scholarly journals Paper-Based Vapor Detection of Formaldehyde: Colorimetric Sensing with High Sensitivity

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 335
Author(s):  
Chenglong Liao ◽  
Miao Zhang ◽  
Nan Gao ◽  
Qingyun Tian ◽  
Jiangfan Shi ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Air Quality ◽  
Color Change ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Colorimetric Sensor ◽  
Thymol Blue ◽  
Vapor Concentration ◽  
Ph Indicators ◽  
Quality Threshold

We report on a novel colorimetric sensor system for highly sensitive detection of formaldehyde (FA) in the gas phase. The sensor is constructed with paper towel as a substrate coated with the sulfuric acid salt of hydroxylamine ((NH2OH)2·H2SO4) together with two pH indicators, bromophenol blue and thymol blue. Upon exposure to FA, the hydroxylamine will react with the absorbed FA to form a Schiff base (H2C=N-OH), thus releasing a stoichiometric amount of sulfuric acid, which in turn induces a color change of the pH indicator. Such a color change was significantly enriched by incorporating two pH indicators in the system. With the optimized molar ratio of the two pH indicators, the color change (from brown to yellow, and to red) could become so dramatic as to be visible to the eye depending on the concentration of FA. In particular, under 80 ppb of FA (the air quality threshold set by WHO) the color of the sensor substrate changes from brown to yellow, which can even be envisioned clearly by the naked eyes. By using a color reader, the observed color change can be measured quantitatively as a function of the vapor concentration of FA, which produces a linear relationship as fitted with the data points. This helps estimate the limit of detection (LOD), to be 10 ppb under an exposure time of 10 min, which is much lower than the air quality threshold set by WHO. The reported sensor also demonstrates high selectivity towards FA with no color change observed when exposed to other common chemicals, including solvents and volatile organic compounds. With its high sensitivity and selectivity, the proposed paper-based colorimetric sensor thus developed can potentially be employed as a low-cost and disposable detection kit that may find broad application in detecting FA in indoor air and many other environments.

Non-enzymatic colorimetric sensor strip based on melamine-functionalized gold nanoparticles assembled on polyamide nanofiber membranes for the detection of metronidazole

2019 ◽  
Vol 11 (29) ◽  
pp. 3706-3713 ◽  
Author(s):  
Mohammed Awad Abedalwafa ◽  
Yan Li ◽  
Chunfang Ni ◽  
Gang Yang ◽  
Lu Wang
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
High Sensitivity ◽  
Colorimetric Sensor ◽  
Eye Detection ◽  
Naked Eye ◽  
Functionalized Gold Nanoparticles ◽  
Sensitivity And Selectivity ◽  
Nanofiber Membranes ◽  
Naked Eye Detection

Non-enzymatic colorimetric sensor strip for detection of metronidazole (MTZ) was designed and constructed, with high sensitivity and selectivity. Which can be used for naked-eye detection of MTZ with a visible color change from pink to purple.

scholarly journals A Naphthalimide-Benzothiazole Conjugate as Colorimetric and Fluorescent Sensor for Selective Trinitrophenol Detection

Chemosensors ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Pramod D. Jawale Patil ◽  
Rajita D. Ingle ◽  
Sopan M. Wagalgave ◽  
Rajesh S. Bhosale ◽  
Sidhanath V. Bhosale ◽  
...  
Keyword(s):  
Color Change ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Uv Light ◽  
High Sensitivity ◽  
Design And Synthesis ◽  
Bonding Interaction ◽  
Sensitivity And Selectivity ◽  
Donor Acceptor ◽  
Aromatic Nitro

Although chemical structural modification of naphthalimides is widely employed for the purpose of sensing explosives, the effects of such modification have been little explored. Herein, we report the design and synthesis of a new naphthalimide-benzothiazole conjugate (1) and its ability to sense various nitrophenols by means of its colorimetric and fluorescent characteristics. Under long-range UV light (365 nm), 1 displayed a color change of its solution from bluish to colorless only upon addition of 2,4,6-trinitrophenol (TNP). Photoluminescence spectroscopy showed quantitative fluorescence quenching by TNP of the emission peaks of 1 at 398 nm and 418 nm due to donor–acceptor electron transfer. The interaction of 1 with TNP was via a cooperative, non-covalent hydrogen-bonding interaction. Receptor 1 exhibited high sensitivity and selectivity towards TNP over various aromatic nitro analytes. The binding constant (K) and Stern–Volmer constant (Ksv) between 1 and TNP were found to be 5.332 × 10−5 M and 2.271 × 106 M−1, respectively. Furthermore, the limit of detection was calculated and found to be as low as 1.613 × 10−10 M.

