| 1. |
- Cherian, Dennis, 1989-
(författare)
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Expanding the versatility and functionality of iontronic devices
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological systems rarely use electrons as signal regulators, most of the transport and communication in these system utilize ions. The discovery of conjugated polymers and polyelectrolytes and their unique properties of mixed ionic electronic properties opened the possibility of using these in the domain of bioelectronics, which paved the way for the field of organic bioelectronics. After the introduction of the organic electronic ion pump (OEIP) in 2007, which utilizes both the ionic properties of conjugated polymers and polyelectrolytes, the new field of “iontronics” evolved. TheOEIP is an organic polymer-based delivery system based on electrophoretic transport of biologically relevant and ionically charged species, without fluid flow and with high spatial, temporal, and dosage precision. These devices have been extensivelystudied for the past 14 years and have found numerous demonstrations in in vivo and in vitro delivery of bio-relevant ions for therapeutic application. This has, in parallel, resulted in the development of custom materials for ion exchange membranes (IEMs) within the OEIP.This thesis focuses on IEMs and device development of OEIPs. Specific focus is given to process development through device design and fabrication through conventional and unconventional technologies. Conventional technologies include microfabrication through photolithography, etching, and thin-film evaporation. Unconventional fabrication techniques include screen printing, inkjet printing, stencil, and laser patterning. In this thesis, we have also scouted a new area of research to utilize the ion-selective properties of polyelectrolytes. Here we discuss a new ion detection technique using IEMs and ion transport based on diffusion coefficients and impedance measurement at a specific frequency using impedance spectroscopy for faster ion detection with low voltage (1–40 V) and liquid-flow-free transport. Further exploring the area of IEMs, we have realized that less attention has been given to stretchable IEMs, even though such materials could find enormous applications in the field of organic bioelectronics and can be used in association with many stretchable electronics applications like stretchable displays and energy storage devices. Current IEMs lack the conformability and stretchability to be used for implantable applications, e.g., including lungs, heart, muscle, soft or brain implants, joints, etc. Keeping this in mind we also discuss our approach for the development of a stretchable IEM. Finally, we focus on developing a hybrid fabrication protocol of flexible OEIPs with micropatterning techniques and inkjet-printed membranes. These OEIPs were fabricated and the functionality was validated by the cell response after the delivery of a nerve-blocking agent to cells in vitro. To date, OEIPs have been fabricated by micropatterning and labor-intensive manual techniques, impeding the budding application areas of this propitious technology. To address this issue, a novel approach to the fabrication of the OEIPs using screen-printing technology is also explored in this thesis. In summary, we were able to successfully explore the field of ion-exchange membranesand put forward a new technique for ion detection and stretchable IEMs for future applications. Fabrication of OEIPs was also examined which resulted in the development of a hybrid fabrication protocol with inkjet printing for OEIPs and a robust fully screen printed OEIPs with high manufacturing yield (>90%) for industrial-scale manufacturing.
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| 2. |
- Abrahamsson, Tobias, 1991-
(författare)
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Synthetic Functionalities for Ion and Electron Conductive Polymers : Applications in Organic Electronics and Biological Interfaces
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the search for understanding and communicating with all biological systems, in humans, animals, plants, and even microorganisms, we find a common language of all communicating via electrons, ions and molecules. Since the discovery of organic electronics, the ability to bridge the gap and communicate be-tween modern technology and biology has emerged. Organic chemistry pro-vides us with tools for understanding and a material platform of polymer electronics for communication. Such insights give us not only the ability to observe fundamental phenomenon but to actively design and construct materials with chemical functionalities towards better interfaces and applications. Organic electronic materials and devices have found their way to be implemented in the field of medicine for diagnostic and therapeutic purposes, but also in water purification and to help tackle the monumental task in creating the next generation of sustainable energy production and storage. Ultimately it’s safe to say that organic electronics are not going to replace our traditional technology based on inorganic materials but rather the two fields can find a way to complement each other for various purposes and applications. Compared to conventional silicon based technology, production of carbon-based organic electronic polymer materials are extremely cheap and devices can even be made flexible and soft with great compatibility towards biology. The main focus of this thesis has been developing and synthesizing new types of