90 research outputs found

    Isomotive dielectrophoresis for enhanced analyses of cell subpopulations.

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    As the relentless dream of creating a true lab-on-a-chip device is closer to realization than ever before, which will be enabled through efficient and reliable sample characterization systems. Dielectrophoresis (DEP) is a term used to describe the motion of dielectric particles/ cells, by means of a non-uniform electric field (AC or DC). Cells of different dielectric properties (i.e., size, interior properties, and membrane properties) will act differently under the influence of dielectrophoretic force. Therefore, DEP can be used as a powerful, robust, and flexible tool for cellular manipulation, separation, characterization, and patterning. However, most recent DEP applications focus on trapping, separation, or sorting particles. The true value of DEP lies in its analytical capabilities which can be achieved by utilizing isomotive dielectrophoresis (isoDEP). In isoDEP, the gradient of the electric field-squared is constant, hence, upon the application of electric field, all particles/cells that share the same dielectric properties will feel the same constant dielectrophoretic force i.e., translate through the micro-channel at the same velocity. However, DEP is not the only acting force upon particles inside an isoDEP device, other electrokinetics, including but not limited to electrothermal hydrodynamics, might act on particles simultaneously. Within this dissertation, electrothermal-based experiments have been conducted to assess the effect of such undesired forces. Also, to maximize the relative DEP force over other forces for a given cell/particle size, design parameters such as microchannel width, height, fabrication materials, lid thickness, and applied electric field must be properly tuned. In this work, scaling law analyses were developed to derive design rules that relate those tunable parameters to achieve the desired dielectrophoretic force for cell analysis. Initial results indicated that for a particle suspended in 10 mS/m media, if the channel width and height are below 10 particle diameters, the electrothermal-driven flow is reduced by ∼ 500 times compared to the 500 µm thick conventional isoDEP device. Also, Replacing glass with silicon as the device’s base for an insulative-based isoDEP, reduces the electrothermal induced flow by ∼ 20 times. Within this dissertation, different device designs and fabrication methods were attempted in order to achieve an isoDEP platform that can characterize and differentiate between live and dead phytoplankton cells suspended in the same solution. Unfortunately, unwanted electrokinetics (predicted by the previously mentioned scaling law analysis) prevented comprehensive isoDEP analysis of phytoplankton cells. Due to isoDEP device limitations and other complications, other techniques were pursued to electrically characterize phytoplankton cells in suspension. An electrochemical-based platform utilizing impedance spectroscopy measurements was used to extract the electrical properties of phytoplankton cells in suspension. Impedance spectroscopy spectra were acquired, and the single-shell model was applied to extract the specific membrane capacitance, cytoplasm permittivity, and conductivity of assumingly spherical cells in suspension utilizing Maxwell’s mixture theory of a controlled volume fraction of cells. The impedance of suspensions of algae were measured at different frequencies ranging from 3 kHz to 10 MHz and impedance values were compared to investigate differences between two types of cells by characterizing their change in cytoplasm permittivity and membrane capacitance. Differentiation between healthy control and nitrogen-depleted cultured algae was attempted. The extracted specific membrane capacitances of Chlamydomonas and Selenastrum were 15:57 ± 3:62 and 40:64 ± 12:6 mF/m2 respectively. Successful differentiation based on the specific membrane capacitance of different algae species was achieved. However, no significant difference was noticed between nitrogen abundant and nitrogen depleted cultures. To investigate the potential of isoDEP for cell analysis, a comparison to existing dielectrophoresis-based electrokinetic techniques was encouraged, including electrorotation (ROT) microfluidic platforms. The ROT microfluidic chip was used to characterize M17, HEK293, T-lymphocytes, and Hela single cells. Through hands-on experience with ROT, the advantages and disadvantages of this approach and isoDEP are apparent. IsoDEP proves to be a good characterization tool for subpopulation cell analysis with potential higher throughput compared to ROT while maintaining simple fabrication and operation processes. To emphasize the role of dielectrophoresis in biology, further studies utilizing the 3DEP analytical system were used to determine the electrical properties of Drosophila melanogaster (Kc167) cells ectopically expressing Late embryogenesis abundant (LEA) proteins from the anhydrobiotic brine shrimp, Artemia franciscana. Dielectrophoretic-based characterization data demonstrates that single expression of two different LEA proteins, AfrLEA3m and AfrLEA6, both increase cytoplasmic conductivity of Kc167 cells to a similar extend above control values. The extracted DEP data supported previously reported data suggesting that AfrLEA3m can interact directly with membranes during water stress. This hypothesis was strengthened using scanning electron microscopy, where cells expressing AfrLEA3m were found to retain their spherical morphology during desiccation, while control cells exhibited a larger variety of shapes in the desiccated state

