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- Buchmann, Sebastian
(författare)
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Organic Electronics and Microphysiological Systems to Interface, Monitor, and Model Biology
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological processes in the human body are regulated through complex and precise arrangements of cell structures and their interactions. In vivo models serve as the most accurate choice for biological studies to understand these processes. However, they are costly, time-consuming, and raise ethical issues. Microphysiological systems have been developed to create advanced in vitro models that mimic in vivo-like microenvironments. They are often combined with integrated sensing technologies to perform real-time measurements to gain additional information. However, conventional sensing electrodes, made of inorganic materials such as gold or platinum, differ fundamentally from biological materials. Organic bioelectronic devices made from conjugated polymers are promising alternatives for biological sensing applications and aim to improve the interconnection between abiotic electronics and biotic materials. The widespread use of these devices is partly hindered by the limited availability of materials and low-cost fabrication methods. In this thesis, we provide new tools and materials that facilitate the use of organic bioelectronic devices for in vitro sensing applications. We developed a method to pattern the conducting polymer poly(3,4‑ethylenedioxythiophene) polystyrene sulfonate and to fabricate organic microelectronic devices using wax printing, filtering, and tape transfer. The method is low-cost, time-effective, and compatible with in vitro cell culture models. To achieve higher resolution, we further developed a patterning method using femtosecond laser ablation to fabricate organic electronic devices such as complementary inverters or biosensors. The method is maskless and independent of the type of conjugated polymer. Besides fabrication processes, we introduced a newly synthesized material, the semiconducting conjugated polymer p(g42T‑T)‑8%OH. This polymer contains hydroxylated side chains that enable surface modifications, allowing control of cell adhesion. Using the new femtosecond laser-based patterning method, we could fabricate p(g42T‑T)‑8%OH‑based organic electrochemical transistors to monitor cell barrier formations in vitro. Microphysological systems are further dependent on precise compartmentalization to study cellular interaction. We used femtosecond laser 3D printing to develop a co-culture neurite guidance platform to control placement and interactions between different types of brain cells. In summary, the thesis provides new tools to facilitate the fabrication of organic electronic devices and microphysiological systems. This increases their accessibility and widespread use to interface, monitor, and model biological systems.
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- Buchmann, Sebastian, et al.
(författare)
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Probabilistic cell seeding and non-autofluorescent 3D-printed structures as scalable approach for multi-level co-culture modeling
- 2023
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Ingår i: Materials Today Bio. - : Elsevier BV. - 2590-0064. ; 21, s. 100706-100706
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Tidskriftsartikel (refereegranskat)abstract
- To model complex biological tissue in vitro, a specific layout for the position and numbers of each cell type isnecessary. Establishing such a layout requires manual cell placement in three dimensions (3D) with micrometricprecision, which is complicated and time-consuming. Moreover, 3D printed materials used in compartmentalizedmicrofluidic models are opaque or autofluorescent, hindering parallel optical readout and forcing serial charac-terization methods, such as patch-clamp probing. To address these limitations, we introduce a multi-level co-culture model realized using a parallel cell seeding strategy of human neurons and astrocytes on 3D structuresprinted with a commercially available non-autofluorescent resin at micrometer resolution. Using a two-stepstrategy based on probabilistic cell seeding, we demonstrate a human neuronal monoculture that forms net-works on the 3D printed structure and can establish cell-projection contacts with an astrocytic-neuronal co-cultureseeded on the glass substrate. The transparent and non-autofluorescent printed platform allows fluorescence-based immunocytochemistry and calcium imaging. This approach provides facile multi-level compartmentaliza-tion of different cell types and routes for pre-designed cell projection contacts, instrumental in studying complextissue, such as the human brain.
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- Enrico, Alessandro, et al.
(författare)
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Cleanroom-Free Direct Laser Micropatterning of Polymers for Organic Electrochemical Transistors in Logic Circuits and Glucose Biosensors
- 2024
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Ingår i: Advanced Science. - : Wiley. - 2198-3844.