organic electronic and ionic conductive polymeric materials. Rational chemical design and modifications of the materials have been utilized to introduce specific functionalities to the materials. The functionalities serving the purpose to facilitate ion and electron conductive charge transport for organic electronics and with biological interface implementation of the polymer materials. Multi-functional ionic conductive hyperbranched polyglycerol polyelectrolytes (dendrolytes) were developed comprising both ionically charged groups and cross-linkable groups. The hyperbranched polyglycerol core structure of the material possesses a hydrophilic solvating platform for both ions and maintenance of solvent molecules, while being a biocompatible structure. Coupled with the peripheral charged ionic functionalities of the polymer, the dendrolyte materials are highly ionic conductive and selective towards cationic and anionic charged atoms and large molecules when implemented as ion-exchange membranes. Homogenous ion-exchange membrane casting has been achieved by the implementation of cross-linkable functionalities in the dendrolytes, utilizing robust click-chemistry for efficient micro and macro fabrication processing of the ion-ex-change membranes for organic electronic devices. The ion-exchange membrane material was implemented in electrophoretic drug delivery devices (organic electronic ion pumps), which are used for delivery of ions and neurotransmitters with spatiotemporal resolution and are able to communicate and be used for therapeutic drug delivery purposes in biological interfaces. The dendrolyte materials were also able to form free-standing membranes, making it possible for implementation in fuel cell and desalination purposes. Trimeric conjugated thiophene pre-polymer structures were also developed in the thesis and synthesized for the purpose of implementation of the material in vivo to form electrically conductive polymer structures, and in such manner to be able to create electrodes and ultimately to connect with the central nervous system. The conjugated pre-polymers being both water soluble and enzymatically polymerizable serve as a platform to realize such a concept. Also, modifying the trimeric structure with cross-linkable functionality created the capability to form better interfaces and stability towards biological environments.
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| 3. |
- Arbring Sjöström, Theresia, 1987-
(författare)
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Organic Bioelectronics for Neurotransmitter Release at the Speed of Life
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The signaling dynamics in neuronal networks includes processes ranging from lifelong neuromodulation to direct synaptic neurotransmission. In chemical synapses, the time delay it takes to pass a signal from one neuron to the next lasts for less than a millisecond. At the post-synaptic neuron, further signaling is either up- or down-regulated, dependent on the specific neurotransmitter and receptor. While this up- and down-regulation of signals usually runs perfectly well and enables complex performance, even a minor dysfunction of this signaling system can cause major complications, in the shape of neurological disorders. The field of organic bioelectronics has the ability to interface neurons with high spatiotemporal recording and stimulation techniques. Local chemical stimulation, i.e. local release of neurotransmitters, enables the possibility of artificially altering the chemical environment in dysfunctional signaling pathways to regain or restore neural function. To successfully interface the biological nervous system with electronics, a range of demands must be met. Organic bioelectronic techniques and materials are capable of reaching the demands on the biological as well as the electronic side of the interface. These demands span from high performance biocompatible materials, to miniaturized and specific device architectures, and high dose control on demand within milliseconds.The content of this thesis is a continuation of the development of organic bioelectronic devices for neurotransmitter delivery. Organic materials are utilized to electrically control the dose of charged neurotransmitters by translating electric charge into controlled artificial release. The first part of the thesis, Papers 1 and 2, includes further development of the resistor-type release device called the organic electronic ion pump. This part includes material evaluation, microfluidic incorporation, and device design considerations. The aim for the second part of this thesis, Papers 3 and 4, is to enhance temporal performance, i.e. reduce the delay between electrical signal and neurotransmitter delivery to corresponding delay in biological neural signaling, while retaining tight dosage control. Diffusion of neurotransmitters between nerve cells is a slow process, but since it is restricted to short distances, the total time delay is short. In our organic bioelectronic devices, several orders of magnitude in speed can be gained by switching from lateral to vertical delivery geometries. This is realized by two different types of vertical diodes combined with a lateral preload and waste configuration. The vertical diode assembly was further expanded with a control electrode that enables individual addressing in each of several combined release sites. These integrated circuits allow for release of neurotransmitters with high on/off release ratios, approaching delivery times on par with biological neurotransmission.