    Industrial-Scale Manufacture of Oleosin 30G for Use as Contrast Agent in Echocardiography

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    In ultrasound sonography, microbubbles are used as contrasting agents to improve the effectiveness of ultrasound imaging. Monodisperse microbubbles are required to achieve the optimal image quality. In order to achieve a uniform size distribution, microbubbles are stabilized with surfactant molecules. One such molecule is Oleosin, an amphiphilic structural protein found in vascular plant oil bodies that contains one hydrophobic and two hydrophilic sections. Controlling the functionalization of microbubbles is a comprehensive and versatile process using recombinant technology to produce a genetically engineered form of Oleosin called Oleosin 30G. With the control of a microfluidic device, uniformly-sized and resonant microbubbles can be readily produced and stored in stable conditions up to one month. Currently, Oleosin microbubbles are limited to the lab-scale; however, through development of an integrated batch bioprocessing model, the overall product yield of Oleosin 30G can be increased to 7.39 kg/year to meet needs on the industrial-scale. An Oleosin-stabilized microbubble suspension as a contrast agent is in a strong position to take a competitive share of the current market, capitalizing on needs unmet by current market leader, Definity®. Based on market dynamics and process logistics, scaled-up production of Oleosin 30G for use as a contrast agent is expected to be both a useful and profitable venture

    Holographic Sensors for the Detection of Liquid Phase Analytes

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    The aim of this project is to design, fabricate and study experimentally photonic structures created by holographic lithography for application in sensing. The aim is to modify the photonic structures with analyte sensitive materials and view of their application in environmental and biomedical sensing. Two types of photonic structures were investigated in these studies: modified surface relief holographic gratings and volume holographic gratings

    Optimization of Oleosin 30G Production for Echocardiography

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    Provided they are uniform in size, monodisperse microbubbles behave as contrast agents to enhance echocardiographic imaging. Compounds like Oleosin 30G with surfactant-like properties help stabilize microbubbles - thereby ensuring their uniform size. Designed herein is an industrial-scale plant to produce medical-grade Oleosin 30G with a process consisting of three steps: 1) upstream production via recombinant E. coli in an integrated batch bioprocessing model, 2) downstream purification, and 3) processing by microfluidic manifolds. Ultimately Oleosin 30G-coated microbubbles are manufactured, ready for injection within one month. Owing to its unique properties and cost-effective production, Oleosin 30G has the potential to outcompete current market leader Definity®. Altogether, overall yield of Oleosin 30G constitutes 7.39 kg/year to provide for 100% market saturation. Financial analysis indicates pursuing Oleosin 30G for echocardiography applications is very profitable with a 296% return on investment and holds potential for production expansion should the market demand increase

    UMaine Today

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    UMaine Today magazine, published twice a year by the University of Maine Division of Marketing and Communications, showcases creativity and achievement at the University of Maine. The goal of the general-interest magazine is to demonstrate the university’s value and contributions to the state, and to advance institutional goals.https://digitalcommons.library.umaine.edu/umaine_today/1077/thumbnail.jp

