Sol-Gel Optical Sensors for Glutamate

2000 ◽  
Vol 662 ◽  
Author(s):  
Jenna L. Rickus ◽  
Esther Lan ◽  
Allan J. Tobin ◽  
Jeffery I. Zink ◽  
Bruce Dunn
Keyword(s):  
Optical Sensors ◽  
Sol Gel ◽  
Kinetic Studies ◽  
Excitatory Neurotransmitter ◽  
Nadh Fluorescence ◽  
Millisecond Time Scale ◽  
Temporal And Spatial ◽  
Sensor Detection ◽  
The Brain ◽  
Amino Acid Glutamate

AbstractThe amino acid glutamate is the major excitatory neurotransmitter used in the nervous system for interneuronal communication. It is used throughout the brain by various neuronal pathways including those involved in learning and memory, locomotion, and sensory perception. Because glutamate is released from neurons on a millisecond time scale into sub-micrometer spaces, the development of a glutamate biosensor with high temporal and spatial resolution is of great interest for the study of neurological function and disease. Here, we demonstrate the feasibility of an optical glutamate sensor based on the sol-gel encapsulation of the enzyme glutamate dehydrogenase (GDH). GDH catalyses the oxidative deamination of glutamate and the reduction of NAD+ to NADH. NADH fluorescence is the basis of the sensor detection. Thermodynamic and kinetic studies show that GDH remains active in the sol-gel matrix and that the reaction rate is correlated to the glutamate concentration.

scholarly journals Monosodium Glutamate in the Diet Does Not Raise Brain Glutamate Concentrations or Disrupt Brain Functions

2018 ◽  
Vol 73 (Suppl. 5) ◽  
pp. 43-52 ◽  
Author(s):  
John D. Fernstrom
Keyword(s):  
Monosodium Glutamate ◽  
Safety Evaluation ◽  
The Body ◽  
Neuronal Function ◽  
Excitatory Neurotransmitter ◽  
Brain Functions ◽  
The Central Nervous System ◽  
Experimental Findings ◽  
The Brain ◽  
Amino Acid Glutamate

The non-essential amino acid glutamate participates in numerous metabolic pathways in the body. It also performs important physiologic functions, which include a sensory role as one of the basic tastes (as monosodium glutamate [MSG]), and a role in neuronal function as the dominant excitatory neurotransmitter in the central nervous system. Its pleasant taste (as MSG) has led to its inclusion as a flavoring agent in foods for centuries. Glutamate’s neurotransmitter role was discovered only in the last 60 years. Its inclusion in foods has necessitated its safety evaluation, which has raised concerns about its transfer into the blood ultimately increasing brain glutamate levels, thereby causing functional disruptions because it is a neurotransmitter. This concern, originally raised almost 50 years ago, has led to an extensive series of scientific studies to examine this issue, conducted primarily in rodents, non-human primates, and humans. The key findings have been that (a) the ingestion of MSG in the diet does not produce appreciable increases in glutamate concentrations in blood, except when given experimentally in amounts vastly in excess of normal intake levels; and (b) the blood-brain barrier effectively restricts the passage of glutamate from the blood into the brain, such that brain glutamate levels only rise when blood glutamate concentrations are raised experimentally via non-physiologic means. These and related discoveries explain why the ingestion of MSG in the diet does not lead to an increase in brain glutamate concentrations, and thus does not produce functional disruptions in brain. This article briefly summarizes key experimental findings that evaluate whether MSG in the diet poses a threat to brain function.

