Papers by Bruno Matarèse
IEEE 24th International Conference on Nanotechnology (NANO), 2024
We present a promising approach for detecting as few as 1% of rare leukemia cells during the earl... more We present a promising approach for detecting as few as 1% of rare leukemia cells during the early stages of blood cancers. This study demonstrates a novel microfluidic chip utilizing a bulk piezoelectric ceramic device to manipulate cells with sound waves. By analyzing the movement patterns of normal mononuclear cells (MNCs) and abnormal THP-1 acute myeloid leukemia (AML) cells within an acoustic field, we observed distinct behaviors. Our findings suggest a label-free, non-targeted approach for sensitive detection of rare abnormal cells within a mixed population. This method, based on acoustophoresis principles, holds promise for analyzing biophysical properties of individual cells for early cancer diagnosis, potentially leading to earlier intervention and improved patient outcomes for leukemia. While this study focuses on microscopic analysis, we also discuss the potential for developing large-scale acoustophoresis-based methods for highthroughput rare cell detection using high-resolution nanofabrication techniques.
Radiation Research, 2024
This paper starts with a brief history of the birth of the field of radioecology during the Cold ... more This paper starts with a brief history of the birth of the field of radioecology during the Cold War with a focus on US activity. We review the establishment of the international system for radiation protection and the science underlying the guidelines. We then discuss the famous ICRP 60 statement that if Man is protected, so is everything else and show how this led to a focus in radioecology on pathways to Man rather than concern about impacts on environments or ecosystems. We then review the contributions of Radiation Research Society members and papers published in Radiation Research which contributed to the knowledge base about effects on nonhuman species. These fed into international databases and computer-based tools such as ERICA and ResRad Biota to guide regulators. We then examine the origins of the concern that ICRP 60 is not sufficient to protect ecosystems and discuss the establishment of ICRP Committee 5 and its recommendations to establish reference animals and plants. The review finishes with current concerns that reference animals and plants (RAPs) are not sufficient to protect ecosystems, given the complexity of interacting factors such as the climate emergency and discusses the efforts of ICRP, the International Union of Radioecologists and other bodies to capture the concepts of ecosystem services and ecosystem complexity modelling in radioecology.
IJMS, 2023
It is well established that cells, tissues, and organisms exposed to low doses of ionizing radiat... more It is well established that cells, tissues, and organisms exposed to low doses of ionizing radiation can induce effects in non-irradiated neighbors (non-targeted effects or NTE), but the mechanisms remain unclear. This is especially true of the initial steps leading to the release of signaling molecules contained in exosomes. Voltage-gated ion channels, photon emissions, and calcium fluxes are all involved but the precise sequence of events is not yet known. We identified what may be a quantum entanglement type of effect and this prompted us to consider whether aspects of quantum biology such as tunneling and entanglement may underlie the initial events leading to NTE. We review the field where it may be relevant to ionizing radiation processes. These include NTE, low-dose hyper-radiosensitivity, hormesis, and the adaptive response. Finally, we present a possible quantum biological-based model for NTE.
IJRB, 2023
The era of high-throughput techniques created big data in the medical field and research discipli... more The era of high-throughput techniques created big data in the medical field and research disciplines. Machine intelligence (MI) approaches can overcome critical limitations on how those largescale data sets are processed, analyzed, and interpreted. The 67 th Annual Meeting of the Radiation Research Society featured a symposium on MI approaches to highlight recent advancements in the radiation sciences and their clinical applications. This article summarizes three of those presentations regarding recent developments for metadata processing and ontological formalization, data mining for radiation outcomes in pediatric oncology, and imaging in lung cancer.
Conjugated polymers are increasingly exploited for biomedical applications. In this work, we expl... more Conjugated polymers are increasingly exploited for biomedical applications. In this work, we explored the optical characteristics of conjugated polymers of variable chemical structures at multiple levels relevant to biological interfacing, from fluorescence yield to their influence on cellular membrane potential. We systematically compared the performance of conjugated polymer as cast thin films and as nanoparticles stabilized with amphiphilic polyethylene glycol-poly lactic acid-co-glycolic acid (PEG-PLGA). We assessed in both the dark and under illumination the stability of key optoelectronic properties in various environments, including air and biologically relevant physiological saline solutions. We found that photoreduction of oxygen correlates with nanoparticle and film degradation in physiologically relevant media. Using patch-clamp recordings in cell lines and primary neurons, we identified two broad classes of membrane potential response, which correspond to photosensitizer-and photothermal-mediated effects. Last, we introduced a metric named OED 50 (optical energy for 50% depolarization), which conveys the phototoxic potency of a given agent and thereby its operational photosafety profile.
