Micro- and nano-patterning of conducting polymers for biomedical applications

La bioélectronique utilise des signaux électriques pour interagir avec des systèmes biologiques. Les capteurs qui permettent la lecture électrique de marqueurs de maladies importantes et les implants/stimulateurs utilisés pour la détection et le traitement d'activité cellulaire pathologique ne sont que quelques exemples de ce que cette technologie peut offrir. Du fait de leurs propriétés électro-actives et mécaniques fascinantes, l'électronique organique ou les matériaux conjugués π ont été largement exploités dans le domaine de la bioélectronique. Le mélange intéressant entre conductivité électronique et ionique de ces polymères conducteurs permet le couplage entre les charges électroniques présentent dans le volume des films organiques avec les flux ioniques du milieu biologique. Le matériau prototypique de la bioélectronique organique est le polymère conducteur poly(3,4-éthylènedioxythiophène) (PEDOT) dopé avec du polystyrène sulfonate (PSS). Dans ce rapport, nous étudierons une approche pour moduler les propriétés mécaniques, électriques et électrochimiques du PEDOT: PSS et étudier leur impact sur la performance des transistors électrochimiques organiques. Par ailleurs, nous évaluerons l'effet de la micro-structuration et du nano-patterning sur l'impédance électrochimique des électrodes en or recouvertes de PEDOT: PSS utiles pour de futurs enregistrements et stimulations neurales. Enfin, nous démontrerons l'utilisation du PEDOT:PSS à micro-motifs pour l'adhésion et la migration de cellules.Bioelectronics uses electrical signals to interact with biological systems. Sensors that allow for electrical read-out of important disease markers, and implants/stimulators used for the detection and treatment of pathological cellular activity are only a few examples of what this technology can offer. Due to their intriguing electroactive and mechanical properties, organic electronics or π-conjugated materials have been extensively explored regarding their use in bioelectronics applications. The attractive mixed electronic/ionic conductivity feature of conducting polymers enables coupling between the electronic charges in the bulk of the organic films with ion fluxes in biological medium. The prototypical material of organic bioelectronics is the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). PEDOT:PSS is commercially available, water-dispersible conjugated polymer complex that can be cast into films of high hole and cation conductivity, good charge storage capacity, biocompatibility, and chemical stability. In the present work we investigate an approach to tailor the mechanical, electrical, and electrochemical properties of PEDOT:PSS and study their impact on the performance of organic electrochemical transistors. In addition, we study the effect of micro-structuring and nano-patterning on the electrochemical impedance of PEDOT:PSS- coated gold electrodes for future neural recordings and stimulation. Moreover we demonstrate the use of micro-patterned PEDOT:PSS in cell adhesion and migration

Micro et nano-patterning de polymères conducteurs pour des applications biomédicales

Bioelectronics uses electrical signals to interact with biological systems. Sensors that allow for electrical read-out of important disease markers, and implants/stimulators used for the detection and treatment of pathological cellular activity are only a few examples of what this technology can offer. Due to their intriguing electroactive and mechanical properties, organic electronics or π-conjugated materials have been extensively explored regarding their use in bioelectronics applications. The attractive mixed electronic/ionic conductivity feature of conducting polymers enables coupling between the electronic charges in the bulk of the organic films with ion fluxes in biological medium. The prototypical material of organic bioelectronics is the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonate (PSS). PEDOT:PSS is commercially available, water-dispersible conjugated polymer complex that can be cast into films of high hole and cation conductivity, good charge storage capacity, biocompatibility, and chemical stability. In the present work we investigate an approach to tailor the mechanical, electrical, and electrochemical properties of PEDOT:PSS and study their impact on the performance of organic electrochemical transistors. In addition, we study the effect of micro-structuring and nano-patterning on the electrochemical impedance of PEDOT:PSS- coated gold electrodes for future neural recordings and stimulation. Moreover we demonstrate the use of micro-patterned PEDOT:PSS in cell adhesion and migration.La bioélectronique utilise des signaux électriques pour interagir avec des systèmes biologiques. Les capteurs qui permettent la lecture électrique de marqueurs de maladies importantes et les implants/stimulateurs utilisés pour la détection et le traitement d'activité cellulaire pathologique ne sont que quelques exemples de ce que cette technologie peut offrir. Du fait de leurs propriétés électro-actives et mécaniques fascinantes, l'électronique organique ou les matériaux conjugués π ont été largement exploités dans le domaine de la bioélectronique. Le mélange intéressant entre conductivité électronique et ionique de ces polymères conducteurs permet le couplage entre les charges électroniques présentent dans le volume des films organiques avec les flux ioniques du milieu biologique. Le matériau prototypique de la bioélectronique organique est le polymère conducteur poly(3,4-éthylènedioxythiophène) (PEDOT) dopé avec du polystyrène sulfonate (PSS). Dans ce rapport, nous étudierons une approche pour moduler les propriétés mécaniques, électriques et électrochimiques du PEDOT: PSS et étudier leur impact sur la performance des transistors électrochimiques organiques. Par ailleurs, nous évaluerons l'effet de la micro-structuration et du nano-patterning sur l'impédance électrochimique des électrodes en or recouvertes de PEDOT: PSS utiles pour de futurs enregistrements et stimulations neurales. Enfin, nous démontrerons l'utilisation du PEDOT:PSS à micro-motifs pour l'adhésion et la migration de cellules

