scholarly journals An Enhanced Lateral Flow Assay Based on Aptamer–Magnetic Separation and Multifold AuNPs for Ultrasensitive Detection of Salmonella Typhimurium in Milk

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1605
Author(s):  
Pingping Gao ◽  
Lihan Wang ◽  
Yang He ◽  
Yitian Wang ◽  
Xinyan Yang ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Au Nanoparticles ◽  
Limit Of Detection ◽  
High Specificity ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Nucleic Acid Amplification ◽  
Visual Signal ◽  
Magnetic Capture ◽  
Magnetic Enrichment

In this paper, a novel and ultrasensitive lateral flow assay (LFA) based on aptamer–magnetic separation, and multifold Au nanoparticles (AuNPs) was developed for visual detecting Salmonella enterica ser. Typhimurium (S. Typhimurium). The method realized magnetic enrichment and signal transduction via magnetic separation and achieved signal amplification through hybridizing AuNPs–capture probes and AuNPs–amplification probes to form multifold AuNPs. Two different thiolated single-strand DNA (ssDNA) on the AuNPs–capture probe played different roles. One was combined with the AuNPs–amplification probe on the conjugate pad to achieve enhanced signals. The other was connected to transduction ssDNA1 released by aptamer–magnetic capture of S. Typhimurium, and captured by the T-line, forming a positive signal. This method had an excellent linear relationship ranging from 8.6 × 102 CFU/mL to 8.6 × 107 CFU/mL with the limit of detection (LOD) as low as 8.6 × 100 CFU/mL in pure culture. In actual samples, the visual LOD was 4.1 × 102 CFU/mL, which did not carry out nucleic acid amplification and pre-enrichment, increasing three orders of magnitudes than unenhanced assays with single–dose AuNPs and no magnetic separation. Furthermore, the system showed high specificity, having no reaction with other nontarget strains. This visual signal amplificated system would be a potential platform for ultrasensitive monitoring S. Typhimurium in milk samples.

A Point of Care Lateral Flow Assay for Rapid and Colorimetric Detection of Interleukin 6 and Perspectives in Bedside Diagnostics

2020 ◽  
Author(s):  
Carla Eiras
Keyword(s):  
Interleukin 6 ◽  
Limit Of Detection ◽  
Inflammatory Diseases ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Aggregation Assay ◽  
Before And After ◽  
Bedside Diagnosis

Interleukin-6 (IL-6) is a multifunctional cytokine and high bloodstream levels of which have been associated with severe inflammatory diseases, such as dengue fever, sepsis, various cancers, and visceral leishmaniasis (VL). Rapid tests for the quantification of IL-6 would be of great assistance for the bedside diagnosis and treatment of diseases such as VL. We have developed a lateral flow assay (LFA) for rapid and colorimetric IL-6 detection, consisting of anti-IL-6 antibodies conjugated to gold nanoparticles (AuNPs). The optimal concentration of anti-IL-6 used in the conjugate was determined to be 800.0 μg/mL, based on an aggregation assay using LFA. A linear relationship between IL-6 standard concentration and color intensity was observed after 20 min, with a linear range between 1.25 ng/mL and 9,000 ng/mL. The limit of detection for this method was estimated a t0.38 ng/mL. The concentration of IL-6 in five patients with severe VL was measured using LFA, and the results were consistent with those obtained using the cytometric bead array (CBA) method. A thorough analysis of the LFA membranes’ surface morphology, before and after sample contact, was performed using atomic force microscopy (AFM).The prototype described here is still being tested and improved, but this LFA will undoubtedly be of great help in the clinical quantification of IL-6.

A Point of Care Lateral Flow Assay for Rapid and Colorimetric Detection of Interleukin 6 and Perspectives in Bedside Diagnostics

2020 ◽  
Author(s):  
Carla Eiras
Keyword(s):  
Interleukin 6 ◽  
Limit Of Detection ◽  
Inflammatory Diseases ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Aggregation Assay ◽  
Before And After ◽  
Bedside Diagnosis

Interleukin-6 (IL-6) is a multifunctional cytokine and high bloodstream levels of which have been associated with severe inflammatory diseases, such as dengue fever, sepsis, various cancers, and visceral leishmaniasis (VL). Rapid tests for the quantification of IL-6 would be of great assistance for the bedside diagnosis and treatment of diseases such as VL. We have developed a lateral flow assay (LFA) for rapid and colorimetric IL-6 detection, consisting of anti-IL-6 antibodies conjugated to gold nanoparticles (AuNPs). The optimal concentration of anti-IL-6 used in the conjugate was determined to be 800.0 μg/mL, based on an aggregation assay using LFA. A linear relationship between IL-6 standard concentration and color intensity was observed after 20 min, with a linear range between 1.25 ng/mL and 9,000 ng/mL. The limit of detection for this method was estimated at a t0.38 ng/mL. The concentration of IL-6 in five patients with severe VL was measured using LFA, and the results were consistent with those obtained using the cytometric bead array (CBA) method. A thorough analysis of the LFA membranes’ surface morphology, before and after sample contact, was performed using atomic force microscopy (AFM). The prototype described here is still being tested and improved, but this LFA will undoubtedly be of great help in the clinical quantification of IL-6.