In Proceedings of the IEEE Conference on Nanotechnology, 2021
Prototype fully biocompatible organic lightemitting diodes are investigated, with a view to creat... more Prototype fully biocompatible organic lightemitting diodes are investigated, with a view to creating a suitable and high-performance light source as a medical implant device. A selection of organic LED materials that have potential suitability for the biological environment are examined. First, the biocompatibility of selected OLED materials was evaluated by the study of cell adhesion and cytotoxicity of HeLa cells cultured on the candidate materials. Thus it was possible to design a device structure composed entirely of biocompatible materials. Second, the characterization of the electroluminescence properties of the prototype OLED is shown and its limitation evaluated. Third, the aqueous stability of the fully biocompatible light source is examined. There is strong evidence that fully biocompatible and stable light-emitting implant devices can be easily constructed. This is the first time a fully biocompatible organic light-emitting diode, albeit embryonic, is reported, with the hope that it may lead to further research to optimize the device performance. Some suggestions on suitable device properties towards in vivo transition are provided.
International Journal of Radiation Biology, 2022
Purpose: We characterise for the first time the emission of acoustic waves from cultured cells ir... more Purpose: We characterise for the first time the emission of acoustic waves from cultured cells irradiated with X-ray photon radiation.
Methods and materials: Human cancer cell lines (MCF-7, HL-60) and control cell-free media were exposed to 1 Gy X-ray photons while recording the sound generated before, during and after irradiation using custom large-bandwidth ultrasound transducer. The effects of dose rate and cell viability were investigated.
Results: We report the first recorded acoustic signals captured from a collective pressure wave response to ionising irradiation in cell culture. The acoustic signal was co-terminous with the radiation pulse, its magnitude was dependent on radiation dose rate, and live and dead cells showed qualitatively and quantitatively different acoustic signal characteristics. The signature of the collective acoustic peaks was temporally wider and with higher acoustic power for irradiated HL-60 than for irradiated MCF-7.
Conclusions: We show that X-ray irradiation induces two cultured cancer cell types to emit a characteristic acoustic signal for the duration of the radiation pulse. The rapid decay of the signal excludes acoustic emissions themselves from contributing to the inter-organism bystander signal previously reported in intact animals, but they remain a potential component of the bystander process in tissues and cell cultures. This preliminary study suggests that further work on the potential role of radiation induced acoustic emission (RIAE) in the inter-cellular bystander effect is merited.
Cell Physiol Biochem, 2021
Background/Aims: The use of novel cryo-additive agents to increase cell viability post-cryopreser... more Background/Aims: The use of novel cryo-additive agents to increase cell viability post-cryopreservation is paramount to improve future cell based-therapy treatments. We aimed to establish the Human Leukemia (HL-60) cells lipidomic and biological patterns when cryo-preserved in DMSO alone and with 300 µM Nigerose (Nig), 200 µM Salidroside (Sal) or a combination of Nig (150 µM) and Sal (100 µM). Methods: HL-60 cells were pre-incubated with Nig/Sal prior, during and post cryopreservation, and subjected to global lipidomic analysis. Malondialdeyhde (MDA), released lactate dehydrogenase (LDH) and reactive oxygen scavenger (ROS) measurements were also carried out to evaluate levels of lipid peroxidation and cytotoxicity. Results: Cryopreserving HL-60 cells in DMSO with Nig and Sal provided optimal protection against unsaturated fatty acid oxidation. Post-thaw, cellular phospholipids and mitochondrial cardiolipins were increased by Nig/Sal as the ratio of unsaturated to saturated fatty acids 2.08 +/-0.03 and 0.95 +/-0.09 folds respectively in comparison to cells cryopreserved in DMSO alone (0.49 +/-0.05 and 0.86 +/-0.10 folds). HL-60 lipid peroxidation levels in the presence of DMSO + Nig and Sal combined were significantly reduced relative to pre-cryopreservation levels (10.91 +/-2.13 nmole) compared to DMSO (17.1 +/-3.96 nmole). DMSO + Nig/Sal combined also significantly reduced cell cytotoxicity post-thaw (0.0128 +/-0.00182 mU/mL) in comparison to DMSO (0.0164 +/-0.00126 mU/mL). The combination of Nig/Sal also reduced significantly ROS levels to the levels of prior cryopreservation of HL-60.
