Preparation and performance of a colorimetric biosensor using acetylcholinesterase and indoxylacetate for assay of nerve agents and drugs

ABSTRACT Different toxic compounds can target the cholinergic nervous system. Acetylcholinesterase (AChE; EC 3.1.1.7) is one of the most crucial components of the cholinergic nervous system and thus many of the toxins interact with this enzyme. As to inhibitors, nerve agents used as chemical warfare, some insecticides, and drugs influencing the cholinergic system are common examples of AChE inhibitors. Once inhibited by a neurotoxic compound, a serious cholinergic crisis can occur. On the other hand, sensitivity of AChE to the inhibition can be used for analytical purposes. In this study, a simple disposable biosensor with AChE as a recognition element was devised. AChE was immobilized onto a cellulose matrix and indoxylacetate was used as a chromogenic substrate. The enzyme reaction was assessed by the naked eye using arbitrary units and pyridostigmine, tacrine, paraoxon, carbofuran, soman and VX were assayed as selected inhibitors. A good stability of the biosensors was found, with no aging over a quarter of a year and minimal sensitivity to the interference of organic solvents. The limit of detection ranged from 10 to 100 nmol/L for the compounds tested with a sample volume of 40 μL

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A submersible battery-powered flow injection (FI) sensor for the determination of nitrate in estuarine and coastal waters

Journal of Automated Methods and Management in Chemistry ◽

10.1155/s1463924699000012 ◽

1999 ◽

Vol 21 (1) ◽

pp. 1-9 ◽

Cited By ~ 6

Author(s):

Anthony R. J. David ◽

Trevor McCormack ◽

Paul J. Worsfold

Keyword(s):

Flow Injection ◽

Coastal Waters ◽

Limit Of Detection ◽

Flow Cell ◽

Sample Volume ◽

Tamar Estuary ◽

Flow Through ◽

And Performance ◽

Design Construction

The design, construction and performance of a remotely deployed submersible flow injection-based nutrient (total oxidized nitrogen) sensor are described. The sensor featured a custom-built microcomputer and a solid-state, flow-through spectrophotometric detector, and the derivatization chemistry was based on in-line coppercadmium reduction of nitrate to nitrite, and diazotization with N1NED and sulphanilamide. The limit of detection was 0.0014 mg l-1NO3-N and the linear range was 0.0014- 0.77 mg l-1with a 260 μl sample volume and a 20 mm path length flow cell. Results from submersed deployments in the Tamar estuary and North Sea are also reported.

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Microfluidic Devices for Enhancing the Sensitivity of ELISA Methods

ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, Volume 2 ◽

10.1115/icnmm2011-58284 ◽

2011 ◽

Author(s):

Debashis Dutta ◽

Naoki Yanagisawa

Keyword(s):

Limit Of Detection ◽

Microfluidic Channel ◽

Enzyme Reaction ◽

Sample Volume ◽

Biological Research ◽

Minimum Detectable Concentration ◽

Permeable Membrane ◽

Microtiter Plates ◽

Detectable Concentration ◽

Elisa Technique

Enzyme-linked immunosorbent assays (ELISA) are critically important tools in biological research, allowing the presence and concentrations of a wide variety of key biochemical intermediates to be determined. While the signal amplification that is the core advantage of ELISA methods is impressive, it is nevertheless the case that it is insufficient for some particularly demanding challenges in terms of sensitivity, assay time, or sample size. In this paper, we discuss three different approaches developed in our laboratory that can improve the sensitivity of ELISA methods by 2–3 orders of magnitude. Two of these approaches have been shown to reduce the minimum detectable concentration of the target analyte in the system through trapping of the analyte species and the enzyme reaction product around a semi-permeable membrane. The third approach, on the other hand, focuses on reducing the sample volume requirement in these assays by implementing multiplex ELISA methods in a single microfluidic channel using the same enzyme label. This multiplex technique relies on the slow diffusion of the enzyme reaction product across adjacent assay segments for accurate quantitation and has been demonstrated to have a limit of detection substantially better than that of commercial microtiter plates. We believe the combination of these approaches could significantly extend the applicability of the ELISA technique to more challenging assays than is currently possible.

