Infrared neural modulation is an optical technique to stimulate or inhibit neural activity with pulsed infrared light (IR). This study focuses on effects of IR and heat on microglial calcium signaling, a main indicator of physiological changes within the immune-like cell. Widefield fluorescence microscopy quantified the intracellular calcium fluxes, cell death, and early apoptosis fluorescent indicators in BV2 immortalized microglia cell culture after irradiation. We have found that unique cellular responses are highly associated with different temperature increases, and the irradiance thresholds for these responses do not drive cells to Caspase-3 apoptosis nor necrotic cellular death.
Pain is currently assessed using subjective measurements, often not aligning with clinical symptoms. Therefore, objective pain level assessments, using minimally-invasive and molecular methods, are needed to assess disease activity and response to treatment in osteoarthritis and rheumatoid arthritis. We report sophisticated quantitative biochemical “signatures” from the label-free hyperspectral imaging (HSI) of cartilage tissue for the characterization of molecular composition, structure and functional status. Further study on sinuvium tissue provides evidence that HSI could be used as a novel technique to delineate disease state. Additionally, HSI could be used to objectively separate individuals based on pain severity providing molecular correlates of pain.
Oxygen metabolism is a necessary process that takes place in animals and plants. Our cells and plant cells produce free radicals known as reactive oxygen species (ROS) continuously as a byproduct of oxygen metabolism and reaction to various environmental stresses, which must be normalized to avoid oxidative stress. Oxidative stress is intimately linked to cellular energy balance and occurs when there’s an imbalance between production and accumulation of ROS in cells and tissues and the ability of a biological system to keep in a redox steady state. We show preliminary results of an optical fiber based reversible in-vivo biosensor for understanding redox balance within living systems. The biosensor measured protein carbonyls (a marker of oxygen metabolism and oxidative stress) in pig-skin, live mouse, and wheat plant.
We demonstrate in-vivo chemical sensing using silk-coated exposed-core microstructured optical fibers (ECFs). The ECF provides advantages in sensitivity due to the direct access of the fiber core to the surrounding environment with integrated measurement along the entire fiber length, rather than simply the fiber tip as is common in other probes. The silk coating provides an encapsulation of the sensor molecules, and is well known as a biocompatible material. This deployable fiber sensor is fabricated with simple splicing and coating techniques, making it practical to be used in a range of biomedical sensing applications, which we demonstrate through pH sensing in a mouse model.
Cytokines play critical roles in homeostatic control of health and they are integral for the creation and maintenance of a myriad of disease states. Their ultra-low concentration, often in the picomolar range, and extremely dynamic transient secretion process place stringent demands on cytokine quantification. We developed a nanoparticle-based strategy to detect trace cytokine secretion from individual, single live cells, for which we coined the term “OnCELISA”. Using a capture surface on the cell membrane and fluorescent magnetic nanoparticles as assay reporters, our universal OnCELISA assay achieved the sensitivity 0.1 pg mL-1, an over 10-fold enhancement, compared to state-of-the-art. The sensitive OnCELISA cell labelling made it possible to select and sort different cell types to determine highly cytokine - secreting cell subpopulations . The capture surfaces on cell membranes did not show noticeable effect on cell viability and their subsequent proliferation. The capability to specifically select such highly cytokine-secreting cells and purify their populations is pivotal for their use in multicellular pathologies such as atherosclerosis. Accordingly, we used this new approach to label cytokine secretion from vascular tissues of apolipoprotein E-/- mice; an in vivo model of atherosclerosis. In response to lipopolysaccharide, we observed increased capture of cytokine using this model. With the capacity of monitoring multiple cytokine secretions (IL-6 and IL-1β)), our OnCELISA method is able to probe how the individual cells and tissues secrete cytokines as they respond in real time to the surrounding signals.
Neurophotonics is an exploding field that spans the intersection of light and neurons for fundamental discovery and clinical translation. Optical technologies have significantly impacted brain research by probing into the mysteries of the brain, modulating brain activity, and improving patient care. Based on a discussion held at the International Conference on Biophotonics 2017, a group of leading researchers brainstormed to identify areas of unmet need in neuroscience and medicine, where biophotonics research could have the highest affect. We present two areas of future growth that spans basic research and clinical needs: management of chronic pain and interventional neuroimmunology. There are many directions within these areas that could be pursued for the ultimate goal of improved understanding of the brain and enhanced care of patients with neurological disorders.
The 5th International Conference on Biophotonics (ICOB) held April 30 to May 1, 2017, in Fremantle, Western Australia, brought together opinion leaders to discuss future directions for the field and opportunities to consider. The first session of the conference, “How to Set a Big Picture Biophotonics Agenda,” was focused on setting the stage for developing a vision and strategies for translation and impact on society of biophotonic technologies. The invited speakers, panelists, and attendees engaged in discussions that focused on opportunities and promising applications for biophotonic techniques, challenges when working at the confluence of the physical and biological sciences, driving factors for advances of biophotonic technologies, and educational opportunities. We share a summary of the presentations and discussions. Three main themes from the conference are presented in this position paper that capture the current status, opportunities, challenges, and future directions of biophotonics research and key areas of applications: (1) biophotonics at the nano- to microscale level; (2) biophotonics at meso- to macroscale level; and (3) biophotonics and the clinical translation conundrum.