arXiv, 2020
https://arxiv.org/abs/2010.14287
arXiv:2010.14287
We report optical brain imaging using a semi-... more https://arxiv.org/abs/2010.14287
arXiv:2010.14287
We report optical brain imaging using a semi-transparent organic light-emitting diode (OLED) based on the orange light-emitting polymer (LEP) Livilux PDO-124. The OLED serves as a compact, extended light source which is capable of uniformly illuminating the cortical surface when placed across a burr hole in the skull. Since all layers of the OLED are substantially transparent to photons with energies below the optical gap of the LEP, light emitted or reflected by the cortical surface may be efficiently transmitted through the OLED and into the objective lens of a low magnification microscope ("macroscope"). The OLED may be placed close to the cortical surface, providing efficient coupling of incident light into the brain cavity; furthermore, the macroscope may be placed close to the upper surface of the OLED, enabling efficient collection of reflected/emitted light from the cortical surface. Hence the use of a semi-transparent OLED simplifies the optical setup, while at the same time maintaining high sensitivity. The OLED is applied here to one of the most demanding forms of optical brain imaging, namely extrinsic optical imaging involving a voltage sensitive dye (VSD). Specifically, we carry out functional imaging of the primary visual cortex (V1) of a rat, using the voltage sensitive dye RH-1691 as a reporter. Imaging through the OLED light-source, we are able to resolve small (~ 0.1 %) changes in the fluorescence intensity of the dye due to changes in the neuronal membrane potential following a visual stimulus. Results are obtained on a single trial basis-i.e. without averaging over multiple measurements-with a time-resolution of ten milliseconds.
https://arxiv.org/abs/2010.14287
International Journal of Radiation Biology , 2020
Objectives: This commentary reviews and evaluates the role of sound signals as part of the infoso... more Objectives: This commentary reviews and evaluates the role of sound signals as part of the infosome of cells and organisms. Emission and receipt of sound has recently been identified as a potentially important universal signalling mechanism invoked when organisms are stressed. Recent evidence from plants, animals and microbes suggests that it could be a stimulus for specific or general molecular cellular stress responses in different contexts, and for triggering population level responses. This paper reviews the current status of the field with particular reference to the potential role of sound signalling as an immediate/early bystander effector (RIBE) during radiation-induced stress. Conclusions: While the chemical effectors involved in intercellular and inter-organismal signalling have been the subject of intense study in the field of Chemical Ecology, less appears to be known about physical signals in general and sound signals in particular. From this review we conclude that these signals are ubiquitous in each kingdom and behave very like physical bystander signals leading to regulation of metabolic pathways and gene expression patterns involved in adaptation, synchronisation of population responses, and repair or defence against damage. We propose the hypothesis that acoustic energy released on interaction of biota with electromagnetic radiation may represent a signal released by irradiated cells leading to, or complementing, or interacting with, other responses, such as endosome release, responsible for signal relay within the unirradiated individuals in the targeted population.
frontiers in Bioengineering and Biotechnology, 2019
Optogenetics combines optics and genetics to enable minimally invasive cell-type-specific stimula... more Optogenetics combines optics and genetics to enable minimally invasive cell-type-specific stimulation in living tissue. For the purposes of bio-implantation, there is a need to develop soft, flexible, transparent and highly biocompatible light sources. Organic semiconducting materials have key advantages over their inorganic counterparts, including low Young's moduli, high strain resistances, and wide color tunability. However, until now it has been unclear whether organic light emitting diodes (OLEDs) are capable of providing sufficient optical power for successful neuronal stimulation, while still remaining within a biologically acceptable temperature range. Here we investigate the use of blue polyfluorene-and orange poly(p-phenylenevinylene)-based OLEDs as stimuli for blue-light-activated Sustained Step Function Opsin (SFFO) and red-light-activated ChrimsonR opsin, respectively. We show that, when biased using high frequency (multi-kHz) drive schemes, the OLEDs permit safe and controlled photostimulation of opsin-expressing neurons and were able to control neuronal firing with high temporal-resolution at operating temperatures lower than previously demonstrated.
