Loop-mediated isothermal amplification in disposable polyester-toner microdevices

Rapid molecular diagnostics of COVID-19 by RT-LAMP in a centrifugal polystyrene-toner based microdevice with end-point visual detection

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.

Recent Advances and Applications of Microfluidic Capillary Electrophoresis: A Comprehensive Review (2017-Mid 2019)

Microfluidic capillary electrophoresis (MCE) is the novel technique resulted from the CE mininaturization as planar separation and analysis device. This review presents and discusses various application fields of this advanced technology published in the period 2017 till mid-2019 in eight different sections including clinical, biological, single cell analysis, environmental, pharmaceuticals, food analysis, forensic and ion analysis. The need for miniaturization of CE and the consequence advantages achieved are also discussed including high-throughput, miniaturized detection, effective separation, portability and the need for micro- or even nano-volume of samples. Comprehensive tables for the MCE applications in the different studied fields are provided. Also, figure comparing the number of the published papers applying MCE in the eight discussed fields within the studied period is included. The future investigation should put into consideration the possibility of replacing conventional CE with the MCE after proper validation. Suitable validation parameters with their suitable accepted ranges should be tailored for analysis methods utilizing such unique technique (MCE).

Ten-minute direct detection of Zika virus in serum samples by RT-LAMP

Zika virus (ZIKV) is a current threat to global health. In most of cases, ZIKV infection has no symptoms; however in some cases, ZIKV can cause paralysis (Guillain-Barré syndrome), and in pregnant women, it can cause birth defects in infants. Rapid and accurate diagnosis can help improve disease control as well as being vital to prenatal care for women living in endemic areas. Molecular diagnostics based on isothermal amplification techniques are an excellent alternative to conventional methods of DNA amplification, such as PCR. Here, we develop and optimized a rapid and sensitive method for direct detection of ZIKV in Serum samples based on RT-LAMP and visual detection. The reaction was thermally controlled with a thermoblock for 10 min at 72 °C. The results show that the use of the Bst 3.0 enzyme and an adequate optimization can further reduce the time needed for the RT-LAMP reaction to detect ZIKV. Our results demonstrate that it is possible to detect ZIKV through RT-LAMP directly from a Serum sample, without prior RNA extraction. As little as 10^-3 copies of RNA in a 10 μL reaction (20 zepto-molar) was detected by RT-LAMP from a panel of 51 Serum samples (16 samples from pregnant women and 35 samples from newborns infected with ZIKV during pregnancy). The RT-LAMP has proven to be a valuable tool for molecular diagnosis of Zika, presenting a great potential for point-of-care applications, especially in developing countries.