scholarly journals Smartphone-Based Microfluidic Colorimetric Sensor for Gaseous Formaldehyde Determination with High Sensitivity and Selectivity

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3141 ◽  
Author(s):  
Xiao-Liang Guo ◽  
Yan Chen ◽  
Hong-Lan Jiang ◽  
Xian-Bo Qiu ◽  
Du-Li Yu
Keyword(s):  
Microfluidic Chip ◽  
Limit Of Detection ◽  
Low Cost ◽  
Sick Building Syndrome ◽  
High Sensitivity ◽  
Colorimetric Sensor ◽  
World Health ◽  
Formaldehyde Determination ◽  
Sensitivity And Selectivity ◽  
Gaseous Formaldehyde

Formaldehyde is one of the most dangerous air pollutants, which can cause sick building syndrome. Thus, it is very crucial to precisely determine formaldehyde with a low cost and simple operation. In this paper, a smartphone-based microfluidic colorimetric sensor is devised for gaseous formaldehyde determination with high sensitivity and selectivity. Specifically, a novel microfluidic chip is proposed based on the 4-aminohydrazine-5-mercapto-1,2,4-triazole (AHMT) method to determine formaldehyde; the chip consists of two reagent reservoirs, one reaction reservoir and a mixing column. In this design to prevent the fluid from flowing out while letting the gas molecule in, a hydrophobic porous poly tetra fluoroethylene (PTFE) membrane is put on the top of the reaction reservoir. Using the microfluidic chip sensor, a smartphone-based formaldehyde determination system is developed, which makes the measuring process automated and simple. As per the experiment results, the limit-of-detection (LOD) of the system is as low as 0.01 ppm, which is much lower than the maximum exposure concentration (0.08 ppm) recommended by the World Health Organization (WHO). Moreover, the sensor is hardly affected by acetaldehyde, volatile organic compounds (VOCs) or acidic-alkaline, which shows great selectivity. Finally, the performance of the proposed sensor is verified by using it for the determination of formaldehyde in a newly decorated house.

scholarly journals Colorimetric Measurement of Deltamethrin Pesticide Using a Paper Sensor Based on Aggregation of Gold Nanoparticles

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 38
Author(s):  
Jingyang Zhu ◽  
Lifeng Yin ◽  
Weiyi Zhang ◽  
Meilian Chen ◽  
Dongsheng Feng ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Color Change ◽  
High Sensitivity ◽  
Cost Effective ◽  
Colorimetric Sensor ◽  
Detection Mechanism ◽  
Colorimetric Measurement ◽  
Fruit Samples ◽  
Pyrethroid Pesticides ◽  
Paper Sensor

Deltamethrin (DEL) is one of the most commonly used pyrethroid pesticides that can cause serious harms to the ecological environment and human health. Herein, we have developed a paper-based colorimetric sensor impregnated with gold nanoparticles (AuNPs) for on-site determination of DEL pesticide. AuNPs show obvious color change on paper device with the presence of DEL. Measuring the gray intensity of the AuNPs on the reaction zone of the paper sensor allows accurate quantitative analysis. The detection mechanism of DEL on paper sensor was confirmed by UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscope (TEM). Under optimal conditions, the colorimetric sensor exhibited high sensitivity, rapid detection, and low detection limit within the values stipulated by Chinese detection standards (LOD = 0.584 mg/L). Besides, detecting DEL in vegetable and fruit samples also gave satisfying results, which were much consistent with those obtained by spectrophotometry. Overall, this work provided a user-friendly, cost-effective and visualized detection platform, which could be applied to rapidly detect DEL pesticides in the food safety field.

scholarly journals Highly Sensitive and Selective Colorimetric Detection of Creatinine Based on Synergistic Effect of PEG/Hg2+–AuNPs

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1424 ◽  
Author(s):  
Xia ◽  
Zhu ◽  
Bian ◽  
Li ◽  
Liu ◽  
...  
Keyword(s):  
Color Change ◽  
Limit Of Detection ◽  
Colorimetric Detection ◽  
High Sensitivity ◽  
Peak Shift ◽  
Creatinine Concentration ◽  
Highly Sensitive ◽  
Coordination Effect ◽  
Bovine Serum Sample