Nanotechnology (IEEE-NANO), 2018
This work investigates the mechanical and dielectric properties of an ion-selective membrane base... more This work investigates the mechanical and dielectric properties of an ion-selective membrane based on PDMS:PEG:valinomycin, with a view to creating practical geometries for high performance ion sensing in a variety of real world settings including healthcare, food industry and agriculture. We focus effort on measuring physical changes in the membrane that can be detected with simple sensors. First a dynamic mechanical analyser instrument was used to determine the effect of potassium ions on the real and imaginary bending storage modulus, loss tangent, glass transition temperature, temperature coefficient of millimeter sized PDMS samples. Second, a microwave dielectric analyser with a coaxial probe fixture was applied to the same sample to isolate dielectric shifts associated with ion uptake, namely the real and imaginary permittivities. These perturbation measurements performed for PDMS, PDMS:PEG and PDMS:PEG:V samples, provide strong evidence that alternatives to traditional electrochemical sensing devices can easily be constructed. Thus a plethora of new acoustic and capacitive sensing geometries arise. Thus there is the opportunity to integrate membranes into quartz crystal microbalance, surface acoustic wave and single-sided capacitance sensors. Some suggestions on suitable dimensions, aspect ratios, operating frequencies are provided.
Langmuir, 2018
π-Conjugated polymer nanoparticles (CPNs) are under investigation as photoluminescent agents for ... more π-Conjugated polymer nanoparticles (CPNs) are under investigation as photoluminescent agents for diagnostics and bioimaging. To determine whether the choice of surfactant can improve CPN properties and prevent protein adsorption, five nonionic polyethylene glycol alkyl ether surfactants were used to produce CPNs from three representative π-conjugated polymers. The surfactant structure did not influence size or yield, which was dependent on the nature of the conjugated polymer. Hydrophobic interaction chromatography, contact angle, quartz crystal microbalance, and neutron reflectivity studies were used to assess the affinity of the surfactant to the conjugated polymer surface and indicated that all surfactants were displaced by the addition of a model serum protein. In summary, CPN preparation methods which rely on surface coating of a conjugated polymer core with amphiphilic surfactants may produce systems with good yields and colloidal stability in vitro, but may be susceptible to significant surface alterations in physiological fluids.
Gold is the most widely used electrode material for bioelectronic applications due to its high el... more Gold is the most widely used electrode material for bioelectronic applications due to its high electrical conductivity, good chemical stability and proven biocompatibility. However, it adheres only weakly to widely used substrate materials such as glass and silicon oxide, typically requiring the use of a thin layer of chromium between the substrate and the metal to achieve adequate adhesion. Unfortunately, this approach can reduce biocompatibility relative to pure gold films due to the risk of the underlying layer of chromium becoming exposed. Here we report on an alternative adhesion layer for gold and other metals formed from a thin layer of the negative-tone photoresist SU-8, which we find to be significantly less cytotoxic than chromium, being broadly comparable to bare glass in terms of its biocompatibility. Various treatment protocols for SU-8 were investigated, with a view to attaining high transparency and good mechanical and biochemical stability. Thermal annealing to induce partial cross-linking of the SU-8 film prior to gold deposition, with further annealing after deposition to complete cross-linking, was found to yield the best electrode properties. The optimized glass/SU8-Au electrodes were highly transparent, resilient to delamination, stable in biological culture medium, and exhibited similar biocompatibility to glass. The development of bioelectrodes that are transparent, biocompatible and capable of extended, stable operation in a broad range of biological media is a critical challenge for the field of bioelectronics 1–3. Optoelectronic devices such as light-emitting diodes 4–8 , photodiodes 9–12 , and phototransistors 13 have been deployed in multiple media, ranging from relatively mild interstitial fluids 14–19 to corrosive solutions 20–22. The most important properties for