Manipulation of Culture Conditions: Tool for Correlating/Improving Lipid and Carotenoid Production by Rhodotorula glutinis

The coproduction of lipid and carotenoid by red yeasts in one cycle is more convenient and economical for the industrial sectors, while the kinetics correlation between both products under different culture conditions has been scarcely studied. This study is aiming to correlate the impact of different carbon sources, carbon to phosphorus ratio (C/P), temperature, aeration, pH, and metals on dry cell weight, lipid (GC and fluorescence microscope), and carotenoid (HPLC) production by Rhodotorula glutinis, and applying a novel feeding approach using a 5 L bioreactor to enhance carotenoid and unsaturated fatty acid production by R. glutinis. Whatever the culture condition is, the reversible correlation between lipid and carotenoid production was detected. Remarkably, when adding 0.1 mM BaCl2, cellular lipid was significantly increased 14% more than the control, with 79.3% unsaturated fatty acid (46% C18:2 and C18:3) and 50% γ-carotene, while adding 1 mM NiSO4, cellular carotenoid was enhanced around 53% than the control (torulene 88%) with 81% unsaturated fatty acid (61% oleic acid). Excitingly, 68.8 g/l biomass with 41% cellular lipid (79% unsaturated fatty acid) and 426 µgpigment/gdcw cellular carotenoid (29.3 mg/L) (71% torulene) were obtained, when the pH-temperature dual controlled process combined with metallo-sulfo-phospho-glucose feeding approach in the 5 L bioreactor during the accumulation phase was conducted. This is the first study on the kinetic correlation between lipid and carotenoid under different C/P ratio and the dual effect of different metals like NiSO4 on lipid and carotenoid production by red oleaginous yeasts, which in turn significant for enhancing the coproduction of lipid and carotenoid by R. glutinis

Effect of trimetazidine on myocardial salvage index in patients with acute ST segment elevation myocardial infarction undergoing primary PCI

Introduction: Acute STEMI is the most serious presentation of CAD. Restoration of the coronary flow facilitates cardiomyocyte salvage and decreases cardiac morbidity and mortality. However, reperfusion may result in paradoxical cardiomyocyte dysfunction, a phenomenon termed reperfusion injury. Trimetazidine is a metabolic anti-ischemic drug which is beneficial in reducing periprocedural myocardial reperfusion injury. The aim of the work is to study the effect of trimetazidine on myocardial salvage index in patients with acute STEMI who underwent primary PCI. Methods: Forty patients presented with acute STEMI, underwent primary PCI with injection of an intravenous dose of Tc-99m labeled Sestamibi before primary PCI then first set of SPECT images were taken within 6 h from injection time to assess the initial size of the perfusion defect. Prior to discharge the patients received another dose of Tc-99m labeled Sestamibi and follow up SPECT images were taken to assess the final perfusion defect and to calculate myocardial salvage and myocardial salvage index. Twenty patients of them received trimetazidine before primary PCI (study group) and the other twenty patients did not receive trimetazidine (control group). Results: (1) Patients with acute STEMI undergoing primary PCI who received trimetazidine before primary PCI had better myocardial salvage index, however it was statistically non significant. (2) Statistically significant better myocardial salvage index with post procedural TIMI 3 flow than with post procedural TIMI 2 flow among patients who received trimetazidine before primary PCI. Conclusion: In the presence of post procedural TIMI3 flow trimetazidine is beneficial in improving myocardial salvage index in patients presented with acute STEMI who underwent primary PCI