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Tidskriftsartikel (refereegranskat)abstract
- Organic electrochemical transistors (OECTs) are promising devices for bioelectronics, such as biosensors. However, current cleanroom-based microfabrication of OECTs hinders fast prototyping and widespread adoption of this technology for low-volume, low-cost applications. To address this limitation, a versatile and scalable approach for ultrafast laser microfabrication of OECTs is herein reported, where a femtosecond laser to pattern insulating polymers (such as parylene C or polyimide) is first used, exposing the underlying metal electrodes serving as transistor terminals (source, drain, or gate). After the first patterning step, conducting polymers, such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), or semiconducting polymers, are spin-coated on the device surface. Another femtosecond laser patterning step subsequently defines the active polymer area contributing to the OECT performance by disconnecting the channel and gate from the surrounding spin-coated film. The effective OECT width can be defined with high resolution (down to 2 mu m) in less than a second of exposure. Micropatterning the OECT channel area significantly improved the transistor switching performance in the case of PEDOT:PSS-based transistors, speeding up the devices by two orders of magnitude. The utility of this OECT manufacturing approach is demonstrated by fabricating complementary logic (inverters) and glucose biosensors, thereby showing its potential to accelerate OECT research. Ultrafast focused femtosecond laser has been introduced for the direct micropatterning of organic electrochemical transistors (OECTs), providing high resolution (2 mu m), selective cleanroom-free patterning of insulating and conjugated polymer layers while preserving device operation, and high flexibility in device design. The approach has been validated in the fabrication of complementary inverters and glucose biosensors.image
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| 6. |
- Enrico, Alessandro, et al.
(författare)
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Ultrafast Direct Writing of Polymers as a Simple Fabrication Method for Organic Electrochemical Transistors
- 2023
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Ingår i: 2023 22nd International Conference on Solid-State Sensors, Actuators and Microsystems, Transducers 2023. - : Institute of Electrical and Electronics Engineers Inc.. ; , s. 1543-1546
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Konferensbidrag (refereegranskat)abstract
- Organic ionic/electronic conductors (OMIECs) offer a promising alternative to metals and inorganic semiconductors for direct interfacing between human-made electronics and biological tissues. A device that takes advantage of the mixed ionic/electronic conductivity of OMIEC materials is the organic electrochemical transistor (OECT). High-density OECTs are typically fabricated using costly cleanroom-based lithography and complex lift-off processes. To simplify the fabrication of OECTs, we propose laser direct writing of conjugated polymers using a commercial two-photon polymerization 3D printer. Ultrafast laser direct writing allows single-digit micrometer resolution and high-speed processing, thereby enabling a cost-effective and simple fabrication process.
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- Kajtez, Janko, et al.
(författare)
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3D-Printed Soft Lithography for Complex Compartmentalized Microfluidic Neural Devices
- 2020
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 7:16
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Tidskriftsartikel (refereegranskat)abstract
- Compartmentalized microfluidic platforms are an invaluable tool in neuroscience research. However, harnessing the full potential of this technology remains hindered by the lack of a simple fabrication approach for the creation of intricate device architectures with high-aspect ratio features. Here, a hybrid additive manufacturing approach is presented for the fabrication of open-well compartmentalized neural devices that provides larger freedom of device design, removes the need for manual postprocessing, and allows an increase in the biocompatibility of the system. Suitability of the method for multimaterial integration allows to tailor the device architecture for the long-term maintenance of healthy human stem-cell derived neurons and astrocytes, spanning at least 40 days. Leveraging fast-prototyping capabilities at both micro and macroscale, a proof-of-principle human in vitro model of the nigrostriatal pathway is created. By presenting a route for novel materials and unique architectures in microfluidic systems, the method provides new possibilities in biological research beyond neuroscience applications.
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| 8. |
- Manning, Peter, et al.
(författare)
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Transferring biodiversity-ecosystem function research to the management of 'real-world' ecosystems
- 2019
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Ingår i: Mechanisms underlying the relationship between biodiversity and ecosystem function. - London : Elsevier. - 9780081029121 - 9780081029138 ; , s. 323-356
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Bokkapitel (refereegranskat)abstract
- Biodiversity-ecosystem functioning (BEF) research grew rapidly following concerns that biodiversity loss would negatively affect ecosystem functions and the ecosystem services they underpin. However, despite evidence that biodiversity strongly affects ecosystem functioning, the influence of BEF research upon policy and the management of 'real-world' ecosystems, i.e., semi-natural habitats and agroecosystems, has been limited. Here, we address this issue by classifying BEF research into three clusters based on the degree of human control over species composition and the spatial scale, in terms of grain, of the study, and discussing how the research of each cluster is best suited to inform particular fields of ecosystem management. Research in the first cluster, small-grain highly controlled studies, is best able to provide general insights into mechanisms and to inform the management of species-poor and highly managed systems such as croplands, plantations, and the restoration of heavily degraded ecosystems. Research from the second cluster, small-grain observational studies, and species removal and addition studies, may allow for direct predictions of the impacts of species loss in specific semi-natural ecosystems. Research in the third cluster, large-grain uncontrolled studies, may best inform landscape-scale management and national-scale policy. We discuss barriers to transfer within each cluster and suggest how new research and knowledge exchange mechanisms may overcome these challenges. To meet the potential for BEF research to address global challenges, we recommend transdisciplinary research that goes beyond these current clusters and considers the social-ecological context of the ecosystems in which BEF knowledge is generated. This requires recognizing the social and economic value of biodiversity for ecosystem services at scales, and in units, that matter to land managers and policy makers.