bioelectrodes are high mechanical and chemical stability, high conductivity, high transparency, and excellent biocompatibility. For this reason, thin-film (≪100 nm) gold is usually considered the electrode of choice for bioe-lectronic applications 23–25. A further requirement of a bioelectrode, however, is strong adhesion to the surface on which it is deposited – often a transparent substrate material such as glass or quartz. Unfortunately, gold exhibits poor adhesion to both these materials, and typically requires the inclusion of a thin layer of an oxidative metal such as chromium to achieve adequate adhesion to the substrate 26. Chromium, however, has significant disadvantages from a bioelectronic perspective, including cumbersome patterning procedures and potential cytotoxicity, leading to a strong demand for alternative adhesion layers. (Note, while some other metals such as titanium have been successfully employed as adhesion layers for conventional electronic applications, the cytotoxicity of these metals and their oxides is also an open question, see e.g. ref. 27). The commercial negative-tone photoresist SU8 28 has previously been used as an alternative adhesion layer to chromium since it adheres well to multiple substrate materials and (once cross-linked) is chemically inert 29,30. SU8 has the further advantage of being photo-patternable, allowing patterned electrodes with feature sizes down to a few microns to be readily fabricated using a simple two-step expose/develop procedure 31. We have previously reported preliminary data 32,33 , showing SU8-supported gold electrodes to have favourable and moderately stable electro-optical characteristics in cell culturing medium, making them a potentially attractive choice for bioelectronics. Unfortunately, we found that, after prolonged periods of immersion in culture medium, gold deposited on SU8 had a tendency to develop wrinkles and cracks on the surface, reducing electrode durability and
—Engineering opto-electronic devices for operation in liquid environments requires a comprehensiv... more —Engineering opto-electronic devices for operation in liquid environments requires a comprehensive understanding of the consequences of exposing electrode materials to an aqueous environment. For this reason, we have investigated the stability of electro-optical properties (namely conductivity, work Function and transmittance) of several commonly used electrode materials for organic optoelectronics. As a potential means of improving the long term performance of the electrodes in solution, we further characterized the stability of the electrodes following their deposition on a transparent SU-8 adhesion interlayer. As such, Indium-Tin Oxide, Gold, Gold-SU8, Silver, Silver-SU8, Aluminum and Aluminium-SU8 were immersed in three different media of varying ionic composition (DI water, Phosphate-Buffered Saline and Dulbecco's Modified Eagle Medium) as well as a control " air immersion " condition. By comparing the electrode materials side by side we aimed to identify their advantages and drawbacks for use in solid/liquid devices, as well as the benefits of an adhesion layer for applications requiring long term aqueous immersion. Our findings indicate that metals show severe delamination when deposited on glass, as indicated by decreased conductance and increased optical transmittance upon immersion in media. The use of an SU8 adhesion layer was effective in bonding Silver and Gold to enhance film lifetime. Finally, since in many applications the electrode must make direct contact with biological species, we also investigated their biocompatibility by evaluating cytotoxicity of HEK293 cells cultured on the candidate materials, the results of which indicate positive biocompatibility profile for the materials investigated.
— We have investigated the stability of key electro-optical properties (Conductivity, Work Functi... more — We have investigated the stability of key electro-optical properties (Conductivity, Work Function, Transmittance) of several commonly used electrode materials for organic optoelectronics (Indium-Tin Oxide, Gold, Silver, Aluminum) in different media (Air, DI water, Phosphate Buffered Saline and Dulbecco's Modified Eagle Medium). By comparing the electrode materials side by side, we aimed to identify their advantages and drawbacks for use in solid/liquid devices. Since many applications of such devices involve the direct contact with biological species, we also investigated their biocompatibility by evaluating cytotoxicity of HEK293 cells cultured on the candidate materials.
