scholarly journals A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guanhua Xun ◽  
Stephan Thomas Lane ◽  
Vassily Andrew Petrov ◽  
Brandon Elliott Pepa ◽  
Huimin Zhao
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Volume ◽  
N Gene ◽  
Testing System ◽  
Target Sequence ◽  
One Pot ◽  
Sequence Detection ◽  
Highly Sensitive ◽  
Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

scholarly journals Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2679 ◽  
Author(s):  
Zheng-Jun Xie ◽  
Xian-Yu Bao ◽  
Chi-Fang Peng
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Limit Of Detection ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Colorimetric Method ◽  
Optimal Conditions ◽  
Surface Deposition ◽  
Highly Sensitive ◽  
Dna Strand

A new colorimetric detection of methylmercury (CH3Hg+) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg+, which was used to capture and separate CH3Hg+ by centrifugation. It was found that the CH3Hg+ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg+ with a linear range of 10–200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg+ detection in environmental samples.

Polyaniline as a Sacrificing Template for the Synthesis of Ultra-small Co3O4 Nanoparticles for the Sensitive and Selective Detection of Methotrexate (MTX)

2021 ◽  
Author(s):  
Irum Naz Qureshi ◽  
Aneela Tahira ◽  
Khoulwod Aljadoa ◽  
Ali M. Alsalme ◽  
Asma A. Al-Othman ◽  
...  
Keyword(s):  
Electrochemical Sensors ◽  
Limit Of Detection ◽  
Low Cost ◽  
Metal Oxide Nanoparticles ◽  
Linear Sweep Voltammetry ◽  
Co3o4 Nanoparticles ◽  
X Ray Diffraction ◽  
Highly Sensitive ◽  
Wide Range ◽  
Average Size

Abstract The successful monitoring of the anticancer drugs using nanostructured materials is very important but very challenging task. Beside this, uniform and ultra-small size of metal oxide nanoparticles is highly needed in order to enhance the catalytic activity which could result into the development of sensitive and selective electrochemical sensors for methotrexate (MTX). For this purpose, we have used a simple approach involving the polyaniline (PANI) as a sacrificing template for the growth of uniform and ultra-small Co3O4 nanoparticles by hydrothermal method. The structure, shape, composition and phase purity were studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform Infrared (FTIR) techniques. The average size of Co3O4 nanoparticles was below 50 nm. The cubic crystallography is confirmed for the Co3O4 nanoparticles. The electrochemical properties of PANI assisted Co3O4 nanoparticles for MTX drug was evaluated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) in Britton–Robinson buffer (BRB) of pH 3.5. The PANI assisted Co3O4 nanoparticles were found highly sensitive for the MTX drug and exhibited a linear range from 5-75µM of MTX and limit of detection for the modified electrode was estimated 1.98µM. The proposed electrochemical sensor is low cost, simple, highly sensitive and selective towards MTX detection. The synthetic methodology using the conducting polymer as a sacrificing template for the growth of controlled and ultra-small Co3O4 nanoparticles can be utilized for the wide range of electrochemical applications.

scholarly journals Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites

Biosensors ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 114
Author(s):  
Yunjeong Park ◽  
Min-Sung Hong ◽  
Woo-Hyuk Lee ◽  
Jung-Gu Kim ◽  
Kyunghoon Kim
Keyword(s):  
Tumor Marker ◽  
Limit Of Detection ◽  
Biological Fluid ◽  
Low Cost ◽  
High Sensitivity ◽  
Label Free ◽  
Electrochemical Aptasensor ◽  
Promising Tool ◽  
Highly Sensitive ◽  
Endothelial Growth Factor

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

scholarly journals An Innovative Polyaniline/Platinum-Coated Fiber Optic – Surface Plasmon Resonance Sensor for Picomolar Detection of 4-Nitrophenol

2021 ◽  
Author(s):  
Iulia ANTOHE ◽  
Iuliana IORDACHE ◽  
Vlad-Andrei ANTOHE ◽  
Gabriel SOCOL
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Fiber Optic ◽  
Limit Of Detection ◽  
Low Cost ◽  
Cost Effective ◽  
Coated Fiber ◽  
Highly Sensitive ◽  
Resonance Sensor

