scholarly journals A Rapid, Simple, Inexpensive, and Mobile Colorimetric Assay COVID-19-LAMP for Mass On-Site Screening of COVID-19

2020 ◽  
Vol 21 (15) ◽  
pp. 5380 ◽  
Author(s):  
Franklin Wang-Ngai Chow ◽  
Tony Tat-Yin Chan ◽  
Anthony Raymond Tam ◽  
Suhui Zhao ◽  
Weiming Yao ◽  
...  
Keyword(s):  
Mass Screening ◽  
Color Change ◽  
Colorimetric Assay ◽  
Point Of Care ◽  
Low Cost ◽  
Lamp Assay ◽  
Virus Infections ◽  
Economic Activities ◽  
Amplification Assay ◽  
Rapid Deployment

To control the COVID-19 pandemic and prevent its resurgence in areas preparing for a return of economic activities, a method for a rapid, simple, and inexpensive point-of-care diagnosis and mass screening is urgently needed. We developed and evaluated a one-step colorimetric reverse-transcriptional loop-mediated isothermal amplification assay (COVID-19-LAMP) for detection of SARS-CoV-2, using SARS-CoV-2 isolate and respiratory samples from patients with COVID-19 (n = 223) and other respiratory virus infections (n = 143). The assay involves simple equipment and techniques and low cost, without the need for expensive qPCR machines, and the result, indicated by color change, is easily interpreted by naked eyes. COVID-19-LAMP can detect SARS-CoV-2 RNA with detection limit of 42 copies/reaction. Of 223 respiratory samples positive for SARS-CoV-2 by qRT-PCR, 212 and 219 were positive by COVID-19-LAMP at 60 and 90 min (sensitivities of 95.07% and 98.21%) respectively, with the highest sensitivities among nasopharyngeal swabs (96.88% and 98.96%), compared to sputum/deep throat saliva samples (94.03% and 97.02%), and throat swab samples (93.33% and 98.33%). None of the 143 samples with other respiratory viruses were positive by COVID-19-LAMP, showing 100% specificity. Samples with higher viral load showed shorter detection time, some as early as 30 min. This inexpensive, highly sensitive and specific COVID-19-LAMP assay can be useful for rapid deployment as mobile diagnostic units to resource-limiting areas for point-of-care diagnosis, and for unlimited high-throughput mass screening at borders to reduce cross-regional transmission.

scholarly journals A Colorimetric Membrane-Based Sensor with Improved Selectivity towards Amphetamine

Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6713
Author(s):  
Neus Jornet-Martínez ◽  
Pilar Campíns-Falcó ◽  
Rosa Herráez-Hernández
Keyword(s):  
Illicit Drugs ◽  
Diffuse Reflectance Spectroscopy ◽  
Colorimetric Assay ◽  
Point Of Care ◽  
Low Cost ◽  
Discrimination Power ◽  
Visual Identification ◽  
Yellow Orange ◽  
Spot Tests ◽  
Care Assistance

Due to their simplicity, speed and low cost, chemical spot tests are increasingly demanded for the presumptive identification of illicit drugs in a variety of contexts such as point-of-care assistance or prosecution of drug trafficking. However, most of the colorimetric reactions used in these tests are, at best, drug class selective. Therefore, the development of tests based on chemical reactions with improved discrimination power is of great interest. In this work, we propose a new colorimetric assay for amphetamine (AMP) based on its reaction with solutions of alkaline gold bromide to form an insoluble yellow–orange derivative. The resulting suspensions are then filtered onto nylon membranes and the precipitate collected is used for the visual identification of AMP. The measurement of the absorbance of the membranes by diffuse reflectance spectroscopy also allows the quantification of AMP in a simple and rapid way, as demonstrated for different synthetic and drug street samples. On the basis of the results obtained, it was concluded that the proposed procedure is highly selective towards AMP, as this compound could be easily differentiated from other common drugs such as methamphetamine (MET), ephedrine (EPH), scopolamine (SCP) and cocaine (COC).

scholarly journals Development of a loop-mediated isothermal amplification (LAMP) method for specific detection of Mycobacterium bovis

2021 ◽  
Vol 15 (1) ◽  
pp. e0008996
Author(s):  
Thoko Flav Kapalamula ◽  
Jeewan Thapa ◽  
Mwangala Lonah Akapelwa ◽  
Kyoko Hayashida ◽  
Stephen V. Gordon ◽  
...  
Keyword(s):  
Developing Countries ◽  
Mycobacterium Bovis ◽  
Color Change ◽  
Low Cost ◽  
Lamp Assay ◽  
Genomic Region ◽  
Isothermal Amplification ◽  
Diagnostic Methods ◽  
Lamp Method ◽  
Loop Mediated Isothermal Amplification

