PEDOT:Nafion for Highly Efficient Supercapacitors

Supercapacitors offer notable properties as energy storage devices, providing high power density and fast charging and discharging while maintaining a long cycling lifetime. Although poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) has become a gold standard among organic electronics materials, researchers are still investigating ways to further improve its capacitive characteristics. In this work, we introduced Nafion as an alternative polymeric counterion to PSS to form highly capacitive PEDOT/Nafion; its advantageous supercapacitive properties were further improved by treatment with either dimethyl sulfoxide or ethylene glycol. Accordingly, electrochemical characterization of PEDOT/Nafion films revealed their high areal capacitance (22 mF cm-2 at 10 mV/s) and low charge transfer resistance (∼380 Ω), together with excellent volumetric capacitance (74 F cm-3), Coulombic efficiency (99%), and an energy density of 23.1 ± 1.5 mWh cm-3 at a power density of 0.5 W cm-3, resulting from a more effective ion diffusion inside the conductive film, as confirmed by the results of spectroscopic studies. A proof-of-concept symmetric supercapacitor based on PEDOT/Nafion was characterized with a specific capacitance of approximately 15.7 F g-1 and impressive long-term stability (Coulombic efficiency ∼99% and capacitance ∼98.7% after 1000 charging/discharging cycles), overperforming the device based on PEDOT/PSS.

Antibacterial coatings for electroceutical devices based on PEDOT decorated with gold and silver particles

The continuous progression in the field of electrotherapies implies the development of multifunctional materials exhibiting excellent electrochemical performance and biocompatibility, promoting cell adhesion, and possessing antibacterial properties. Since the conditions favouring the adhesion of mammalian cells are similar to conditions favouring the adhesion of bacterial cells, it is necessary to engineer the surface to exhibit selective toxicity, i.e., to kill or inhibit the growth of bacteria without damaging mammalian tissues. The aim of this paper is to introduce a surface modification approach based on a subsequent deposition of silver and gold particles on the surface of a conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT). The resulting PEDOT-Au/Ag surface is found to possess optimal wettability, roughness, and surface features making it an excellent platform for cell adhesion. By depositing Ag particles on PEDOT surface decorated with Au particles, it is possible to reduce toxic effects of Ag particles, while maintaining their antibacterial activity. Besides, electroactive and capacitive properties of PEDOT-Au/Ag account for its applicability in various electroceutical therapies.

Surface grafting of poly-L-lysine via diazonium chemistry to enhance cell adhesion to biomedical electrodes

The ability to study and regulate cell behavior at a biomaterial interface requires a strict control over its surface chemistry. Significance of studying cell adhesion in vitro and in vivo has become increasingly important, particularly in the field of tissue engineering and regenerative medicine. A promising surface modification route assumes using organic layers prepared by the method of electrografting of diazonium salts and their further functionalization with biologically active molecules as cell adhesion promoters. This work reports the modification of platinum electrodes with selected diazonium salts and poly-L-lysine to increase the number of sites available for cell adhesion. As-modified electrodes were characterized in terms of their chemical and morphological properties, as well as wettability. In order to monitor the process of cell attachment, biofunctionalized electrodes were used as substrates for culturing human neuroblastoma SH-SY5Y cells. The experiments revealed that cell adhesion is favored on the surface of diazonium-modified and poly-L-lysine coated electrodes, indicating proposed modification route as a valuable strategy enhancing the integration between bioelectronic devices and neural cells.

Biodegradable Scaffolds for Vascular Regeneration Based on Electrospun Poly(L-Lactide-co-Glycolide)/Poly(Isosorbide Sebacate) Fibers

Vascular regeneration is a complex process, additionally limited by the low regeneration potential of blood vessels. Hence, current research is focused on the design of artificial materials that combine biocompatibility with a certain rate of biodegradability and mechanical robustness. In this paper, we have introduced a scaffold material made of poly(L-lactide-co-glycolide)/poly(isosorbide sebacate) (PLGA/PISEB) fibers fabricated in the course of an electrospinning process, and confirmed its biocompatibility towards human umbilical vein endothelial cells (HUVEC). The resulting material was characterized by a bimodal distribution of fiber diameters, with the median of 1.25 µm and 4.75 µm. Genotyping of HUVEC cells collected after 48 h of incubations on the surface of PLGA/PISEB scaffolds showed a potentially pro-angiogenic expression profile, as well as anti-inflammatory effects of this material. Over the course of a 12-week-long hydrolytic degradation process, PLGA/PISEB fibers were found to swell and disintegrate, resulting in the formation of highly developed structures resembling seaweeds. It is expected that the change in the scaffold structure should have a positive effect on blood vessel regeneration, by allowing cells to penetrate the scaffold and grow within a 3D structure of PLGA/PISEB, as well as stabilizing newly-formed endothelium during hydrolytic expansion.

