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.

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.

Phage as a molecular recognition element in biosensors immobilized by physical adsorption

2007 ◽  
Vol 22 (6) ◽  
pp. 986-992 ◽  
Author(s):  
Viswaprakash Nanduri ◽  
Iryna B. Sorokulova ◽  
Alexandre M. Samoylov ◽  
Aleksandr L. Simonian ◽  
Valery A. Petrenko ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Physical Adsorption ◽  
Recognition Element ◽  
Molecular Recognition Element

Specific Immobilization of Streptavidin on Mixed Self-Assembled Monolayers as Mixing Ratio

2007 ◽  
Vol 121-123 ◽  
pp. 495-498 ◽  
Author(s):  
Jun Hyung Park ◽  
Buyng Su Park ◽  
Gu Huh ◽  
Seung Hyun Lee ◽  
Hyun Sook Lee ◽  
...  
Keyword(s):  
Colorimetric Detection ◽  
Gold Surface ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Local Domain ◽  
Mixing Ratio ◽  
Tunneling Microscopy ◽  
Self Assembled Monolayer ◽  
Assembled Monolayers ◽  
Self Assembled

We report on the distribution of mixed self-assembled monolayers (SAMs) composed of biotinylated and diluent alkylthiolates for streptavidin immobilization. Two thiol derivatives, 11-mercapto-1-undecanol (MUOH) and 11-mercaptoundecanoic-(8-biotinylamido-3,6-dioxaoctyl) amide (MBDA), were employed for mixed SAM. These thiols formed self-assembled monolayer without local domain, and streptavidins were immobilized onto biotinylated gold surface without nonspecific binding. In order to find the optimized condition of immobilization of streptavidin, we controlled the mixing ratio of two kind thiols by colorimetric detection assay, and the immobilization was characterized by atomic force microscopy (AFM), scanning tunneling microscopy (STM), and ellipsometer.

Colorimetric H2O2 Detection Using Ag-Nanoparticle-Decorated Silica Microspheres

NANO ◽  
2020 ◽  
Vol 15 (01) ◽  
pp. 2050009 ◽  
Author(s):  
Zhikun Zhang ◽  
Qingqing Liu ◽  
Yumin Liu ◽  
Ran Qi ◽  
Lilong Zhou ◽  
...  
Keyword(s):  
Color Change ◽  
Colorimetric Detection ◽  
Hydroxyl Groups ◽  
Ag Nanoparticle ◽  
Silica Microspheres ◽  
Ag Nps ◽  
Practical Applications ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
H2o2 Detection

In view of the importance of convenient and rapid H2O2 detection for biological analysis, we herein propose Ag nanoparticle (NP)-decorated silica microspheres as a probe for instant and non-enzymatic on-site colorimetric detection of H2O2. The surface hydroxyl groups of silica microspheres were reacted with (3-mercaptopropyl)trimethoxysilane to afford thiolated microspheres that subsequently bind Ag NPs. The oxidation of residual –SH groups on the silica surface to –S–S– moieties in the presence of H2O2 induces the aggregation of decorated microspheres and is accompanied by a color change. Sensor response is found to be proportional to H2O2 concentration in the range from 100[Formula: see text]nM to 1[Formula: see text]mM, with UV–Vis and colorimetric detection limits determined as 10[Formula: see text][Formula: see text]M and 10[Formula: see text][Formula: see text]M, respectively. The developed platform is successfully used to detect H2O2 in simulated human urine and is, therefore, concluded to be sufficiently stable and selective for practical applications.

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.

Preparation of porphyrin modified CO9S8 nanocomposites and application for colorimetric biosensing of H2O2

2018 ◽  
Vol 22 (09n10) ◽  
pp. 935-943 ◽  
Author(s):  
Yan Gao ◽  
Chunqiao Jin ◽  
Miaomiao Chen ◽  
Xixi Zhu ◽  
Min Fu ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Peroxidase Activity ◽  
Catalytic Mechanism ◽  
Color Change ◽  
Colorimetric Detection ◽  
Buffer Solution ◽  
Hydrogen Peroxide Detection ◽  
Steady State Kinetics ◽  
One Step