Bovine tuberculosis (TB) caused by Mycobacterium bovis is a significant health threat to cattle and a zoonotic threat for humans in many developing countries. Rapid and accurate detection of M. bovis is fundamental for controlling the disease in animals and humans, and for the proper treatment of patients as one of the first-line anti-TB drug, pyrazinamide, is ineffective against M. bovis. Currently, there are no rapid, simplified and low-cost diagnostic methods that can be easily integrated for use in many developing countries. Here, we report the development of a loop-mediated isothermal amplification (LAMP) assay for specific identification of M. bovis by targeting the region of difference 4 (RD4), a 12.7 kb genomic region that is deleted solely in M. bovis. The assay's specificity was evaluated using 139 isolates comprising 65 M. bovis isolates, 40 M. tuberculosis isolates, seven M. tuberculosis complex reference strains, 22 non-tuberculous mycobacteria and five other bacteria. The established LAMP detected only M. bovis isolates as positive and no false positives were observed using the other mycobacteria and non-mycobacteria tested. Our LAMP assay detected as low as 10 copies of M. bovis genomic DNA within 40 minutes. The procedure of LAMP is simple with an incubation at a constant temperature. Results are observed with the naked eye by a color change, and there is no need for expensive equipment. The established LAMP can be used for the detection of M. bovis infections in cattle and humans in resource-limited areas.

scholarly journals Nucleic acid amplification by a transparent graphene Visual-PCR chip and a disposable thermocycler

2019 ◽  
Author(s):  
Guozhi Zhu ◽  
Miao Qiao
Keyword(s):  
Nucleic Acids ◽  
Color Change ◽  
Point Of Care ◽  
Low Cost ◽  
Nucleic Acid Amplification ◽  
Driving Voltage ◽  
Conductive Films ◽  
Cooling Fan ◽  
Resource Limited ◽  
Polymerase Chain

ABSTRACTPolymerase chain reaction (PCR) is a method widely used to amplify trace amount of nucleic acids. It needs a process of thermocycling (repeated alternation of temperature). Traditional thermocycler relies on bulk size of metal block to achieve thermocycling, which results in high cost and the lack of portability. Here, a PCR chip made of graphene Transparent Conductive Films (TCFs) was employed. The thermocycling of the chip was fulfilled by a temperature programed microcontroller and a cooling fan under a low driving voltage (12V). A 35 cycles PCR was accomplished within 13 minutes using the chip and the thermocycler. The transparency of the graphene PCR chip enables the PCR reaction to be visually monitored by naked eye for a color change. The PCR chip and the thermocycler have a low cost at $2.5 and $6 respectively, and thus are feasible for Point-of-care testing (POCT) of nucleic acids in a disposable manner. The whole platform makes it possible to perform a low-cost testing of nucleic acids for varieties of purposes outside of laboratories or at resource limited locations.

scholarly journals Handyfuge-LAMP: low-cost and electricity-free centrifugation for isothermal SARS-CoV-2 detection in saliva

2020 ◽  
Author(s):  
Ethan Li ◽  
Adam Larson ◽  
Anesta Kothari ◽  
Manu Prakash
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Lamp Assay ◽  
Sample Collection ◽  
Rna Detection ◽  
Open Hardware ◽  
Point Of Care Diagnostics ◽  
Simple Protocol ◽  
Specialized Equipment ◽  
The Cost

AbstractPoint of care diagnostics for COVID-19 detection are vital to assess infection quickly and at the source so appropriate measures can be taken. The loop-mediated isothermal amplification (LAMP) assay has proven to be a reliable and simple protocol that can detect small amounts of viral RNA in patient samples (<10 genomes per μL) (Nagamine, Hase, and Notomi 2002). Recently, Rabe and Cepko at Harvard published a sensitive and simple protocol for COVID-19 RNA detection in saliva using an optimized LAMP assay (Rabe and Cepko, 2020).This LAMP protocol has the benefits of being simple, requiring no specialized equipment; rapid, requiring less than an hour from sample collection to readout; and cheap, costing around $1 per reaction using commercial reagents. The pH based colorimetric readout also leaves little ambiguity and is intuitive. However, a shortfall in many nucleic acid-based methods for detection in saliva samples has been the variability in output due to the presence of inhibitory substances in saliva. Centrifugation to separate the reaction inhibitors from inactivated sample was shown to be an effective way to ensure reliable LAMP amplification. However, a centrifuge capable of safely achieving the necessary speeds of 2000 RPM for several minutes often costs hundreds of dollars and requires a power supply.We present here an open hardware solution- Handyfuge - that can be assembled with readily available components for the cost of <5 dollars a unit and could be used together with the LAMP assay for point of care detection of COVID-19 RNA from saliva. The device is then validated using the LAMP protocol from Rabe and Cepko. With the use of insulated coolers for reagent supply chain and delivery, the assay presented can be completed without the need for electricity or any laboratory scale infrastructure.