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- Matthiesen, Isabelle, et al.
(författare)
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Astrocyte 3D culture and bioprinting using peptide functionalized hyaluronan hydrogels
- 2023
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Ingår i: Science and Technology of Advanced Materials. - : Informa UK Limited. - 1468-6996 .- 1878-5514. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes play an important role in the central nervous system, contributing to the development of and maintenance of synapses, recycling of neurotransmitters, and the integrity and function of the blood-brain barrier. Astrocytes are also linked to the pathophysiology of various neurodegenerative diseases. Astrocyte function and organization are tightly regulated by interactions mediated by the extracellular matrix (ECM). Engineered hydrogels can mimic key aspects of the ECM and can allow for systematic studies of ECM-related factors that govern astrocyte behaviour. In this study, we explore the interactions between neuroblastoma (SH-SY5Y) and glioblastoma (U87) cell lines and human fetal primary astrocytes (FPA) with a modular hyaluronan-based hydrogel system. Morphological analysis reveals that FPA have a higher degree of interactions with the hyaluronan-based gels compared to the cell lines. This interaction is enhanced by conjugation of cell-adhesion peptides (cRGD and IKVAV) to the hyaluronan backbone. These effects are retained and pronounced in 3D bioprinted structures. Bioprinted FPA using cRGD functionalized hyaluronan show extensive and defined protrusions and multiple connections between neighboring cells. Possibilities to tailor and optimize astrocyte-compatible ECM-mimicking hydrogels that can be processed by means of additive biofabrication can facilitate the development of advanced tissue and disease models of the central nervous system.
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| 12. |
- Peaucelle, Marc, et al.
(författare)
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Covariations between plant functional traits emerge from constraining parameterization of a terrestrial biosphere model
- 2019
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 28:9, s. 1351-1365
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The mechanisms of plant trait adaptation and acclimation are still poorly understood and, consequently, lack a consistent representation in terrestrial biosphere models (TBMs). Despite the increasing availability of geo-referenced trait observations, current databases are still insufficient to cover all vegetation types and environmental conditions. In parallel, the growing number of continuous eddy-covariance observations of energy and CO2 fluxes has enabled modellers to optimize TBMs with these data. Past attempts to optimize TBM parameters mostly focused on model performance, overlooking the ecological properties of ecosystems. The aim of this study was to assess the ecological consistency of optimized trait-related parameters while improving the model performances for gross primary productivity (GPP) at sites. Location: Worldwide. Time period: 1992–2012. Major taxa studied: Trees and C3 grasses. Methods: We optimized parameters of the ORCHIDEE model against 371 site-years of GPP estimates from the FLUXNET network, and we looked at global covariation among parameters and with climate. Results: The optimized parameter values were shown to be consistent with leaf-scale traits, in particular, with well-known trade-offs observed at the leaf level, echoing the leaf economic spectrum theory. Results showed a marked sensitivity of trait-related parameters to local bioclimatic variables and reproduced the observed relationships between traits and climate. Main conclusions: Our approach validates some biological processes implemented in the model and enables us to study ecological properties of vegetation at the canopy level, in addition to some traits that are difficult to observe experimentally. This study stresses the need for: (a) implementing explicit trade-offs and acclimation processes in TBMs; (b) improving the representation of processes to avoid model-specific parameterization; and (c) performing systematic measurements of traits at FLUXNET sites in order to gather information on plant ecophysiology and plant diversity, together with micro-meteorological conditions.
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| 13. |
- Porter, Ashleigh F., et al.