Conducting Polymers as Versatile Tools for the Electrochemical Detection of Cancer Biomarkers

The detection of cancer biomarkers has recently become an established method for the early diagnosis of cancer. The sensitive analysis of specific biomarkers can also be clinically applied for the determination of response to treatment and monitoring of disease progression. Because of the ultra-low concentration of cancer biomarkers in body fluids, diagnostic tools need to be highly sensitive and specific. Conducting polymers (CPs) are particularly known to exhibit numerous features that enable them to serve as excellent materials for the immobilization of biomolecules and the facilitation of electron transfer. Their large surface area, porosity, and the presence of functional groups provide CPs with binding sites suitable for capturing biomarkers, in addition to their sensitive and easy detection. The aim of this review is to present a comprehensive summary of the available electrochemical biosensors based on CPs and their composites for the ultrasensitive detection of selected cancer biomarkers. We have categorized the study based on different types of targeted biomarkers such as DNAs, miRNAs, proteins, enzymes, neurotransmitters and whole cancer cells. The sensitivity of their detection is enhanced by the presence of CPs, providing a limit of detection as low as 0.5 fM (for miRNA) and 10 cells (for the detection of cancer cells). The methods of multiplex biomarker detection and cell capture are indicated as the most promising category, since they furnish more accurate and reliable results. Ultimately, we discuss the available CP-based electrochemical sensors and promising approaches for facilitating cancer diagnosis and treatment.

Dopant-Dependent Electrical and Biological Functionality of PEDOT in Bioelectronics

The aspiration to interact living cells with electronics challenges researchers to develop materials working at the interface of these two distinct environments. A successful interfacing coating should exhibit both biocompatibility and desired functionality of a bio-integrated device. Taking into account biodiversity, the tissue interface should be fine-tuned to the specific requirements of the bioelectronic systems. In this study, we pointed to electrochemical doping of conducting polymers as a strategy enabling the efficient manufacturing of interfacing platforms, in which features could be easily adjusted. Consequently, we fabricated conducting films based on a poly(3,4-ethylenedioxythiophene) (PEDOT) matrix, with properties modulated through doping with selected ions: PSS- (poly(styrene sulfonate)), ClO4- (perchlorate), and PF6- (hexafluorophosphate). Striving to extend the knowledge on the relationships governing the dopant effect on PEDOT films, the samples were characterized in terms of their chemical, morphological, and electrochemical properties. To investigate the impact of the materials on attachment and growth of cells, rat neuroblastoma B35 cells were cultured on their surface and analyzed using scanning electron microscopy and biological assays. Eventually, it was shown that through the choice of a dopant and doping conditions, PEDOT-based materials can be efficiently tuned with diversified physicochemical properties. Therefore, our results proved electrochemical doping of PEDOT as a valuable strategy facilitating the development of promising tissue interfacing materials with characteristics tailored as required.

Electrical percolation in extrinsically conducting, poly(ε-decalactone) composite neural interface materials

By providing a bidirectional communication channel between neural tissues and a biomedical device, it is envisaged that neural interfaces will be fundamental in the future diagnosis and treatment of neurological disorders. Due to the mechanical mismatch between neural tissue and metallic neural electrodes, soft electrically conducting materials are of great benefit in promoting chronic device functionality. In this study, carbon nanotubes (CNT), silver nanowires (AgNW) and poly(hydroxymethyl 3,4-ethylenedioxythiophene) microspheres (MSP) were employed as conducting fillers within a poly(ε-decalactone) (EDL) matrix, to form a soft and electrically conducting composite. The effect of a filler type on the electrical percolation threshold, and composite biocompatibility was investigated in vitro. EDL-based composites exhibited favourable electrochemical characteristics: EDL/CNT-the lowest film resistance (1.2 ± 0.3 kΩ), EDL/AgNW-the highest charge storage capacity (10.7 ± 0.3 mC cm- 2), and EDL/MSP-the highest interphase capacitance (1478.4 ± 92.4 µF cm-2). All investigated composite surfaces were found to be biocompatible, and to reduce the presence of reactive astrocytes relative to control electrodes. The results of this work clearly demonstrated the ability of high aspect ratio structures to form an extended percolation network within a polyester matrix, resulting in the formulation of composites with advantageous mechanical, electrochemical and biocompatibility properties.

