scholarly journals Carbon Nanoelectrodes for the Electrochemical Detection of Neurotransmitters

2018 ◽  
Vol 2018 ◽  
pp. 1-19 ◽  
Author(s):  
Alexander G. Zestos
Keyword(s):  
Electrode Materials ◽  
Brain Regions ◽  
Fused Silica ◽  
Carbon Fiber Microelectrode ◽  
Disease States ◽  
Surface Areas ◽  
Fused Silica Capillaries ◽  
Living Organisms ◽  
Carbon Based

Carbon-based electrodes have been developed for the detection of neurotransmitters over the past 30 years using voltammetry and amperometry. The traditional electrode for neurotransmitter detection is the carbon fiber microelectrode (CFME). The carbon-based electrode is suitable for in vivo neurotransmitter detection due to the fact that it is biocompatible and relatively small in surface area. The advent of nanoscale electrodes is in high demand due to smaller surface areas required to target specific brain regions that are also minimally invasive and cause relatively low tissue damage when implanted into living organisms. Carbon nanotubes (CNTs), carbon nanofibers, carbon nanospikes, and carbon nanopetals among others have all been utilized for this purpose. Novel electrode materials have also required novel insulations such as glass, epoxy, and polyimide coated fused silica capillaries for their construction and usage. Recent research developments have yielded a wide array of carbon nanoelectrodes with superior properties and performances in comparison to traditional electrode materials. These electrodes have thoroughly enhanced neurotransmitter detection allowing for the sensing of biological compounds at lower limits of detection, fast temporal resolution, and without surface fouling. This will allow for greater understanding of several neurological disease states based on the detection of neurotransmitters.

scholarly journals Wireless, battery-free optoelectronic systems as subdermal implants for local tissue oximetry

2019 ◽  
Vol 5 (3) ◽  
pp. eaaw0873 ◽  
Author(s):  
Hao Zhang ◽  
Philipp Gutruf ◽  
Kathleen Meacham ◽  
Michael C. Montana ◽  
Xingyue Zhao ◽  
...  
Keyword(s):  
Animal Models ◽  
Tissue Oxygenation ◽  
Human Subjects ◽  
Brain Regions ◽  
Disease States ◽  
Data Output ◽  
Subdermal Implants ◽  
Underlying Mechanisms ◽  
Tissue Oximetry

Monitoring regional tissue oxygenation in animal models and potentially in human subjects can yield insights into the underlying mechanisms of local O2-mediated physiological processes and provide diagnostic and therapeutic guidance for relevant disease states. Existing technologies for tissue oxygenation assessments involve some combination of disadvantages in requirements for physical tethers, anesthetics, and special apparatus, often with confounding effects on the natural behaviors of test subjects. This work introduces an entirely wireless and fully implantable platform incorporating (i) microscale optoelectronics for continuous sensing of local hemoglobin dynamics and (ii) advanced designs in continuous, wireless power delivery and data output for tether-free operation. These features support in vivo, highly localized tissue oximetry at sites of interest, including deep brain regions of mice, on untethered, awake animal models. The results create many opportunities for studying various O2-mediated processes in naturally behaving subjects, with implications in biomedical research and clinical practice.

A new design of carbon fiber microelectrode for in vivo voltammetry using fused silica

1997 ◽  
Vol 73 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Artur H Swiergiel ◽  
Vitaly S Palamarchouk ◽  
Adrian J Dunn
Keyword(s):  
Carbon Fiber ◽  
Fused Silica ◽  
In Vivo Voltammetry ◽  
Carbon Fiber Microelectrode

scholarly journals Angle-Tuned Coils: Enabling Building Blocks for High Performance and Multisite TMS Systems

2021 ◽  
Author(s):  
Hedyeh Bagherzadeh ◽  
QINGLEI MENG ◽  
Zhi-De Deng ◽  
Hanbing Lu ◽  
Elliott Hong ◽  
...  
Keyword(s):  
Electric Field ◽  
Composite Structures ◽  
High Performance ◽  
Near Field ◽  
Building Blocks ◽  
Brain Regions ◽  
Brain Functions ◽  
Surface Areas ◽  
Head Surface