Thesis Chapters by Bruno Matarèse
Imperial College London, 2017
https://doi.org/10.25560/68710
Optical imaging, optical detection (e.g. biosensors), and opsin b... more https://doi.org/10.25560/68710
Optical imaging, optical detection (e.g. biosensors), and opsin based neuromodulation (e.g. optogenetics) are the major techniques that have changed the practice of neuroscience. All these techniques use arc lamps, Light Emitting Diodes (LEDs) and lasers as conventional light sources. However, these light sources are not biocompatible and are excessively bulky, which limits their effectiveness as brain implants. Many improvements are necessary, such as the development of appropriate alternative light sources integrated with biological cells to ensure their compatibility with established techniques in biological laboratories. Organic Light Emitting Diodes (OLEDs) combine optical and electrical properties with known advantages of customized materials providing appropriate color tunability, lightness, and low-cost solution processing. In addition, mechanical flexibility combined with the high elastic modulus and biological inertness of carbon-based polymers and nanomaterials confer major advantages for use in non-conformal body cavities. These attractive and innovative qualities of OLEDs make them an alternative and better light source for organic neuro-optoelectronics - the optoelectronic aspect of bioelectronics. However, engineering optoelectronic devices for operation in liquid environments requires a comprehensive understanding of the consequences that may arise. This research is innovative in designing and engineering stable and biocompatible OLEDs for incorporation into living tissues. As a result, organic LEDs do not have to alter cell morphology and electrophysiological integrity/function. The principal challenge is ensuring they can operate in a highly saline and biologically active aqueous environment. Finding materials that are inherently stable in the environment in which they function is key to device optimization. The research will investigate the stability and biocompatibility of commonly used OLED materials. Key electrodes, indium, tin, oxide, gold, aluminum and silver are characterized to examine their suitability for an aqueous environment. Treating organic light emitting polymers with laminin has shown enhanced cell adhesion and biocompatibility. Prolonged immersion in cell culture medium highlights the importance of cross-linkable polymers maintaining electrical, optical and morphological properties. These properties are critical to device performance. Insulator materials play complementary and necessary roles at the interface of the OLED/bio environment – ensuring the protection of the device against oxidative or reductive processes. Insulators are critical for extending the lifetime of devices in aqueous operation. They must be encapsulated with hydrophobic polymers for protection against neuron damage from electrical stimulation. Following from the above it becomes possible to design both a highly biocompatible prototype OLED device, which is suitable for fluorescence microscopy, and patch-clamp technique for electrophysiological investigations. This would be based on opsin activation and would also include the investigation of critical design parameters for efficient OLED-opsin coupling stimulation. Additionally, OLED devices have been investigated for in vivo optical imaging of functional cortical architecture and dynamics. https://doi.org/10.25560/68710
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Papers by Bruno Matarèse
Methods and materials: Human cancer cell lines (MCF-7, HL-60) and control cell-free media were exposed to 1 Gy X-ray photons while recording the sound generated before, during and after irradiation using custom large-bandwidth ultrasound transducer. The effects of dose rate and cell viability were investigated.
Results: We report the first recorded acoustic signals captured from a collective pressure wave response to ionising irradiation in cell culture. The acoustic signal was co-terminous with the radiation pulse, its magnitude was dependent on radiation dose rate, and live and dead cells showed qualitatively and quantitatively different acoustic signal characteristics. The signature of the collective acoustic peaks was temporally wider and with higher acoustic power for irradiated HL-60 than for irradiated MCF-7.
Conclusions: We show that X-ray irradiation induces two cultured cancer cell types to emit a characteristic acoustic signal for the duration of the radiation pulse. The rapid decay of the signal excludes acoustic emissions themselves from contributing to the inter-organism bystander signal previously reported in intact animals, but they remain a potential component of the bystander process in tissues and cell cultures. This preliminary study suggests that further work on the potential role of radiation induced acoustic emission (RIAE) in the inter-cellular bystander effect is merited.
arXiv:2010.14287
We report optical brain imaging using a semi-transparent organic light-emitting diode (OLED) based on the orange light-emitting polymer (LEP) Livilux PDO-124. The OLED serves as a compact, extended light source which is capable of uniformly illuminating the cortical surface when placed across a burr hole in the skull. Since all layers of the OLED are substantially transparent to photons with energies below the optical gap of the LEP, light emitted or reflected by the cortical surface may be efficiently transmitted through the OLED and into the objective lens of a low magnification microscope ("macroscope"). The OLED may be placed close to the cortical surface, providing efficient coupling of incident light into the brain cavity; furthermore, the macroscope may be placed close to the upper surface of the OLED, enabling efficient collection of reflected/emitted light from the cortical surface. Hence the use of a semi-transparent OLED simplifies the optical setup, while at the same time maintaining high sensitivity. The OLED is applied here to one of the most demanding forms of optical brain imaging, namely extrinsic optical imaging involving a voltage sensitive dye (VSD). Specifically, we carry out functional imaging of the primary visual cortex (V1) of a rat, using the voltage sensitive dye RH-1691 as a reporter. Imaging through the OLED light-source, we are able to resolve small (~ 0.1 %) changes in the fluorescence intensity of the dye due to changes in the neuronal membrane potential following a visual stimulus. Results are obtained on a single trial basis-i.e. without averaging over multiple measurements-with a time-resolution of ten milliseconds.