(författare)
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Novel hepaci- and pegi-like viruses in native Australian wildlife and non-human primates
- 2020
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Ingår i: Virus Evolution. - : OXFORD UNIV PRESS. - 2057-1577. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- The Flaviviridae family of positive-sense RNA viruses contains important pathogens of humans and other animals, including Zika virus, dengue virus, and hepatitis C virus. The Flaviviridae are currently divided into four genera-Hepacivirus, Pegivirus, Pestivirus, and Flavivirus-each with a diverse host range. Members of the genus Hepacivirus are associated with an array of animal species, including humans, non-human primates, other mammalian species, as well as birds and fish, while the closely related pegiviruses have been identified in a variety of mammalian taxa, also including humans. Using a combination of total RNA and whole-genome sequencing we identified four novel hepaci-like viruses and one novel variant of a known hepacivirus in five species of Australian wildlife. The hosts infected comprised native Australian marsupials and birds, as well as a native gecko (Gehyra lauta). From these data we identified a distinct marsupial clade of hepaci-like viruses that also included an engorged Ixodes holocyclus tick collected while feeding on Australian long-nosed bandicoots (Perameles nasuta). Distinct lineages of hepaci-like viruses associated with geckos and birds were also identified. By mining the SRA database we similarly identified three new hepaci-like viruses from avian and primate hosts, as well as two novel pegi-like viruses associated with primates. The phylogenetic history of the hepaci-and pegi-like viruses as a whole, combined with co-phylogenetic analysis, provided support for virus-host co-divergence over the course of vertebrate evolution, although with frequent cross-species virus transmission. Overall, our work highlights the diversity of the Hepacivirus and Pegivirus genera as well as the uncertain phylogenetic distinction between.
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| 14. |
- Yao, Yunjun, et al.
(författare)
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Estimation of high-resolution terrestrial evapotranspiration from Landsat data using a simple Taylor skill fusion method
- 2017
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 553, s. 508-526
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Tidskriftsartikel (refereegranskat)abstract
- Estimation of high-resolution terrestrial evapotranspiration (ET) from Landsat data is important in many climatic, hydrologic, and agricultural applications, as it can help bridging the gap between existing coarse-resolution ET products and point-based field measurements. However, there is large uncertainty among existing ET products from Landsat that limit their application. This study presents a simple Taylor skill fusion (STS) method that merges five Landsat-based ET products and directly measured ET from eddy covariance (EC) to improve the global estimation of terrestrial ET. The STS method uses a weighted average of the individual ET products and weights are determined by their Taylor skill scores (S). The validation with site-scale measurements at 206 EC flux towers showed large differences and uncertainties among the five ET products. The merged ET product exhibited the best performance with a decrease in the averaged root-mean-square error (RMSE) by 2–5 W/m2 when compared to the individual products. To evaluate the reliability of the STS method at the regional scale, the weights of the STS method for these five ET products were determined using EC ground-measurements. An example of regional ET mapping demonstrates that the STS-merged ET can effectively integrate the individual Landsat ET products. Our proposed method provides an improved high-resolution ET product for identifying agricultural crop water consumption and providing a diagnostic assessment for global land surface models.
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| 15. |
- Yasuga, Hiroki, et al.
(författare)
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Fluid interfacial energy drives the emergence of three-dimensional periodic structures in micropillar scaffolds
- 2021
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Ingår i: Nature Physics. - : Springer Nature. - 1745-2473 .- 1745-2481. ; 17:7, s. 794-800
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Tidskriftsartikel (refereegranskat)abstract
- Structures that are periodic on a microscale in three dimensions are abundant in nature, for example, in the cellular arrays that make up living tissue. Such structures can also be engineered, appearing in smart materials(1-4), photonic crystals(5), chemical reactors(6), and medical(7) and biomimetic(8) technologies. Here we report that fluid-fluid interfacial energy drives three-dimensional (3D) structure emergence in a micropillar scaffold. This finding offers a rapid and scalable way of transforming a simple pillar scaffold into an intricate 3D structure that is periodic on a microscale, comprising a solid microscaffold, a dispersed fluid and a continuous fluid. Structures generated with this technique exhibit a set of unique features, including a stationary internal liquid-liquid interface. Using this approach, we create structures with an internal liquid surface in a regime of interest for liquid-liquid catalysis. We also synthesize soft composites in solid, liquid and gas combinations that have previously not been shown, including actuator materials with temperature-tunable microscale pores. We further demonstrate the potential of this method for constructing 3D materials that mimic tissue with an unprecedented level of control, and for microencapsulating human cells at densities that address an unresolved challenge in cell therapy.
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