scholarly journals An Attempt to Develop an Aptamer Lateral-Flow Assay (ALFA) for Easy, Rapid, and Sensitive Detection of Lethal Mushroom Toxin α-amanitin

2021 ◽  
Author(s):  
Qingchuan Chen ◽  
Chen Fan ◽  
Haozhe Huang ◽  
Binglin Xu ◽  
Yeqing Zong
Keyword(s):  
Test Line ◽  
Test Strip ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Detection Methods ◽  
Mushroom Poisoning ◽  
Control Line ◽  
Ph Tolerance ◽  
Higher Temperature ◽  
Target Binding

Amatoxins contribute to the majority of mushroom poisoning, most prominently, α-amanitin. Since mushroom is a common foodstuff worldwide, an easy, rapid, sensitive test for α-amanitin is needed. Several detection methods for α-amanitin have been developed, including HPLC, LC-MS, and ELISA, and LFIA. Aptamers have several advantages compared to antibodies: easy development via SELEX, longer shelf life, and higher temperature- and pH-tolerance. Aptamer Lateral Flow Assay (ALFA) is a similar technology compared to LFIA but incorporates aptamers as target-recognizing agents. This study attempted to develop an ALFA test strip for α-amanitin using a previously-developed aptamer, however failure of generating a colorimetric readout at the test line is persisted throughout all experiments, even though the concept is fully-proved and the control line functions normally. The failure is attributed to the small size of the molecule, leading to immobilization difficulties on the nitrocellulose membrane to form the test line, and the hindering of effective "surround" mechanism of aptamer-target binding (instead of "adhere", when the target molecule is large, e.g. a protein). It is concluded that ALFAs for small-molecules whose aptamer-target interaction has not yet been studied and modeled in detail remains a challenge, despite ALFAs' large potential.

scholarly journals Recombinase Polymerase Amplification (RPA) Combined with Lateral Flow Immunoassay for Rapid Detection of Salmonella in Food

Foods ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 27 ◽  
Author(s):  
Jiali Li ◽  
Biao Ma ◽  
Jiehong Fang ◽  
Antong Zhi ◽  
Erjing Chen ◽  
...  
Keyword(s):  
Test Line ◽  
Point Of Care ◽  
Limited Resource ◽  
Test Strip ◽  
Lateral Flow ◽  
Recombinase Polymerase Amplification ◽  
Lateral Flow Immunoassay ◽  
Quantitative Detection ◽  
Control Line ◽  
Test Strip Reader

Salmonella can cause serious foodborne diseases. We have developed a lateral flow immunoassay combined with recombinase polymerase amplification (LFD-RPA) for detection of Salmonella in food. The conserved fragment (fimY) was selected as the target gene. Under an optimal condition (37 °C, 10 min), the sensitivity was 12 colony-forming units (CFU)/mL in a pure culture. Testing with 16 non-Salmonella strains as controls revealed that LFD-RPA was specific to the fimY gene of Salmonella. The established assay could detect Salmonella at concentrations as low as 1.29 × 102 CFU/mL in artificially contaminated samples. This detection was at a slightly higher level than that for a pure bacterial culture. Combined with the test strip reader, the LFD-RPA is a feasible method for quantitative detection of Salmonella based on the test line intensity, which was the ratio for the test line and control line of the reflected light. The method could be a potential point-of-care test in limited resource areas and provides a new approach and technical support for the diagnosis of food safety.

scholarly journals Evaluation of LDBio Aspergillus ICT Lateral Flow Assay for IgG and IgM Antibody Detection in Chronic Pulmonary Aspergillosis

2019 ◽  
Vol 57 (9) ◽  
Author(s):  
Elizabeth Stucky Hunter ◽  
Malcolm D. Richardson ◽  
David W. Denning
Keyword(s):  
United Kingdom ◽  
Line Intensity ◽  
Test Line ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Antibody Detection ◽  
Resource Constrained ◽  
Pulmonary Aspergillosis ◽  
Chronic Pulmonary Aspergillosis ◽  
Specific Igg