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| 4. |
- Ghorbani Shiraz, Hamid, 1989-
(författare)
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Electrochemical reduction of protons and organic molecules in hydrogen technologies : Liquid Organic Hydrogen carrier and Hydrogen Evolution
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In accordance with preventable actions to mitigate the effect of climate change in the modern societal applications, renewable energy is an unavoidable and decisive factor in the energy industry. The energy sources that offer non-depleted and environment-friendly pathways for the energy sector are in focus. Amongst, hydrogen has been defined as one of the best candidates to meet the criteria such as high energy-content and zero-emission of CO2, and of course, renewability. In this work, we focused on the areas of hydrogen generation and hydrogen storage.In the first part, we employed an inorganic electrocatalyst (nanosheets) to drive the hydrogen evolution reaction (HER), where we proved that the overpotential of few millivolts (0.016 V) is enough to run the HER reaction. We studied the effect of interlayer gap (for the nanosheets) on the catalytic performance. The chemical intercalation showed a huge effect for the suppression of the HER, which could be applicable for the devices like batteries the formation of any gaseous species has detrimental effect on the performance. It should not be left unmentioned that the measurements were carried out in a platinum group metal free (PGM-free) system, where graphite felt were used as a counter electrode, to avoid any platinum contamination. Next, we investigated the effect of oxygen poisoning on both pristine electrocatalyst and intercalated one. The XPS and UPS measurements confirmed the formation of oxygen-containing groups on the electrocatalysts. Electrochemical measurements showed the increase of the overpotential toward HER as the electrocatalysts are exposed to air for longer time. However, study of the hydrogen oxidation reaction (HOR) showed that there is an optimum concentration of oxygenic functional groups that can lead to a high current density of HOR process. The study of exchange current density showed that, after 10 days of exposure of electrocatalyst to atmospheric air, pristine sample possesses the best performance toward HER and intercalated one shows the highest performance for the HOR. In the other section, hydrogen storage for the organic redox-active molecule (dissolved in organic solvent) was studied. One of the main problems in hydrogen economy concept, is the storage of the hydrogen for transportation. The new concept of Liquid Organic Hydrogen Carrier (LOHC) offers a low-cost and safe approach to this challenge. Herein, we demonstrated an electrochemical pathway to hydrogenate the organic system via conversion of proton of a proton donor into a covalent-bonded hydrogen, through a proton coupled electron transfer (PCET) reaction of 2nH+ + 2ne¯ + Rox nH2Rred. Here, we studied the 9-fluorenone/fluorenol (Fnone/Fnol) as a model PCET reaction. The electrochemical activation of starting component of (Fnone), through two successive electron transfers was investigated with in-situ and operando spectroscopies purely, and in presence of different proton donors of different reactivity. We succeed to both quantify and qualify the investigated the reaction. The hydrogen release step was demonstrated chemically with the aid of catalyst. To conclude, we employed a PGM-free system to demonstrate and characterize a high performing electrocatalyst for hydrogen evolution. Surprisingly, HOR was revealed to perform well using the oxygen poisoned electrocatalyst for HER. In the other section of this work, an electrochemical assisted synthesis of LOHC, in the lab-scale, was proved. A PCET pathway was conceptualized with mechanistic insight. Our work opens new avenue for the technology of hydrogenation of LOHC as we showed for the first time that this could be realized by electrochemistry without the need of hydrogen gas as a prerequisite. We believe that in the future both works could contribute slightly to the concept of the hydrogen economy.
