scholarly journals Competitive HRP-Linked Colorimetric Aptasensor for the Detection of Fumonisin B1 in Food based on Dual Biotin-Streptavidin Interaction

Biosensors ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 31 ◽  
Author(s):  
Zui Tao ◽  
You Zhou ◽  
Xiang Li ◽  
Zhouping Wang
Keyword(s):  
Reliable Method ◽  
Visual Detection ◽  
Color Change ◽  
Colorimetric Assay ◽  
Fusarium Species ◽  
Fumonisin B1 ◽  
Food Samples ◽  
Optimal Conditions ◽  
Complementary Strand ◽  
Streptavidin Binding

Fumonisin B1 (FB1) is the most prevalent and toxic form among fumonisin homologues which are produced by fusarium species and it contaminates various types of food products, posing serious health hazards for humans and animals. In this work, a colorimetric assay for the detection of FB1 has been developed based on competitive horseradish peroxidase (HRP)-linked aptamer and dual biotin-streptavidin interaction. In short, a biotinylated aptamer of FB1 was immobilized on the microplate by biotin-streptavidin binding; the complementary strand (csDNA) of the aptamer was ligated with HRP by biotin-streptavidin binding again to form a csDNA-HRP sensing probe, competing with FB1 to bind to the aptamer. The color change can be observed after the addition of chromogenic and stop solution, thereby realizing the visual detection of FB1. Under optimal conditions, good linearity was observed within the concentration range of 0.5 to 300 ng/mL, with a detection of limit of 0.3 ng/mL. This assay is further validated by spike recovery tests towards beer and corn samples, it provides a simple, sensitive and reliable method for the screening of FB1 in food samples and may be potentially used as an alternative to conventional assays.

scholarly journals Bioactive Paper Sensor Based on the Acetylcholinesterase for the Rapid Detection of Organophosphate and Carbamate Pesticides

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Mohamed E. I. Badawy ◽  
Ahmed F. El-Aswad
Keyword(s):  
Color Change ◽  
Response Times ◽  
Colorimetric Assay ◽  
Food Samples ◽  
Carbamate Pesticides ◽  
Ache Inhibitors ◽  
Yellow Color ◽  
Bioactive Paper ◽  
Acetylthiocholine Iodide ◽  
Food And Feed

In many countries, people are becoming more concerned about pesticide residues which are present in or on food and feed products. For this reason, several methods have been developed to monitor the pesticide residue levels in food samples. In this study, a bioactive paper-based sensor was developed for detection of acetylcholinesterase (AChE) inhibitors including organophosphate and carbamate pesticides. Based on the Ellman colorimetric assay, the assay strip is composed of a paper support (1×10 cm), onto which a biopolymer chitosan gel immobilized in crosslinking by glutaraldehyde with AChE and 5,5′-dithiobis(2-nitrobenzoic) acid (DTNB) and uses acetylthiocholine iodide (ATChI) as an outside reagent. The assay protocol involves introducing the sample to sensing zone via dipping of a pesticide-containing solution. Following an incubation period, the paper is placed into ATChI solution to initiate enzyme catalyzed hydrolysis of the substrate, causing a yellow color change. The absence or decrease of the yellow color indicates the levels of the AChE inhibitors. The biosensor is able to detect organophosphate and carbamate pesticides with good detection limits (methomyl=6.16×10-4 mM andprofenofos=0.27 mM) and rapid response times (~5 min). The results show that the paper-based biosensor is rapid, sensitive, inexpensive, portable, disposable, and easy-to-use.

Au@Ag Core/Shell Nanorods Based Colorimetric Assay for the Rapid and Selective Detection of Cyanide Anions

2019 ◽  
Vol 11 (12) ◽  
pp. 1739-1744
Author(s):  
Rui-Ling Zhang ◽  
Shi-Liang Jia ◽  
Kai-Ming Wang
Keyword(s):  
High Selectivity ◽  
Color Change ◽  
Colorimetric Assay ◽  
Water Solution ◽  
Blue Shift ◽  
Core Shell ◽  
Optimal Conditions ◽  
Sample Analysis ◽  
Aspect Ratios ◽  
Naked Eye Detection

A colorimetric assay based on Au@Ag core/shell nanorods was developed to rapidly determine cyanide in aqueous solution. The aspect ratios of Au@Ag core/shell nanorods were changed with the dissolution of metals in cyanide solution, which led to the decrease of Ag shell absorption spectra and the blue shift of longitudinal plasmon absorption band of Au core, as well as the color change of Au@Ag core/shell nanorods. In contrast to spherical Au@Ag nanoparticles with less sample analysis time (1 min per sample), the distinguish ability of this assay was proven to be higher. Under optimal conditions, the developed colorimetric assay gave a linear range of 1–200 μM for cyanide in water solution and a naked-eye detection limit of 0.5 μM. On the side, the colorimetric assay exhibited high selectivity towards cyanide over other common anions. The developed Au@Ag nanorods probes have been successfully applied to determine the level of cyanide in local lake, river and industrial water samples.