Objective: A novel angle-tuned ring coil is proposed for improving the depth-spread performance of Transcranial Magnetic Stimulation (TMS) coils and serve as the building blocks for high-performance composite coils and multisite TMS systems. Approach: Improving depth-spread performance by reducing field divergence through creating a more elliptical emitted field distribution from the coil. To accomplish that, instead of enriching the Fourier components along the planarized (x-y) directions, which requires different arrays to occupy large brain surface areas, we worked along the radial (z) direction by using tilted coil angles and stacking coil numbers to reduce the divergence of the emitted near field without occupying large head surface areas. The emitted electric field distributions were theoretically simulated in spherical and real human head models to analyze the depth-spread performance of proposed coils and compare with existing figure-8 coils. The results were then experimentally validated with field probes and in-vivo animal tests. Main Results: The proposed "angle-tuning" concept improves the depth-spread performance of individual coils with a significantly smaller footprint than existing and proposed coils. For composite structures, using the proposed coils as basic building blocks simplifies the design and manufacturing process and helps accomplish a leading depth-spread performance. In addition, the footprint of the proposed system is intrinsically small, making them suitable for multisite stimulations of inter and intra-hemispheric brain regions with an improved spread and less electric field divergence. Significance: Few brain functions are operated by isolated single brain regions but rather by coordinated networks involving multiple brain regions. Simultaneous or sequential multisite stimulations may provide tools for mechanistic studies of brain functions and the treatment of neuropsychiatric disorders. The proposed AT coil goes beyond the traditional depth-spread tradeoff rule of TMS coils, which provides the possibility of building new composite structures and new multisite TMS tools.

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

Nitroxyl Modified Tobacco Mosaic Virus as a Metal-Free High-Relaxivity MRI and EPR Active Superoxide Sensor

2018 ◽  
Author(s):  
Madushani Dharmarwardana ◽  
André F. Martins ◽  
Zhuo Chen ◽  
Philip M. Palacios ◽  
Chance M. Nowak ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Single Molecule ◽  
Biological Fluids ◽  
Cellular Respiration ◽  
Organic Radical ◽  
Paramagnetic Resonance ◽  
Metal Free ◽  
Disease States

Superoxide overproduction is known to occur in multiple disease states requiring critical care yet non-invasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by “click conjugating” paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced <i>in vivo</i> to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species—in particular superoxide—and are largely unaffected by peroxides and molecular oxygen. Unfortunately, single molecule ORCAs typically offer weak MRI contrast. In contrast, our data confirm that the macromolecular ORCA-TMV conjugates show marked enhancement for <i>T<sub>1</sub></i> contrast at low field (<3.0 T), and <i>T<sub>2</sub></i> contrast at high field (9.4 T). Additionally, we demonstrated that the unique topology of TMV allows for “quenchless fluorescent” bimodal probe for concurrent fluorescence and MRI/EPR imaging, which was made possible by exploiting the unique inner and outer surface of the TMV nanoparticle. <a>Finally, we show TMV-ORCAs do not respond to normal cellular respiration, minimizing the likelihood for background, yet still respond to enzymatically produced superoxide in complicated biological fluids like serum.</a>

In vivo Experiments of Natural Products Protection of Antagonistic Effects of Lead on Iron

2018 ◽  
Vol 68 (12) ◽  
pp. 2747-2751
Author(s):  
Marioara Nicula ◽  
Nicolae Pacala ◽  
Lavinia Stef ◽  
Ioan Pet ◽  
Dorel Dronca ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Iron Homeostasis ◽  
Iron Concentration ◽  
Antagonistic Effect ◽  
Tissue Samples ◽  
Antagonistic Effects ◽  
In Vivo Experiments ◽  
Living Organisms ◽  
Toxic Potential

Living organisms take nutrients from the environment, and together with them, substances with toxic potential � such as heavy metals. Lead is one common metal pollutant especially in aquatic environment, from where the fish can be intoxicated very easily. Bioavailability, distribution, toxic action, synergistic and antagonistic effects are characteristics which can alter the fish health. Our experimental study followed the effects of lead overload in water on iron distribution, in different tissues sample Carassius gibelio Bloch fish. We performed the experiment in four different fish groups: control C; lead � Pb (administration of lead in water 0.075mg/mL of water, as Pb(NO3)2 x � H2O); lead (the same dose) and 2% of freeze-dry garlic incorporated into fishes� food � Pb+garlic; lead (the same dose) and 2% chlorella incorporated into fishes� food � Pb+chlorella, for 21 consecutive days. The iron concentration was analysed with AAS (Atomic Absorption Spectroscopy) from gills, muscle, skin (and scales), intestine, liver, heart, brain, ovary, testicles, and kidney. The obtained data presented a significantly decrease of iron content in all tested tissue samples that demonstrated, alteration of iron homeostasis, explained by a strong antagonistic effect of lead on iron. Our experiment showed that biologic active principles from garlic and chlorella act like natural protectors, and potentiate the iron deficiency even in the case of lead overload in aquatic environment, for fish.

