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- Routier, Cyril, 1996-
(author)
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Plant Nanobionics : From Localized Carbon Capture to Precision Molecular Delivery
- 2024
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Doctoral thesis (other academic/artistic)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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| 2. |
- Dufil, Gwennaël, 1995-
(author)
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Living biohybrid systems via in vivo polymerization of thiophene oligomers
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Life is the result of a multitude of electrical signals which drives our nervous system but also accomplishes a cascade of electrochemical reactions. In the 18th century, Lucia Galeazzi and Luigi Galvani got the idea to stimulate frog legs with electrodes. This first step into the world of bioelectronics showed that electronic systems were able to communicate with living organisms through electrical stimulation, as well as by recording electrical signals from organisms. Until the end of the 20th century, the field of bioelectronics kept progressing using metal electrodes. This class of material inherently exhibits a high conductivity from their dispersed cloud of shared electrons. However, an obvious physical mismatch occurs when inserting metal electrodes inside a living organism. Since these materials are not as soft as living tissues, internal damage followed by an immune response impacts the impedance of such probes.In the late 80s', the large-scale commercialization of water processable conducting polymers brought a new paradigm in the choice of electronic material for bioelectronics devices. Compared to metals, conducting polymers are composed of semi-crystalline blocks that interact through electrostatic forces. These soft structures make these materials permeable to aqueous solutions, which allow the introduction of ionic species in the vicinity of the polymer backbone. Ions close to the polymer backbone can tune the conductivity of the material creating a unique ion/electron dialogue that increases the electronic signal resolution. Additionally, these soft structures considerably reduce scaring effects and therefore enable the devices to trigger lower immune responses. Conducting polymers could also be directly inserted within living tissues to create electronic platforms inside a host. Living organisms with new material properties could unravel new functions such as collecting electrophysiological data without surgery.Plants are living organisms that made their way out of the ocean and conquered most of the available land on earth. Saying that plants are good climate controllers is a euphemism since plants are legitimately the organisms that have settled the climate conditions for the development of more advanced life forms. Plant biohybrid is a new technological concept where plants are not only seen for their nutritious or environmental aspect but also as devices that can record and transfer information about their local environmental conditions. Such data could be used in a positive feedback loop to improve the production yield of crops or understand the underlying communication mechanism that occurs between plants or with plant micro-biomes. Most of the approaches toward plant biohybrids nowadays focus on nanomaterials that act as fluorescent probes in leaves and detect analytes from plants' local environment.In this thesis, we push forward a plant biohybrid strategy that instead uses conducting polymers as vectors to build conductors inside plants with the aim to build electrochemical platforms that could be used for applications such as energy storage, sensing, and energy production. Works developed in this thesis are going in an array of directions that aims for the better integration of electronic platforms in living systems with more focus on plants.We first identified a plant enzymatic mechanism that triggers the polymerization of a thiophene oligomer, namely ETE-S in vivo and in vitro. Such plant enzymatic pathways can then be reused to develop electronic systems in plantae without additional reagents. In the next work, we presented the synthesis of three new oligomers called ETE-N, EEE-S, and EEE-N that have a similar architecture compared to ETE-S but with different chemical moieties such as a different ionic side chain or an EDOT instead of thiophene in the middle position of the oligomer. We then demonstrated the effective enzymatic polymerization of these oligomers both in vivo and in vitro and how the resulting polymers' optoelectronic and tissue integrations properties differ. Towards even more versatility, we demonstrated that this electronic integration in vivo was also observed in the case of an animal: the freshwater hydra polyp. The polymerization was observed mostly in differentiated cells from the gastric column of the animal that normally secretes an adhesive used to fix the animal underwater. P(ETE-S) was incorporated in this glue that we managed to characterize using electrochemical methods. Lastly, we performed demonstrations of electrochemical applications with a plant root system. By dipping several roots in an ETE-S solution, we created a network of conducting roots that can effectively store charge as a capacitor with performance comparable to what is classically obtained with conducting polymers. In addition, we modified roots with two different surface modification concepts to make them specific to glucose oxidation: the first method uses a traditional redox hydrogel with a crosslinker and glucose oxidase. The second one uses the embedment of a glucosespecific enzyme inside the p(ETE-S) layer during its formation. These devices are presented as possible new solutions for environmental glucose sensors that could collect current from the environment and store it in neighbouring capacitive roots.Overall, this thesis shows that the enzymatic activity of living systems can be used from an engineering point of view as part of a deposition methods for the development of biohybrid applications.
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