    Art as we don't know it

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    2018 marked the 10th anniversary of the Bioart Society and created the impetus for the publication of Art as We Don’t Know It. For this publication, the Bioart Society joined forces with the School of Arts, Design and Architecture of the Aalto University. The close history and ongoing collaborative relationship between the Bioart Society and Biofilia – Base for Biological Arts in the Aalto University lead to this mutual effort to celebrate together a diverse and nurturing environment to foster artistic practices on the intersection of art, science and society. Rather than stage a retrospective, we decided to invite writings that look forward and invite speculations about the potential directions of bioarts. The contributions range from peer-reviewed articles to personal accounts and inter-views, interspersed with artistic contributions and Bioart Society projects. The selection offers a purview of the rich variety, both in content and form, of the work currently being made within the field of bioart. The works and articles clearly trouble the porous and provisional definitions of what might be understood as bioart, and indeed definitions of bioart have been usefully and generativity critiqued since the inception of the term. Whilst far from being definitive, we consider the contributions of the book to be tantalising and valuable indicators of trends, visions and impulses. We also invite into the reading of this publication a consideration of potential obsolescences knowing that some of today’s writing will become archaic over time as technologies driven by contemporary excitement and hype are discarded. In so doing we also acknowledge and ponder upon our situatedness and the partialness of our purview in how we begin and find points of departure from which to anticipate the unanticipated. Whilst declining the view of retrospection this book does present art and research that has grown and flourished within the wider network of both the Bioart Society and Biofilia during the previous decade. The book is structured into four thematic sections Life As We Don’t Know It, Convergences, Learnings/Unlearnings, Redraw and Refigure and rounded off with a glossary

    Development of a novel 3D nanofibre co-culture model for characterisation of neural cell degeneration

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    Neurodegenerative diseases are prolonged and progressive. In general, they affect individuals in the latter stages of their lives. The pathology of neural cell degeneration is widely researched, and most current therapeutic strategies aim to delay its progression by either promoting neuronal regeneration, resurrecting the lost brain function with stimulation electrodes or by cell replacement therapies. Neuronal and glial cells are researched to better understand the physiological condition and to find a cure for degenerative diseases. In current in vitro techniques, cells dissociated from their natural three-dimensional (3D) tissue and cultured on flat surfaces present a significant drawback in drug discovery and cell therapy research. Communication and various signal transduction between neuronal and glial cells in the in vivo system are purely based on a dynamic convoluted systematic network constructed and expanded in a 3D manner. Recently, electrospun 3D nanofibre scaffolds have gained attention among researchers for their ability to mimic the natural 3D microenvironment that cells inhabit. Developing an in vitro system which emulates the in vivo 3D habitat of neural cells has been a significant challenge. This thesis reports on the advantages of using novel 3D suspended nanofibre membrane technology to create better models for both drug discovery and therapeutic implants. In this study, we focused on developing a suitable sterile nanofibre porous membrane using Polyacrylonitrile (PAN), and Jeffamine® ED-2003 modified polyacrylonitrile (PJ) to provide favourable conditions for neuronal and glial proliferation, differentiation and survival. The study was designed, engineered and optimised three different state-of-the-art fully suspended nanofibre models that are highly multi-functional and suitable for investigating several diseases and chronic conditions. We have characterised the growth and survival of human SH-SY5Y neuroblastoma, human U-87MG glioblastoma, human ReNcell CX neural progenitor and primary neural cells from E18 rat hippocampal tissue on both PAN and PJ nanofibre scaffolds. Our investigations and chronic studies have shown extended survival of cells on a scaffold in comparison to these cells cultured on the base of cell adherent tissue culture plates (TCP). Differentiation cell culture trials have demonstrated that both PAN and PJ are capable of supporting cell differentiation and immunofluorescence and western blot analysis has shown elevated levels of key differentiation marker proteins on the cells cultured on the suspended scaffolds compared to TCP. Our findings indicate that the new 3D suspended nanofibre scaffolds support improved growth, survival and differentiation of both cell populations as well as increasing the sensitivity of the cells to Toxins when compared to the sensitivity of cells growth of the base of TCPs. Moreover, chronic exposures to Toxins using the novel co-culture scaffold model has shown prolonged neuronal survival in the presence of astrocytes. Together, our findings suggest the potential for the 3D nanofibre approach to improve in vitro therapeutic studies and our co-culture system, which creates a better mimic, should lead to a reduced number of animals used for pharmaceutical development and in the screening of compounds to find neuroprotective compounds to prevent degeneration of neural cells

    Photonic Integrated Circuit (PIC) Device Structures: Background, Fabrication Ecosystem, Relevance to Space Systems Applications, and Discussion of Related Radiation Effects

