Detect early stage lung cancer by a LAMP microfluidic chip system with a real-time fluorescent filter processor

Microfluidics Technology in SARS-CoV-2 Diagnosis and Beyond: A Systematic Review

With the progression of the COVID-19 pandemic, new technologies are being implemented for more rapid, scalable, and sensitive diagnostics. The implementation of microfluidic techniques and their amalgamation with different detection techniques has led to innovative diagnostics kits to detect SARS-CoV-2 antibodies, antigens, and nucleic acids. In this review, we explore the different microfluidic-based diagnostics kits and how their amalgamation with the various detection techniques has spearheaded their availability throughout the world. Three other online databases, PubMed, ScienceDirect, and Google Scholar, were referred for articles. One thousand one hundred sixty-four articles were determined with the search algorithm of microfluidics followed by diagnostics and SARS-CoV-2. We found that most of the materials used to produce microfluidics devices were the polymer materials such as PDMS, PMMA, and others. Centrifugal force is the most commonly used fluid manipulation technique, followed by electrochemical pumping, capillary action, and isotachophoresis. The implementation of the detection technique varied. In the case of antibody detection, spectrometer-based detection was most common, followed by fluorescence-based as well as colorimetry-based. In contrast, antigen detection implemented electrochemical-based detection followed by fluorescence-based detection, and spectrometer-based detection were most common. Finally, nucleic acid detection exclusively implements fluorescence-based detection with a few colorimetry-based detections. It has been further observed that the sensitivity and specificity of most devices varied with implementing the detection-based technique alongside the fluid manipulation technique. Most microfluidics devices are simple and incorporate the detection-based system within the device. This simplifies the deployment of such devices in a wide range of environments. They can play a significant role in increasing the rate of infection detection and facilitating better health services.

A fully automated centrifugal microfluidic system for sample-to-answer viral nucleic acid testing

The outbreak of virus-induced infectious diseases poses a global public-health challenge. Nucleic acid amplification testing (NAAT) enables early detection of pandemic viruses and plays a vital role in preventing onward transmission. However, the requirement of skilled operators, expensive instrumentation, and biosafety laboratories has hindered the use of NAAT for screening and diagnosis of suspected patients. Here we report development of a fully automated centrifugal microfluidic system with sample-in-answer-out capability for sensitive, specific, and rapid viral nucleic acid testing. The release of nucleic acids and the subsequent reverse transcription loop-mediated isothermal amplification (RT-LAMP) were integrated into the reaction units of a microfluidic disc. The whole processing steps such as injection of reagents, fluid actuation by rotation, heating and temperature control, and detection of fluorescence signals were carried out automatically by a customized instrument. We validate the centrifugal microfluidic system using oropharyngeal swab samples spiked with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) armored RNA particles. The estimated limit of detection for armored RNA particles is 2 copies per reaction, the throughput is 21 reactions per disc, and the assay sample-to-answer time is approximately 70 min. This enclosed and automated microfluidic system efficiently avoids viral contamination of aerosol, and can be readily adapted for virus detection outside the diagnostic laboratory.

Polymerase chain reaction in microfluidic devices

The invention of the polymerase chain reaction (PCR) has caused a revolution in molecular biology, giving access to a method of amplifying deoxyribonucleic acid (DNA) molecules across several orders of magnitude. Since the first application of PCR in a microfluidic device was developed in 1998, an increasing number of researchers have continued the development of microfluidic PCR systems. In this review, we introduce recent developments in microfluidic-based space and time domain devices as well as discuss various designs integrated with multiple functions for sample preparation and detection. The development of isothermal nucleic acid amplification and digital PCR microfluidic devices within the last five years is also highlighted. Furthermore, we introduce various commercial microfluidic PCR devices.