Initial T wave morphology in the chest leads in patients presenting with anterior ST-segment elevation myocardial infarction and its correlation with spontaneous reperfusion of the left anterior descending coronary artery

Background: T wave inversion in leads with ST-segment elevation after reperfusion therapy is considered a sign of reperfusion. However, the significance of T wave inversion on presentation before the initiation of reperfusion therapy is unclear. Aim of the Work: The current study aimed to assess whether the initial T wave morphology in the electrocardiographic (ECG) at presentation can predict patency of the left anterior descending artery (LAD) in patients with acute anterior ST segment elevation myocardial infarction (STEMI) before undergoing primary percutaneous coronary interventions (PCIs). Methods: This study included ninety patients who presented to the emergency department with acute anterior ST-elevation MI. We excluded patients with bundle branch block, postcoronary artery bypass grafting patients, patients with paced rhythm, and patients who received thrombolytic therapy. The T wave morphology in the 2 leads with maximal ST-segment elevation on the presenting ECG was identified as one of the three morphologies, positive T waves (T+; initial positive deflection ≥0.5 mm above the isoelectric line), biphasic T waves (T+/−; where the T wave initially showed a positive deflection above the ST segment afterward followed by a negative deflection ≥0.5 mm below the isoelectric line), and negative T waves (T−; where the T wave initially showed a negative deflection ≥0.5 mm below the isoelectric line without showing any initial positive deflection). Then, according to the results of the initial angiography, patients were classified into spontaneous reperfusion (SR) (those with thrombolysis in MI [TIMI] II or TIMI III flow in the infarct-related artery [IRA] prior to intervention) or non-SR (those with TIMI 0 or TIMI I flow in the IRA prior to intervention). Results: Ninety consecutive patients (77 males and 13 females) presented by STEMI and treated by primary PCI at cath lab of Ainshams University Hospitals (a 24/7 tertiary referral center for primary PCI) between January 2015 and March 2016 were included in this study, of which 40 patients (44.4%) had positive T waves (T+), 34 patients (37.8%) had negative T waves (T−), and 16 patients (17.8%) had biphasic T waves (T+/−). Initial angiogram showed that 18 patients had SR and 72 patients had no SR. With regard to T wave morphology, negative T waves were significantly present in SR group (66.7% vs. 30.6%, P = 0.004), whereas positive T waves were predominantly present in non-SR (50% vs. 22.2%, P = 0.033). Conclusions: For SR of LAD in anterior STEMI patients, prior to primary PCI, T wave inversion had a good sensitivity of 66.7%, a specificity of 69.4%, and a good negative predictive value of 89.29%

Smaller Counter Cation for Higher Transconductance in Anionic Conjugated Polyelectrolytes

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Conjugated polyelectrolytes (CPEs) are a focus of research because combine their inherent electrical conductivity and the ability to interact with ions in aqueous solutions or biological systems. However, it is still not understood to what degree the counter ion in CPEs influences the properties of the CPE itself and the performance of electron ic transducers. In order to investigate this, three different conjugated polyelectrolytes, poly(6-(thiophen-3-yl)hexane-1-sulfonate)s (PTHS − X + ), are synthesized, which have the same polythiophene backbone but different X + counter ions: the bulky tetrabutylammonium (TBA + ), tetraethylammonium (TEA + ), and the smallest tetramethylammonium (TMA + ). At the interface with biological systems, thin CPE films have to be stable in an aqueous environment and should allow the inward and outward flow of ions from the electrolyte. Since the studied PTHS − X + have different solubilities in water, the optical properties of pristine PTHS − X + as well as of crosslinked PTHS − X + via UV–vis absorption spectroscopy are investigated additionally. PTHS − TMA + exhibits better aggregation, fast interdiffusion of ions, and fast recovery from the oxidized state. Additionally, spectroelectrochemical and cyclic voltammetric as well as electrochemical capacitance investigations show that PTHS − TMA + can be oxidized to a higher degree. This leads to a better performance of PTHS − TMA + -based organic electrochemical transistors

