scholarly journals HAT-field: a very cheap, robust and quantitative point-of-care serological test for Covid-19.

2022 ◽  
Author(s):  
Etienne Joly ◽  
Agnes Maurel Ribes
Keyword(s):  
Room Temperature ◽  
Serological Test ◽  
Point Of Care ◽  
Low Cost ◽  
Single Step ◽  
Test Protocol ◽  
Laboratory Equipment ◽  
Human Red Blood Cells ◽  
The Stability ◽  
Disposable Equipment

We have recently described a very simple and cheap serological test called HAT to detect antibodies directed against the RBD of the SARS-Cov-2 virus. HAT is based on hemagglutination, triggered by a single reagent (IH4-RBD) comprised of the viral RBD domain fused to a nanobody specific for glycophorin, which is expressed at very high levels at the surface of human red blood cells (RBCs). One of the main initial goals of this study was to devise a test protocol that would be sensitive and reliable, yet require no specialized laboratory equipment such as adjustable pipets, so that it could be performed in the most remote corners of the world by people with minimal levels of training. Because antibody levels against the viral RBD have been found to correlate closely with sero-neutralisation titers, and thus with protection against reinfection, it has become obvious during the course of this study that making this test reliably quantitative would be a further significant advantage. We have found that, in PBN, a buffer which contains BSA and sodium azide, IH4-RBD is stable for over 6 months at room temperature, and that PBN also improves HAT performance compared to using straight PBS. We also show that performing HAT at either 4°C, room temperature or 37°C has minimal influence on the results, and that quantitative evaluation of the levels of antibodies directed against the SARS-CoV-2 RBD can be achieved in a single step using titration of the IH4-RBD reagent. The HAT-field protocol described here requires only very simple disposable equipment and a few microliters of whole blood, such as can be obtained by finger prick. Because it is based on a single soluble reagent, the test can be adapted very simply and rapidly to detect antibodies against variants of the SARS-CoV-2, or conceivably against different pathogens. HAT-field appears well suited to provide quantitative assessments of the serological protection of populations as well as individuals, and given its very low cost, the stability of the IH4-RBD reagent in the adapted buffer, and the simplicity of the procedure, could be deployed pretty much anywhere, including in the poorest countries and the most remote corners of the globe.

scholarly journals Longevity of Raw and Lyophilized Crude Urease Extracts

2021 ◽  
Vol 2 (2) ◽  
pp. 325-334
Author(s):  
Neda Javadi ◽  
Hamed Khodadadi Tirkolaei ◽  
Nasser Hamdan ◽  
Edward Kavazanjian
Keyword(s):  
Crude Extract ◽  
Room Temperature ◽  
Low Cost ◽  
Extraction Process ◽  
Crude Extracts ◽  
Simple Extraction ◽  
Commercial Applications ◽  
Stable Source ◽  
The Stability ◽  
The Cost

The stability (longevity of activity) of three crude urease extracts was evaluated in a laboratory study as part of an effort to reduce the cost of urease for applications that do not require high purity enzyme. A low-cost, stable source of urease will greatly facilitate engineering applications of urease such as biocementation of soil. Inexpensive crude extracts of urease have been shown to be effective at hydrolyzing urea for carbonate precipitation. However, some studies have suggested that the activity of a crude extract may decrease with time, limiting the potential for its mass production for commercial applications. The stability of crude urease extracts shown to be effective for biocementation was studied. The crude extracts were obtained from jack beans via a simple extraction process, stored at room temperature and at 4 ℃, and periodically tested to evaluate their stability. To facilitate storage and transportation of the extracted enzyme, the longevity of the enzyme following freeze drying (lyophilization) to reduce the crude extract to a powder and subsequent re-hydration into an aqueous solution was evaluated. In an attempt to improve the shelf life of the lyophilized extract, dextran and sucrose were added during lyophilization. The stability of purified commercial urease following rehydration was also investigated. Results of the laboratory tests showed that the lyophilized crude extract maintained its activity during storage more effectively than either the crude extract solution or the rehydrated commercial urease. While incorporating 2% dextran (w/v) prior to lyophilization of the crude extract increased the overall enzymatic activity, it did not enhance the stability of the urease during storage.