The Need for Using An Enzymatic Colorimetric Assay in Creatinine Determination of Peritoneal Dialysis Solutions

1990 ◽  
Vol 10 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Liliane Larpent ◽  
Christian Verger
Keyword(s):  
Peritoneal Dialysis ◽  
Reliable Method ◽  
Colorimetric Assay ◽  
Colorimetric Method ◽  
Peritoneal Membrane ◽  
Creatinine Kinetics ◽  
Dialysis Solutions ◽  
Peritoneal Dialysis Solutions ◽  
Enzymatic Test

The fate of the peritoneal membrane on continuous ambulatory peritoneal dialysis (CAPD) is usually evaluated through the modification of its permeability to various solutes as glucose, creatinine, and urea. Therefore, the accuracy of the methods used for measurements of creatinine is of great importance. A particular problem does exist for creatinine determination as it may be influenced by the presence of glucose. We studied a new enzymatic colorimetric method for creatinine determination in peritoneal dialysis solutions which contain high dextrose concentrations. Creatinine was measured in plasma, urine, and dialysate from 18 patients on CAPD and in pure dextrose solutions, with an enzymatic test (Boehringer Mannheim) and with Jaffe's reaction on two different analyzers: Astra (Beckman) and Eris (Merck). Creatinine results were similar with both assays (Jaffe's reaction and enzymatic test) when measured in blood and urine. However the Jaffe's reaction gave higher creatinine results than the enzymatic test (p < 0.001), when assays were performed in peritoneal dialysis solutions and in pure glucose solutions. In addition, it appeared that other components of dialysis solutions, mainly calcium chloride, influenced unpredictably the results of creatinine with the Jaffe's reaction. We conclude that specific enzymatic test is a more accurate and reliable method to evaluate creatinine kinetics through the peritoneal membrane when determined in CAPD solutions.

Visual detection of carbonate ions by inverse opal photonic crystal polymers in aqueous solution

2015 ◽  
Vol 3 (37) ◽  
pp. 9524-9527 ◽  
Author(s):  
Lu Li ◽  
Bin Zhao ◽  
Yue Long ◽  
Jin-Ming Gao ◽  
Guoqiang Yang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photonic Crystal ◽  
Polymer Films ◽  
Visual Detection ◽  
Color Change ◽  
Ph Dependence ◽  
Inverse Opal ◽  
Carbonate Ions ◽  
Crystal Polymer

This communication demonstrates a facile method to detect CO32− by naked eyes through color change based on the pH dependence of inverse opal photonic crystal polymer films.

An ultra-sensitive colorimetric assay for reliable visual detection of telomerase activity

The Analyst ◽  
2017 ◽  
Vol 142 (17) ◽  
pp. 3235-3240 ◽  
Author(s):  
Yaocai Wang ◽  
Luzhu Yang ◽  
Yanjun Wang ◽  
Wei Liu ◽  
Baoxin Li ◽  
...  
Keyword(s):  
Hela Cell ◽  
Visual Detection ◽  
Colorimetric Assay ◽  
Telomerase Activity ◽  
Cell Lysates ◽  
Naked Eye ◽  
Vis Spectroscopy

We proposed a sensitive colorimetric assay for detecting telomerase activity. The telomerase activity of 5 and 20 HeLa cell lysates can be detected via UV-vis spectroscopy and the naked eye, respectively.

scholarly journals A Novel Design Combining Isothermal Exponential Amplification and Gold-Nanoparticles Visualization for Rapid Detection of miRNAs

2018 ◽  
Vol 19 (11) ◽  
pp. 3374 ◽  
Author(s):  
Jiquan Jiang ◽  
Bin Zhang ◽  
Chi Zhang ◽  
Yifu Guan
Keyword(s):  
Early Phase ◽  
Color Change ◽  
Direct Detection ◽  
Colorimetric Assay ◽  
Disease Diagnosis ◽  
Dna Probes ◽  
Time Saving ◽  
Promising Alternative ◽  
Sandwich Hybridization ◽  
Wide Range