Hybrid Micro-Optical Sensors via Sol-Gel Soft Lithography

2000 ◽  
Vol 628 ◽  
Author(s):  
Mark A. Clarner ◽  
Michael J. Lochhead
Keyword(s):  
Optical Sensors ◽  
Soft Lithography ◽  
Sol Gel ◽  
Silica Gels ◽  
Ph Sensing ◽  
Ambient Conditions ◽  
Sensor Applications ◽  
Patterned Structures ◽  
Biological Functionality ◽  
Indicator Dyes

ABSTRACTOrganically modified silica gels and dye-doped silica gels have been patterned into micrometer-scale structures on a substrate using micro molding in capillaries (MIMIC). This approach is from a class of elastomeric stamping and molding techniques collectively known as soft lithography. Soft lithography and sol-gel processing share attractive features in that they are relatively benign processes performed at ambient conditions, which makes both techniques compatible with a wide variety of organic molecules, molecular assemblies, and biomolecules. The combination of sol-gel and soft lithography, therefore, holds enormous promise as a tool for microfabrication of materials with optical, chemical, or biological functionality that are not readily patterned with conventional methods. This paper describes our investigation of micro-patterned organic-inorganic hybrid materials containing indicator dyes for microfluidic sensor applications. Reversible colorimetric pH sensing via entrapped reagents is demonstrated in a prototype microfluidic sensor element. Patterned structures range from one to tens of micrometers in cross-section and are up to centimeters in length. Fundamental chemical processing issues associated with mold filling, cracking and sensor stability are discussed.

scholarly journals The current state of electrocorticography-based brain–computer interfaces

2020 ◽  
Vol 49 (1) ◽  
pp. E2 ◽  
Author(s):  
Kai J. Miller ◽  
Dora Hermes ◽  
Nathan P. Staff
Keyword(s):  
Functional Limitations ◽  
Brain Computer Interfaces ◽  
Brain Surface ◽  
Computer Interfaces ◽  
Brain Signals ◽  
Current State ◽  
Temporal And Spatial ◽  
Direct Feedback ◽  
The Brain ◽  
Lateral Sclerosis

Brain–computer interfaces (BCIs) provide a way for the brain to interface directly with a computer. Many different brain signals can be used to control a device, varying in ease of recording, reliability, stability, temporal and spatial resolution, and noise. Electrocorticography (ECoG) electrodes provide a highly reliable signal from the human brain surface, and these signals have been used to decode movements, vision, and speech. ECoG-based BCIs are being developed to provide increased options for treatment and assistive devices for patients who have functional limitations. Decoding ECoG signals in real time provides direct feedback to the patient and can be used to control a cursor on a computer or an exoskeleton. In this review, the authors describe the current state of ECoG-based BCIs that are approaching clinical viability for restoring lost communication and motor function in patients with amyotrophic lateral sclerosis or tetraplegia. These studies provide a proof of principle and the possibility that ECoG-based BCI technology may also be useful in the future for assisting in the cortical rehabilitation of patients who have suffered a stroke.

scholarly journals SiO2-SnO2:Er3+ Glass-Ceramic Monoliths

2018 ◽  
Author(s):  
Lam Thi Ngoc Tran ◽  
Damiano Massella ◽  
Lidia Zur ◽  
Alessandro Chiasera ◽  
Stefano Varas ◽  
...  
Keyword(s):  
Rare Earth ◽  
Optical Sensors ◽  
Tin Dioxide ◽  
Sol Gel ◽  
Glass Ceramics ◽  
Building Blocks ◽  
Spectroscopic Properties ◽  
Silica Matrix ◽  
Rare Earth Ions ◽  
Planar Waveguides

The development of efficient luminescent systems, such as microcavities, solid state lasers, integrated optical amplifiers, optical sensors is the main topic in glass photonics. The building blocks of these systems are glass-ceramics activated by rare earth ions because they exhibit specific morphologic, structural and spectroscopic properties. Among various materials that could be used as nanocrystals to be imbedded in silica matrix, tin dioxide presents some interesting peculiarities, e.g. the presence of tin dioxide nanocrystals allows increase in both solubility and emission of rare earth ions. Here, we focus our attention on Er3+ - doped silica – tin dioxide photonic glass-ceramics fabricated by sol-gel route. Although the SiO2-SnO2:Er3+ could be fabricated in different geometrical systems: thin films, monoliths and planar waveguides we herein limit ourselves to the monoliths. The effective role of tin dioxide as luminescence sensitizer for Er3+ ions is confirmed by spectroscopic measurements and detailed fabrication protocols are discussed.