ABSTRACT Detecting Aspergillus-specific IgG is critical to diagnosing chronic pulmonary aspergillosis (CPA). Existing assays are often cost- and resource-intensive and not compatible with resource-constrained laboratory settings. LDBio Diagnostics has recently commercialized a lateral flow assay based on immunochromatographic technology (ICT) that detects Aspergillus antibodies (IgG and IgM) in less than 30 min, requiring minimal laboratory equipment. A total of 154 CPA patient sera collected at the National Aspergillosis Centre (Manchester, United Kingdom) and control patient sera from the Peninsula Research Bank (Exeter, United Kingdom) were evaluated. Samples were applied to the LDBio Aspergillus ICT lateral flow assay, and results were read both visually and digitally. Results were compared with Aspergillus IgG titers in CPA patients, measured by ImmunoCAP-specific IgG assays. For proven CPA patients versus controls, sensitivity and specificity for the LDBio Aspergillus ICT were 91.6% and 98.0%, respectively. In contrast, the routinely used ImmunoCAP assay exhibited 80.5% sensitivity for the same cohort (cutoff value, 40 mg of antigen-specific antibodies [mgA]/liter). The assay is easy to perform but challenging to read when only a very faint band is present (5/154 samples tested). The ImmunoCAP Aspergillus IgG titer was also compared with the Aspergillus ICT test line intensity or rate of development, with weak to moderate correlations. The Aspergillus ICT lateral flow assay exhibits excellent sensitivity for serological diagnosis of CPA. Quantifying IgG from test line intensity measurements is not reliable. Given the short run time, simplicity, and limited resources needed, the LDBio Aspergillus ICT is a suitable diagnostic tool for CPA in resource-constrained settings.

scholarly journals A Lateral Flow Strip Based on a Truncated Aptamer-Complementary Strand for Detection of Type-B Aflatoxins in Nuts and Dried Figs

Toxins ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 136 ◽  
Author(s):  
Zhilei Zhao ◽  
He Wang ◽  
Wenlei Zhai ◽  
Xiaoyuan Feng ◽  
Xia Fan ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Cdna Probe ◽  
Test Strip ◽  
Lateral Flow ◽  
Sensitive Detection ◽  
Detection Methods ◽  
Complementary Strand ◽  
Type B ◽  
Experimental Conditions ◽  
Lateral Flow Strip

Type-B aflatoxins (AFB1 and AFB2) frequently contaminate food, especially nuts and fried figs, and seriously threaten human health; hence, it is necessary for the newly rapid and sensitive detection methods to prevent the consumption of potentially contaminated food. Here, a lateral flow aptasensor for the detection of type-B aflatoxins was developed. It is based on the use of fluorescent dye Cy5 as a label for the aptamer, and on the competition between type-B aflatoxins and the complementary DNA of the aptamer. This is the first time that the complementary strand of the aptamer has been used as the test line (T-line) to detect type-B aflatoxins. In addition, the truncated aptamer was used to improve the affinity with type-B aflatoxins in our study. Therefore, the lengths of aptamer and cDNA probe were optimized as key parameters for higher sensitivity. In addition, binding buffer and organic solvent were investigated. The results showed that the best pair for achieving improved sensitivity and accuracy in detecting AFB1 was formed by a shorter aptamer (32 bases) coupled with the probe complementary to the AFB1 binding region of the aptamer. Under the optimal experimental conditions, the test strip showed an excellent linear relationship in the range from 0.2 to 20 ng/mL with a limit of detection of 0.16 ng/mL. This aptamer-based strip was successfully applied to the determination of type-B aflatoxins in spiked and commercial peanuts, almonds, and dried figs, and the recoveries of the spiked samples were from 93.3%−112.0%. The aptamer-complementary strand-based lateral flow test strip is a potential alternative tool for the rapid and sensitive detection of type-B aflatoxins in nuts and dried figs. It is of help for monitoring aflatoxins to avoid the consumption of unsafe food.