Abstract The paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic – surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection. The Pt thin film was coated over an unclad core of an optical fiber (FO) using a DC magnetron sputtering technique, while the 4-NP responsive PANI layer was synthetized using a cost-effective electroless polymerization method. The presence of the electrolessly-grown PANI on the Pt-coated FO was observed by field-emission scanning electron microscopy (FE-SEM) and subsequently evidenced by energy dispersive X-ray analysis (EDX). These FO-SPR sensors with a demonstrated sensitivity of 1515 nm/RIU were then employed for 4-NP sensing, exhibiting am excellent limit of detection (LOD) in the low picomolar range (0.17 pM). The proposed sensor’s configuration has many other advantages, such as low-cost production, small size, immunity to electromagnetic interferences, remote sensing capability, and moreover, can be operated as a “stand-alone device”, making it thus well-suited for applications such as “on-site” screening of extremely low-level trace pollutants.

scholarly journals Low-Cost Manually Assembled Open Source Reader for Isothermal Pathogen Detection from Saliva using RT-LAMP: SARS-CoV-2 Use Case

2020 ◽  
Author(s):  
John C. Bramley ◽  
Jason E. Waligorski ◽  
Colin L. Kremitzki ◽  
Mariel J. Liebeskind ◽  
Alex L. Yenkin ◽  
...  
Keyword(s):  
Pathogen Detection ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
One Pot ◽  
Home Testing ◽  
Wide Range ◽  
Platform Technology ◽  
Crude Sample ◽  
Analytical Limit

AbstractDistributed “Point-of-Care” or “at-Home” testing is an important component for a complete suite of testing solutions. This manuscript describes the construction and operation of a platform technology designed to meet this need. The ongoing COVID-19 pandemic will be used as the proof-of-concept for the efficacy and deployment of this platform. The technology outlined consists of a one-pot, reverse-transcription loop-mediated isothermal amplification (RT-LAMP) chemistry coupled with a low-cost and user-assembled reader using saliva as input. This platform is readily adapted to a wide range of pathogens due to the genetic basis of the reaction. A complete guide to the construction of the reader as well as the production of the reaction chemistry are provided here. Additionally, analytical limit of detection data and the results from saliva testing of SARS-CoV-2, are presented. The platform technology outlined here demonstrates a rapid, distributed, molecular point-of-care solution for pathogen detection using crude sample input.

scholarly journals Direct diagnostic testing of SARS-CoV-2 without the need for prior RNA extraction

2020 ◽  
Author(s):  
Shan Wei ◽  
Esther Kohl ◽  
Alexandre Djandji ◽  
Stephanie Morgan ◽  
Susan Whittier ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Diagnostic Testing ◽  
Rna Extraction ◽  
Nucleic Acid Amplification ◽  
Nasopharyngeal Swab ◽  
Viral Transport ◽  
Extraction Step ◽  
Highly Sensitive

AbstractThe COVID-19 pandemic has resulted in an urgent global need for rapid, point-of-care diagnostic testing. Existing methods for nucleic acid amplification testing (NAAT) require an RNA extraction step prior to amplification of the viral RNA. This step necessitates the use of a centralized laboratory or complex and costly proprietary cartridges and equipment, and thereby prevents low-cost, scalable, point-of-care testing. We report the development of a highly sensitive and robust, easy-to-implement, SARS-CoV-2 test that utilizes isothermal amplification and can be run directly on viral transport media following a nasopharyngeal swab without the need for prior RNA extraction. Our assay provides visual results in 30 min with 85% sensitivity, 100% specificity, and a limit of detection (LoD) of 2.5 copies/μl, and can be run using a simple heat block.