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| 5. |
- Isacsson, Patrik, 1991-
(författare)
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Materials Design for Paper Electrodes : A Papermaking Perspective on Electrode Fabrication
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The electrification and digitalization of our society has propelled the demand for energy storage solutions. High-end technologies have been developed to satisfy the requirements of demanding applications, such as electromobility and portable consumer electronics, which also increasingly find markets for less demanding applications. These markets include grid and domestic energy storage, as well as Internet of Things (IoT). However, using high-end technologies for low-end applications is a waste of resources that puts unnecessary stress on the supply lines. Thus, more low-cost cost and environmentally friendly alternative technologies are sought, among which renewable biobased materials derived from agriculture and forestry play a prominent role.The dominant chemical constituents in plants, cellulose and lignin, exhibit some intriguing electrochemical and colloidal properties. Cellulose has been found to efficiently stabilize various electronic materials, whereas lignin can be used as an electronic material itself. Lignocellulosic materials also open for papermaking as an alternative manufacturing approach. Taking the step to using papermaking methods is, however, a bit far from the technology readiness level, as the vast majority of the research on paper electrodes is based on nanocellulose. The material properties of such nanopapers are indeed extraordinary, but the lack of large-scale production methods for nanopapers is a serious challenge.To circumvent this obstacle and find a shortcut to the realization of paper electrodes, this thesis has turned to conventional papermaking techniques. Fibres are essentially different to nanofibrils by their difference in size, and the papermaking process requires careful composition of the formulations. Thus, as the research on nanopaper electrodes cannot be directly translated into conventional papermaking techniques, this calls for separate studies on fibre-based systems.This thesis is based on four separate works carried out by an explorative approach, where different kinds of paper electrodes have been investigated with touchdowns in example applications. Based on these studies, general knowledge has been concluded. This has been summarized by four important aspects for materials design of paper electrodes:Colloidal Systems. The paper electrode formulations exhibit both familiar and unfamiliar colloidal interactions. Established wet-end chemistry including charge balance control and electrostatic interactions remain important in parallel with unconventional behaviours. Exfoliated graphite forms water-stable coatings around pulp fibres and exhibit auto-retention mechanism(s). The conducting polymer system PEDOT:PSS, which can adsorb to chemical pulp fibres, does not exhibit affinity to chemi-thermomechanical pulp.Percolating Networks. Cellulosic fibres constitute an insulative matrix, in which efficient percolating conductive networks must be formed. The way a conducting additive is introduced, as well as the morphology of the additive, is important. Combining conducting polymers with nanocarbons is a promising concept for material-efficient networks. For a filler used as an electrode active material, it is important to acknowledge whether it is electronically conductive or not. A higher amount of conductive additives is required for insulative electrode active materials than for those with internal conductivity.Lignin Electrochemistry. Residual lignin present in softwood pulps, in both mechanical and chemical pulps, is electrochemically active. This can either be wanted or unwanted depending on application. Fines differ from fibres in terms of electrochemical stability and oxidative activity. Substantial competing electrochemical reactions occur, which might be related to the electrochemical stability.Mechanical Properties. Percolating conductive networks require high interconnectivity, which entails a cross-linked structure. This brings increased stiffness to the papers, which can be observed both for exfoliated graphite as a filler as well as for papers impregnated with PEDOT:PSS.Based on the four aspects described above, prospects for a few paper electrode applications have been reviewed. The prospects are mixed, each with their own challenges and opportunities which requires further research and development. While this thesis can conclude that we have not yet reached the point where paper electrodes can be realized, it certainly paves the way to get there.
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| 6. |
- Jakešová, Marie, 1991-
(författare)
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Wireless Bioelectronic Devices Driven by Deep Red Light
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of electronic devices in medical care is one of the main targets of precision medicine. The field of bioelectronic medicine uses electronic devices to diagnose or treat diseases and disorders in a complementary or alternative way to chemical drugs. It has been more than sixty years since the world’s first implantable battery-driven cardiac pacemaker was implanted here in Sweden. Since then, electronic therapies have been implemented for neurological disorders such as Parkinson’s disease, epilepsy, sensory and motor function restoration, and many more. However, electronics can also be used for delivery of conventional drugs in a more controlled, localized, and specific fashion.Therapeutic utility and patient comfort are maximized when the devices are as minimally invasive as possible. The most important milestone in the development of the cardiac stimulator was making it wireless. The early versions of the device required bulky parts to be placed outside of the body with transcutaneous electrical leads to the target site which led to high infection risk and frequent failures. To date, batteries remain the most common way to power implantable electronics. However, their large size and the necessity for replacement surgeries makes the technology relatively invasive. Alternative approaches to wireless power transfer are thus sought after. The most promising technologies are based on electromagnetic, ultrasound, or light-coupling methods. The aim of this thesis is to utilize tissue-penetrating deep red light for powering implantable devices. The overarching concept is an organic photovoltaic based on small molecule donor-acceptor bilayer junctions, which allows for ultrathin, flexible, minimally-invasive devices. Within this thesis, the photovoltaic device was utilized in two ways. Firstly, the photovoltaics are fabricated to act as an integrated driver for other implantable electronic components: 1) an organic electronic ion pump for acetylcholine delivery; 2) a depth-probe microelectrode stimulation device for epilepsy applications. Secondly, an alternative device, the organic electrolytic photocapacitor, is formed by replacing one of the solid electrodes by an electrolytic contact, thus yielding a minimalistic device acting as a direct photoelectrical stimulator. Within the thesis, the photocapacitive stimulation mechanism is validated by studying voltage-gated ion channels in a frog oocyte model. Next, two lithography-based patterning techniques are developed for fabricating these devices with better resolution and on flexible substrates suitable for in vivo operation. Finally, a chronic implant is demonstrated for in vivo sciatic nerve stimulation in rodents. The end result of this thesis is a series of novel device concepts and methods for stimulation of the nervous system using deep red light.