https://arxiv.org/abs/2010.14287
Thesis Chapters by Bruno Matarèse
Optical imaging, optical detection (e.g. biosensors), and opsin based neuromodulation (e.g. optogenetics) are the major techniques that have changed the practice of neuroscience. All these techniques use arc lamps, Light Emitting Diodes (LEDs) and lasers as conventional light sources. However, these light sources are not biocompatible and are excessively bulky, which limits their effectiveness as brain implants. Many improvements are necessary, such as the development of appropriate alternative light sources integrated with biological cells to ensure their compatibility with established techniques in biological laboratories. Organic Light Emitting Diodes (OLEDs) combine optical and electrical properties with known advantages of customized materials providing appropriate color tunability, lightness, and low-cost solution processing. In addition, mechanical flexibility combined with the high elastic modulus and biological inertness of carbon-based polymers and nanomaterials confer major advantages for use in non-conformal body cavities. These attractive and innovative qualities of OLEDs make them an alternative and better light source for organic neuro-optoelectronics - the optoelectronic aspect of bioelectronics. However, engineering optoelectronic devices for operation in liquid environments requires a comprehensive understanding of the consequences that may arise. This research is innovative in designing and engineering stable and biocompatible OLEDs for incorporation into living tissues. As a result, organic LEDs do not have to alter cell morphology and electrophysiological integrity/function. The principal challenge is ensuring they can operate in a highly saline and biologically active aqueous environment. Finding materials that are inherently stable in the environment in which they function is key to device optimization. The research will investigate the stability and biocompatibility of commonly used OLED materials. Key electrodes, indium, tin, oxide, gold, aluminum and silver are characterized to examine their suitability for an aqueous environment. Treating organic light emitting polymers with laminin has shown enhanced cell adhesion and biocompatibility. Prolonged immersion in cell culture medium highlights the importance of cross-linkable polymers maintaining electrical, optical and morphological properties. These properties are critical to device performance. Insulator materials play complementary and necessary roles at the interface of the OLED/bio environment – ensuring the protection of the device against oxidative or reductive processes. Insulators are critical for extending the lifetime of devices in aqueous operation. They must be encapsulated with hydrophobic polymers for protection against neuron damage from electrical stimulation. Following from the above it becomes possible to design both a highly biocompatible prototype OLED device, which is suitable for fluorescence microscopy, and patch-clamp technique for electrophysiological investigations. This would be based on opsin activation and would also include the investigation of critical design parameters for efficient OLED-opsin coupling stimulation. Additionally, OLED devices have been investigated for in vivo optical imaging of functional cortical architecture and dynamics. https://doi.org/10.25560/68710
Methods and materials: Human cancer cell lines (MCF-7, HL-60) and control cell-free media were exposed to 1 Gy X-ray photons while recording the sound generated before, during and after irradiation using custom large-bandwidth ultrasound transducer. The effects of dose rate and cell viability were investigated.
Results: We report the first recorded acoustic signals captured from a collective pressure wave response to ionising irradiation in cell culture. The acoustic signal was co-terminous with the radiation pulse, its magnitude was dependent on radiation dose rate, and live and dead cells showed qualitatively and quantitatively different acoustic signal characteristics. The signature of the collective acoustic peaks was temporally wider and with higher acoustic power for irradiated HL-60 than for irradiated MCF-7.