Alternative technology concepts for low-cost and high-speed 2D and 3D interconnect manufacturing

2013 ◽  
Vol 2013 (1) ◽  
pp. 000001-000006
Author(s):  
F. Roozeboom ◽  
M. Smets ◽  
B. Kniknie ◽  
M. Hoppenbrouwers ◽  
G. Dingemans ◽  
...  
Keyword(s):  
High Speed ◽  
Room Temperature ◽  
Microelectromechanical Systems ◽  
Low Cost ◽  
Industrial Process ◽  
Atomic Layer ◽  
Single Step ◽  
Thermal Mode ◽  
Different Types ◽  
Sidewall Passivation

The current industrial process of choice for Deep Reactive Ion Etching (DRIE) of 3D features, e.g. Through-Silicon Vias (TSVs), Microelectromechanical Systems (MEMS), etc., is the Bosch process, which uses alternative SF6 etch cycles and C4F8-based sidewall passivation cycles in a time-sequenced mode. An alternative, potentially faster and more accurate process is to have wafers pass under spatially-divided reaction zones, which are individually separated by so-called N2-gas bearings ‘curtains’ of heights down to 10–20 μm. In addition, the feature sidewalls can be protected by replacing the C4F8-based sidewall passivation cycles by cycles forming chemisorbed and highly uniform passivation layers of Al2O3 or SiO2 deposited by Atomic Layer Deposition (ALD), also in a spatially-divided mode. ALD is performed either in thermal mode, or plasma-assisted mode in order to achieve near room-temperature processing. For metal filling of 3D-etched TSVs, or for deposition of 2D metal conductor lines one can use Laser-Induced Forward Transfer (LIFT) of metals. LIFT is a maskless, ‘solvent’-free deposition method, utilizing different types of pulsed lasers to deposit thin material (e.g. Cu, Au, Al, Cr) layers with μm-range resolution from a transparent carrier (ribbon) onto a close-by acceptor substrate. It is a dry, single-step, room temperature process in air, suitable for different types of interconnect fabrication, e.g. TSV filling and redistribution layers (RDL), without the use of wet chemistry.

scholarly journals Ultra-Sensitive Colorimetric Plasmonic Sensing and Microfluidics for Biofluid Diagnostics Using Nanohole Array

2015 ◽  
Vol 2015 ◽  
pp. 1-21 ◽  
Author(s):  
Abid Ameen ◽  
Manas Ranjan Gartia ◽  
Austin Hsiao ◽  
Te-Wei Chang ◽  
Zhida Xu ◽  
...  
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Colorimetric Sensor ◽  
Limiting Factors ◽  
Plastic Substrate ◽  
Plasmonic Sensor ◽  
Transparent Plastic ◽  
Laboratory Equipment ◽  
Nanohole Array ◽  
Lab On Chip

Colorimetric techniques provide a useful approach for sensing application because of their low cost, use of inexpensive equipment, requirement of fewer signal transduction hardware, and, above all, their simple-to-understand results. Colorimetric sensor can be used for both qualitative analyte identification as well as quantitative analysis for many application areas such as clinical diagnosis, food quality control, and environmental monitoring. A gap exists between high-end, accurate, and expensive laboratory equipment and low-cost qualitative point-of-care testing tools. Here, we present a label-free plasmonic-based colorimetric sensor fabricated on a transparent plastic substrate consisting of about one billion nanocups in an array with a subwavelength opening and decorated with metal nanoparticles on the side walls, to bridge that gap. The fabrication techniques of the plasmonic sensor, integration to portable microfluidic devices for lab on chip applications, demonstration of highly sensitive refractive-index sensing, DNA hybridization detection, and protein-protein interaction will be reviewed. Further, we anticipate that the colorimetric sensor can be applied to point-of-care diagnostics by utilizing proper surface functionalization techniques, which seems to be one of the current limiting factors. Finally, the future outlook for the colorimetric plasmonic sensors is discussed.

scholarly journals A Graphene-Based Enzymatic Biosensor Using a Common-Gate Field-Effect Transistor for L-Lactic Acid Detection in Blood Plasma Samples

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1852
Author(s):  
Ariadna Schuck ◽  
Hyo Eun Kim ◽  
Júlia Konzen Moreira ◽  
Priscila Schmidt Lora ◽  
Yong-Sang Kim
Keyword(s):  
Lactic Acid ◽  
Point Of Care ◽  
Low Cost ◽  
Lactic Acid Production ◽  
Active Surface ◽  
The Body ◽  
Human Organism ◽  
Buffer Solution ◽  
Common Gate ◽  
The Stability

