scholarly journals Indium Nitrite (InN)-Based Ultrasensitive and Selective Ammonia Sensor Using an External Silicone Oil Filter for Medical Application

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3887 ◽  
Author(s):  
Sujeet Rai ◽  
Kun-Wei Kao ◽  
Shanjgr Gwo ◽  
Ashish Agarwal ◽  
Wei Lin ◽  
...  
Keyword(s):  
Silicone Oil ◽  
Operating Temperature ◽  
Medical Application ◽  
Noninvasive Diagnosis ◽  
Selective Detection ◽  
Detection Time ◽  
Ammonia Sensor ◽  
Ammonia Gas ◽  
Lower Detection Limit ◽  
Lower Detection

Ammonia is an essential biomarker for noninvasive diagnosis of liver malfunction. Therefore, selective detection of ammonia is essential for medical application. Here, we demonstrate a portable device to selectively detect sub-ppm ammonia gas. The presented gas sensor is composed of a Pt coating on top of an ultrathin Indium nitrite (InN) epilayer with a lower detection limit of 0.2 ppm, at operating temperature of 200 °C, and detection time of 1 min. The sensor connected with the external filter of nonpolar 500 CS silicone oil to diagnose liver malfunction. The absorption of 0.7 ppm acetone and 0.4 ppm ammonia gas in 10 cc silicone oil is 80% (0.56 ppm) and 21.11% (0.084 ppm), respectively, with a flow rate of 10 cc/min at 25 °C. The absorption of acetone gas is 6.66-fold higher as compared to ammonia gas. The percentage variation in response for 0.7 ppm ammonia and 0.7 ppm acetone with and without silicone oil on InN sensor is 17.5% and 4%, and 22.5%, and 14% respectively. Furthermore, the percentage variation in response for 0.7 ppm ammonia gas with silicone oil on InN sensor is 4.3-fold higher than that of 0.7 ppm acetone. The results show that the InN sensor is suitable for diagnosis of liver malfunction.

scholarly journals Ppb-Level Butanone Sensor Based on ZnO-TiO2-rGO Nanocomposites

Chemosensors ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 284
Author(s):  
Zhijia Liao ◽  
Yao Yu ◽  
Zhenyu Yuan ◽  
Fanli Meng
Keyword(s):  
Gas Sensing ◽  
Operating Temperature ◽  
Skin Irritation ◽  
Optimum Operating ◽  
Optimum Operating Temperature ◽  
Lower Detection Limit ◽  
Gas Sensing Properties ◽  
Lower Detection ◽  
Organic Gases ◽  
Sensing Performance

In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, triggering skin irritation in mild cases and affecting our breathing in severe cases. In this paper, the gas-sensing properties of TiO2, ZnO, ZnO-TiO2, and ZnO-TiO2-rGO nanomaterials to butanone vapor were studied. The optimum operating temperature of the ZnO-TiO2-rGO sensor is 145 °C, which is substantially lower than the other three sensors. The selectivity for butanone vapor is greatly improved, and the response is 5.6 times higher than that of other organic gases. The lower detection limit to butanone can reach 63 ppb. Therefore, the ZnO-TiO2-rGO sensor demonstrates excellent gas-sensing performance to butanone. Meanwhile, the gas-sensing mechanism of the ZnO-TiO2-rGO sensor to butanone vapor was also analyzed.

High Sensitivity NO2 Gas Sensor Based on 3D WO3 Microflowers Assembled by Numerous Nanoplates

2020 ◽  
Vol 20 (3) ◽  
pp. 1790-1798 ◽  
Author(s):  
Pei-Jiang Cao ◽  
Meng Li ◽  
Ch. N. Rao ◽  
Shun Han ◽  
Wang-Ying Xu ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Operating Temperature ◽  
Average Pore Size ◽  
Hydrothermal Process ◽  
High Sensitivity ◽  
Average Pore ◽  
Lower Detection Limit ◽  
No2 Gas Sensor ◽  
Lower Detection ◽  
Key Features

Tungsten oxide microflowers (WO3 MFs) were fabricated by a simple hydrothermal process through adjusting the pH of the solution by HCl. These MFs possess the outer diameters of about 2 μm and are composed of numerous nanoplates with the average pore size of 10.9 nm. Chemiresistive activity of as-fabricated WO3 MFs sensor was attempted towards oxidizing and reducing target gases, revealing a superior selectivity to NO2 with a maximum response of 22.95 (2 ppm NO2) @105 °C compared to other target gases. One of the key features of as-fabricatedWO3 MFs sensor is the lower detection limit of 125 ppb and operating temperature of 105 °C to NO2 with better reproducibility, signifying commercial prospective of the developed sensor materials. Finally, the gas sensing mechanism of WO3 MFs sensor has been proposed.