scholarly journals Development of a LAMP Method for Detecting SDHI Fungicide Resistance in Botrytis cinerea

Plant Disease ◽  
2018 ◽  
Vol 102 (8) ◽  
pp. 1612-1618 ◽  
Author(s):  
F. Fan ◽  
W. X. Yin ◽  
G. Q. Li ◽  
Y. Lin ◽  
C. X. Luo
Keyword(s):  
Succinate Dehydrogenase ◽  
Botrytis Cinerea ◽  
High Efficiency ◽  
Color Change ◽  
Low Cost ◽  
Point Mutations ◽  
Lamp Assay ◽  
High Specificity ◽  
Lamp Method ◽  
Development Of Resistance

Resistance to succinate dehydrogenase inhibitors (SDHI) in Botrytis cinerea is associated with point mutations in the target gene succinate dehydrogenase subunit B (SdhB). The substitution from histidine to arginine at codon 272 (H272R) is currently the predominant mutation in SDHI-resistant populations in B. cinerea worldwide. In order to monitor the development of resistance to SDHI, a rapid, simple, and efficient method with high specificity to the H272R point mutation was developed based on loop-mediated isothermal amplification (LAMP). To specifically detect the H272R mutation, a set of four primers was designed based on the sequence of SdhB, and the LAMP reaction was optimized. When SYBR Green I was added after reaction, only samples with the H272R mutation showed the color change (from brown to fluorescent yellow), indicating that this set of primers could successfully discriminate the H272R genotype from other genotypes. Specificity and accuracy tests showed that this LAMP assay had high specificity and accuracy. Moreover, the LAMP method was further simplified with fungal mycelia and conidia as the amplification template which could be prepared within 5 min. Due to the low cost, simplicity, high efficiency, and specificity, the developed LAMP assay may contribute to the monitoring of resistance development to SDHI in B. cinerea, especially in field and high-throughput experiments.

scholarly journals Real-Time Fluorometric Isothermal LAMP Assay for Detection of Chlamydia pecorum in Rapidly Processed Ovine Abortion Samples: A Veterinary Practitioner’s Perspective

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1157
Author(s):  
Tom Clune ◽  
Susan Anstey ◽  
Vasilli Kasimov ◽  
Caroline Jacobson ◽  
Martina Jelocnik
Keyword(s):  
Point Of Care ◽  
Low Cost ◽  
Lamp Assay ◽  
Test Results ◽  
Tissue Samples ◽  
Chlamydia Pecorum ◽  
Foetal Liver ◽  
Polymerase Chain ◽  
Foetal Lung ◽  
Positive Agreement

Traditional methods of detecting Chlamydia pecorum in tissue samples such as polymerase chain reaction or cell culture are laborious and costly. We evaluated the use of a previously developed C. pecorum LAMP assay using minimally processed ovine samples. Cotyledon (n = 16), foetal liver (n = 22), foetal lung (n = 2), and vaginal (n = 6) swabs, in addition to cotyledon (n = 6) and foetal liver (n = 8) tissue samples, were rapidly processed and used for LAMP testing without DNA extraction. Overall, LAMP test results were highly congruent with the in-house reference qPCR, with 80.43% (37/46; 72.73% positive agreement (PA); 84.75% negative agreement (NA)) overall agreeance for swab samples, and 85.71% (12/14; 80% PA; 88.89% NA) overall agreeance for tissue samples. Out of the 11 total discrepant results, discrepancy was mainly observed in samples (n = 10) with less than 100 copies/µL C. pecorum DNA. While sensitivity could be improved, the simplicity, low cost, and accuracy of detection makes this test amenable for use at point-of-care for detecting C. pecorum in sheep.

scholarly journals A Robust, Low-Cost Instrument for Real-time Colorimetric Isothermal Nucleic Acid Amplification

2021 ◽  
Author(s):  
Frank Myers ◽  
Brian Moffatt ◽  
Ragheb El Khaja ◽  
Titash Chatterjee ◽  
Gurmeet Marwaha ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Real Time ◽  
Point Of Care ◽  
Low Cost ◽  
Lamp Assay ◽  
Nucleic Acid Amplification ◽  
Diagnostic Assays ◽  
Isothermal Nucleic Acid Amplification ◽  
Point Of Care Diagnostics ◽  
Time Readout