Lactate is an important organic molecule that is produced in excess during anaerobic metabolism when oxygen is absent in the human organism. The concentration of this substance in the body can be related to several medical conditions, such as hemorrhage, respiratory failure, and ischemia. Herein, we describe a graphene-based lactate biosensor to detect the concentrations of L-lactic acid in different fluids (buffer solution and plasma). The active surface (graphene) of the device was functionalized with lactate dehydrogenase enzyme using different substances (Nafion, chitosan, and glutaraldehyde) to guarantee stability and increase selectivity. The devices presented linear responses for the concentration ranges tested in the different fluids. An interference study was performed using ascorbic acid, uric acid, and glucose, and there was a minimum variation in the Dirac point voltage during detection of lactate in any of the samples. The stability of the devices was verified at up to 50 days while kept in a dry box at room temperature, and device operation was stable until 12 days. This study demonstrated graphene performance to monitor L-lactic acid production in human samples, indicating that this material can be implemented in more simple and low-cost devices, such as flexible sensors, for point-of-care applications.

scholarly journals Aerosolised fluorescein can quantify FFP mask faceseal leakage: a cost-effective adaptation to the existing point of care fit-test.

2020 ◽  
Author(s):  
Sameer Zaman ◽  
Henry Seligman ◽  
Freya Hepworth Lloyd ◽  
Keval Tushar Patel ◽  
Digby Chappell ◽  
...  
Keyword(s):  
Filter Paper ◽  
Point Of Care ◽  
Low Cost ◽  
Cost Effective ◽  
Test Protocol ◽  
Taste Test ◽  
Significant Difference ◽  
Fit Testing ◽  
Total Fluorescence ◽  
Low Levels

Abstract Background Filtering facepiece (FFP) respirators must provide an adequate faceseal to protect healthcare workers from harmful particles. A qualitative fit-test using bitter-tasting aerosols the commonest way to determine if an FFP mask is safe enough for clinical use. This taste-test is subjective and can be biased by placebo. We propose a cheap and quantitative modification of the taste-test, by measuring the amount of fluorescein staining filter paper behind the FFP mask after a fit-test protocol, using digital image analysis. Methods Medical grade fluorescein was added to bitter-tasting denatonium benzoate solution and Aerosolised during a mask fit-testing protocol. Scientific filter paper was placed on the inner surface of the mask. Participants were asked if they could taste the solution to determine their qualitative ‘pass’ or ‘fail’ result. Filter paper photographs were analysed after the test to quantify total fluorescence (TF). TF levels in the taste-test ‘pass’ and ‘fail’ groups were compared.Results Fifty-six healthcare professionals completed the fluorescein mask fit-test protocol. 32 (57%) ‘passed’ the qualitative (taste) test and the remainder ‘failed’. There was a significant difference in TF between the groups based on their qualitative results (p <0.001). A cut-off of TF = 5.0 x 106 fluorescence units was determined by analysing the precision (78%) and recall (84%) of the fluorescein test. Applying this cut-off resulted in 5 out of 56 participants (9%) being reclassified from ‘pass’ to ‘fail’ by the fluorescein test. 7 out of 56 (12%) participants were reclassified from ‘fail’ to ‘pass’.Conclusions Fluorescein is detectable and sensitive to identify faceseal leaks in FFP masks. The fluorescein fit-test is discriminating in its ability to divide people into ‘pass’ and ‘fail’ groups similarly to the taste-test. The adaptations are low-cost and could be incorporated in the point-of-care setting. After further validation the fluorescein test could increase safety for staff by reducing the number of false ‘pass’ by the taste-test. It could also reassure people who have ‘failed’ the taste-test that they have low levels of fluorescein leak, enabling them to return to clinical practice safely.

scholarly journals Analytical Molecular Diagnosis of Cervical Cancer via Paper Microfluidic Chip

Proceedings ◽  
2018 ◽  
Vol 2 (25) ◽  
pp. 1556
Author(s):  
Melike Karakaya
Keyword(s):  
Microfluidic Chip ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Extraction Process ◽  
Single Step ◽  
Enzymatic Amplification ◽  
Whole Process ◽  
Low Concentrations ◽  
Paper Microfluidic

In this work, we focused on the development of a novel point of care (POC) paper-based analytical microfluidic chip. The system has been developed for paper-based extraction, non-enzymatic amplification and electroanalytical detection of human papillomavirus (HPV). The device comprises paper extraction support material as well as paper-based detection tool. Herein, a special DNA modification method has been utilized to allow non-enzymatic amplification by using microbeads and silver nanoparticles labeled primers. The device is capable of extracting more than 10–100 copies per mL of DNA approximately in 15 min along with a single step extraction process from patient samples. In addition, it is able to detect low concentrations taking just less than 10 min with high selectivity to HPV kinds of 16&18. It only takes the low-cost point of care device less than 40 min with a low limit of detection (LOD) to complete the whole process.