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Counteracting poisoning with chemical warfare nerve agents

Archives of Industrial Hygiene and Toxicology ◽

10.2478/aiht-2020-71-3459 ◽

2020 ◽

Vol 71 (4) ◽

pp. 266-284

Author(s):

Nikolina Maček Hrvat ◽

Zrinka Kovarik

Keyword(s):

Nervous System ◽

Peripheral Nervous System ◽

Standard Therapy ◽

Nerve Agents ◽

Respiratory Arrest ◽

Chemical Warfare ◽

Membrane Receptors ◽

Irreversible Inhibition ◽

Oxime Reactivator ◽

Prompt Action

AbstractPhosphylation of the pivotal enzyme acetylcholinesterase (AChE) by nerve agents (NAs) leads to irreversible inhibition of the enzyme and accumulation of neurotransmitter acetylcholine, which induces cholinergic crisis, that is, overstimulation of muscarinic and nicotinic membrane receptors in the central and peripheral nervous system. In severe cases, subsequent desensitisation of the receptors results in hypoxia, vasodepression, and respiratory arrest, followed by death. Prompt action is therefore critical to improve the chances of victim’s survival and recovery. Standard therapy of NA poisoning generally involves administration of anticholinergic atropine and an oxime reactivator of phosphylated AChE. Anticholinesterase compounds or NA bioscavengers can also be applied to preserve native AChE from inhibition. With this review of 70 years of research we aim to present current and potential approaches to counteracting NA poisoning.

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The Effects of CW (Chemical Warfare)-Related Chemicals on Social Behavior and Performance

10.21236/ada190431 ◽

1984 ◽

Author(s):

Bradford N. Bunnell ◽

W. B. Iturrian

Keyword(s):

Social Behavior ◽

Chemical Warfare ◽

And Performance

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A verified genomic reference sample for assessing performance of cancer panels detecting small variants of low allele frequency

Genome Biology ◽

10.1186/s13059-021-02316-z ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Wendell Jones ◽

Binsheng Gong ◽

Natalia Novoradovskaya ◽

Dan Li ◽

Rebecca Kusko ◽

...

Keyword(s):

Quality Control ◽

Allele Frequency ◽

Liquid Biopsy ◽

Limit Of Detection ◽

Reference Sample ◽

Digital Pcr ◽

Detection Sensitivity ◽

Analytical Accuracy ◽

And Performance ◽

Reference Samples

Abstract Background Oncopanel genomic testing, which identifies important somatic variants, is increasingly common in medical practice and especially in clinical trials. Currently, there is a paucity of reliable genomic reference samples having a suitably large number of pre-identified variants for properly assessing oncopanel assay analytical quality and performance. The FDA-led Sequencing and Quality Control Phase 2 (SEQC2) consortium analyze ten diverse cancer cell lines individually and their pool, termed Sample A, to develop a reference sample with suitably large numbers of coding positions with known (variant) positives and negatives for properly evaluating oncopanel analytical performance. Results In reference Sample A, we identify more than 40,000 variants down to 1% allele frequency with more than 25,000 variants having less than 20% allele frequency with 1653 variants in COSMIC-related genes. This is 5–100× more than existing commercially available samples. We also identify an unprecedented number of negative positions in coding regions, allowing statistical rigor in assessing limit-of-detection, sensitivity, and precision. Over 300 loci are randomly selected and independently verified via droplet digital PCR with 100% concordance. Agilent normal reference Sample B can be admixed with Sample A to create new samples with a similar number of known variants at much lower allele frequency than what exists in Sample A natively, including known variants having allele frequency of 0.02%, a range suitable for assessing liquid biopsy panels. Conclusion These new reference samples and their admixtures provide superior capability for performing oncopanel quality control, analytical accuracy, and validation for small to large oncopanels and liquid biopsy assays.

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Validation of a Novel Diagnostic Approach Combining the VersaTREK™ System for Recovery and Real-Time PCR for the Identification of Mycobacterium chimaera in Water Samples

Microorganisms ◽

10.3390/microorganisms9051031 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1031

Author(s):

Roberto Zoccola ◽

Alessia Di Blasio ◽

Tiziana Bossotto ◽

Angela Pontei ◽

Maria Angelillo ◽

...

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Limit Of Detection ◽

Detection System ◽

Bacterial Load ◽

Microbial Control ◽

Hospital Setting ◽

Sample Volume ◽

Analytical Sensitivity ◽

Initial Water

Mycobacterium chimaera is an emerging pathogen associated with endocarditis and vasculitis following cardiac surgery. Although it can take up to 6–8 weeks to culture on selective solid media, culture-based detection remains the gold standard for diagnosis, so more rapid methods are urgently needed. For the present study, we processed environmental M. chimaera infected simulates at volumes defined in international guidelines. Each preparation underwent real-time PCR; inoculates were placed in a VersaTREK™ automated microbial detection system and onto selective Middlebrook 7H11 agar plates. The validation tests showed that real-time PCR detected DNA up to a concentration of 10 ng/µL. A comparison of the isolation tests showed that the PCR method detected DNA in a dilution of ×102 CFU/mL in the bacterial suspensions, whereas the limit of detection in the VersaTREK™ was <10 CFU/mL. Within less than 3 days, the VersaTREK™ detected an initial bacterial load of 100 CFU. The detection limit did not seem to be influenced by NaOH decontamination or the initial water sample volume; analytical sensitivity was 1.5 × 102 CFU/mL; positivity was determined in under 15 days. VersaTREK™ can expedite mycobacterial growth in a culture. When combined with PCR, it can increase the overall recovery of mycobacteria in environmental samples, making it potentially applicable for microbial control in the hospital setting and also in environments with low levels of contamination by viable mycobacteria.