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| 7. |
- Lienemann, Samuel Lukas, 1988-
(författare)
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Materials and Devices for Stretchable Electronic Nerve Interfaces
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within our body, there is a large network of nerves that facilitates communication between the brain and the body’s organs. This network is called our peripheral nervous system, consisting of soft and stretchable nerve bundles that gradually increase in their functional specificity as they split and branch out the closer they get to their target organ. Communication within the nerve is based on action potentials, fast fluctuations in electric trans-membrane potential along the neurons within the nerve. These action potentials can be recorded and artificially triggered by interfacing electronically with peripheral nerves. In doing so, modern medicine is able to elucidate the mechanisms behind disorders related to the nervous system and even applies novel electronic therapies to treat them. Over the last decade, the field of biomedical engineering has therefore seen a surge of interest in electronic devices that interface with the peripheral nervous system, such as cuff electrodes. The device function is based on electrodes that are implanted in close proximity of the nerves they intend to record or stimulate. A cuff electrode, specifically, is wrapped around a peripheral nerve and applies stimulation pulses at electrodes located on the inside of the cuff to evoke action potentials within the nerve. Our body is not welcoming to foreign objects though. Any implant within our body triggers a foreign body reaction with an intensity dependent on the biocompatibility of the implant. Recent studies have found that one of the major factors governing the foreign body reaction is the mechanical mismatch of the implant to the interfacing tissue, with softer, more mechanically similar implants, exhibiting reduced foreign body response. This has prompted an ongoing push for thin and soft peripheral nerve interfaces. However, to truly match the mechanical properties of peripheral nerves, peripheral nerve interfaces need not only to be soft and flexible, they need to become as elastic and stretchable as the nerve themselves. A common strategy to achieve stretchable conductors is by incorporating highly conductive filler materials in an elastomeric matrix. The resulting composite remains conductive even when stretched due to the ability of the filler material to dislocate with the elastomeric matrix while retaining its interconnectivity and thus conductivity. Electronic composites based on gold nanowires and silicones are promising candidates for stretchable peripheral nerve interfaces, due to their material-based biocompatibility, good stretchability, and versatile patterning possibilities.Based on this, the thesis at hand investigated stretchable electronic composite materials and devices to interface with the peripheral nervous system. Publication I and II develop gold-nanowire/polydimethylsiloxane-based cuff electrodes, which are functional even at 50% strain, as peripheral nerve interfaces in vivo. These publications highlight the beneficial conformability of stretchable devices, with a stretchable bi-polar cuff for low-voltage stimulation of the rat sciatic nerve in publication I and a stretchable multi-electrode cuff for selective stimulation of the pig sciatic nerve in publication II. Publication III investigates stretchable gold-nanowire composites based on a variety of elastomers, therein, elucidating the influence of the varying elastomer properties on the electromechanical performance of gold-nanowire composites. Lastly, publication IV establishes a stretchable ion delivery device with potential use for the peripheral nervous system. The device is based on an ionically conductive membrane as the conductive filler, and the device can be reversibly stretched to 100% strain. Overall, this thesis presents stretchable materials and devices that advance the possibilities for peripheral nerve interfaces.