Vitamin B12 (cobalamin and its derivatives) deficiency has been identified as a potential modifiable risk factor for dementia and Alzheimer’s disease. Chronic deficiency of vitamin B12 has been significantly associated with an increased risk of cognitive decline. An effective and efficient method for measuring vitamin B12 concentration in human blood would enable ongoing tracking and assessment of this potential modifiable risk factor. In this work we present an optical sensor based on resonance Raman spectroscopy for rapid measurements of vitamin B12 in human blood serum. The measurement takes less than a minute and requires minimum preparation (centrifuging) of the collected blood samples.
Fluorescence-based bio-imaging methods have been extensively used to identify molecular changes occurring in biological samples in various pathological adaptations. Auto-fluorescence generated by endogenous fluorescent molecules within these samples can interfere with signal to background noise making positive antibody based fluorescent staining difficult to resolve. Hyperspectral imaging uses spectral and spatial imaging information for target detection and classification, and can be used to resolve changes in endogenous fluorescent molecules such as flavins, bound and free NADH and retinoids that are involved in cell metabolism. Hyperspectral auto-fluorescence imaging of spinal cord slices was used in this study to detect metabolic differences within pain processing regions of non-pain versus sciatic chronic constriction injury (CCI) animals, an established animal model of peripheral neuropathy. By using an endogenous source of contrast, subtle metabolic variations were detected between tissue samples, making it possible to distinguish between animals from non-injured and injured groups. Tissue maps of native fluorophores, flavins, bound and free NADH and retinoids unveiled subtle metabolic signatures and helped uncover significant tissue regions with compromised mitochondrial function. Taken together, our results demonstrate that hyperspectral imaging provides a new non-invasive method to investigate central changes of peripheral neuropathic injury and other neurodegenerative disease models, and paves the way for novel cellular characterisation in health, disease and during treatment, with proper account of intrinsic cellular heterogeneity.
Optical fiber sensors for Raman spectroscopy based on hollow core optical fibers have shown great promise due to their low glass background, and high signal collection efficiency. We have previously demonstrated how glass billet extrusion can be used to make simplified hollow core fibers based on a single suspended ring. In this work we investigate the performance of these optical fibers as sensors for Raman spectroscopy. These fibers are used to excite samples at a range of laser excitation wavelengths to scan across the transmission profile of the optical fibers, allowing comparison of the performance of these fibers against commercially-available alternatives.
KEYWORDS: Ultraviolet radiation, Molecules, Biomedical optics, Control systems, Toxicity, Modulation, Switching, Biological research, Process control, In vivo imaging
The photoisomerisation of azobenzenes between trans and cis results in well-defined changes in geometry and a considerable change of polarity. Thus, incorporating an azobenezene into a bioactive compound provides an opportunity to control biological activity, with ideally one configuration being active and the other inactive. This can allow the role of a specific biomolecule to be probed in its native environment by controlling activity both spatially and temporally using light. Incorporating such a photoswitchable moiety into the structure of a known GRK2 inhibitor can generate photoswitchable inhibitors, which can be used to reversibly regulate the activity of GRK2, and hence GPRCs.
KEYWORDS: Optical fibers, In vivo imaging, Brain, Temperature metrology, Biomedical optics, Body temperature, Glasses, Luminescence, Optical testing, Optical alignment
We report on the development of an optical fiber based probe for in vivo measurements of brain temperature. By using a thin layer of rare-earth doped tellurite glass on the tip of a silica optical fiber a durable probe, suitable for long-term in vivo measurements of temperature can be fabricated. The probe can be interrogated using a portable optical measurement setup, allowing for measurements to be performed outside of standard optical laboratories as no alignment of components is required. This setup is deployed to a medical research laboratory to show preliminary results on the use of these optical fibers for in vivo pre-clinical measurements of brain temperature.
Despite significant advancement in the methodology used to conjugate, incorporate and visualize fluorescent molecules at the cellular and tissue levels, biomedical imaging predominantly relies on the limitations of established fluorescent molecules such as fluorescein, cyanine and AlexaFluor dyes or genetic incorporation of fluorescent proteins by viral or other means. These fluorescent dyes and conjugates are highly susceptible to photobleaching and compete with cellular autofluorescence, making biomedical imaging unreliable, difficult and time consuming in many cases. In addition, some proteins have low copy numbers and/or poor antibody recognition, further making detection and imaging difficult. We are developing better methods for imaging central nervous system neuroinflammatory markers using targeted mRNA transcripts labelled with fluorescent nanodiamonds or lanthanide chelates. These tags have increased signal and photostability and can also discriminate against tissue/cell autofluorescence. Brains and spinal cords from BALB/c mice with a chronic constriction model of neuropathic pain (neuroinflammation group) or that have undergone sham surgeries (control group) were collected. A subset of brains and spinal cords were perfused and fixed with paraformaldehyde (n=3 sham and n=3 pain groups) prior to sectioning and in situ hybridization using nanodiamond or lanthanide chelate conjugated complementary RNA probes. Another subset of brains and spinal cords from the same cohort of animals were perfused and processed for CLARITY hydrogel based clearing prior to in situ hybridization with the same probes. We will present our findings on the photostability, sensitivity and discrimination from background tissue autofluorescence of our novel RNA probes, compared to traditional fluorophore tags.
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