A molecular dynamics study of Fe50-XMXAl50 ternary alloy (M=Ag, Pt, Pd)

MRS Advances ◽  
2020 ◽  
Vol 5 (23-24) ◽  
pp. 1185-1193
Author(s):  
C S Mkhonto ◽  
P E Ngoepe ◽  
H R Chauke
Keyword(s):  
Molecular Dynamics ◽  
Room Temperature ◽  
Mechanical Stability ◽  
Low Cost ◽  
Industrial Applications ◽  
Iron Aluminide ◽  
Intermetallic Alloys ◽  
Room Temperature Ductility ◽  
The Stability ◽  
Experimental Findings

ABSTRACTIron aluminide intermetallic alloys are of great importance in many industries due to their excellent oxidation resistance, low cost, low density, resistance to corrosion and good ductility at room temperature. However, these alloys suffer limited room temperature ductility above 873 K. In this paper, a molecular dynamics-based LAMMPS-EAM was used to model Fe50-XMXAl doped systems with either Ag, Pt or Pd. The lattice side preferences of the dopant were deduced from their energy landscape, and Fe sub-lattices showed promising properties. It was found that the addition of Ag, Pt and Pd enhances the stability of Fe50-XMXAl composition. More importantly, Ag and Pd doped systems gave comparable transition temperatures to experimental findings of 1273 K and 1073 K, respectively. Their thermodynamic and the mechanical stability trends showed promising properties for industrial applications, displaying stability at a high temperature below 1300 K.

Scanning and Transmission Electron Microscopy of Human Red Blood Cells

1969 ◽  
Vol 27 ◽  
pp. 44-45
Author(s):  
A.J. Tousimis ◽  
T.R. Padden
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Cells ◽  
Room Temperature ◽  
Type Specimen ◽  
New Combination ◽  
Human Red Blood Cells ◽  
Transmission Electron ◽  
Microscope Slides ◽  
Scanning Electron

The size, shape and surface morphology of human erythrocytes (RBC) were examined by scanning electron microscopy (SEM), of the fixed material directly and by transmission electron microscopy (TEM) of surface replicas to compare the relative merits of these two observational procedures for this type specimen.A sample of human blood was fixed in glutaraldehyde and washed in distilled water by centrifugation. The washed RBC's were spread on freshly cleaved mica and on aluminum coated microscope slides and then air dried at room temperature. The SEM specimens were rotary coated with 150Å of 60:40- gold:palladium alloy in a vacuum evaporator using a new combination spinning and tilting device. The TEM specimens were preshadowed with platinum and then rotary coated with carbon in the same device. After stripping the RBC-Pt-C composite film, the RBC's were dissolved in 2.5N HNO3 followed by 0.2N NaOH leaving the preshadowed surface replicas showing positive topography.

Methods for the Concentration of Bovine Ac-Globulin (Factor V)

1961 ◽  
Vol 06 (03) ◽  
pp. 435-444 ◽  
Author(s):  
Ricardo H. Landaburu ◽  
Walter H. Seegers
Keyword(s):  
Room Temperature ◽  
Barium Carbonate ◽  
Deae Cellulose ◽  
Reducing Agents ◽  
Factor V ◽  
Isoelectric Precipitation ◽  
Stabilizing Agent ◽  
Bovine Plasma ◽  
The Stability

SummaryAn attempt was made to obtain Ac-globulin from bovine plasma. The concentrates contain mostly protein, and phosphorus is also present. The stability characteristics vary from one preparation to another, but in general there was no loss before 1 month in a deep freeze or before 1 week in an icebox, or before 5 hours at room temperature. Reducing agents destroy the activity rapidly. S-acetylmercaptosuccinic anhydride is an effective stabilizing agent. Greatest stability was at pH 6.0.In the purification bovine plasma is adsorbed with barium carbonate and diluted 6-fold with water. Protein is removed at pH 6.0 and the Ac-globulin is precipitated at pH 5.0. Rivanol and alcohol fractionation is followed by chromatography on Amberlite IRC-50 or DEAE-cellulose. The final product is obtained by isoelectric precipitation.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

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