A Simple Paper-Based Lab-on-a-Chip for the Detection of a Highly Pathogenic Strain of Porcine Reproductive and Respiratory Syndrome Virus

2014 ◽  
Vol 67 (10) ◽  
pp. 1434 ◽  
Author(s):  
Piyasak Chaumpluk ◽  
Annop Suriyasomboon
Keyword(s):  
Signal Detection ◽  
Limit Of Detection ◽  
Low Cost ◽  
Dna Amplification ◽  
High Specificity ◽  
Visual Observation ◽  
Nucleic Acid Amplification ◽  
Pathogenic Strain ◽  
Respiratory Syndrome Virus ◽  
Highly Pathogenic

A paper-based laboratory-on-a-chip assay for the rapid detection of a highly pathogenic strain of porcine reproductive and respiratory syndrome virus (HP-PRRSV) was developed for the first time. The single-unit chip was simply fabricated using Whatman filter paper and plastic lamination. The chip measured 2.5 × 3.0 cm2 and was divided into two parts, one for nucleic acid amplification and the other for signal detection. The HP-PRRSV assay was performed by specific ORF I Nsp 2 gene amplification via an isothermal reverse transcription loop-mediated DNA amplification platform, whereas the cDNA signal detection was performed by visual observation of colorimetric changes in blue silver nanoplates (AgNPls). Positive results caused non-aggregation of the blue AgNPls on the detection pad, whereas negative results induced colorimetric changes in the AgNPls from blue to colourless on the pad. The assay had a limit of detection of 100 copies of the target Nsp 2 gene and high specificity for other types of infectious viruses. The assay required only one hour to complete. This work demonstrates a simple and rapid assay for viruses using a simple, low-cost, paper-based chip.

scholarly journals One-Tube SARS-CoV-2 Detection Platform Based on RT-RPA and CRISPR/Cas12a

2020 ◽  
Author(s):  
Yangyang Sun ◽  
Lei Yu ◽  
Chengxi Liu ◽  
Wei Chen ◽  
Dechang Li ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Limit Of Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
N Gene ◽  
Clinical Samples ◽  
Nucleic Acid Detection ◽  
Detection Process ◽  
Human Coronaviruses ◽  
Negative Controls

Abstract Background: COVID-19 has spread rapidly around the world, affecting almost every person. When lifting certain mandatory measures for an economic restart, robust surveillance must be established and implemented, with nucleic acid detection for SARS-CoV-2 as an essential component. Methods: We designed RT-RPA (Reverse Transcription and Recombinase Polymerase Isothermal Amplification) primers of RdRp gene and N gene according to the SARS-CoV-2 gene sequence. We optimized the components in the reaction so that the detection process could be carried out in one tube. The specificity was demonstrated through detecting nucleic acid samples from seven human coronaviruses. Clinical samples were used to validate the platform and all results were compared to rRT-PCR. RNA standards diluted by different gradients were used to demonstrate the limit of detection. Furthermore, we have developed a lateral flow assay based on OR-DETECTR for the detection of COVID-19. Results: We have developed a o ne-tube detection platform based on R T- R PA and DNA Endonuclease-Targeted CRISPR Trans Reporter ( DETECTR ) technology, termed OR-DETECTR, to detect SARS-CoV-2. The detection process is completed in one tube, and the time is 50min. The method can specifically detect SARS-CoV-2 from seven human coronaviruses with a low detection limit of 2.5 copies/µl input. Results from six SARS-CoV-2 patient samples, eight samples from patients with fever but no SARS-CoV-2 infection, and one mixed sample from 40 negative controls showed that OR-DETECTR is 100% consistent with rRT-PCR. Furthermore, we have developed a lateral flow assay based on OR-DETECTR for the detection of COVID-19. Conclusions: OR-DETECTR detection platform is rapid, accurate, tube closed, easy-to-operate, and free of large instruments for COVID-19 detection.

scholarly journals Engineered CRISPR/Cas12a Enables Rapid SARS-CoV-2 Detection

2020 ◽  
Author(s):  
Long T. Nguyen ◽  
Santosh R. Rananaware ◽  
Brianna L.M. Pizzano ◽  
Brandon T. Stone ◽  
Piyush K. Jain
Keyword(s):  
High Sensitivity ◽  
High Specificity ◽  
Single Copy ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Magnesium Concentration ◽  
Clinical Validation ◽  
Respiratory Pathogens ◽  
Reporter Assay ◽  
Wide Range