A portable point-of-care testing system to diagnose lung cancer through the detection of exosomal miRNA in urine and saliva

2020 ◽  
Vol 56 (63) ◽  
pp. 8968-8971 ◽  
Author(s):  
Ping Zhou ◽  
Fei Lu ◽  
Jianbo Wang ◽  
Kaiye Wang ◽  
Bo Liu ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Point Of Care ◽  
Low Cost ◽  
Testing System ◽  
Point Of Care Testing ◽  
Lung Cancers ◽  
Non Invasive ◽  
Diagnose Lung Cancer ◽  
Highly Sensitive ◽  
Exosomal Mirna

A low-cost, easy-to-operate, highly sensitive and effective lung cancer diagnostic kit (LCDK) was developed, and can realize non-invasive detection of early-, middle- and late-stage lung cancers using clinical salivary and urine samples.

scholarly journals Paper-based aptamer-antibody biosensor for gluten detection in a deep eutectic solvent (DES)

2021 ◽  
Author(s):  
Rossella Svigelj ◽  
Nicolò Dossi ◽  
Cristian Grazioli ◽  
Rosanna Toniolo
Keyword(s):  
Dynamic Range ◽  
Limit Of Detection ◽  
Low Cost ◽  
Deep Eutectic Solvent ◽  
Electrochemical Sensing ◽  
Sensing Platform ◽  
Screen Printed Carbon Electrode ◽  
Highly Sensitive ◽  
Rapid Tests

AbstractPaper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L−1 of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L−1 and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract

scholarly journals A polyaniline/platinum coated fiber optic surface plasmon resonance sensor for picomolar detection of 4-nitrophenol

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Iulia Antohe ◽  
Iuliana Iordache ◽  
Vlad-Andrei Antohe ◽  
Gabriel Socol
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Fiber Optic ◽  
Limit Of Detection ◽  
Low Cost ◽  
Cost Effective ◽  
Coated Fiber ◽  
Highly Sensitive ◽  
Resonance Sensor

AbstractThe paper reports for the first time an innovative polyaniline (PANI)/platinum (Pt)-coated fiber optic-surface plasmon resonance (FO-SPR) sensor used for highly-sensitive 4-nitrophenol (4-NP) pollutant detection. The Pt thin film was coated over an unclad core of an optical fiber (FO) using a DC magnetron sputtering technique, while the 4-NP responsive PANI layer was synthetized using a cost-effective electroless polymerization method. The presence of the electrolessly-grown PANI on the Pt-coated FO was observed by field-emission scanning electron microscopy and subsequently evidenced by energy dispersive X-ray analysis. These FO-SPR sensors with a demonstrated bulk sensitivity of 1515 nm/RIU were then employed for 4-NP sensing, exhibiting an excellent limit-of-detection (LOD) in the low picomolar range (0.34 pM). The proposed sensor’s configuration has many other advantages, such as low-cost production, small size, immunity to electromagnetic interferences, remote sensing capability, and moreover, can be operated as a “stand-alone device”, making it thus well-suited for applications such as “on-site” screening of extremely low-level trace pollutants.

scholarly journals A Label-Free Fluorescent AND Logic Gate Aptasensor for Sensitive ATP Detection

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3281 ◽  
Author(s):  
Jingjing Zhang ◽  
Chunzheng Yang ◽  
Chaoqun Niu ◽  
Chen Liu ◽  
Xuepin Cai ◽  
...  
Keyword(s):  
Deoxyribonucleic Acid ◽  
Limit Of Detection ◽  
Low Cost ◽  
Logic Gate ◽  
Label Free ◽  
Detection Range ◽  
Sensitivity Range ◽  
Highly Sensitive ◽  
Input Signals ◽  
Atp Detection

In this study, a label-free fluorescent, enzyme-free, simple, highly sensitive AND logic gate aptasensor was developed for the detection of adenosine triphosphate (ATP). Double-stranded deoxyribonucleic acid (DNA) with cohesive ends was attached to graphene oxide (GO) to form an aptasensor probe. ATP and single-stranded DNA were used as input signals. Fluorescence intensity of PicoGreen dye was used as an output signal. The biosensor-related performances, including the logic gate construction, reaction time, linearity, sensitivity, and specificity, were investigated and the results showed that an AND logic gate was successfully constructed. The ATP detection range was found to be 20 to 400 nM (R2 = 0.9943) with limit of detection (LOD) of 142.6 pM, and the sensitivity range was 1.846 × 106 to 2.988 × 106 M−1. This method for the detection of ATP has the characteristics of being simple, low cost, and highly sensitive.

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