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Carlos Abelardo Dos Santos

Bio: Carlos Abelardo Dos Santos is an academic researcher from Universidade Federal de Goiás. The author has contributed to research in topics: Loop-mediated isothermal amplification & Nucleic acid amplification technique. The author has an hindex of 1, co-authored 2 publications receiving 7 citations.

Papers
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Journal ArticleDOI
22 Feb 2021-Analyst
TL;DR: In this paper, a polystyrene-toner (PS-T) centrifugal microfluidic device was used for molecular diagnosis of COVID-19 by RT-LAMP, with integrated and automated colorimetric detection.
Abstract: Infection caused by the new coronavirus (SARS-CoV-2) has become a serious worldwide public health problem, and one of the most important strategies for its control is mass testing. Loop-mediated isothermal amplification (LAMP) has emerged as an important alternative to simplify the diagnostics of infectious diseases. In addition, an advantage of LAMP is that it allows for easy reading of the final result through visual detection. However, this step must be performed with caution to avoid contamination and false-positive results. LAMP performed on microfluidic platforms can minimize false-positive results, in addition to having potential for point-of-care applications. Here, we describe a polystyrene-toner (PS-T) centrifugal microfluidic device manually controlled by a fidget spinner for molecular diagnosis of COVID-19 by RT-LAMP, with integrated and automated colorimetric detection. The amplification was carried out in a microchamber with 5 μL capacity, and the reaction was thermally controlled with a thermoblock at 72 °C for 10 min. At the end of the incubation time, the detection of amplified RT-LAMP fragments was performed directly on the chip by automated visual detection. Our results demonstrate that it is possible to detect COVID-19 in reactions initiated with approximately 10-3 copies of SARS-CoV-2 RNA. Clinical samples were tested using our RT-LAMP protocol as well as by conventional RT-qPCR, demonstrating comparable performance to the CDC SARS-CoV-2 RT-qPCR assay. The methodology described in this study represents a simple, rapid, and accurate method for rapid molecular diagnostics of COVID-19 in a disposable microdevice, ideal for point-of-care testing (POCT) systems.

39 citations

Journal ArticleDOI
TL;DR: In this article, a colorimetric Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) was used to detect SARS-CoV-2 using different protocols.
Abstract: SARS-CoV-2 currently represents a serious global public health problem. Non-pharmaceutical intervention measures (NPIs) have been widely adopted, and the testing strategy since the beginning of the infection is the most effective tool for tracking, isolating, and minimizing transmission. The high operating costs and the need for sophisticated instrumentation related to gold standard diagnostic for COVID-19, Reverse Transcription quantitative Polymerase Chain Reaction (RT-qPCR), have highlighted the urgency and importance of developing and applying new diagnostic techniques, especially in places with scarce resources. Thus, alternative molecular tests, such as Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP), based on isothermal amplification have been used to detect SARS-CoV-2 using different protocols. The potential for field application of RT-LAMP is due to the lower cost and time and not requiring high-cost instrumentation. Here, we evaluate the colorimetric RT-LAMP to detect SARS-CoV-2 in a hospital environment and correlate its performance with tests performed in a reference laboratory. The analysis performed at the hospital showed high sensitivity (88.89%), specificity (98.55%), accuracy (95.83%), and a Cohen's kappa of 0.895. However, we achieved 100% of agreement when comparing the RT-LAMP results with the gold standard (qRT-PCR) results for samples with Ct < 30 in the hospital-based test. In addition, a similar performance was found in the field compared to the reference laboratory, corroborating the proposal to apply the test directly at point-of-care.

5 citations


Cited by
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Journal ArticleDOI
14 Aug 2021
TL;DR: In this article, a paper-based device was developed to detect nucleic acids of pathogens of interest in complex samples using loop-mediated isothermal amplification (LAMP) by producing a colorimetric response visible to the human eye.
Abstract: Herein, we describe the development of a paper-based device to detect nucleic acids of pathogens of interest in complex samples using loop-mediated isothermal amplification (LAMP) by producing a colorimetric response visible to the human eye. To demonstrate the utility of this device in emerging public health emergencies, we developed and optimized our device to detect SARS-CoV-2 in human saliva without preprocessing. The resulting device was capable of detecting the virus within 60 min and had an analytical sensitivity of 97% and a specificity of 100% with a limit of detection of 200 genomic copies/μL of patient saliva using image analysis. The device consists of a configurable number of reaction zones constructed of Grade 222 chromatography paper separated by 20 mil polystyrene spacers attached to a Melinex® backing via an ARclean® double-sided adhesive. The resulting device is easily configurable to detect multiple targets and has the potential to detect a variety of pathogens simply by changing the LAMP primer sets.

31 citations

Journal ArticleDOI
TL;DR: In this paper, the potential of isothermal amplification combined with the revolutionary CRISPR/Cas system for a more powerful detection tool is also critically reviewed and the commercial success of several isothermal methods in the pandemic and different variants of SARS-CoV-2 and their implication on disease diagnosis are discussed.

18 citations

Journal ArticleDOI
TL;DR: A review of microfluidics-based molecular diagnostics for infectious diseases from academic perspectives and industrial outlooks is presented in this paper , where four categories of micro-fluidic platforms are compared with respect to features, merits, and demerits.
Abstract: Traditional diagnostic strategies for infectious disease detection require benchtop instruments that are inappropriate for point-of-care testing (POCT). Emerging microfluidics, a highly miniaturized, automatic, and integrated technology, are a potential substitute for traditional methods in performing rapid, low-cost, accurate, and on-site diagnoses. Molecular diagnostics are widely used in microfluidic devices as the most effective approaches for pathogen detection. This review summarizes the latest advances in microfluidics-based molecular diagnostics for infectious diseases from academic perspectives and industrial outlooks. First, we introduce the typical on-chip nucleic acid processes, including sample preprocessing, amplification, and signal read-out. Then, four categories of microfluidic platforms are compared with respect to features, merits, and demerits. We further discuss application of the digital assay in absolute nucleic acid quantification. Both the classic and recent microfluidics-based commercial molecular diagnostic devices are summarized as proof of the current market status. Finally, we propose future directions for microfluidics-based infectious disease diagnosis.

18 citations

Journal ArticleDOI
TL;DR: An integrated microfluidic platform (IMP) utilizing real-time reverse-transcription loop-mediated isothermal amplification (RT-LAMP) was developed in this article for detection and quantification of three genes of SARS-CoV-2.
Abstract: An integrated microfluidic platform (IMP) utilizing real-time reverse-transcription loop-mediated isothermal amplification (RT-LAMP) was developed here for detection and quantification of three genes of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; i.e., coronavirus diseases 2019 (COVID-19)): RNA-dependent RNA polymerase, the envelope gene, and the nucleocapsid gene for molecular diagnosis. The IMP comprised a microfluidic chip, a temperature control module, a fluidic control module that collectively carried out viral lysis, RNA extraction, RT-LAMP, and the real-time detection within 90 min in an automatic format. A limit of detection of 5 × 103 copies/reaction for each gene was determined with three samples including synthesized RNAs, inactive viruses, and RNAs extracted from clinical samples; this compact platform could be a useful tool for COVID-19 diagnostics.

18 citations

Journal ArticleDOI
TL;DR: In this article , a comprehensive study of the literature, several promising isothermal amplification methods for the detection of SARS-CoV-2 are critically reviewed that can also be applied to other infectious viruses detection.

18 citations