| 1. |
- Aydemir, Umut, et al.
(author)
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In situ assembly of an injectable cardiac stimulator
- 2024
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In: Nature Communications. - 2041-1723. ; 15
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Journal article (peer-reviewed)abstract
- Without intervention, cardiac arrhythmias pose a risk of fatality. However, timely intervention can be challenging in environments where transporting a large, heavy defibrillator is impractical, or emergency surgery to implant cardiac stimulation devices is not feasible. Here, we introduce an injectable cardiac stimulator, a syringe loaded with a nanoparticle solution comprising a conductive polymer and a monomer that, upon injection, forms a conductive structure around the heart for cardiac stimulation. Following treatment, the electrode is cleared from the body, eliminating the need for surgical extraction. The mixture adheres to the beating heart in vivo without disrupting its normal rhythm. The electrofunctionalized injectable cardiac stimulator demonstrates a tissue-compatible Young’s modulus of 21 kPa and a high conductivity of 55 S/cm. The injected electrode facilitates electrocardiogram measurements, regulates heartbeat in vivo, and rectifies arrhythmia. Conductive functionality is maintained for five consecutive days, and no toxicity is observed at the organism, organ, or cellular levels.
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| 2. |
- Aydemir, Umut, et al.
(author)
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In situ assembly of an injectable cardiac stimulator
- 2024
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In: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- Without intervention, cardiac arrhythmias pose a risk of fatality. However, timely intervention can be challenging in environments where transporting a large, heavy defibrillator is impractical, or emergency surgery to implant cardiac stimulation devices is not feasible. Here, we introduce an injectable cardiac stimulator, a syringe loaded with a nanoparticle solution comprising a conductive polymer and a monomer that, upon injection, forms a conductive structure around the heart for cardiac stimulation. Following treatment, the electrode is cleared from the body, eliminating the need for surgical extraction. The mixture adheres to the beating heart in vivo without disrupting its normal rhythm. The electrofunctionalized injectable cardiac stimulator demonstrates a tissue-compatible Young's modulus of 21 kPa and a high conductivity of 55 S/cm. The injected electrode facilitates electrocardiogram measurements, regulates heartbeat in vivo, and rectifies arrhythmia. Conductive functionality is maintained for five consecutive days, and no toxicity is observed at the organism, organ, or cellular levels. Heart pacing devices are bulky or rely on surgery. Here, the authors present an injectable cardiac stimulator based on a nanoparticle solution which attaches to the heart and forms a conductive path to the skin for external connection. It can regulate heartbeats and is thereafter cleared from the body.
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| 3. |
- Burtscher, Bernhard, 1991-, et al.
(author)
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Functionalization of PEDOT:PSS for aptamer-based sensing of IL6 using organic electrochemical transistors
- 2024
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In: npj Biosensing. - 3004-8656. ; 1:1
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Journal article (peer-reviewed)abstract
- Here we propose a strategy to functionalize poly(ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) based organic electrochemical transistors (OECTs) for sensing the inflammatory cytokine interleukin 6 (IL6). For this aim we use diazonium chemistry to couple 4-aminobenzoic acid to sulfonate moieties on the PSS, which can act as anchors for aptamers or other recognition elements (e.g., fluorescent, or redox probes). We investigated this approach with a commercial screen-printable PEDOT:PSS formulation but also studied the effect of PEDOT to PSS ratio as well as the amount of crosslinker in other PEDOT:PSS formulations. For screen printed OECTs, it was possible to distinguish between IL6 and bovine serum albumin (BSA) in buffer solution and detect IL6 when added in bovine plasma in the nanomolar range. Furthermore, functionalization of PEDOT:PSS formulations with higher PSS content (compared to the "standard" solutions used for OECTs) combined with frequency dependent measurements showed the potential to detect IL6 concentrations below 100 pM.
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| 4. |
- Burtscher, Bernhard, 1991-
(author)
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OECT-based biosensors for capacitive and faradaic sensing
- 2024
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Doctoral thesis (other academic/artistic)abstract
- Bioelectronics represents an interdisciplinary field merging biology with electronics with the focus on developing devices that interact with biological systems. Therefore, bioelectronics can help us to understand and utilize biological processes with electronic means. This can aid in the progression of healthcare such as improved diagnostic tools, innovative therapy, or personalized medicine. Interfacing biology and electronics presents significant challenges in material science, necessitating the continuous exploration of new materials and measurement systems that meet both electronic and biological requirements. Organic mixed ionic-electronic conductive polymers are one material class that has gained great interest due to, as the name suggests, their dual ionic and electronic properties. Furthermore, these polymers have shown greatly adaptability at interfacing with biology, often superior to traditional materials as has been observed in neural probes. This curious interplay of ions and electrons in these polymers is harnessed by organic electrochemical transistors (OECTs), which transduce biological signals into electrical ones. OECTs are used to amplify measured electric signals or when functionalized with specific biorecognition elements to detect analytes. Given the operation principle of OECTs within aqueous environments, a variety of (bio-)sensors can be realized to interact with biological processes based on capacitive or faradaic currents. An adaptable sensor platform that can be used as a point-of-care device is highly sought after, as for example glucose sensors. In general, biosensors and their point-of-care applications play an important role in society for diagnostics, as evidenced by the COVID-19 pandemic, and for personalized medicine.This work explores various aspects of OECT biosensors, including capacitive sensors with aptamers, enzymatic sensing, and enzymatically polymerized OECTs. OECTs are integrated with recognition elements on different surfaces to measure biomarkers for inflammation, and enzymes are incorporated into ad-hoc formed glucose sensor. The first works employ a classical layer-by-layer technique, clearly delineating the interaction sites. Later investigations utilize the small size of electro-polymerizable monomers to achieve conformability between enzymes and polymers, resulting in seamless, interconnected bioelectronic devices. Furthermore, biological processes can be utilized in the fabrication of enzymatically formed OECTs. Lastly OECTs formed by enzymatic polymerization exhibit high electrical stability with bio-integrability. These studies highlight various facets of OECTs and their interactions with biological entities, underscoring their potential in advancing bioelectronic applications.
