wübbenhorst M. Asymmetric polarization and hysteresis behaviour in ferroelectric P(VDF–TrFE) (76 : 24) copolymer thin films spatially resolved via LIMM. Phys Chem Chem Phys 2015; 17:7767-74. [DOI: 10.1039/c4cp06033d] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [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
The role of charges for achieving and stabilizing the ferroelectric polarization in PVDF–TrFE (76 : 24) is revisited using advanced photothermal methods.
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Affiliation(s)
- T. Putzeys
- Dept. of Physics and Astronomy
- Soft Matter and Biophysics section
- Leuven
- Belgium
| | - M. Wübbenhorst
- Dept. of Physics and Astronomy
- Soft Matter and Biophysics section
- Leuven
- Belgium
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19
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20
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Goris R, Putzeys T, Wagemans J, Wichmann F. A neural population model for pattern detection. J Vis 2011. [DOI: 10.1167/11.11.1165] [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: 11/24/2022] Open
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21
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Vancleef K, Putzeys T, Gheorghiu E, Machilsen B, Wagemans J. Region-based texture segregation and orientation-similarity grouping. J Vis 2011. [DOI: 10.1167/11.11.1080] [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: 11/24/2022] Open
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22
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Putzeys T, Goris R, Wagemans J, Bethge M. Inferring characteristics of stimulus encoding mechanisms using rippled noise stimuli. J Vis 2010. [DOI: 10.1167/9.8.349] [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: 11/24/2022] Open
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23
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Dry MJ, Kogo N, Putzeys T, Wagemans J. Image descriptions in early and mid-level vision: What kind of model is this and what kind of models do we really need? Br J Psychol 2010; 101:27-32; author reply 41-6. [DOI: 10.1348/000712609x458053] [Citation(s) in RCA: 2] [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]
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24
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Bossaert LL, Putzeys T, Monsieurs KG, Van Hoeyweghen RJ. Knowledge, skills and counselling behaviour of Belgian general practitioners on CPR-related issues. Resuscitation 1992; 24:49-54. [PMID: 1332161 DOI: 10.1016/0300-9572(92)90172-9] [Citation(s) in RCA: 7] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
General practitioners (GP) can identify potential cardiac arrest victims. They have the opportunity to inform cardiac patients and their families about the risk of sudden cardiac death and can motivate family members to attend a CPR-course. To study actual counselling practices concerning basic CPR-training a questionnaire was mailed to a representative sample of Belgian GPs (n = 1119). The level of CPR-training of the GPs was fairly good: 67% had received BLS training on a manikin and 63% had already attended a cardiac arrest event. A discrepancy was observed between the positive attitude towards CPR and the counselling of family members to attend a CPR-course (9%). GPs feared to inflict additional stress to the patient (32%) or the family (43%) or did not know where CPR courses were organised (37%). GPs are a primary target group for CPR-training and should learn how to counsel potential bystanders of a cardiac arrest to attend a CPR-course without inflicting additional anxiety on the patient or his family.
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Affiliation(s)
- L L Bossaert
- Department of Intensive Care, University Hospital Antwerp, UIA, Belgium
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