Analysis of a poly(ε-decalactone)/silver nanowire composite as an electrically conducting neural interface biomaterial

Background

Advancement in polymer technologies, facilitated predominantly through chemical engineering approaches or through the identification and utilization of novel renewable resources, has been a steady focus of biomaterials research for the past 50 years. Aliphatic polyesters have been exploited in numerous biomedical applications including the formulation of soft-tissue sutures, bone fixation devices, cardiovascular stents etc. Biomimetic ‘soft’ polymer formulations are of interest in the design of biological interfaces and specifically, in the development of implantable neuroelectrode systems intended to interface with neural tissues. Critically, soft polymer formulations have been shown to address the challenges associated with the disregulation of mechanotransductive processes and micro-motion induced inflammation at the electrode/tissue interface. In this study, a polyester-based poly(ε-decalactone)/silver nanowire (EDL:Ag) composite was investigated as a novel electrically active biomaterial with neural applications.

Neural interfaces were formulated through spin coating of a polymer/nanowire formulation onto the surface of a Pt electrode to form a biocompatible EDL matrix supported by a percolated network of silver nanowires. As-formed EDL:Ag composites were characterized by means of infrared spectroscopy, scanning electron microscopy and electrochemical methods, with their cytocompatibility assessed using primary cultures of a mixed neural population obtained from the ventral mesencephalon of Sprague-Dawley rat embryos.

Results

Electrochemical characterization of various EDL:Ag composites indicated EDL:Ag 10:1 as the most favourable formulation, exhibiting high charge storage capacity (8.7 ± 1.0 mC/cm²), charge injection capacity (84.3 ± 1.4 μC/cm²) and low impedance at 1 kHz (194 ± 28 Ω), outperforming both pristine EDL and bare Pt electrodes. The in vitro biological evaluation showed that EDL:Ag supported significant neuron viability in culture and to promote neurite outgrowth, which had the average length of 2300 ± 6 μm following 14 days in culture, 60% longer than pristine EDL and 120% longer than bare Pt control substrates.

Conclusions

EDL:Ag nanocomposites are shown to serve as robust neural interface materials, possessing favourable electrochemical characteristics together with high neural cytocompatibility.

Psychogenic voice disorders

INTRODUCTION

Voice express the psyche and personality of a person. Psychogenic dysphonia is called Phononeurosis. Neurosis, depression or family, occupational and social conflicts are the cause of voice disturbances. The most frequent type of dysphonia is hyperfunctional dysphonia, rarer - hypofunctional type.

AIM

The aim of this study is an analysis of voice quality and diagnosis of clinical type of psychogenic dysphonia.

MATERIAL AND METHODS

The analyzed group consisted of 50 patients with voice disorders treated in 2017 and the control group - 30 people with physiological voice. In the diagnosed group 60% of patients were treated for neurosis, 12% due to depression, the others reported conflict situations. In the diagnosis of clinical type of psychogenic dysphonia GRBAS scale was used, maximum phonation time (MPT) and type of breathing were assessed. The visualisation of the larynx was performed using High Speed Digital Imaging (HSDI) technique. The parametric acoustic evaluation of voice was conducted.

RESULTS

The most often clinical type of psychogenic dysphonia was hyperfunctional dysphonia, rarer hypofunctional type and vestibular voice. Dysphonia occurred the most often in women during the highest professional activity period. In the diagnosis of clinical type HSDI technique was especially useful allowing to visualization of the real vocal fold vibration and objective differentiation of hyper- and hypofunctional dysphonia. The acoustic analysis of the voice objectively confirmed the presence non-harmonic components - noise generated in the glottis in hypofunctional dysphonia. Disturbances in the way and breathing type caused irregularities in respiratory-phonic and articulation coordination.

Usefulness of high-speed digital imaging (HSDI) in the diagnosis of oedematous - hypertrophic changes of the larynx in people using voice occupationally

INTRODUCTION

The aim of the study is the evaluation of the usefulness of High-Speed Digital Imaging (HSDI) in the diagnosis of organic dysphonia in a form of oedematous-hypertrophic changes of vocal fold mucosa, morphologically confirmed by Transmission Electron Microscopy (TEM) method in patients working with voice occupationally.

MATERIAL AND METHODS

The group consisted of 30 patients working with voice occupationally with oedematous-hypertrophic changes of vocal fold mucosa. Parameters of vocal folds vibrations were evaluated using HSDI technique with a digital HS camera, HRES Endocam Richard Wolf GmbH. The image of vocal folds was recorded with a rate of 4000 frames per second. Postoperative material of the larynx was prepared in a routine way and observed in transmission electron microscope OPTON 900-PC.

RESULTS

HSDI technique allows to assess the real vibrations of vocal folds and determine many parameters. The results of TEM in the postoperative material showed destruction of epithelial cells with severe vacuolar degeneration, the enlargement of intercellular spaces and a large number of blood vessels in the stroma, which indicates the presence of oedematous-hypertrophic changes of the larynx.

DISCUSSION

The ultrastructural assessment confirm the particular usefulness of HSDI method in the diagnosis of organic dysphonia in a form of oedematous-hypertrophic changes. Key words: High-Speed Digital Imaging, oedematous-hypertrophic changes, vocal fold mucosa, larynx.