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Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽

10.3390/bios11010004 ◽

2020 ◽

Vol 11 (1) ◽

pp. 4

Author(s):

Donggee Rho ◽

Seunghyun Kim

Keyword(s):

Limit Of Detection ◽

Point Of Care ◽

Low Cost ◽

Optical Cavity ◽

Sample Volume ◽

Small Sample ◽

Label Free ◽

C Reactive Protein ◽

Reactive Protein ◽

Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

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Acid-beta-glycerophosphatase reaction products in the central nervous system mitochondria following x-ray irradiation.

Journal of Histochemistry & Cytochemistry ◽

10.1177/23.6.168247 ◽

1975 ◽

Vol 23 (6) ◽

pp. 402-410 ◽

Cited By ~ 4

Author(s):

L Roizin ◽

D Orlovskaja ◽

J C Liu ◽

A L Carsten

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Acid Phosphatase ◽

Enzyme Reaction ◽

Reaction Products ◽

Huntington's Chorea ◽

X Ray ◽

System A ◽

Chemical Lesion ◽

The Central Nervous System

A survey of the literature to date on the enzyme histochemistry of intracellular organelles has not yielded any reference to the presence of acid phosphatase reaction products in the mammalian mitochondria of the central nervous system. A combination of Gomori's acid phosphatase mehtod, however, with standard electron microscopy has disclosed the presence of enzyme reaction products in the mitochondria of the central nervous system of rats from 2 hr to 22 weeks after x-ray irradiation, as well as in a cerebral biopsy performed on a patient affected by Huntington's chorea. No enzyme reaction products, on the other hand, were observed in serial sections that had been incubated in substrates either containing sodium fluoride or lacking in beta-glycerophosphate. The abnormal mitochondrial enzyme reaction (chemical lesion) is considered to be the consequenco of the pathologic process affecting the ultrastructural-chemical organization of the organelle.

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A Model for Competency Assessment of the Faculty in Islamic Azad University

International Education Studies ◽

10.5539/ies.v10n3p76 ◽

2017 ◽

Vol 10 (3) ◽

pp. 76

Author(s):

Aliasghar Mashinchi ◽

Seyed Ahmad Hashemi ◽

Kamran Mohammad Khani

Keyword(s):

Evaluation Method ◽

Research Society ◽

Sample Volume ◽

Competency Assessment ◽

Fars Province ◽

Evaluation Indexes ◽

Performance Dimensions ◽

Main Dimension ◽

And Performance ◽

Competency Evaluation

Today country success in economic, social, political, cultural tendencies etc. … is approved to be the hostages and pawns of coherent and dynamic didactic system. The education and didactic programs for qualification improvement and dynamism need to quantitatively and qualitatively evaluation and scrutiny. Current study started with the goal of presenting faculty competency evaluation for the reason of qualitative improvement of Islamic Azad University. Research in terms of to the way of collecting and compiling the details descriptive- survey and in terms of the goal and target type is so practical that by conducting general scrutiny in literature and subject history and past, we drawn the theoretical frame and conceptual model in this study. Nominee educational members’ opinions faculty members (self-assessment), supervisors (superiors), students of (clients) Fars province different Islamic Azad Universities are as the research society. In this research, with researcher evaluation in 24 active units in Fars province, approximately 125000 persons were examined. That sample volume was selected equal to 380 persons by using the clustered random sampling method (Krejcie and Morgan formulas). For collecting data, we used a researcher-made questionnaire whose validity was confirmed by the specialists and its stability was calculated by using the Cronbach’s alpha method equal to 0.84. Researcher-made questionnaire includes effective component in competency in five general axes for collecting the data. Then, with using 360-degree evaluation method, it was executed. For the data analysis, we used the descriptive statistic method and elicitation statistic (fact oral analysis, Wilcoxon and Friedman) and the results of the study are as follows: 1. drawing the model of competency evaluation of faculty (main dimension of evaluation indexes of faculty competencies), and 2. In the field of evaluation of the current situation from the dimensions and competence skill parameters, the ethical values, role, personal, and favorable statuses are evaluated. But in the performance and functional dimensions, and its subcomponents unfavorable status and lower than average level evaluated and the results of ranking of evaluation of dimensions of competencies of faculty in order to select the most priority is related to skill dimension, and the least priority is related to the functional and performance dimensions.

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