scholarly journals Identification and Research of Adhd and Healthy Controls using Fmri

2019 ◽  
Vol 8 (6S) ◽  
pp. 370-372
Keyword(s):  
Brain Regions ◽  
Healthy Controls ◽  
Hyperactivity Disorder ◽  
Network Activation ◽  
Healthy Control ◽  
Temporal And Spatial ◽  
The Individual ◽  
The Brain ◽  
Coronal View

Analyzing the brain regions for different activations corresponding to the activation input for an experimental setup of task functional MRI or a resting state functional Magnetic Resonance Imaging(fMRI) for a diagnosed or healthy control is a challenging issue as the processing data is voluminous 4D data with nearly 1,51,552 voxels for a single volume of 261 scans fMRI. The data considered for analysis consists of 10 healthy controls and 10 Attention Deficit Hyperactivity Disorder(ADHD) fMRI. The workflow starts with preprocessing the individual scan for realignment, coregistration and Normalisation to Montreal Neurological Institute (MNI) space. Single site scan visit consists of 64x64x37 voxels. Seventy independent components are obtained from processed data by data reduction, Independent Component Analysis (ICA) calculation, Back reconstruction and Component Calibration. ICA performs satisfactorily well on temporal and spatial localization. Visual medial network activation is pronounced in ADHD Controls than in healthy people. Sagittal, Axial and Coronal view of ADHD controls is obtained as component number 42.The analysis is further used for the automatic classification of healthy controls and ADHD people.

Expression patterns of nicotinic subunits α2, α7, α8, and β1 affect the kinetics and pharmacology of ACh-induced currents in adult bee olfactory neuropiles

2011 ◽  
Vol 106 (4) ◽  
pp. 1604-1613 ◽  
Author(s):  
Julien Pierre Dupuis ◽  
Monique Gauthier ◽  
Valérie Raymond-Delpech
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Expression Patterns ◽  
Insect Brain ◽  
Olfactory Pathway ◽  
Excitatory Neurotransmitter ◽  
Kenyon Cells ◽  
Inward Currents ◽  
Induced Currents ◽  
The Brain

Acetylcholine (ACh) is the main excitatory neurotransmitter of the insect brain, where nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission. In the honeybee Apis mellifera, nAChRs are expressed in diverse structures including the primary olfactory centers of the brain, the antennal lobes (ALs) and the mushroom bodies (MBs), where they participate in olfactory information processing. To understand the nature and properties of the nAChRs involved in these processes, we performed a pharmacological and molecular characterization of nAChRs on cultured Kenyon cells of the MBs, using whole cell patch-clamp recordings combined with single-cell RT-PCR. In all cells, applications of ACh as well as nicotinic agonists such as nicotine and imidacloprid induced inward currents with fast desensitization. These currents were fully blocked by saturating doses of the antagonists α-bungarotoxin (α-BGT), dihydroxy-β-erythroidine (DHE), and methyllycaconitine (MLA) (MLA ≥ α-BGT ≥ DHE). Molecular analysis of ACh-responding cells revealed that of the 11 nicotinic receptor subunits encoded within the honeybee genome, α2, α8, and β1 subunits were expressed in adult Kenyon cells. Comparison with the expression pattern of adult AL cells revealed the supplementary presence of subunit α7, which could be responsible for the kinetic and pharmacological differences observed when comparing ACh-induced currents from AL and Kenyon cells. Together, our data demonstrate the existence of functional nAChRs on adult MB Kenyon cells that differ from nAChRs on AL cells in both their molecular composition and pharmacological properties, suggesting that changing receptor subsets could mediate different processing functions depending on the brain structure within the olfactory pathway.