[Rehabilitation of phonosurgically treated patients with edematous-hypertrophic changes of larynx]

Advanced change of organic dysphonia are an indication for phonosurgery. Edematous-hypertrophic changes are cause of serious disturbances of voice. High-speed digital imaging (HSDI) technique is the unique method, allowing for assessment the effects of therapy and rehabilitation.

AIM

The aim of the study is evaluation the usefulness of vibratory method in voice rehabilitation of patients with edematous-hypertrophic changes treated phonosurgically.

MATERIALS AND METHODS

The group I contained 40 patients with edematous-hypertrophical changes phonosurgically treated. Type of clinical dysphonia was diagnosed with HSDI technique. Glottal closure was evaluated according to Committee on Phoniatrics of the European Laryngological Society (ELS) classification, postoperative material was pathomorphologically verified by Transmission Electron Microscopy (TEM). Patients with hyperfunction of larynx were rehabilitated for 21 days using massage device and after that visualization of larynx by HSDI technique was made again. Control group contains people with physiological voice.

RESULTS

Severe dysphonia with oedematous-hypertrophic changes was found by HSDI technique in group I. Postoperative material was evaluated histopathological by TEM and confirmed the existing clinical morphological changes of larynx. Hyperfunction of phonation organ were diagnosed in 30 patients (75%). After 21 days of rehabilitation using massage device, hyperfunction was reduced as confirmed by HSDI. Normalization of amplitude, regularity, synchrony of vibration and physiological glottal closure were found at 67% cases.

CONCLUSIONS

HSDI technique in digital sequence is useful in the diagnosis of edematous-hypertrophic changes of the larynx and monitoring the effects of the rehabilitation. Pathomorphological evaluation of postoperative material made by TEM confirmed the rightness of clinical diagnosis of the edematous-hypertrophic changes by HSDI. The consequence of phonosurgical procedures in edematous-hypertrophic changes of larynx is hyperfunction of larynx, confirmed objectively by HSDI technique. The use of massage device causes relaxation of laryngeal structures, normalizing parameters of visualizing evaluation.

[High-speed digital imaging in the diagnosis of voice pathologies]

Technique of high-speed digital imaging (HSDI) is unique technique, allowing for assessment of real vocal fold vibrations.

AIM

The aim of the study is to present the usefulness of HSDI in the diagnosis of clinical type of dysphonia.

MATERIALS AND METHODS

The study group was diagnosed at the Department of Clinical Phonoaudiology and Logopedics at the Medical University of Białystok and treated at the Phoniatric Clinic in years 2012-2015. HSDI technique with a digital camera was used for visualization of the larynx. The rigid endoscope with 90° optics was used for visualizing the vocal folds vibrations during phonation of "e" vowel, at the rate of 4000 frames per second. Playback of recorded sequence set at 15 frames per second, what allowed to assess vocal folds vibrations in slow motion mode during over 8 minutes. Mucosal wave (MW), glottal closure, symmetry, regularity and synchrony of vocal fold vibration were analyzed. Digital kymography (DKG) of the larynx was made for analyzing the value of the Open Quotient (OQ) in the assessment of degree of glottal insufficiency.

RESULTS

In the analyzed group of patients, the functional dysphonia was diagnosed in 71%, organic dysphonia in 29% patients. In 68%, glottal insufficiency was registered in the rear part at the glottis. The oedematous-hypertrophic changes were diagnosed in 21% of the cases, hypertrophic changes of larynx - in 6%, vocal fold polyps - in 3% and vocal fold nodules - in 2% of patients.

CONCLUSIONS

Examination of the larynx by using HSDI technique is quick, non-invasive to patient. HSDI allows to objective assessment of the degree of severity of insufficiency of glottal closure, what is confirmed by the objective values of the OQ. Evaluation of MW allows for the differentiation of clinical type and severity of organic dysphonia.

The ability of soil-borne fungi to degrade organophosphonate carbon-to-phosphorus bonds

The ability of a wide variety of soil-borne fungal strains to degrade four structurally different compounds containing P-C bonds, namely the naturally occurring amino acid ciliatine, the popular herbicide glyphosate, phosphonoacetic acid and 2-amino-3-phosphonopropionic acid, was studied in order to show that soil fungi may play an important role in the biodegradation of organophosphonates. Most of the strains appeared to utilize ciliatine as the sole source of phosphorus for growth. Only a limited number of strains were able to grow on the other phosphonates used in this work. The strains of Trichoderma harzianum, Scopulariopsis sp. and Aspergillus niger chosen for more detailed study show the ability to degrade ciliatine, glyphosate and also amino(3-methoxyphenyl)methylphosphonic acid effectively.