Potential Rapid and Simple Lateral Flow Assay for Escherichia coli O111

2013 ◽  
Vol 76 (5) ◽  
pp. 755-761 ◽  
Author(s):  
YOSHITAKA TERAO ◽  
TARO YONEKITA ◽  
NAOKI MORISHITA ◽  
TATSUYA FUJIMURA ◽  
TAKASHI MATSUMOTO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Direct Detection ◽  
Culture Method ◽  
Test Strip ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
E Coli ◽  
Negative Results ◽  
Meat Samples ◽  
Positive Results

We developed and evaluated a lateral flow assay (LFA) as a simple and rapid method for direct detection of Escherichia coli O111 in food after enrichment. When cell suspensions of 8 E. coli O111 strains and 77 non–E. coli O111 strains were tested with the LFA, the former all yielded positive results and the latter all yielded negative results. The minimum detection limits for the E. coli O111 strains were 1.8 × 103 to 5.6 × 105 CFU/ml of cell suspension, and the LFA was able to detect live cultures or those killed by autoclaving at nearly the same level of sensitivity. To evaluate the ability of LFA to detect its target in food, enrichment cultures of meat samples inoculated with 10-fold serial dilutions of E. coli O111 were tested with the LFA and PCR. Even when there were very few E. coli O111 cells in the meat samples (1.6 × 100 to 1.6 × 101 CFU/25 g of food), when they were cultured in modified E. coli broth with novobiocin for 22 h at 42°C, the LFA yielded positive results that corresponded to the PCR results. Although the LFA requires further evaluation and field study, these results suggest that this assay has sufficient sensitivity and specificity. This procedure can be completed with a one-step incubation after the test strip has been inserted into the sample after 22 h of culture, whereas the standard culture method requires multiple cultures, skilled personnel, a well-equipped laboratory, and 4 or 5 days. The speed and simplicity of this LFA make it suitable for use as part of routine screening assays in the food industry.

scholarly journals Lateral-Flow Assay for Rapid Serodiagnosis of Human Leptospirosis

2001 ◽  
Vol 8 (1) ◽  
pp. 166-169 ◽  
Author(s):  
Henk L. Smits ◽  
C. K. Eapen ◽  
Sheela Sugathan ◽  
Mariamma Kuriakose ◽  
M. Hussein Gasem ◽  
...  
Keyword(s):  
Positive Result ◽  
Immunosorbent Assay ◽  
Rapid Detection ◽  
Test Line ◽  
Lateral Flow ◽  
Immunoglobulin M ◽  
Lateral Flow Assay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Specific Immunoglobulin ◽  
Human Sera

ABSTRACT An assay device for the rapid detection ofLeptospira-specific immunoglobulin M (IgM) antibodies in human sera is presented. The sensitivity (85.8%) and specificity (93.6%) of the assay compared well (91.9% agreement) with those of an IgM enzyme-linked immunosorbent assay routinely used in the serodiagnosis of leptospirosis. The sensitivity of the assay varied with the stage of the disease. The assay uses stabilized components and is simply performed by the addition of serum and sample fluid to the sample well of the assay device. The assay is read after 10 min, and a positive result is obtained when staining of the test line is observed.

Electrochemical studies of lateral flow assay test results for procalcitonin detection

2021 ◽  
Author(s):  
Yachana Gupta Gupta ◽  
Kalpana ◽  
Aditya Sharma Ghrera
Keyword(s):  
Gold Nanoparticles ◽  
Detection Limit ◽  
Qualitative Analysis ◽  
Test Line ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Quantitative Detection ◽  
Cyclic Voltammograms ◽  
Paper Strip ◽  
Electrochemical Studies

In this study, the lateral flow assay (LFA) has been developed for the detection of bacterial infection (BI) by specific biomarker procalcitonin (PCT), without a need for complicated instrumentations and technical expertise. For the development of the assay, gold nanoparticles (AuNP) and their conjugates with antibodies specific to the model antigen PCT are assessed. Polyclonal antibody (pAb) labelled with gold nanoparticles (AuNP) to obtain the AuNP-pAb complex and the specific monoclonal antibody (mAb) have been dropped at the test zone. This complex is placed over the conjugate line of the LFA strip. In the absence of PCT or the presence of other biomarkers, the test line remained colourless, which revealed the specificity of assay towards PCT among a pool of various analytes. Herein, observations have been made through two different platforms for quantitative and qualitative analysis for the detection of PCT biomarker. The qualitative analysis has been performed on the basis of appearance red color in the test band, while for quantitative analysis, a novel approach has been adopted. Herein, the nitrocellulose membrane (paper strip) is cut out from the LFA strip and used for electrochemical studies under similar solution conditions. Different paper strips presented different cyclic voltammograms (CV) that could be correlated to varying PCT concentrations captured at the test line of the paper strip. The qualitative detection limit for PCT using this LFA was determined to be 2 ng/ml and the quantitative detection limit was 1 ng/ml. The electrochemical response studies of the paper strip by CV technique revealed the sensitivity value of 0.695 mA ng/ml.