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| 8. |
- Mohammadi, Mohsen, 1992-
(författare)
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Stretchable electronics using wood-based functional materials
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stretchable electronics allows for direct integration into deforming systems like clothing, skin, and tissue, thereby enabling novel applications in soft robotics, wearable electronics, health monitoring, therapeutics, and human-machine interfaces. However, achieving seamless integration with the human body poses significant challenges, necessitating the development of functional materials with a low Young’s modulus matching biological tissues to avoid any discomfort or immune response. Additionally, as electronic devices are becoming increasingly used in different settings, accumulation of electronic waste, and the utilization of unsustainable raw materials are emerging as pressing environmental challenges. Therefore, it is important that the design and fabrication of these devices consider not only high performance, but also its environmental sustainability. Therefore the focus of this thesis is on enhancing the performance and sustainability aspects of stretchable electronics through using renewable wood-based functional wood-based materials in 4 papers. Paper I focuses on the development of versatile soft electromagnetic actuators for soft robotic applications. These stretchable electromagnetic actuators were capable of contraction, expansion, hopping, and locomotion without the need for external magnetic fields. By embedding strain sensors made of conductive cellulose nanofibril (CNF)-based foam, the actuators could internally monitor their states, enhancing their controllability and autonomy. In Paper II, a soft haptic system was designed to stimulate the sense of touch. The haptic system was based on a soft electromagnetic actuator concept that included a soft magnet and stretchable conducting composite consisting of silver flakes and a styrene elastomer. The system demonstrated an improved tactile response enabled by vibration amplitude sensing through conductive CNF-based foams. This novel design offers potential applications in human–machine interfaces and virtual reality tools. Paper III presents a scalable approach for the fabrication of ultra-soft high-resolution multilayer stretchable printed circuit boards (sPCBs). A wood derived biopolymer, lignin, was used to develop a water processable sacrificial mask bio-composite for laser-patterning of high-resolution prints of ultra-soft and stretchable conductors with high-aspect-ratio structures. Additionally, this method enabled the stable integration of rigid components onto the sPCBs that can facilitate their use for miniaturized electronic devices. Lastly, paper IV introduces a fluid-based electrode concept for stretchable batteries using the biopolymer lignin. Fluidity is engineered into the cathode and anode, thereby decoupling the mechanical and electrochemical properties of the battery electrodes, allowing for high deformability without sacrificing capacity. The developed wood-based fluid stretchable battery could potentially be used as a sustainable energy storage component to power wearable devices. Overall, the thesis has contributed to the advancement of the field of stretchable electronics. It provided valuable insights into the potential utilization of wood-based functional materials into a variety of devices, fabrication methods, and design concepts in stretchable electronics, incorporating both high performance and environmental sustainability. The knowledge generated from this thesis can be used as a prospective guideline to design next-generation stretchable electronics devices.
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| 9. |
- Nissa, Josefin, 1987-
(författare)
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Interacting with biological membranes using organic electronic devices
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many physiological processes are reliant on activities in the cell membrane. These activities are of great importance to our well-being since they allow the cells to respond to their environment and communicate with each other to function as tissues and organs. In this thesis the use of organic electronic devices to interface with cell membranes has been explored. Organic electronics are especially suited for the task given their ability to transduce ionic to electronic signals. Four scientific papers are included in the thesis, where organic electronic devices are used together with living cells and supported lipid bilayers (SLB). In the first paper a ferroelectric cell release surface is presented. Release of cells cultured on the surface was induced by a polarization change in the ferroelectric polymer. This non-enzymatic release method was developed primarily for treatment of severe burns.The remaining three papers strive to combine lipid bilayers and the conjugated polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) in biosensors. The target device is an organic electrochemical transistor (OECT) functionalized with a supported lipid bilayer. Several aspects of the integration are explored, including promotion of vesicle fusion onto PEDOT:PSS and optimization of OECT design and biasing conditions for sensing. For SLB formation on PEDOT:PSS two different silica material systems, one PEDOT:PSS/silica composite and one mesoporous silica film, were evaluated with respect to electrical properties and quality of the resulting bilayer. The electrical properties were found to be similar, but the quality of the bilayer was better on the mesoporous silica film.In the last two papers the focus is on optimization of OECTs for sensing purposes. Biasing conditions for operation at high transconductance were identified, as well as design principles for large sensor output in impedance sensing.
