scholarly journals Screen-Printed Sensors for Colorimetric Detection of Hydrogen Sulfide in Ambient Air

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1182 ◽  
Author(s):  
Laura Engel ◽  
Karina Tarantik ◽  
Carolin Pannek ◽  
Jürgen Wöllenstein
Keyword(s):  
Hydrogen Sulfide ◽  
Color Change ◽  
Colorimetric Detection ◽  
Preliminary Test ◽  
Ambient Air ◽  
Sensitive Material ◽  
Long Term Stability ◽  
Colorimetric Response ◽  
Vis Spectroscopy ◽  
Printed Sensors

A fast and sensitive method to monitor hydrogen sulfide (H2S) in ambient air based on a visible color change of a printed disposable sensor has been developed. As gas-sensitive material, an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in an ethyl cellulose matrix for screen printing. If H2S is present in ambient air, the gas sensitive layer changes its color from purple to yellow. A pre-primed polyethylene (PE) foil and a coated offset paper served as the printing substrate. The colorimetric response to the target gas was measured by UV/Vis spectroscopy in reflection at H2S concentrations between 1 to 20 ppm. Possible cross-sensitivities of the printed sensors towards methane (CH4), formaldehyde (CH2O), carbon monoxide (CO), ammonia (NH3), and nitrogen dioxide (NO2), as well as the long-term stability was investigated. Furthermore, reflection measurements of the Cu-PAN complex on an amorphous silica powder under gas admission served as preliminary test for the subsequent paste development.

scholarly journals Colorimetric Detection of Hydrogen Sulfide in Ambient Air

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 804
Author(s):  
Laura Engel ◽  
Karina R. Tarantik ◽  
Carolin Pannek ◽  
Jürgen Wöllenstein
Keyword(s):  
Hydrogen Sulfide ◽  
Azo Dye ◽  
Screen Printing ◽  
Color Change ◽  
Colorimetric Detection ◽  
Ambient Air ◽  
Fast Method ◽  
Vis Spectroscopy

We present a fast method to monitor hydrogen sulfide (H2S) in ambient air based on a visible color change. Therefore, an immobilized copper(II) complex of the azo dye 1-(2-pyridylazo)-2-naphtol (H-PAN) was synthesized and prepared in a matrix for screen printing. Different materials, reaching from opaque paper to transparent foils served as substrate. The reaction of the copper(II) complex (Cu-PAN) to the target gas H2S was measured in reflection via UV/VIS spectroscopy.

scholarly journals Paper-Based Multiplexed Colorimetric Device for the Simultaneous Detection of Salivary Biomarkers

Biosensors ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 443
Author(s):  
Tania Pomili ◽  
Paolo Donati ◽  
Pier Paolo Pompa
Keyword(s):  
Color Change ◽  
Colorimetric Detection ◽  
Simultaneous Detection ◽  
Spectral Shift ◽  
Fully Integrated ◽  
Salivary Biomarkers ◽  
Colorimetric Response ◽  
Test Zone ◽  
One Step ◽  
Pre Treatment

In this study, we describe a monolithic and fully integrated paper-based device for the simultaneous detection of three prognostic biomarkers in saliva. The pattern of the proposed multiplexed device is designed with a central sample deposition zone and three identical arms, each containing a pre-treatment and test zone. Its one-step fabrication is realized by CO2 laser cutting, providing remarkable parallelization and rapidity (ca. 5 s/device). The colorimetric detection is based on the sensitive and selective target-induced reshaping of plasmonic multibranched gold nanoparticles, which exhibit a clear spectral shift (and blue-to-pink color change) in case of non-physiological concentrations of the three salivary biomarkers. A rapid and multiplexed naked-eye or smartphone-based readout of the colorimetric response is achieved within 10 min. A prototype kit for POCT testing is also reported, providing robustness and easy handling of the device.

Printed sensor labels for colorimetric detection of ammonia, formaldehyde and hydrogen sulfide from the ambient air

2021 ◽  
Vol 330 ◽  
pp. 129281
Author(s):  
Laura Engel ◽  
Ismael Benito-Altamirano ◽  
Karina R. Tarantik ◽  
Carolin Pannek ◽  
Martin Dold ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Colorimetric Detection ◽  
Ambient Air

Colorimetric Detection of Cr3+ in Aqueous Solution Based on Cofunctionalized Silver Nanoparticles Modified with 4-Nitrobenzenethiol and 4-Mercaptobenzoic Acid

NANO ◽  
2015 ◽  
Vol 10 (07) ◽  
pp. 1550095 ◽  
Author(s):  
Zhikun Zhang ◽  
Ying Zhou ◽  
Jing-Kui Yang ◽  
Peilong Wang ◽  
Xiaoou Su ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Color Change ◽  
Colorimetric Detection ◽  
Ligand Interaction ◽  
Bright Yellow ◽  
Colorimetric Response ◽  
Icp Ms ◽  
Highly Sensitive ◽  
Highly Sensitive Detection ◽  
Good Agreement