Hydrogen peroxide detection has been widely applied in the fields of biology, medicine, and chemistry. Colorimetric detection of hydrogen peroxide has proven to be a fast and convenient method. In this work, 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin modified Co[Formula: see text]S[Formula: see text] nanocomposites (H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] were prepared via a facile one-step hydrothermal method. H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] nanocomposites were demonstrated to possess an enhanced mimetic peroxidase activity toward the substrate, 3,3[Formula: see text],5,5[Formula: see text]-tetramethylbenzidine (TMB), which can be oxidized to oxTMB (oxidized TMB) in a buffer solution of hydrogen peroxide with a color change from colorless to blue. The catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] was further analyzed by steady-state kinetics, and H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] had high affinity towards both TMB and H[Formula: see text]O[Formula: see text]. Furthermore, fluorescence and ESR data revealed that the catalytic mechanism of the peroxidase activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text] is due to hydroxyl radicals generated from decomposition of H[Formula: see text]O[Formula: see text]. Based on the catalytic activity of H[Formula: see text]TClPP-Co[Formula: see text]S[Formula: see text], a sensitive colorimetric sensor of H[Formula: see text]O[Formula: see text] with a detection limit of 6.803 [Formula: see text]M as well as a range of 7–100 [Formula: see text]M was designed.

Preparation of Poly(Acrylic Acid) Crosslinked-Gold Nanoparticles for Colorimetric Detection of Analytes

2019 ◽  
Vol 950 ◽  
pp. 138-143
Author(s):  
Erindyah Retno Wikantyasning ◽  
Mutmainnah Mutmainnah ◽  
Ghiyats Ramadhan ◽  
Zakky Cholisoh ◽  
Muhammad Da'i
Keyword(s):  
Gold Nanoparticles ◽  
Herbal Medicine ◽  
Acrylic Acid ◽  
Color Change ◽  
Colorimetric Detection ◽  
Ph Responsive ◽  
Herbal Medicine Product ◽  
Responsive Polymer ◽  
Medicine Product ◽  
Poly Acrylic Acid

The aims of this study are to synthesize and characterize gold nanoparticles (AuNPs) crosslinked by pH-responsive polymer poly (acrylic acid) (PAA) and its application for detection of some analytes in herbal medicine product. In this study, a pH-responsive polymer, poly (acrylic acid) was prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization method. The polymer was then cross-linked by gold nanoparticles, which was synthesized by the Turkevich method. The response of the AuNPs-crosslinked PAA was observed by the color change from red to blue at a specific pH (4-5) and was characterized by TEM. The reversible color change was resulted from aggregation and disaggregation of the AuNPs due to the shrinking and swelling of the polymer when different pH was introduced as a stimulant. This sensor has the capability of recognizing analytes such as aspirin and tolbutamide added in the herbal medicine product at the concentration of 0.04-0.05 M.

scholarly journals Facile and One Pot Synthesis of Gold Nanoparticles Using Tetraphenylborate and Polyvinylpyrrolidone for Selective Colorimetric Detection of Mercury Ions in Aqueous Medium

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Sidhureddy Boopathi ◽  
Shanmugam Senthilkumar ◽  
Kanala Lakshminarasimha Phani
Keyword(s):  
Gold Nanoparticles ◽  
Alkaline Medium ◽  
Color Change ◽  
Colorimetric Detection ◽  
Spherical Shape ◽  
Reducing Agent ◽  
Nanoparticle Dispersion ◽  
Mercury Ions ◽  
One Pot ◽  
Resonance Band

In this work, we reported for the first time, a facile and one step synthesis of gold nanoparticles from HAuCl4, employing tetraphenylborate as the reducing agent. The synthesis is not only facile but also yields “dumb-bell-shaped”particles. This shape appears to arise from a possible emulsion of the products of oxidation/decomposition of tetraphenylborate by HAuCl4, surrounding the particle. The size and shape of the AuNPs were characterized by Transmission electron microscopy (TEM) and UV-visible Spectroscopy. Interestingly, the addition of polyvinylpyrrolidone (PVP) during the synthesis was found to enhance the stability of the nanoparticle dispersion. The particles synthesized under these conditions assume “spherical” shape with the appearance of only transverse surface plasmon resonance band. The highlight of the observations is that the gold nanoparticles synthesized using tetraphenylborate as reducing agent and PVP as stabilizer are highly stable in alkaline medium, in contrast to the synthesis wherein borohydride is used as reducing agent. The AuNPs synthesized using tetraphenylborate and PVP show their mercury sensing behavior only in the alkaline medium. The color of the nanoparticle dispersion undergoes distinct color change from pink to blue with the addition of mercury ions. They also show dramatic selectivity to mercury ions in presence of other interfering ions, Pb2+, Zn2+and Ca2+.

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