ABSTRACTThe coronavirus disease (COVID-19) caused by SARS-CoV-2 has swept through the globe at an unprecedented rate. CRISPR-based detection technologies such as DETECTR, SHERLOCK, and STOPCovid have emerged as a rapid and affordable platform that can shape the future of diagnostics. Recently, we reported engineered crRNAs for Cas12a, called ENHANCE, that enables enhanced detection of nucleic acids. Here we report development, clinical validation, and advancement of ENHANCE platform for detecting SARS-CoV-2. With an RT-LAMP pre-amplification step, ENHANCE detects samples down to a single copy with 95% accuracy and shows high specificity towards various isolates of SARS-CoV-2 against 31 highly similar and common respiratory pathogens. Utilizing LbCas12a-mediated trans-cleavage activity, ENHANCE works robustly in a wide range of magnesium concentration (3 mM-13 mM), allowing for further assay optimization. Additionally, ENHANCEv2 is developed to further improve the previously reported ENHANCE. ENHANCEv2 employs mutated LbCas12aD156R, engineered chimeric DNA-extended crRNA, and a dual reporter for both fluorescence-based reporter assay and lateral flow assay. Both ENHANCE and ENHANCEv2 are validated in 62 clinical nasopharyngeal swabs, showing 60/62 (96.7%) agreement with RT-qPCR results, and using only 5 μL of sample and 20 minutes of CRISPR reaction. Lateral flow assay on paper strips displays 100% agreement with fluorescence-based reporter assay in the clinical validation. Following a 30-minute pre-amplification RT-LAMP step, the lyophilized ENHANCEv2 is shown to achieve high sensitivity and specificity while reducing CRISPR reaction time to as low as 3 minutes and maintaining its detection capability upon storage at room temperature for several weeks.

scholarly journals A new lateral flow assay to detect sIL-2R during T-cell mediated rejection after kidney transplantation

The Analyst ◽  
2021 ◽  
Author(s):  
Lisa K. Seiler ◽  
Rebecca Jonczyk ◽  
Patrick Lindner ◽  
Ncog Linh Phung ◽  
Christine S. Falk ◽  
...  
Keyword(s):  
Kidney Transplantation ◽  
T Cell ◽  
Point Of Care ◽  
High Specificity ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Point Of Care Test ◽  
Specificity And Sensitivity ◽  
Kidney Rejection ◽  
Acute Kidney Rejection

In this work a novel point of care test to detect sIL-2R during acute kidney rejection with high specificity and sensitivity was developed.

scholarly journals CASLFA: CRISPR/Cas9-mediated lateral flow nucleic acid assay

2019 ◽  
Author(s):  
Xusheng Wang ◽  
Erhu Xiong ◽  
Tian Tian ◽  
Meng Cheng ◽  
Wei Lin ◽  
...  
Keyword(s):  
Genetically Modified Organisms ◽  
African Swine Fever Virus ◽  
Point Of Care ◽  
African Swine Fever ◽  
Analytical Techniques ◽  
High Specificity ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Nucleic Acid Assay ◽  
Ancillary Equipment

AbstractThe lateral flow assay is one of the oldest and most convenient analytical techniques for analyzing the immune response, but its applicability to precise genetic analyses is limited by the tedious and inefficient hybridization steps. Here, we have introduced a new version of the lateral flow assay, termed Cas9-mediated lateral flow nucleic acids assay (CASLFA), to address such issues. In this study, CASLFA is utilized to identify Listeria monocytogenes, genetically modified organisms (GMOs), and African swine fever virus (ASFV) at a sensitivity of hundreds of copies of genome samples with high specificity within 1 h. CASLFA satisfies some of the characteristics of a next-generation molecular diagnostics tool due to its rapidity and accuracy, allowing for point-of-care use without the need for technical expertise and complex ancillary equipment. This method has great potential for analyzing genes in resource-poor or nonlaboratory environments.

scholarly journals Advantages of Highly Spherical Gold Nanoparticles as Labels for Lateral Flow Immunoassay

Sensors ◽  
2020 ◽  
Vol 20 (12) ◽  
pp. 3608
Author(s):  
Nadezhda A. Byzova ◽  
Anatoly V. Zherdev ◽  
Boris N. Khlebtsov ◽  
Andrey M. Burov ◽  
Nikolai G. Khlebtsov ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Troponin I ◽  
Limit Of Detection ◽  
Average Diameter ◽  
Covalent Immobilization ◽  
Lateral Flow ◽  
Antibody Immobilization ◽  
Site Testing ◽  
Spherical Gold Nanoparticles