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    Electronic integrated circuits are considered one of the most significant technological advances of the 20th century, with demonstrated impact in their ability to incorporate successively higher numbers transistors and construct electronic devices onto a single CMOS chip. Photonic integrated circuits (PICs) exist as the optical analog to integrated circuits; however, in place of transistors, PICs consist of numerous scaled optical components, including such "building-block" structures as waveguides, MMIs, lasers, and optical ring resonators. The ability to construct electronic and photonic components on a single microsystems platform offers transformative potential for the development of technologies in fields including communications, biomedical device development, autonomous navigation, and chemical and atmospheric sensing. Developing on-chip systems that provide new avenues for integration and replacement of bulk optical and electro-optic components also reduces size, weight, power and cost (SWaP-C) limitations, which are important in the selection of instrumentation for specific flight projects. The number of applications currently emerging for complex photonics systems-particularly in data communications-warrants additional investigations when considering reliability for space systems development. This Body of Knowledge document seeks to provide an overview of existing integrated photonics architectures; the current state of design, development, and fabrication ecosystems in the United States and Europe; and potential space applications, with emphasis given to associated radiation effects and reliability

    Sewage sludge heavy metal analysis and agricultural prospects for Fiji

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    Insoluble residues produced in Waste Water Treatment Plants (WWTP) as by products are known as sewage sludge (SS). Land application of SS, particularly in agricultural lands, is becoming an alternative disposal method in Fiji. However, currently there is no legislative framework governing its use. SS together with its high nutrient and organic matter contents, constitutes some undesired pollutants such as heavy metals, which may limit its extensive use. The focus of this study therefore was to determine the total concentrations of Pb, Zn, Cd, Cu, Cr, Ni and Mn in the SS produced at the Kinoya WWTP (Fiji) and in the non-fertile soil amended with the SS at 20, 40, 60, 80% application rates and in the control (100% Soil). The bioavailable heavy metals were also determined as it depicts the true extent of metal contamination. The treatment mixtures were then used to cultivate cabbage plants in which the total heavy metal uptake was investigated. Total Zn (695.6 mg/kg) was present in the highest amounts in the 100% SS (control), followed by Pb (370.9 mg/kg), Mn (35.0 mg/kg), Cu (65.5 mg/kg), Cr (20.5 mg/kg) and finally Cd (13.5 mg/kg) and hence a similar trend was seen in all treatment mixtures. The potential mobility of sludgeborne heavy metals can be classified as Ni > Cu > Cd > Zn > Mn > Cr > Pb. Total metal uptake in plant leaves and stems showed only the bioavailable metals Cu, Cd, Zn and Mn, with maximum uptake occurring in the leaves. Ni, despite being highly mobile was not detected, due to minute concentrations in the SS treatments. Optimum growth occurred in the 20 and 40% SS treatments. However maximum Cu and Mn uptake occurred in the 40% SS treatment thereby making the 20% treatment the most feasible. Furthermore the total and bioavailable metal concentrations observed were within the safe and permitted limits of the EEC and USEPA legislations

    Emerging Threats of Synthetic Biology and Biotechnology

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    Synthetic biology is a field of biotechnology that is rapidly growing in various applications, such as in medicine, environmental sustainability, and energy production. However these technologies also have unforeseen risks and applications to humans and the environment. This open access book presents discussions on risks and mitigation strategies for these technologies including biosecurity, or the potential of synthetic biology technologies and processes to be deliberately misused for nefarious purposes. The book presents strategies to prevent, mitigate, and recover from ‘dual-use concern’ biosecurity challenges that may be raised by individuals, rogue states, or non-state actors. Several key topics are explored including opportunities to develop more coherent and scalable approaches to govern biosecurity from a laboratory perspective up to the international scale and strategies to prevent potential health and environmental hazards posed by deliberate misuse of synthetic biology without stifling innovation. The book brings together the expertise of top scholars in synthetic biology and biotechnology risk assessment, management, and communication to discuss potential biosecurity governing strategies and offer perspectives for collaboration in oversight and future regulatory guidance
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