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| 5. |
- Donahue, Mary, et al.
(author)
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Polymers/PEDOT Derivatives for Bioelectronics
- 2020. - 1
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In: Redox Polymers for Energy and Nanomedicine. - : Royal Society of Chemistry. - 9781788018715 - 9781788019743 - 9781788019750 ; , s. 488-545
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Book chapter (peer-reviewed)abstract
- The advancement of bioelectronics depends greatly on new material development and engineering solutions. Redox polymers are promising candidates to contribute to this advancement of biointerfacing devices. For such devices to be clinically useful, they must fulfill an assortment of requirements, including biocompatibility, stability, mechanical compliancy and the ability to effectively monitor or influence biological systems. The use of redox polymers in bioelectronic research has demonstrated a great deal of potential in satisfying these constraints. In this chapter, we consider the advantageous aspects of polymer electronics for biomedical applications including electrophysiological recording, neuromodulation, biosensor technologies and drug delivery. Particular emphasis is given to PEDOT-based systems as these have demonstrated the highest degree of bioelectronic device success to date, however, other polymers are also discussed when pertinent.
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| 6. |
- Gryszel, Maciej, et al.
(author)
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Vertical Organic Electrochemical Transistor Platforms for Efficient Electropolymerization of Thiophene Based Oligomers
- 2024
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In: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534.
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Journal article (peer-reviewed)abstract
- Organic electrochemical transistors (OECTs) have emerged as promising candidates for various fields, including bioelectronics, neuromorphic computing, biosensors, and wearable electronics. OECTs operate in aqueous solutions, exhibit high amplification properties, and offer ion-to-electron signal transduction. The OECT channel consists of a conducting polymer, with PEDOT:PSS receiving the most attention to date. While PEDOT:PSS is highly conductive, and benefits from optimized protocols using secondary dopants and detergents, new p-type and n-type polymers are emerging with desirable material properties. Among these, low-oxidation potential oligomers are highly enabling for bioelectronics applications, however the polymers resulting from their polymerization lag far behind in conductivity compared with the established PEDOT:PSS. In this work we show that by careful design of the OECT geometrical characteristics, we can overcome this limitation and achieve devices that are on-par with transistors employing PEDOT:PSS. We demonstrate that the vertical architecture allows for facile electropolymerization of a family of trimers that are polymerized in very low oxidation potentials, without the need for harsh chemicals or secondary dopants. Vertical and planar OECTs are compared using various characterization methods. We show that vOECTs are superior platforms in general and propose that the vertical architecture can be expanded for the realization of OECTs for various applications.
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| 7. |
- Méhes, Gábor, et al.
(author)
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Organic Microbial Electrochemical Transistor Monitoring Extracellular Electron Transfer
- 2020
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In: Advanced Science. - : WILEY. - 2198-3844. ; 7:15
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Journal article (peer-reviewed)abstract
- Extracellular electron transfer (EET) denotes the process of microbial respiration with electron transfer to extracellular acceptors and has been exploited in a range of microbial electrochemical systems (MESs). To further understand EET and to optimize the performance of MESs, a better understanding of the dynamics at the microscale is needed. However, the real-time monitoring of EET at high spatiotemporal resolution would require sophisticated signal amplification. To amplify local EET signals, a miniaturized bioelectronic device, the so-called organic microbial electrochemical transistor (OMECT), is developed, which includes Shewanella oneidensis MR-1 integrated onto organic electrochemical transistors comprising poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) combined with poly(vinyl alcohol) (PVA). Bacteria are attached to the gate of the transistor by a chronoamperometric method and the successful attachment is confirmed by fluorescence microscopy. Monitoring EET with the OMECT configuration is achieved due to the inherent amplification of the transistor, revealing fast time-responses to lactate. The limits of detection when using microfabricated gates as charge collectors are also investigated. The work is a first step toward understanding and monitoring EET in highly confined spaces via microfabricated organic electronic devices, and it can be of importance to study exoelectrogens in microenvironments, such as those of the human microbiome.