A smart device for label-free and real-time detection of gene point mutations based on the high dark phase contrast of vapor condensation

A smart device for label-free and real-time detection of gene point mutation-related diseases was developed based on the high dark phase contrast of vapor condensation. The main components of the device included a Peltier cooler and a mini PC board for image processing. Heat from the hot side of the Peltier cooler causes the fluid in a copper chamber to evaporate, and the vapor condenses on the surface of a microarray chip placed on the cold side of the cooler. The high dark phase contrast of vapor condensation relative to the analytes on the microarray chip was explored. Combined with rolling circle amplification, the device visualizes less-to-more hydrophilic transitions caused by gene trapping and DNA amplification. A lung cancer gene point mutation was analysed, proving the high selectivity and multiplex analysis capability of this low-cost device.

fM to aM nucleic acid amplification for molecular diagnostics in a non-stick-coated metal microfluidic bioreactor

A sensitive DNA isothermal amplification method for the detection of DNA at fM to aM concentrations for pathogen identification was developed using a non-stick-coated metal microfluidic bioreactor. A portable confocal optical detector was utilized to monitor the DNA amplification in micro- to nanoliter reaction assays in real-time, with fluorescence collection near the optical diffraction limit. The non-stick-coated metal microfluidic bioreactor, with a surface contact angle of 103°, was largely inert to bio-molecules, and DNA amplification could be performed in a minimum reaction volume of 40 nL. The isothermal nucleic acid amplification for Mycoplasma pneumoniae identification in the non-stick-coated microfluidic bioreactor could be performed at a minimum DNA template concentration of 1.3 aM, and a detection limit of three copies of genomic DNA was obtained. This microfluidic bioreactor offers a promising clinically relevant pathogen molecular diagnostic method via the amplification of targets from only a few copies of genomic DNA from a single bacterium.

Development and evaluation of a real-time fluorogenic loop-mediated isothermal amplification assay integrated on a microfluidic disc chip (on-chip LAMP) for rapid and simultaneous detection of ten pathogenic bacteria in aquatic animals

Rapid, low-cost, and user-friendly strategies are urgently needed for early disease diagnosis and timely treatment, particularly for on-site screening of pathogens in aquaculture. In this study, we successfully developed a real-time fluorogenic loop-mediated isothermal amplification assay integrated on a microfluidic disc chip (on-chip LAMP), which was capable of simultaneously detecting 10 pathogenic bacteria in aquatic animals, i.e., Nocardia seriolae, Pseudomonas putida, Streptococcus iniae, Vibrio alginolyticus, Vibrio anguillarum, Vibrio fluvialis, Vibrio harveyi, Vibrio parahaemolyticus, Vibrio rotiferianus, and Vibrio vulnificus. The assay provided a nearly-automated approach, with only a single pipetting step per chip for sample dispensing. This technique could achieve limits of detection (LOD) ranging from 0.40 to 6.42pg per 1.414μL reaction in less than 30 min. The robust reproducibility was demonstrated by a little variation among duplications for each bacterium with the coefficient of variation (CV) for time to positive (Tp) value less than 0.10. The clinical sensitivity and specificity of this on-chip LAMP assay in detecting field samples were 96.2% and 93.8% by comparison with conventional microbiological methods. Compared with other well-known techniques, on-chip LAMP assay provides low sample and reagent consumption, ease-of-use, accelerated analysis, multiple bacteria and on-site detection, and high reproducibility, indicating that such a technique would be applicable for on-site detection and routine monitoring of multiple pathogens in aquaculture.

A novel HBV genotypes detecting system combined with microfluidic chip, loop-mediated isothermal amplification and GMR sensors

Genotyping of hepatitis B virus (HBV) can be used for clinical effective therapeutic drug-selection. A novel microfluidic biochip for HBV genotyping has been fabricated, for the first time, integrating loop-mediated isothermal amplification (LAMP), line probes assay (LiPA) and giant magnetoresistive (GMR) sensors. Coupling LAMP with LiPA in microfluidic chip shortened reaction time substantially, and combining LAMP with GMR sensor enabled limit of detection to attain 10 copies mL(-1) target HBV DNA molecules in 1 h. Furthermore, the independent designed GMR sensors and microfluidic chip can decrease manufacturing cost and patient's test-cost, and facilitate GMR detector repeating use for signal detection. In addition, the detection system has a lower background signal owing to application of superparamagnetic nanoclusters. And it can be expected to use for multiple target molecules synchronous detection in microfluidic chip based on a characteristic of stationary reaction temperature of LAMP. In conclusion, the neoteric detecting system is well suitable for quick genotyping diagnosis of clinical HBV and other homothetic biomolecule detection in biological and medical fields.