A new method has been proposed to realize the visual detection of Cr 3+ using 4-nitrobenzenethiol (4-NBT) and 4-mercaptobenzoic acid (4-MBA) modified silver nanoparticles ( AgNPs ). The presence of Cr 3+ induces the aggregation of AgNPs through cooperative metal–ligand interaction, resulting in a color change from bright yellow to purple. Consequently, Cr 3+ could be monitored by colorimetric response of AgNPs by a UV-Vis spectrophotometer or even naked eyes. We firstly used ethylene diamine tetraacetic acid (EDTA) as a masking agent to selectively detect Cr 3+, and other metal ions have little influence on the Cr 3+– AgNPs system. The cofunctionalized AgNPs exhibited a highly sensitive detection limit of Cr 3+, which is as low as 5 × 10-9 mol L-1, and the absorbance ratio (A600nm/A387nm) is linear with the concentration of Cr 3+ ranging from 5 × 10-9 mol L-1 to 2 × 10-6 mol L-1 with a coefficient of 0.993. Particularly, the sensor has been further evaluated to monitor the concentration of Cr 3+ in drinking water, the recovery was in good agreement with those obtained by ICP-MS, indicating that this proposed method is successfully applied in real samples.

scholarly journals Functionalized Silver Nano-Sensor for Colorimetric Detection of Hg2+ Ions: Facile Synthesis and Docking Studies

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2698 ◽  
Author(s):  
Kollur Shiva Prasad ◽  
Govindaraju Shruthi ◽  
Chandan Shivamallu
Keyword(s):  
Silver Nanoparticles ◽  
Color Change ◽  
Colorimetric Detection ◽  
Docking Studies ◽  
Facile Synthesis ◽  
Colorimetric Response ◽  
Yellow Color ◽  
Deep Yellow ◽  
Uv Visible ◽  
Average Size

In the present study, we describe the facile synthesis of silver nanoparticles (AgNPs) and their nanostructures functionalized with 2-aminopyrimidine-4,6-diol (APD-AgNPs) for Hg2+ ion detection. The promising colorimetric response of APD-AgNPs to detect Hg2+ ions was visible with naked eyes and spectroscopic changes were examined by using a UV-Visible spectrophotometer. The aggregation of APD-AgNPs upon addition of Hg2+ ions was due to the chelation effect of the functionalized nanostructures and results in a color change from pale brown to deep yellow color. The probing sensitivity was observed within five minutes with a detection limit of about 0.35 µM/L. The TEM images of APD-AgNPs showed polydispersed morphologies with hexagonal, heptagonal and spherical nanostructures with an average size between 10 to 40 nm. Furthermore, the sensing behavior of APD-AgNPs towards Hg2+ ions detection was investigated using docking and interaction studies.

scholarly journals Essential properties and pitfalls of colorimetric Reverse Transcription Loop-mediated Isothermal Amplification as a point-of-care test for SARS-CoV-2 diagnosis

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Bruna de Oliveira Coelho ◽  
Heloisa Bruna Soligo Sanchuki ◽  
Dalila Luciola Zanette ◽  
Jeanine Marie Nardin ◽  
Hugo Manuel Paz Morales ◽  
...  
Keyword(s):  
Viral Load ◽  
Internal Control ◽  
Reverse Transcription ◽  
Color Change ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
False Negative ◽  
Isothermal Amplification ◽  
Clinical Samples ◽  
Loop Mediated Isothermal Amplification

Abstract Background SARS-CoV-2 Reverse Transcription Loop-mediated Isothermal Amplification (RT-LAMP) colorimetric detection is a sensitive and specific point-of-care molecular biology technique used to detect the virus in only 30 min. In this manuscript we have described a few nuances of the technique still not properly described in the literature: the presence of three colors clusters; the correlation of the viral load with the color change; and the importance of using an internal control to avoid false-negative results. Methods To achieve these findings, we performed colorimetric RT-LAMP assays of 466 SARS-CoV-2 RT-qPCR validated clinical samples, with color quantification measured at 434 nm and 560 nm. Results First we determinate a sensitivity of 93.8% and specificity of 90.4%. In addition to the pink (negative) and yellow (positive) produced colors, we report for the first time the presence of an orange color cluster that may lead to wrong diagnosis. We also demonstrated using RT-qPCR and RT-LAMP that low viral loads are related to Ct values > 30, resulting in orange colors. We also demonstrated that the diagnosis of COVID-19 by colorimetric RT-LAMP is efficient until the fifth symptoms day when the viral load is still relatively high. Conclusion This study reports properties and indications for colorimetric RT-LAMP as point-of-care for SARS-CoV-2 diagnostic, reducing false results, interpretations and optimizing molecular diagnostics tests application.