A novel 3D Zn-coordination polymer based on a multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for the efficient detection of multiple analytes

2021 ◽  
Author(s):  
Yu Liu ◽  
Yan Wang ◽  
Xiao-Sa Zhang ◽  
Yu-Shu Sheng ◽  
Wen-Ze Li ◽  
...  
Keyword(s):  
Detection Limit ◽  
Coordination Polymer ◽  
Fluorescent Sensor ◽  
Lower Detection Limit ◽  
Ph Values ◽  
Efficient Detection ◽  
Wide Range ◽  
Lower Detection ◽  
Multiple Analytes

A Zn-CP exhibits remarkable fluorescence behaviours and stability in a wide range of pH values. It can become an outstanding candidate in the selective sensing of Fe3+, Mg2+, Cr2O72−, MnO4−, NB and NM at a lower detection limit.

scholarly journals Rapid Method Using Two Microbial Enzymes for Detection of l-Abrine in Food as a Marker for the Toxic Protein Abrin

2014 ◽  
Vol 81 (5) ◽  
pp. 1610-1615 ◽  
Author(s):  
Anthony G. Dodge ◽  
Kelvin Carrasquillo ◽  
Luis Rivera ◽  
Lei Xu ◽  
Lawrence P. Wackett ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Visual Detection ◽  
Food Samples ◽  
Content Type ◽  
Toxic Protein ◽  
Beverage Samples ◽  
Lower Detection Limit ◽  
Lower Detection ◽  
Complex Sample ◽  
Food And Beverage

ABSTRACTAbrin is a toxic protein produced by the ornamental plantAbrus precatorius, and it is of concern as a biothreat agent. The small coextracting moleculeN-methyl-l-tryptophan (l-abrine) is specific to members of the genusAbrusand thus can be used as a marker for the presence or ingestion of abrin. Current methods for the detection of abrin orl-abrine in foods and other matrices require complex sample preparation and expensive instrumentation. To develop a fast and portable method for the detection ofl-abrine in beverages and foods, theEscherichia coliproteinsN-methyltryptophan oxidase (MTOX) and tryptophanase were expressed and purified. The two enzymes jointly degradedl-abrine to products that included ammonia and indole, and colorimetric assays for the detection of those analytes in beverage and food samples were evaluated. An indole assay using a modified version of Ehrlich's/Kovac's reagent was more sensitive and less subject to negative interferences from components in the samples than the Berthelot ammonia assay. The two enzymes were added into food and beverage samples spiked withl-abrine, and indole was detected as a degradation product, with the visual lower detection limit being 2.5 to 10.0 μM (∼0.6 to 2.2 ppm)l-abrine in the samples tested. Results could be obtained in as little as 15 min. Sample preparation was limited to pH adjustment of some samples. Visual detection was found to be about as sensitive as detection with a spectrophotometer, especially in milk-based matrices.

Glucose Biosensor Based on Glucose Oxidase-Horseradish Peroxidase/Multiporous Tin Oxide (SnO2) Modified Electrode

2021 ◽  
Vol 21 (5) ◽  
pp. 3059-3064
Author(s):  
A. K. M. Kafi ◽  
Aizam Bin Kasri ◽  
Rajan Jose
Keyword(s):  
Horseradish Peroxidase ◽  
Glucose Oxidase ◽  
Tin Oxide ◽  
Electrode Potential ◽  
High Sensitivity ◽  
Glucose Biosensor ◽  
Glucose Detection ◽  
Lower Detection Limit ◽  
Vis Spectroscopy ◽  
Lower Detection

The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized onto a glassy carbon electrode (GCE) and its utilization as a biosensor for glucose detection is reported. The network established with GOx-HRP/SnO2 possess high sensitivity and stability by performing the electrocatalytic features in the sensing of glucose. The turbidity of fabrication had been scanned and analyzed using UV-vis spectroscopy. The morphology and composition of the fabricated GOx-HRP/SnO2 networks were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were employed to study the electrochemical properties of the proposed biosensor. The effect of applied electrode potential and pH were systemically investigated. The biosensor responds to glucose at work potential values between −400 mV, and exhibited a lower detection limit (0.025 mM) and long linear range (0.25 to 7.0 mM), and was resistant to common interferences.