Current Challenges in the Development of Vaccines and Drugs Against Emerging Vector-borne Diseases

2019 ◽  
Vol 26 (16) ◽  
pp. 2974-2986 ◽  
Author(s):  
Kwang-sun Kim
Keyword(s):  
New Host ◽  
In Vivo Models ◽  
Vector Borne Diseases ◽  
Novel Drugs ◽  
Huge Impact ◽  
Tick Borne Disease ◽  
Vector Borne ◽  
Living Organisms

Vectors are living organisms that transmit infectious diseases from an infected animal to humans or another animal. Biological vectors such as mosquitoes, ticks, and sand flies carry pathogens that multiply within their bodies prior to delivery to a new host. The increased prevalence of Vector-Borne Diseases (VBDs) such as Aedes-borne dengue, Chikungunya (CHIKV), Zika (ZIKV), malaria, Tick-Borne Disease (TBD), and scrub typhus has a huge impact on the health of both humans and livestock worldwide. In particular, zoonotic diseases transmitted by mosquitoes and ticks place a considerable burden on public health. Vaccines, drugs, and vector control methods have been developed to prevent and treat VBDs and have prevented millions of deaths. However, development of such strategies is falling behind the rapid emergence of VBDs. Therefore, a comprehensive approach to fighting VBDs must be considered immediately. In this review, I focus on the challenges posed by emerging outbreaks of VBDs and discuss available drugs and vaccines designed to overcome this burden. Research into promising drugs needs to be upgraded and fast-tracked, and novel drugs or vaccines being tested in in vitro and in vivo models need to be moved into human clinical trials. Active preventive tactics, as well as new and upgraded diagnostics, surveillance, treatments, and vaccination strategies, need to be monitored constantly if we are to manage VBDs of medical importance.

scholarly journals Facile sonochemical-assisted synthesis of orthorhombic phase black phosphorus/rGO hybrids for effective photothermal therapy

Nanophotonics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 3023-3034
Author(s):  
Weiyuan Liang ◽  
Dou Wang ◽  
Xiaohui Ren ◽  
Chenchen Ge ◽  
Hanyue Wang ◽  
...  
Keyword(s):  
Electrode Materials ◽  
Orthorhombic Phase ◽  
Cost Effective ◽  
Black Phosphorus ◽  
Antitumor Effects ◽  
Covalent Bonds ◽  
Preparation Conditions ◽  
Reduced Graphene

AbstractTwo-dimensional black phosphorus (BP) has been demonstrated to be promising in photoelectronic devices, electrode materials, and biomedicine owing to its outstanding properties. However, the application of BP has been hindered by harsh preparation conditions, high costs, and easy degradation in ambient condition. Herein, we report a facile and cost-effective strategy for synthesis of orthorhombic phase BP and a kind of BP-reduced graphene oxide (BP/rGO) hybrids in which BP remains stable for more than 4 weeks ascribed to the formation of phosphorus-carbon covalent bonds between BP and rGO as well as the protection effect of the unique wrinkle morphology of rGO nanosheets. Surface modification BP/rGO hybrids (PEGylated BP/rGO) exhibit excellent photothermal performance with photothermal conversion efficiency as high as 57.79% at 808 nm. The BP/rGO hybrids exhibit enhanced antitumor effects both in vitro and in vivo, showing promising perspectives in biomedicine.

scholarly journals Growth Factor Therapy for Parkinson’s Disease: Alternative Delivery Systems

2021 ◽  
pp. 1-7
Author(s):  
Sarah Jarrin ◽  
Abrar Hakami ◽  
Ben Newland ◽  
Eilís Dowd
Keyword(s):  
Parkinson’S Disease ◽  
Gene Therapy ◽  
Parkinson's Disease ◽  
Growth Factors ◽  
Growth Factor ◽  
Ex Vivo ◽  
Brain Regions ◽  
Delivery Systems ◽  
Alternative Delivery

Despite decades of research and billions in global investment, there remains no preventative or curative treatment for any neurodegenerative condition, including Parkinson’s disease (PD). Arguably, the most promising approach for neuroprotection and neurorestoration in PD is using growth factors which can promote the growth and survival of degenerating neurons. However, although neurotrophin therapy may seem like the ideal approach for neurodegenerative disease, the use of growth factors as drugs presents major challenges because of their protein structure which creates serious hurdles related to accessing the brain and specific targeting of affected brain regions. To address these challenges, several different delivery systems have been developed, and two major approaches—direct infusion of the growth factor protein into the target brain region and in vivo gene therapy—have progressed to clinical trials in patients with PD. In addition to these clinically evaluated approaches, a range of other delivery methods are in various degrees of development, each with their own unique potential. This review will give a short overview of some of these alternative delivery systems, with a focus on ex vivo gene therapy and biomaterial-aided protein and gene delivery, and will provide some perspectives on their potential for clinical development and translation.

scholarly journals Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cody L. Call ◽  
Dwight E. Bergles
Keyword(s):  
Cortical Neurons ◽  
Regional Differences ◽  
Brain Regions ◽  
Axon Diameter ◽  
Neuronal Identity ◽  
Cortical Areas ◽  
Myelin Sheaths ◽  
Parvalbumin Interneurons ◽  
Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

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