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| 8. |
- Mousa, Abdelrazek H., et al.
(author)
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Method Matters: Exploring Alkoxysulfonate-Functionalized Poly(3,4-ethylenedioxythiophene) and Its Unintentional Self-Aggregating Copolymer toward Injectable Bioelectronics
- 2022
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In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 34:6, s. 2752-2763
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Journal article (peer-reviewed)abstract
- Injectable bioelectronics could become an alternative or a complement to traditional drug treatments. To this end, a new self-doped p- type conducting PEDOT-S copolymer (A5) was synthesized. This copolymer formed highly water-dispersed nanoparticles and aggregated into a mixed ion-electron conducting hydrogel when injected into a tissue model. First, we synthetically repeated most of the published methods for PEDOT-S at the lab scale. Surprisingly, analysis using high-resolution matrix-assisted laser desorption ionization-mass spectroscopy showed that almost all the methods generated PEDOT-S derivatives with the same polymer lengths (i.e., oligomers, seven to eight monomers in average); thus, the polymer length cannot account for the differences in the conductivities reported earlier. The main difference, however, was that some methods generated an unintentional copolymer P(EDOT-S/EDOT-OH) that is more prone to aggregate and display higher conductivities in general than the PEDOT-S homopolymer. Based on this, we synthesized the PEDOT-S derivative A5, that displayed the highest film conductivity (33 S cm(-1)) among all PEDOT-S derivatives synthesized. Injecting A5 nanoparticles into the agarose gel cast with a physiological buffer generated a stable and highly conductive hydrogel (1-5 S cm(-1)), where no conductive structures were seen in agarose with the other PEDOT-S derivatives. Furthermore, the ion-treated A5 hydrogel remained stable and maintained initial conductivities for 7 months (the longest period tested) in pure water, and A5 mixed with Fe3O4 nanoparticles generated a magnetoconductive relay device in water. Thus, we have successfully synthesized a water-processable, syringe-injectable, and self-doped PEDOT-S polymer capable of forming a conductive hydrogel in tissue mimics, thereby paving a way for future applications within in vivo electronics.
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| 9. |
- Petsagkourakis, Ioannis, et al.
(author)
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Improved Performance of Organic Thermoelectric Generators Through Interfacial Energetics
- 2023
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In: Advanced Science. - : WILEY. - 2198-3844. ; 10:20
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Journal article (peer-reviewed)abstract
- The interfacial energetics are known to play a crucial role in organic diodes, transistors, and sensors. Designing the metal-organic interface has been a tool to optimize the performance of organic (opto)electronic devices, but this is not reported for organic thermoelectrics. In this work, it is demonstrated that the electrical power of organic thermoelectric generators (OTEGs) is also strongly dependent on the metal-organic interfacial energetics. Without changing the thermoelectric figure of merit (ZT) of polythiophene-based conducting polymers, the generated power of an OTEG can vary by three orders of magnitude simply by tuning the work function of the metal contact to reach above 1000 mu W cm(-2). The effective Seebeck coefficient (S-eff) of a metal/polymer/metal single leg OTEG includes an interfacial contribution (V-inter/Delta T) in addition to the intrinsic bulk Seebeck coefficient of the polythiophenes, such that S-eff = S + V-inter/Delta T varies from 22.7 mu V K-1 [9.4 mu V K-1] with Al to 50.5 mu V K-1 [26.3 mu V K-1] with Pt for poly(3,4-ethylenedioxythiophene):p-toluenesulfonate [poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)]. Spectroscopic techniques are used to reveal a redox interfacial reaction affecting locally the doping level of the polymer at the vicinity of the metal-organic interface and conclude that the energetics at the metal-polymer interface provides a new strategy to enhance the performance of OTEGs.
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| 10. |
- Priyadarshini, Diana, et al.
(author)
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Enzymatically Polymerized Organic Conductors on Model Lipid Membranes
- 2023
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In: Langmuir. - : AMER CHEMICAL SOC. - 0743-7463 .- 1520-5827. ; 39:23, s. 8196-8204
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Journal article (peer-reviewed)abstract
- Seamless integration between biological systems and electricalcomponents is essential for enabling a twinned biochemical-electricalrecording and therapy approach to understand and combat neurologicaldisorders. Employing bioelectronic systems made up of conjugated polymers,which have an innate ability to transport both electronic and ioniccharges, provides the possibility of such integration. In particular,translating enzymatically polymerized conductive wires, recently demonstratedin plants and simple organism systems, into mammalian models, is ofparticular interest for the development of next-generation devicesthat can monitor and modulate neural signals. As a first step towardachieving this goal, enzyme-mediated polymerization of two thiophene-basedmonomers is demonstrated on a synthetic lipid bilayer supported ona Au surface. Microgravimetric studies of conducting films polymerizedin situ provide insights into their interactions with a lipid bilayermodel that mimics the cell membrane. Moreover, the resulting electricaland viscoelastic properties of these self-organizing conducting polymerssuggest their potential as materials to form the basis for novel approachesto in vivo neural therapeutics.
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