The COVID-19 pandemic has highlighted the need for broader access to molecular diagnostics. Colorimetric isothermal nucleic acid amplification assays enable simplified instrumentation over more conventional PCR diagnostic assays and, as such, represent a promising approach for addressing this need. In particular, colorimetric LAMP (loop-mediated isothermal amplification) has received a great deal of interest recently. However, there do not currently exist robust instruments for performing these kinds of assays in high throughput with real-time readout of amplification signals. To address this need, we developed LARI, the LAMP Assay Reader Instrument. We have deployed over 50 LARIs for routine use in R&D and production environments, with over 12,000 assays run to date. In this paper, we present the design and construction of LARI along with thermal, optical, and assay performance characteristics. LARI can be produced for under $1500 and has broad applications in R&D, point-of-care diagnostics, and global health.

scholarly journals Rapid and sensitive detection of Salmonella species targeting the hilA gene using a loop-mediated isothermal amplification assay

2021 ◽  
Vol 19 (3) ◽  
pp. e30
Author(s):  
Jiyon Chu ◽  
Juyoun Shin ◽  
Shinseok Kang ◽  
Sun Shin ◽  
Yeun-Jun Chung
Keyword(s):  
Point Of Care ◽  
Lamp Assay ◽  
Conventional Polymerase Chain Reaction ◽  
Isothermal Amplification ◽  
Sensitive Detection ◽  
Conventional Pcr ◽  
Pcr Assay ◽  
Loop Mediated Isothermal Amplification ◽  
Amplification Assay ◽  
Specific Amplification

Salmonella species are among the major pathogens that cause foodborne illness outbreaks. In this study, we aimed to develop a loop-mediated isothermal amplification (LAMP) assay for the rapid and sensitive detection of Salmonella species. We designed LAMP primers targeting the hilA gene as a universal marker of Salmonella species. A total of seven Salmonella species strains and 11 non-Salmonella pathogen strains from eight different genera were used in this study. All Salmonella strains showed positive amplification signals with the Salmonella LAMP assay; however, there was no non-specific amplification signal for the non-Salmonella strains. The detection limit was 100 femtograms (20 copies per reaction), which was ~1,000 times more sensitive than the detection limits of the conventional polymerase chain reaction (PCR) assay (100 pg). The reaction time for a positive amplification signal was less than 20 minutes, which was less than one-third the time taken while using conventional PCR. In conclusion, our Salmonella LAMP assay accurately detected Salmonella species with a higher degree of sensitivity and greater rapidity than the conventional PCR assay, and it may be suitable for point-of-care testing in the field.

New two dimensional liquid-phase colorimetric assay based on old iodine–starch complexation for the naked-eye quantitative detection of analytes

2016 ◽  
Vol 52 (47) ◽  
pp. 7454-7457 ◽  
Author(s):  
Jinfang Nie ◽  
Tom Brown ◽  
Yun Zhang
Keyword(s):  
Liquid Phase ◽  
Colorimetric Assay ◽  
Point Of Care ◽  
Low Cost ◽  
Quantitative Detection ◽  
Complexation Reaction ◽  
Two Dimensional ◽  
Eye Detection ◽  
Naked Eye ◽  
Naked Eye Detection

This work describes a new point-of-care two dimensional liquid-phase colorimetric assay (2D LPCA) based on old iodine–starch complexation reaction firstly discovered in 1814 for simple, low-cost, portable, naked-eye detection and quantification of two model analytes.

scholarly journals 2-LED-µSpectrophotometer for Rapid On-Site Detection of Pathogens Using Noble-Metal Nanoparticle-Based Colorimetric Assays

2020 ◽  
Vol 10 (8) ◽  
pp. 2658 ◽  
Author(s):  
Cornelia Reuter ◽  
Matthias Urban ◽  
Manuel Arnold ◽  
Ondrej Stranik ◽  
Andrea Csáki ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Pathogen Detection ◽  
Color Change ◽  
Colorimetric Assay ◽  
Point Of Care ◽  
Colorimetric Detection ◽  
Dna Amplification ◽  
Metal Nanoparticle ◽  
Colorimetric Assays ◽  
Induced Aggregation

Novel point-of-care compatible methods such as colorimetric assays have become increasingly important in the field of early pathogen detection. A simple and hand-held prototype device for carrying out DNA-amplification assay based on plasmonic nanoparticles in the colorimetric detection is presented. The low-cost device with two channels (sample and reference) consists of two spectrally different light emitting diodes (LEDs) for detection of the plasmon shift. The color change of the gold-nanoparticle-DNA conjugates caused by a salt-induced aggregation test is examined in particular. A specific and sensitive detection of the waterborne human pathogen Legionella pneumophila is demonstrated. This colorimetric assay, with a simple assay design and simple readout device requirements, can be monitored in real-time on-site.

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