Conclusions: We show that X-ray irradiation induces two cultured cancer cell types to emit a characteristic acoustic signal for the duration of the radiation pulse. The rapid decay of the signal excludes acoustic emissions themselves from contributing to the inter-organism bystander signal previously reported in intact animals, but they remain a potential component of the bystander process in tissues and cell cultures. This preliminary study suggests that further work on the potential role of radiation induced acoustic emission (RIAE) in the inter-cellular bystander effect is merited.
arXiv:2010.14287
We report optical brain imaging using a semi-transparent organic light-emitting diode (OLED) based on the orange light-emitting polymer (LEP) Livilux PDO-124. The OLED serves as a compact, extended light source which is capable of uniformly illuminating the cortical surface when placed across a burr hole in the skull. Since all layers of the OLED are substantially transparent to photons with energies below the optical gap of the LEP, light emitted or reflected by the cortical surface may be efficiently transmitted through the OLED and into the objective lens of a low magnification microscope ("macroscope"). The OLED may be placed close to the cortical surface, providing efficient coupling of incident light into the brain cavity; furthermore, the macroscope may be placed close to the upper surface of the OLED, enabling efficient collection of reflected/emitted light from the cortical surface. Hence the use of a semi-transparent OLED simplifies the optical setup, while at the same time maintaining high sensitivity. The OLED is applied here to one of the most demanding forms of optical brain imaging, namely extrinsic optical imaging involving a voltage sensitive dye (VSD). Specifically, we carry out functional imaging of the primary visual cortex (V1) of a rat, using the voltage sensitive dye RH-1691 as a reporter. Imaging through the OLED light-source, we are able to resolve small (~ 0.1 %) changes in the fluorescence intensity of the dye due to changes in the neuronal membrane potential following a visual stimulus. Results are obtained on a single trial basis-i.e. without averaging over multiple measurements-with a time-resolution of ten milliseconds.
https://arxiv.org/abs/2010.14287
Optical imaging, optical detection (e.g. biosensors), and opsin based neuromodulation (e.g. optogenetics) are the major techniques that have changed the practice of neuroscience. All these techniques use arc lamps, Light Emitting Diodes (LEDs) and lasers as conventional light sources. However, these light sources are not biocompatible and are excessively bulky, which limits their effectiveness as brain implants. Many improvements are necessary, such as the development of appropriate alternative light sources integrated with biological cells to ensure their compatibility with established techniques in biological laboratories. Organic Light Emitting Diodes (OLEDs) combine optical and electrical properties with known advantages of customized materials providing appropriate color tunability, lightness, and low-cost solution processing. In addition, mechanical flexibility combined with the high elastic modulus and biological inertness of carbon-based polymers and nanomaterials confer major advantages for use in non-conformal body cavities. These attractive and innovative qualities of OLEDs make them an alternative and better light source for organic neuro-optoelectronics - the optoelectronic aspect of bioelectronics. However, engineering optoelectronic devices for operation in liquid environments requires a comprehensive understanding of the consequences that may arise. This research is innovative in designing and engineering stable and biocompatible OLEDs for incorporation into living tissues. As a result, organic LEDs do not have to alter cell morphology and electrophysiological integrity/function. The principal challenge is ensuring they can operate in a highly saline and biologically active aqueous environment. Finding materials that are inherently stable in the environment in which they function is key to device optimization. The research will investigate the stability and biocompatibility of commonly used OLED materials. Key electrodes, indium, tin, oxide, gold, aluminum and silver are characterized to examine their suitability for an aqueous environment. Treating organic light emitting polymers with laminin has shown enhanced cell adhesion and biocompatibility. Prolonged immersion in cell culture medium highlights the importance of cross-linkable polymers maintaining electrical, optical and morphological properties. These properties are critical to device performance. Insulator materials play complementary and necessary roles at the interface of the OLED/bio environment – ensuring the protection of the device against oxidative or reductive processes. Insulators are critical for extending the lifetime of devices in aqueous operation. They must be encapsulated with hydrophobic polymers for protection against neuron damage from electrical stimulation. Following from the above it becomes possible to design both a highly biocompatible prototype OLED device, which is suitable for fluorescence microscopy, and patch-clamp technique for electrophysiological investigations. This would be based on opsin activation and would also include the investigation of critical design parameters for efficient OLED-opsin coupling stimulation. Additionally, OLED devices have been investigated for in vivo optical imaging of functional cortical architecture and dynamics. https://doi.org/10.25560/68710