Electrically controlled cellular migration on a periodically micropatterned PEDOT:PSS conducting polymer platform

© 2018 Wiley Periodicals, Inc. In the field of tissue engineering, the study of cellular adhesion and migration is of crucial interest. Conducting polymers such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) provide an outstanding interface with biology due to their soft nature, which is closer to the mechanical, chemical, and morphological properties of biological systems. In this work, periodically micropatterned PEDOT:PSS thin films are used as a platform to investigate cellular migration. Human cerebral microvascular endothelial cells (hCMEC) show alignment and linear motion along PEDOT:PSS microstripes of varying widths (10–30 μm). In addition, an electrochemical gradient is created on the PEDOT:PSS film along these microstripes to influence the cell behavior. hCMEC cells linearly change their velocities depending on the redox state of the conducting polymer film. This work demonstrates the potential of such conducting polymer platforms to combine, at the same time, several key physicochemical factors for controlling cellular migration. In the future, we envision that these conducting polymer platforms will deliver tools for tissue regeneration and lead to new opportunities in regenerative medicine. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 47029

The role of absorbed water in ionic liquid cellulosic electrolytes for ionic thermoelectrics

The advantages of large output thermovoltage and sustainable constituent materials have generated a rapid growth in research about ionic thermoelectrics. Recently, giant values of ionic Seebeck coefficients up to 10-26 mV K-1 have been reported. However, the fundamental understanding of the ionic thermoelectric effect is still rudimentary and there is a lack of a well-established measurement standard. In this work, we systematically studied the ionic thermoelectric properties of gel electrolytes made of hydroxyethyl cellulose and an ionic liquid. We discovered that the absorbed water from the atmosphere into the cellulose/ionic liquid gel dramatically increases the apparent ionic Seebeck coefficient from 3 to 12.5 mV K-1. We identified the contribution of a hydrovoltaic voltage generated from water concentration difference as the main reason for the enhanced apparent ionic Seebeck coefficient, which depends on the kinetics of water absorption and desorption on the cold and hot side of the device. Finally, we demonstrated that it is possible to harvest electricity and charge a supercapacitor with intermittent temperature gradients by using this combination of ionic Seebeck voltage and hydrovoltaic voltage.Funding Agencies|Swedish Research Council VRSwedish Research Council [2016-05990, 2018-04037]; Advanced Functional Materials Center at Linkoping University [2009-00971]; Vinnova for the Digital Cellulose Competence Center (DCC)Vinnova [2016-05193]</p

Low-Temperature Cross-Linking of PEDOT:PSS Films Using Divinylsulfone

Recent interest in bioelectronics has prompted the exploration of properties of conducting polymer films at the interface with biological milieus. Poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) from a commercially available source has been used as a model system for these studies. Different cross-linking schemes have been used to stabilize films of this material against delamination and redispersion, but the cost is a decrease in the electrical conductivity and/or additional heat treatment. Here we introduce divinylsulfone (DVS) as a new cross-linker for PEDOT:PSS. Thanks to the higher reactiveness of the vinyl groups of DVS, the cross-linking can be performed at room temperature. In addition, DVS does not reduce electronic conductivity of PEDOT:PSS but rather increases it by acting as a secondary dopant. Cell culture studies show that PEDOT:PSS:DVS films are cytocompatible and support neuroregeneration. As an example, we showed that this material improved the transconductance value and stability of an organic electrochemical transistor (OECT) device. These results open the way for the utilization of DVS as an effective cross-linker for PEDOT:PSS in bioelectronics applications