Water-dispersible silicon dots as a peroxidase mimetic for the highly-sensitive colorimetric detection of glucose

Lactoferrin is an abundant glycoprotein in human body fluids and is known as a biomarker for various diseases. Therefore, point-of-care testing (POCT) for lactoferrin is of interest. Microfluidic paper-based analytical devices (µPADs) have gained a lot of attention as next-generation POCT device candidates, due to their inexpensiveness, operational simplicity, and being safely disposable. This work presents a colorimetric sensing approach for quantitative lactoferrin analysis. The detection mechanism takes advantage of the high affinity of lactoferrin to ferric ions (Fe3+). Lactoferrin is able to displace an indicator from a colorimetric 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-Fe3+ complex, resulting in a color change. A 5-Br-PADAP-Fe3+ complex was encapsulated into water-dispersible poly(styrene- block-vinylpyrrolidone) particles, whose physical entrapment in the cellulosic fiber network results in the immobilization of the complex to the paper matrix. The complex-encapsulating particles showed a color change response in accordance with lactoferrin concentration. Both color intensity-based paper well plates and distance readout-based µPADs are demonstrated. Color intensity-based devices allowed quantitative analysis of lactoferrin concentrations with a limit of detection of 110 µg/mL, using a smartphone and a color readout app. On the other hand, distance readout-based µPADs showed changes of the length of colored sections in accordance with lactoferrin concentration. In summary, we successfully developed both colorimetric intensity-based paper wells and distance-based µPADs for lactoferrin detection. This work demonstrates a user-friendly colorimetric analysis platform for lactoferrin without requiring lab equipment and expensive antibodies.

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

Nanomaterials ◽

10.3390/nano9101424 ◽

2019 ◽

Vol 9 (10) ◽

pp. 1424 ◽

Cited By ~ 1

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.

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

NANO ◽

10.1142/s1793292015500952 ◽

2015 ◽

Vol 10 (07) ◽

pp. 1550095 ◽

Cited By ~ 4

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.

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Highly sensitive colorimetric detection of NH3 based on Au@Ag@AgCl core-shell nanoparticles

Chinese Chemical Letters ◽

10.1016/j.cclet.2021.02.029 ◽

2021 ◽

Author(s):

Zhiwei Qiu ◽

Yitong Xue ◽

Jiyong Li ◽

Yunzhi Zhang ◽

Xinyi Liang ◽

...

Keyword(s):

Colorimetric Detection ◽

Core Shell ◽

Shell Nanoparticles ◽

Highly Sensitive ◽

Core Shell Nanoparticles

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Immobilization of Pseudomonas aeruginosa static biomass on eggshell powder for on-line preconcentration and determination of Cr (VI)

Open Chemistry ◽

10.1515/chem-2020-0031 ◽

2020 ◽

Vol 18 (1) ◽

pp. 303-313 ◽

Cited By ~ 1

Author(s):

Aamir Rasheed ◽

Tahseen Ghous ◽

Sumaira Mumtaz ◽

Muhammad Nadeem Zafar ◽

Kalsoom Akhter ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Low Cost ◽

Colorimetric Detection ◽

Time Flow ◽

Highly Sensitive ◽

Glass Column ◽

On Line ◽

Preconcentration Time ◽

Ultra Trace

AbstractIn the present work, a novel continuous flow system (CFS) is developed for the preconcentration and determination of Cr (VI) using Pseudomonas aeruginosa static biomass immobilized onto an effective and low-cost solid support of powdered eggshells. A mini glass column packed with the immobilized biosorbent is incorporated in a CFS for the preconcentration and determination of Cr (VI) from aqueous solutions. The method is based on preconcentration, washing and elution steps followed by colorimetric detection with 1,5-diphenyl carbazide in sulphuric acid. The effects of several variables such as pH, retention time, flow rate, eluent concentration and loaded volume are studied. Under optimal conditions, the CFS method has a linear range between 10 and 100 μg L-1 and a detection limit of 6.25 μg L-1 for the determination of Cr (VI). The sampling frequency is 10 samples per hour with a preconcentration time of 5 mins. Furthermore, after washing with a 0.1 M buffer (pH 3.0), the activity of the biosorbent is regenerated and remained comparable for more than 200 cycles. Scanning electron microscopy reveals a successful immobilization of biomass on eggshells powder and precipitation of Cr (VI) on the bacterial cell surface. The proposed method proves highly sensitive and could be suitable for the determination of Cr (VI) at an ultra-trace level.

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An anthracene–quinoline based dual-mode fluorometric–colorimetric sensor for the detection of Fe3+ and its application in live cell imaging

New Journal of Chemistry ◽

10.1039/d1nj00178g ◽

2021 ◽

Author(s):

Tahereh Tehrani ◽

Soraia Meghdadi ◽

Zohreh Salarvand ◽

Behnam Tavakoli ◽

Kiamars Eskandari ◽

...

Keyword(s):

Live Cell Imaging ◽

Cell Imaging ◽

Colorimetric Detection ◽

Colorimetric Sensor ◽

Live Cell ◽

Dual Mode ◽

Highly Sensitive

A highly sensitive anthracene–quinoline based dual-mode sensor has been synthesized and used for the fluorometric and colorimetric detection of Fe3+ and in live cell imaging.

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Highly sensitive and selective colorimetric detection of dual metal ions (Hg2+ and Sn2+) in water: an eco-friendly approach

RSC Advances ◽

10.1039/d0ra09926k ◽

2021 ◽

Vol 11 (24) ◽

pp. 14700-14709

Author(s):

Rintumoni Paw ◽

Moushumi Hazarika ◽

Purna K. Boruah ◽

Amlan Jyoti Kalita ◽

Ankur K. Guha ◽

...

Keyword(s):

Metal Ions ◽

Ag Nanoparticles ◽

Limit Of Detection ◽

Colorimetric Detection ◽

Garlic Extract ◽

Selective Detection ◽

Highly Sensitive ◽

Dual Metal

Synthesis of Ag nanoparticles using Allin based garlic extract for highly sensitive and selective detection of metal ions Hg2+ and Sn2+ in water. The limit of detection (LoD) for Hg2+ and Sn2+ ions were found as 15.7 nM and 11.25 nM respectively.

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

Molecular Medicine ◽

10.1186/s10020-021-00289-0 ◽

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.

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