HIGH-ACIDITY OPTICAL SENSORS BASED ON SOL-GEL-DERIVED THIN FILMS

2001 ◽  
Vol 34 (10) ◽  
pp. 1603-1616 ◽  
Author(s):  
Mojtaba Shamsipur ◽  
Gholamhassan Azimi
Keyword(s):  
Thin Films ◽  
Optical Sensors ◽  
Sol Gel ◽  
High Acidity

Structural, Textural and Thermal Characterization of Nano-Mg/Al Hydrotalcite before and after Cr (VI) Removal

2013 ◽  
Vol 755 ◽  
pp. 53-60
Author(s):  
Esthela Ramos Ramírez ◽  
Norma Leticia Gutiérrez Ortega ◽  
Cesar Augusto Contreras Soto ◽  
Gustavo Rangel Porras
Keyword(s):  
Crystalline Structure ◽  
Sol Gel ◽  
Textural Properties ◽  
Kinetic Studies ◽  
Thermal Characterization ◽  
Gel Method ◽  
Sol Gel Method ◽  
Before And After ◽  
Short Time

In this work there was studied the structural, textural and effect that has treat thermal on the removal of Cr (VI) of nanoMg/Al hydrotalcite (NHT) synthesized by the sol-gel method with a ratio of Mg/Al=3. These present the characterization of the nanoMg/Al hydrotalcite before and after Cr (VI) removal, as well as the kinetic studies and of balance. In agreement with the results, when the NHT are thermal treated to 350 °C the hydrotalcite crystalline structure remains but the textural properties are improved and structural. The NHT synthesized by the sol-gel method present a good capacity of removal with values of 91 mg of Cr (VI) removed / g of NHT. The above mentioned capacity of removal gets improved after thermal treating the material, reaching values of removal of 124 mg of Cr (VI) removed / g of NHT. The NHT with the Cr (VI) absorbed show decrease of the crystalline structure, as well as a saturation of the pores that annuls the porosity due to the fact that the Cr (VI) lodges both at the pores and at the intersheets. The time that him takes the HLM to remove the Cr (VI) of the watery solution is alone of 2 minutes, with which it is possible to conclude that the NHT have an excellent aptitude to remove Cr (VI) of watery solutions in an interval of very short time.

scholarly journals Optimization, equilibrium and kinetic studies of Zn2+ and Ni2+ adsorption from aqueous solutions using composite adsorbent

2018 ◽  
Vol 67 (3) ◽  
pp. 279-290 ◽  
Author(s):  
Haider M. Zwain ◽  
Mohammadtaghi Vakili ◽  
Irvan Dahlan
Keyword(s):  
Contact Time ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Freundlich Isotherm ◽  
Kinetic Studies ◽  
Isotherm Models ◽  
Experimental Conditions ◽  
Palm Oil Fuel Ash ◽  
Composite Adsorbent ◽  
Oil Fuel

Abstract A novel RHA/PFA/CFA composite adsorbent was synthesized from rice husk ash (RHA), palm oil fuel ash (PFA), and coal fly ash (CFA) by modified sol-gel method. Effect of different parameters such as adsorbent dosage, contact time, and pH were studied using batch experiment to optimize the maximum zinc (Zn2+) and nickel (Ni2) adsorption conditions. Results showed that the maximum adsorption condition occurred at adsorbent amount of 10 g/L, contact time of 60 min, and pH 7. At this condition, the removal efficiencies were 81% and 61% for Zn2+ and Ni2+, in which the adsorption capacities (qmax) were 21.74 mg/g and 17.85 mg/g, respectively. Adsorption behavior of RHA/PFA/CFA composite adsorbent was studied through the various isotherm models at different adsorbent amounts. The results indicated that the Freundlich isotherm model gave an excellent agreement with the experimental conditions. Based on the results obtained from the kinetic studies, pseudo-second-order was suitable for the adsorption of Ni2+ and Zn2+, compared to the pseudo-first-order model. The results presented in this study showed that RHA/PFA/CFA composite adsorbent successfully adsorbed Zn2+ and Ni2.

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