MicroRNAs (miRNAs) play important roles in a wide range of biological processes, and their aberrant expressions are associated with various diseases. The levels of miRNAs can be useful biomarkers for cellular events or disease diagnosis; thus, sensitive and selective detection of microRNAs is of great significance in understanding biological functions of miRNAs, early-phase diagnosis of cancers, and discovery of new targets for drugs. However, traditional approaches for the detection of miRNAs are usually laborious and time-consuming, with a low sensitivity. Here, we develop a simple, rapid, ultrasensitive colorimetric assay based on the combination of isothermal Exponential Amplification Reaction (EXPAR) and AuNP-labeled DNA probes for the detection of miRNAs (taking let-7a as a model analyte). In this assay, the presence of let-7a is converted to the reporter Y through EXPAR under isothermal conditions. The subsequent sandwich hybridization of the reporter Y with the AuNP-labeled DNA probes generates a red-to-purple color change. In other words, if the reporter Y is complementary to the AuNP-labeled DNA probes, the DNA-functionalized AuNPs will be aggregated, resulting in the change of solution color from red to purple/blue, while when the AuNP-labeled DNA probes are mismatched to the reporter Y, the solution remains red. This assay represents a simple, time-saving technique, and its results can be visually detected with the naked eye due to the colorimetric change. The method provides superior sensitivity, with a detection limit of 4.176 aM over a wide range from 1 nM to 1 aM under optimal conditions. The method also shows high selectivity for discriminating even single-nucleotide differences between let-7 miRNA family members. Notably, it is comparable to the most sensitive method reported to date, thus providing a promising alternative to standard approaches for the direct detection of let-7a miRNA. Importantly, through combination with specific templates, different miRNAs can be converted to the same reporter Y, which can hybridize with the same set of AuNP-labeled DNA probes to form sandwich hybrids. The color change of the solution can be observed in the presence of the target miRNA. This technique has potential as a routine method for assessing the levels of miRNAs, not only for let-7, but also for various miRNAs in the early phase of cancers. In addition, it can be a useful tool in biomedical research and clinical diagnosis, as well as diagnosis or surveillance programs in field conditions.

scholarly journals Fabrication of a Malaria-Ab ELISA Bioassay Platform with Utilization of Syringe-Based and 3D Printed Assay Automation

Micromachines ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 502 ◽  
Author(s):  
Christopher Lim ◽  
Yangchung Lee ◽  
Lawrence Kulinsky
Keyword(s):  
Fused Deposition Modeling ◽  
Color Change ◽  
Colorimetric Assay ◽  
Smart Phone ◽  
Automated System ◽  
Fused Deposition ◽  
Colorimetric Test ◽  
Qualitative Detection ◽  
Deposition Modeling ◽  
Automated Platform

We report on the fabrication of a syringe-based platform for automation of a colorimetric malaria-Ab assay. We assembled this platform from inexpensive disposable plastic syringes, plastic tubing, easily-obtainable servomotors, and an Arduino microcontroller chip, which allowed for system automation. The automated system can also be fabricated using stereolithography (SLA) to print elastomeric reservoirs (used instead of syringes), while platform framework, including rack and gears, can be printed with fused deposition modeling (FDM). We report on the optimization of FDM and SLA print parameters, as well as post-production processes. A malaria-Ab colorimetric test was successfully run on the automated platform, with most of the assay reagents dispensed from syringes. Wash solution was dispensed from an SLA-printed elastomeric reservoir to demonstrate the feasibility of both syringe and elastomeric reservoir-based approaches. We tested the platform using a commercially available malaria-Ab colorimetric assay originally designed for spectroscopic plate readers. Unaided visual inspection of the assay solution color change was sufficient for qualitative detection of positive and negative samples. A smart phone application can also be used for quantitative measurement of the assay color change.

scholarly journals Fumonisin B1 Production by Fusarium Species and Mycotoxigenic Effect on Larval Zebrafish

2020 ◽  
Vol 31 (3) ◽  
pp. 91-107 ◽  
Author(s):  
Najihah Azman ◽  
Nur Ain Izzati Mohd Zainudin ◽  
Wan Norhamidah Wan Ibrahim
Keyword(s):  
Liquid Chromatography ◽  
Danio Rerio ◽  
Morphological Changes ◽  
Fusarium Species ◽  
Fumonisin B1 ◽  
Larval Zebrafish ◽  
Zebrafish Larvae ◽  
Significant Difference ◽  
Successful Amplification ◽  
Fast Liquid Chromatography