A colorimetric sensor, based on the synergistic coordination effect on a gold nanoparticle (AuNP) platform has been developed for the determination of creatinine. The sensor selects citrate stabilized AuNPs as a platform, polyethylene glycol (PEG) as a decorator, and Hg2+ as a linkage to form a colorimetric probe system (PEG/Hg2−–AuNPs). By forming hydrogen bond between the oxygen-containing functional groups of PEG and citrate ions on the surface of AuNPs, this probe shows good stability. PEG coordinated with Hg2+ synergistically and specifically on the surface of dispersed AuNPs, and the existence of creatinine could induce the aggregation of AuNPs with a corresponding color change and an obvious absorption peak shift within 5 min. This PEG/Hg2+–AuNPs probe towards creatinine shows high sensitivity, and a good linear relationship (R2 = 0.9948) was obtained between A620–522 nm and creatinine concentration, which can achieve the quantitative calculations of creatinine. The limit of detection (LOD) of this PEG/Hg2+–AuNPs probe was estimated to be 9.68 nM, lower than that of many other reported methods (Supplementary Materials Table S3). Importantly, the sensitive probe can be successfully applied in a urine simulating fluid sample and a bovine serum sample. The unique synergistic coordination sensing mechanism applied in the designation of this probe further improves its high selectivity and specificity for the detection of creatinine. Thus, the proposed probe may give new inspirations for colorimetric detection of creatinine and other biomolecules.

scholarly journals Cost-Effective Foam-Based Colorimetric Sensor for Roadside Testing of Alcohol in Undiluted Saliva

Chemosensors ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 334
Author(s):  
Krittapas Kaewnu ◽  
Kiattisak Promsuwan ◽  
Apichai Phonchai ◽  
Adul Thiangchanya ◽  
Dongsayam Somapa ◽  
...  
Keyword(s):  
Color Change ◽  
Limit Of Detection ◽  
Potassium Dichromate ◽  
Cost Effective ◽  
Colorimetric Sensor ◽  
Alcohol Concentration ◽  
Blood Alcohol ◽  
Spectrophotometric Detection ◽  
Significant Difference ◽  
Alcohol Sensor

A novel foam-based colorimetric alcohol sensor was developed for the detection of alcohol in saliva. Detection was based on the color change of a potassium dichromate-sulfuric acid solution absorbed by melamine foam. In the presence of alcohol, the orange colorimetric sensor changed color to brown, green and, ultimately, blue, depending on the concentration of alcohol in the sample. The response of the proposed sensor toward alcohol was linear from 0.10 to 2.5% v/v. The limit of detection was 0.03% v/v. Alcohol concentration could be determined using the naked eye in the range of 0.00 to 10% v/v. The developed alcohol sensor presented good operational accuracy (RSD = 0.30–1.90%, n = 8) and good stability for 21 days when stored at 25 °C and 75 days when stored at 4 °C. The results of alcohol detection with the developed sensor showed no significant difference from the results of spectrophotometric detection at a 95% confidence level (p > 0.05). The sensor was easy to use, small, inexpensive and portable, enabling drivers to accurately measure their own blood alcohol level and providing convenient speed in forensic applications.

Dimalononitrile-containing probe based on aggregation-enhanced emission features for the multi-mode fluorescence detection of volatile amines

2017 ◽  
Vol 196 ◽  
pp. 101-111 ◽  
Author(s):  
Lingwei Kong ◽  
Yahui Zhang ◽  
Huiling Mao ◽  
Xiaoling Pan ◽  
Yong Tian ◽  
...  
Keyword(s):  
Fluorescence Detection ◽  
Color Change ◽  
Limit Of Detection ◽  
Uv Light ◽  
Real Life ◽  
High Sensitivity ◽  
Naked Eye ◽  
Highly Sensitive ◽  
Multi Mode ◽  
Volatile Amines

A novel multi-mode probe consisting of a hexaphenyl-1,3-butadiene derivative, 2,2′-((((1Z,3Z)-1,2,3,4-tetraphenylbuta-1,3-diene-1,4-diyl)bis(4,1-phenylene))bis(methanylylidene))dimalononitrile (ZZ–HPB–CN), with typical aggregation-enhanced emission (AEE) features was easily prepared for the highly sensitive and rapid detection of amine vapors. The ZZ–HPB–CN sensor, which was prepared by simply depositing ZZ–HPB–CN on filter paper, could detect low concentration vapors of volatile amines using fluorescence, ultraviolet and naked-eye detection. The limit of detection of the sensor was as low as 1 ppb for the fluorescence detection. The color change of the sensor caused by 1–10 ppm amine vapors could be observed under UV light or with the naked eye. The high sensitivity, quick response and easy operation of the probe give it great potential for real-life applications.

Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

2018 ◽  
Vol 9 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Shubhangi J. Mane-Gavade ◽  
Sandip R. Sabale ◽  
Xiao-Ying Yu ◽  
Gurunath H. Nikam ◽  
Bhaskar V. Tamhankar
Keyword(s):  
Green Synthesis ◽  
Color Change ◽  
Limit Of Detection ◽  
Aqueous Media ◽  
Suitable Condition ◽  
Cost Effective ◽  
Spectroscopic Studies ◽  
Calibration Plot ◽  
First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

scholarly journals Ratiometric Fluorescent Biosensors for Glucose and Lactate Using an Oxygen-Sensing Membrane

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 208
Author(s):  
Hong Dinh Duong ◽  
Jong Il Rhee
Keyword(s):  
Limit Of Detection ◽  
Oxygen Sensing ◽  
High Sensitivity ◽  
Glucose Sensing ◽  
Oxidation Reactions ◽  
Lactate Oxidase ◽  
Lactate Oxidation ◽  
Detection Range ◽  
Quenching Effect ◽  
Sensing Membrane

In this study, ratiometric fluorescent glucose and lactate biosensors were developed using a ratiometric fluorescent oxygen-sensing membrane immobilized with glucose oxidase (GOD) or lactate oxidase (LOX). Herein, the ratiometric fluorescent oxygen-sensing membrane was fabricated with the ratio of two emission wavelengths of platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) doped in polystyrene particles and coumarin 6 (C6) captured into silica particles. The operation mechanism of the sensing membranes was based on (i) the fluorescence quenching effect of the PtP dye by oxygen molecules, and (ii) the consumption of oxygen levels in the glucose or lactate oxidation reactions under the catalysis of GOD or LOX. The ratiometric fluorescent glucose-sensing membrane showed high sensitivity to glucose in the range of 0.1–2 mM, with a limit of detection (LOD) of 0.031 mM, whereas the ratiometric fluorescent lactate-sensing membrane showed the linear detection range of 0.1–0.8 mM, with an LOD of 0.06 mM. These sensing membranes also showed good selectivity, fast reversibility, and stability over long-term use. They were applied to detect glucose and lactate in artificial human serum, and they provided reliable measurement results.

scholarly journals Ag nanoparticles outperform Au nanoparticles for the use as label in electrochemical point-of-care sensors

2021 ◽  
Author(s):  
Franziska Beck ◽  
Carina Horn ◽  
Antje J. Baeumner
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Automatic Measurement ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Small Sample ◽  
Blood Protein ◽  
User Friendliness ◽  
Response Curves ◽  
Assay Protocol

AbstractElectrochemical immunosensors enable rapid analyte quantification in small sample volumes, and have been demonstrated to provide high sensitivity and selectivity, simple miniaturization, and easy sensor production strategies. As a point-of-care (POC) format, user-friendliness is equally important and most often not combinable with high sensitivity. As such, we demonstrate here that a sequence of metal oxidation and reduction, followed by stripping via differential pulse voltammetry (DPV), provides lowest limits of detection within a 2-min automatic measurement. In exchanging gold nanoparticles (AuNPs), which dominate in the development of POC sensors, with silver nanoparticles (AgNPs), not only better sensitivity was obtained, but more importantly, the assay protocol could be simplified to match POC requirements. Specifically, we studied both nanoparticles as reporter labels in a sandwich immunoassay with the blood protein biomarker NT-proBNP. For both kinds of nanoparticles, the dose-response curves easily covered the ng∙mL−1 range. The mean standard deviation of all measurements of 17% (n ≥ 4) and a limit of detection of 26 ng∙mL−1 were achieved using AuNPs, but their detection requires addition of HCl, which is impossible in a POC format. In contrast, since AgNPs are electrochemically less stable, they enabled a simplified assay protocol and provided even lower LODs of 4.0 ng∙mL−1 in buffer and 4.7 ng∙mL−1 in human serum while maintaining the same or even better assay reliability, storage stability, and easy antibody immobilization protocols. Thus, in direct comparison, AgNPs clearly outperform AuNPs in desirable POC electrochemical assays and should gain much more attention in the future development of such biosensors.

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