The use of lateral flow immunoassays (LFIAs) for rapid on-site testing is restricted by their relatively high limit of detection (LoD). One possible way to decrease the LoD is to optimize nanoparticle properties that are used as labels. We compare two types of Au nanoparticles: usual quasispherical gold nanoparticles (C-GNPs), obtained by the Turkevich–Frens method, and superspherical gold nanoparticles (S-GNPs), obtained by a progressive overgrowth technique. Average diameters were 18.6–47.5 nm for C-GNPs and 20.2–90.4 nm for S-GNPs. Cardiomarker troponin I was considered as the target analyte. Adsorption and covalent conjugation with antibodies were tested for both GNP types. For C-GNPs, the minimal LoD was obtained with 33.7 nm nanoparticles, reaching 12.7 ng/mL for covalent immobilization and 9.9 ng/mL for adsorption. The average diameter of S-GNPs varied from 20.2 to 64.5 nm, which resulted in a decrease in LoD for an LFIA of troponin I from 3.4 to 1.2 ng/mL for covalent immobilization and from 2.9 to 2.0 ng/mL for adsorption. Thus, we obtained an 8-fold decrease in LoD (9.9 to 1.2 ng/mL) by using S-GNPs. This effect can be related to more effective antibody immobilization and improved S-GNP optical properties. The obtained results can improve LFIAs for various practically significant analytes.

Sample Preincubation Strategy for Sensitive and Quantitative Detection of Clenbuterol in Swine Urine Using a Fluorescent Microsphere–Based Immunochromatographic Assay

2014 ◽  
Vol 77 (11) ◽  
pp. 1998-2003 ◽  
Author(s):  
SHENG L. DENG ◽  
SHAN SHAN ◽  
CHAO L. XU ◽  
DAO F. LIU ◽  
YONG H. XIONG ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Rapid Screening ◽  
Immunochromatographic Assay ◽  
Quantitative Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Fluorescent Microsphere ◽  
Swine Urine ◽  
Relative Standard

We describe an ultrasensitive and quantitative immunochromatographic assay to determine the amount of clenbuterol (CLB) in swine urine. In this study, fluorescein isothiocyanate polystyrene fluorescent microspheres were used as probes. A sample preincubation strategy was introduced to this immunochromatographic assay. Results showed that the strategy evidently improved the sensitivity and accuracy of lateral flow assay. The method was completed in 20 min, and a half-maximal inhibitory concentration of 0.13 μg liter−1 was obtained. The limit of detection of the proposed method to determine CLB in swine urine was 0.01 μg liter−1, which was lower than the limit of detection of immunochromatographic assays without preincubation. Intra-and interday recoveries of spiked swine urine ranged from 85.0 to 107.5%. The relative standard deviation values of the preincubated test strip ranged from 2.7 to 12.5%. Analysis of the CLB in swine urine samples showed that the result obtained from the lateral flow assay is consistent with that obtained from a commercial enzyme-linked immunosorbent assay kit. Our results suggest that the developed fluorescent microsphere–based immunochromatographic assay may be useful as a rapid screening method to detect CLB quantitatively.

scholarly journals Design of Multiplex Lateral Flow Tests: A Case Study for Simultaneous Detection of Three Antibiotics

2019 ◽  
Author(s):  
Anastasiya V. Bartosh ◽  
Dmitriy V. Sotnikov ◽  
Olga D. Hendrickson ◽  
Anatoly V. Zherdev ◽  
Boris B. Dzantiev
Keyword(s):  
Limit Of Detection ◽  
Simultaneous Detection ◽  
Optimal Location ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Immunochromatographic Test ◽  
Equilibrium Conditions ◽  
Lateral Flow Tests ◽  
The Impact

The presented study is focused on the impact of binding zones locations at immunochromatographic test strips into analytical parameters of multiplex lateral flow assay. Due to non-equilibrium conditions for such assays the duration of immune reactions influences significantly on analytical parameters, and the integration of several analytes into one multiplex strip may cause essential decrease of sensitivity. To choose the best location of binding zones, we have tested reactants for immunochromatographic assays of lincomycin, chloramphenicol, and tetracycline. The influence of the distance to the binding zones on the intensity of coloration and limit of detection (LOD) was rather different. Basing on the obtained data, the best order of binding zones was chosen. In comparison with non-optimal location the LODs were 5-10 fold improved. The final assay provides LODs 0.4, 0.4 and 1.0 ng/mL for lincomycin, chloramphenicol, and tetracycline, respectively. The proposed approach can be applied for multiassays of other analytes.

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