Fumonisin B1 (FB1) is a common mycotoxin produced by Fusarium species particularly F. proliferatum and F. verticillioides. The toxin produced can cause adverse effects on humans and animals. The objectives of this study were to detect the production of FB1 based on the amplification of FUM1 gene, to quantify FB1 produced by the isolates using Ultra-fast Liquid Chromatography (UFLC) analysis, to examine the embryotoxicity effect of FB1 and to determine EC50 toward the larvae of zebrafish (Danio rerio). Fifty isolates of Fusarium species were isolated from different hosts throughout Malaysia. Successful amplification of the FUM1 gene showed the presence of this gene (800 bp) in the genome of 48 out of 50 isolates. The highest level of FB1 produced by F. proliferatum isolate B2433 was 6677.32 ppm meanwhile F. verticillioides isolate J1363 was 954.01 ppm. From the assessment of embryotoxicity test of FB1 on larvae of zebrafish, five concentrations of FB1 (0.43 ppm, 0.58 ppm, 0.72 ppm, 0.87 ppm and 1.00 ppm) were tested. Morphological changes of the FB1 exposed-larvae were observed at 24 to 168 hpf. The mortality rate and abnormality of zebrafish larvae were significantly increased at 144 hpf exposure. Meanwhile, the spontaneous tail coiling showed a significant difference. There were no significant differences in the heartbeat rate. As a conclusion, the presence of FUM1 in every isolate can be detected by FUM1 gene analysis and both of the species produced different concentrations of FB1. This is the first report of FB1 produced by Fusarium species gave a significant effect on zebrafish development.

scholarly journals Gamma Ray-Induced Synthesis of Silver Nanoparticles using Bacterial Cellulose as a Multi-Functional Agent and its Application

2021 ◽  
Author(s):  
Nasser H. Mohammad ◽  
gamal Mohamed elsherbiny ◽  
Ali A. Hammad ◽  
Ahmed A. Askar ◽  
Salwa A. Abou El Nour
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Cellulose ◽  
Food Packaging ◽  
Gamma Ray ◽  
Color Change ◽  
Spherical Shape ◽  
Inhibition Zone ◽  
Food Samples ◽  
One Step ◽  
Novel Method

Abstract Antibacterial coatings based on bacterial cellulose (BC) have been widely used in many fields including food packaging and wound dressing. In this study, we aimed to synthesis of colloidal AgNPs and BC/ AgNP composite by using BC as a reducing and capping agent in one step reaction induced by gamma-ray. Bacterial strain Komagataeibacter rhaeticus N1 MW322708 was used for biosynthesis BC by inoculation on Hestrin and Schramm medium and incubated statically at 35 °C for 10 days. BC sheet was formed, harvested, purified, and dried, then used for the synthesis of AgNPs and BC/AgNP by soaked 0.05 g of dried BC in 10ml of 1mM aqueous AgNO3 solution for 2h and then irradiated by gamma-ray under different doses. Color change from yellow to deep brown indicated the synthesis of AgNPs and BC/AgNP. The optical spectra of synthesized AgNPs revealed that the surface plasmon resonance was localized around 420 nm. DLS analysis showed that the mean diameter of AgNPs was 49.5 nm with a -19.36-mV value of zeta potential. TEM images revealed the spherical shape of synthesized AgNPs. The results of FESEM, FTIR, and XRD confirmed the formation of BC/AgNO3 composite. The highly crystalline nature of the BC membrane and BC/AgNP composite was observed in XRD measurements with a crystal size of 5.416 and 5.409 nm, respectively. The antibacterial activity of BC and BC/AgNP against pathogenic bacterial isolated from Pastirma food samples revealed that BC does not show antibacterial activity, while BC/AgNP composite showed antibacterial potency against Staphylococcus aureus, Enterococcus faecalis, Listeria monocytogenes, Proteus mirabilis, and Escherichia coli, with an inhibition zone of (mm) 9±1, 9±0.57, 10±1.15, 8±0.5 and 7±0.28, respectively. We concluded that this novel method presented in this paper offers a promising route for both AgNPs and BC/AgNP composites synthesis using a green, renewable biopolymer as a multifunctional agent and potential to be applied in the future development of food packing, biomedical instruments, and therapeutics.

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