scholarly journals Comparison of Single- and Mixed-Sized Gold Nanoparticles on Lateral Flow Assay for Albumin Detection

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 209
Author(s):  
Sasima Chotithammakul ◽  
Michael B. Cortie ◽  
Dakrong Pissuwan
Keyword(s):  
Chronic Kidney Disease ◽  
Gold Nanoparticles ◽  
Test Line ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Analytical Performance ◽  
Detection Mechanism ◽  
Multiple Factors ◽  
20 Nm ◽  
Target Analyte

The sensitivity and reproducibility of the lateral flow assay can be influenced by multiple factors, such as the size of gold nanoparticles (GNPs) employed. Here, we evaluated the analytical performance of single-sized and mixed-sized GNPs using a simple lateral flow assay (LFA) platform. This platform was used as a model assay to diagnose albumin levels and demonstrate the analytical performance of single-sized and mixed-sized GNPs in LFA tests. Two sizes of GNPs@anti-bovine serum albumin (BSA) conjugate proteins were mixed at different ratios. The unique optical properties of the GNPs induced a distinguishing color-shedding effect on the single- and mixed-sized GNPs@anti-BSA conjugates interacting with the target analyte BSA spotted on the test line. The use of mixed-sized GNPs@anti-BSA conjugates enhanced signal relative to the 20 nm GNPs, and provided superior stability compared with solely employing the large GNPs (50 nm). The proposed platform in this study could provide an efficient BSA detection mechanism that can be utilized as a model biomarker for confronting chronic kidney disease.

scholarly journals Lateral Flow Assay for the Detection of African Swine Fever Virus Antibodies Using Gold Nanoparticle-Labeled Acid-Treated p72

2022 ◽  
Vol 9 ◽  
Author(s):  
Wenzhuang Zhu ◽  
Kaiwen Meng ◽  
Yueping Zhang ◽  
Zhigao Bu ◽  
Dongming Zhao ◽  
...  
Keyword(s):  
Gold Nanoparticle ◽  
African Swine Fever Virus ◽  
African Swine Fever ◽  
High Sensitivity ◽  
Lateral Flow ◽  
Fever Virus ◽  
Lateral Flow Assay ◽  
Diagnostic Methods ◽  
Detection Methods ◽  
Antibody Detection

African swine fever is a widespread and highly contagious disease in the porcine population, which is caused by African swine fever virus (ASFV). The PCR and ELISA detection methods are the main conventional diagnostic methods for ASFV antigen/antibody detection in the field. However, these methods have limitations of expensive equipment, trained technicians, and time-consuming results. Thus, a rapid, inexpensive, accurate and on-site detection method is urgently needed. Here we describe a double-antigen-sandwich lateral-flow assay based on gold nanoparticle-conjugated ASFV major capsid protein p72, which can detect ASFV antibody in serum samples with high sensitivity and specificity in 10 min and the results can be determined by naked eyes. A lateral flow assay was established by using yeast-expressed and acid-treated ASFV p72 conjugated with gold nanoparticles, which are synthesized by seeding method. A high coincidence (97.8%) of the assay was determined using clinical serum compared to a commercial ELISA kit. In addition, our lateral flow strip can detect as far as 1:10,000 diluted clinically positive serum for demonstration of high sensitivity. In summary, the assay developed here was shown to be rapid, inexpensive, accurate and highly selective. It represents a reliable method for on-site ASFV antibody detection and may help to control the ASFV pandemic.

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