scholarly journals Microstructure and long-term stability of solder joints on nickel-plated aluminium formed during short soldering times

RSC Advances ◽  
2020 ◽  
Vol 10 (66) ◽  
pp. 40215-40224
Author(s):  
Angela De Rose ◽  
Gabriele Mikolasch ◽  
Mathias Kamp ◽  
Achim Kraft ◽  
Mathias Nowottnick
Keyword(s):  
Solder Joints ◽  
Ambient Air ◽  
Mechanical Reliability ◽  
Term Stability ◽  
Long Term Stability

High mechanical reliability of tin-based solder joints processed by joining copper and nickel-coated aluminium with short soldering times in ambient air.

Selective Colorimetric Detection of Hydrogen Sulfide Based on Primary Amine-Active Ester Cross-Linking of Gold Nanoparticles

2015 ◽  
Vol 87 (14) ◽  
pp. 7267-7273 ◽  
Author(s):  
Zhiqin Yuan ◽  
Fengniu Lu ◽  
Meihua Peng ◽  
Chia-Wei Wang ◽  
Yu-Ting Tseng ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Hydrogen Sulfide ◽  
Primary Amine ◽  
Colorimetric Detection ◽  
Cross Linking ◽  
Active Ester

scholarly journals Molecular Diagnostic of Ochratoxin A with Specific Aptamers in Corn and Groundnut via Fabrication of A Microfluidic Device

2021 ◽  
Author(s):  
Deepshikha Shahdeo ◽  
Azmat Ali Khan ◽  
Amer M Alanazi ◽  
Yun Suk Huh ◽  
Shruti Shukla ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Limit Of Detection ◽  
Colorimetric Assay ◽  
Animal Health ◽  
Colorimetric Detection ◽  
Molecular Diagnostic ◽  
Detection Range ◽  
Vis Spectroscopy ◽  
Wide Range ◽  
Analytical Device

Abstract Ochratoxin A (OTA) is one of the predominant mycotoxins that contaminate a wide range of food commodities. In the present study, a 36-mer aptamer was used as a molecular recognition element coupled with gold nanoparticles (AuNPs) for colorimetric detection of OTA in a microfluidic paper-based analytical device (µPADs). The µPADs consisted of three zones: control, detection, and sample, interconnected by channels. The biophysical characterizations of aptamer conjugated AuNPs were done by UV-vis spectroscopy (UV-vis), dynamic Light Scattering (DLS), and transmission electron microscopy (TEM). The developed colorimetric assay for OTA showed a limit of detection of 242, 545, and 95.69 ng/mL in water, corn, and groundnut, respectively. The HPLC detection method achieved acceptable coefficient in standard curves (r2 = 0.9995), better detection range, and recovery rates in spiked corn and groundnut samples as 43.61 ± 2.18% to 87.10 ± 1.82% and 42.01 ± 1.31% to 86.03 ± 2.64% after multiple sample extractions and cleanup steps. However, the developed µPADs analytical device had the potent ability to rapidly detect OTA without any extraction pre-requirement, derivatization, and cleanup steps, thus illustrating its feasibility in the animal health sector, agricultural, and food industries.

scholarly journals Direct Colorimetric Detection of Virus by a Polymerized Bilayer Assembly

1993 ◽  
Vol 330 ◽  
Author(s):  
Deborah H. Charych ◽  
Jon O. Nagy ◽  
Wayne Spevak ◽  
Joel Ager ◽  
Mark D. Bednarski
Keyword(s):  
Color Change ◽  
Colorimetric Detection ◽  
Self Assembled Monolayer ◽  
Visible Absorption ◽  
Polymer Backbone ◽  
Color Transition ◽  
Recognition Element ◽  
Ligand Interactions ◽  
Molecular Recognition Element ◽  
Bilayer Assembly

ABSTRACTScreening and detecting virus by receptor-ligand interactions presents an important challenge in medical and environmental diagnostics, and in drug development. We have developed a direct colorimetric detection method based on a polymeric bilayer assembly. The bilayer is composed of a self-assembled monolayer of octadecyl siloxane and a Langmuir-Blodgett layer of polydiacetylene. The polydiacetylene layer is functionalized with receptor-specific ligands such as analogs of sialic acid. The ligand serves as a molecular recognition element, while the conjugated polymer backbone signals binding at the surface by a chromatic transition. The color transition is readily visible to the naked eye as a blue to red color change and can be quantified by visible absorption spectroscopy. The color transition can be inhibited by the presence of soluble inhibitors. Raman spectroscopic analysis shows that the color transition may arise from binding induced strain on the material resulting in bond elongation and conjugation length reduction.

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