Manual Immunonephelometric Assay of Proteins, with Use of Polymer Enhancement

1974 ◽  
Vol 20 (9) ◽  
pp. 1181-1186 ◽  
Author(s):  
Jorge Lizana ◽  
Kristoffer Hellsing
Keyword(s):  
Detection Limit ◽  
Urinary Albumin ◽  
Optimal Time ◽  
Immunological Reaction ◽  
Reaction Conditions ◽  
Enhancing Effect ◽  
Lower Detection Limit ◽  
Small Series ◽  
Lower Detection ◽  
Immunonephelometric Assay

Abstract A manual immunonephelometric method for proteins has been developed by using an ordinary fluorometer as a nephelometer. By applying the enhancing effect of polyethylene glycol (av mol wt, 6000) on the immunological reaction, albumin and fibrinogen were quantitated after a 10-min reaction time. Under the present conditions the sensitivity was increased and thus antiserum consumption was decreased. The reaction conditions were carefully studied with respect to optimal time and concentration of the reactants. The precision of the method was 2.6-3.6% (CV). The lower detection limit in the albumin-antialbumin system was 0.1 mg/liter. Comparative studies showed a correlation coefficient of 0.991 with an automated immunonephelometric method for urinary albumin, and of 0.908 with a thrombin clottable method for plasma fibrinogen. We especially suggest use of this manual immunonephelometric method where small series of samples are to be analyzed.

Evaluation of a Bead-based Enzyme Immunoassay for the Rapid Detection of Osteocalcin in Human Serum

2000 ◽  
Vol 46 (2) ◽  
pp. 252-257 ◽  
Author(s):  
Alexandra M Crăciun ◽  
Cees Vermeer ◽  
Hans-Georg Eisenwiener ◽  
Norbert Drees ◽  
Marjo H J Knapen
Keyword(s):  
Human Serum ◽  
Microtiter Plate ◽  
Lower Detection Limit ◽  
Unknown Sample ◽  
Linear Dose ◽  
Human Volunteers ◽  
Lower Detection ◽  
Routine Clinical Setting ◽  
Commercial Kits ◽  
Time Required

Abstract Background: Circulating osteocalcin is a well-known marker for bone formation, but none of the commercial kits currently available can be used in automated systems. Here we present the first semiautomated assay for human serum osteocalcin. Methods: Polystyrene beads were coated with antibodies against the COOH terminus of osteocalcin and used in the COBAS® EIA System. Osteocalcin was detected with peroxidase-conjugated antibodies against the osteocalcin NH2 terminus. Results: The time required to analyze an unknown sample was 60 min, with a lower detection limit of 4.5 μg/L and a linear dose–response curve between 4.5 and 100 μg/L. The intraassay imprecision (CV) was 5–8% (n = 21); the interassay variation was 6–9% (n = 14). In samples from human volunteers and patients, data generated with the newly developed assay were comparable to those obtained with standard microtiter plate-based assays. Conclusions: The coated beads assay may be implemented on fully automated analyzers, which not only may further reduce imprecision but may also substantially increase the applicability of osteocalcin as a marker for bone metabolism in the routine clinical setting.

New noncompetitive immunoassays of small analytes

1995 ◽  
Vol 41 (7) ◽  
pp. 986-990 ◽  
Author(s):  
U Piran ◽  
W J Riordan ◽  
L A Livshin
Keyword(s):  
Detection Limit ◽  
Liquid Phase ◽  
Binding Sites ◽  
Dynamic Range ◽  
Lower Detection Limit ◽  
Controlled Pore Glass ◽  
Lower Detection ◽  
Pore Glass ◽  
Clinically Significant ◽  
Acridinium Ester

Abstract We developed a novel noncompetitive immunoassay format for monoepitopic analytes and describe here a model assay for triiodothyronine (T3), performed on Ciba Corning's ACS:180 analyzer. Acridinium ester (AE)-labeled bivalent anti-T3 was incubated with the sample, producing AE-anti-T3/T3 complexes and unreacted AE-anti-T3. Controlled-pore glass particles (CPG) with immobilized diiodothyronine (T2) were then added in excess, to bind AE-anti-T3 possessing two unoccupied binding sites but not AE-anti-T3 bound to one or two T3 molecules. Paramagnetic particles (PMP) with immobilized anti-AE were then added to the same cuvette to capture AE-anti-T3/T3 complexes; AE-anti-T3 bound to the surface of CPG, however, was not captured, because of steric hindrance. After the incubation, the PMP was magnetically separated to remove the liquid phase and the suspended CPG from the cuvette. The chemiluminescence associate with the PMP remaining in the cuvette was then measured. This noncompetitive T3 assay exhibited a 10-fold lower detection limit than the equivalent competitive T3 assay, i.e., 0.3 vs pg/test. Imprecision (CV) in the clinically significant range was 6% or less. The assay also displayed two- to sevenfold lower cross-reactivities and a wider dynamic range.

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