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| 10. |
- Routier, Cyril, 1996-
(författare)
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Plant Nanobionics : From Localized Carbon Capture to Precision Molecular Delivery
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Photosynthesis is an evolutionary marvel that not only sustains plant life but also profoundly shaped the climatic conditions necessary for the development of other advanced forms of life and the ecosystems we know today. During photosynthesis, plants harness the energy of light to convert carbon dioxide (CO2), one of the main greenhouse gases, into sugars for the growth of both themselves and organisms that consume plants, and oxygen that sustains life on Earth. As we face the challenges of a rapidly changing climate and growing global population, understanding and enhancing the functions of plants such as photosynthesis and drought tolerance is of major importance.With advances in materials science over the years, an increasing number of nanotechnologies harnessing the unique properties of materials with sizes in the nanometer range (<100 nm) are emerging, holding promise to revolutionize various sectors, including agriculture and plant biology. At the intersection of materials science and plant biology, the field of plant nanobionics emerges as a transformative discipline pioneering a novel approach to integrating nanomaterials directly into plant systems. Departing from traditional genetic modification, this interdisciplinary field seeks to create bio-hybrid systems to enhance plants’ natural functions such as photosynthesis or introduce entirely new capabilities such as environmental sensing, monitoring, or even light emission.Various strategies exist in plant nanobionics, including the use of carbon nanotubes, silica nanoparticles, liposomes, or even quantum dots. The use of polymers, which consist of long chains of molecules with repeating units, has also been particularly intriguing for nanotechnological and nanobionic approaches due to their versatile and tunable properties.The primary focus of this thesis was to increase the diffusion rate of atmospheric CO2 in the leaves of tobacco plants using polymeric nanoparticles. The nanoparticles are engineered to directly capture CO2 from the atmosphere and are able to cross various plant cell membranes to deliver it to the photosynthetic reaction centers. The initial carboxylation reaction of photosynthesis, where atmospheric CO2 is converted into sugar precursors (3-phosphoglyceric acid or 3-PGA) with the help of the enzyme RuBisCO, is often considered the limiting step of the photosynthetic process. The poor affinity of RuBisCO to CO2 coupled with the limited diffusion of CO2 to the reaction sites is responsible for a considerable reduction in the potential photosynthetic efficiency of plants.With that in mind, we designed nanoparticles based on polyethyleneimine, a polymer able to capture atmospheric CO2 and cross cellular membranes, and modified it with chitosan, a biocompatible polymer, to design nanoparticles that we further labeled with fluorescein isothiocyanate (FITC) for fluorescent observation purposes. We studied their ability to self-integrate into plant cells and the plant chloroplasts, where the photosynthetic reaction occurs, without causing harm to the cells or the plants in general. We further evaluated the capacity of the nanoparticles to integrate into plant cells in culture and demonstrated that the nanoparticles have a natural affinity for the cells and self-integrate in the cells, crossing the cell wall, after 3 days. The nanoparticles also had no negative impact on the capacity of the cells to keep growing and dividing. We also demonstrated the nanoparticles' ability to still capture atmospheric CO2 when integrated into plant leaves and, in vitro, to redistribute it to RuBisCO enhancing the production of 3-PGA by 20%. Since the entry of the nanoparticles into plant leaves requires forced infiltration using a syringe infiltration method, we also studied the impact of the method itself on the plants' natural capacity to uptake CO2 and perform photosynthesis. We found there was a temporary impact of the infiltration process on the leaves’ natural CO2 uptake that also resulted in a reduction of their natural photosynthetic abilities. This will enable future studies to reliably quantify the impact of the nanoparticles on plant processes. We also used an organic electronic ion pump as a precision delivery method to study the impact of various biomolecules, such as malic and abscisic acid, on the plants' natural regulation of carbon dioxide uptake through the leaf pores known as stomata.Our work elucidates the various mechanisms at play when infiltrating nanoparticles or delivering biomolecules into plant leaves and plant cells in culture. We demonstrated a proof-of-concept use of phytocompatible nanoparticles in vivo, paving the way for a nanomaterials-based CO2-concentrating mechanism in plants that can potentially increase plants’ photosynthetic efficiency and overall CO2 storage.
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