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Mosaic Patterned SurfacesIn article number 2206274, Yanjun Hu, Lin Li, and co‐workers report a mosaic patterned surface‐based chip that acquires mutually independent and hardly‐volatile capsular droplet arrays. The concept shows high compatibility and practicability, paving the way for the new microfluidic chips used in COVID‐19 diagnosis and other high‐precision detection.
ABSTRACT
Real-time polymerase chain reaction (real-time PCR) tests were successfully conducted in an aluminum-based microfluidic chip developed in this work. The reaction chamber was coated with silicone-modified epoxy resin to isolate the reaction system from metal surfaces, preventing the metal ions from interfering with the reaction process. The patterned aluminum substrate was bonded with a hydroxylated glass mask using silicone sealant at room temperature. The effect of thermal expansion was counteracted by the elasticity of cured silicone. With the heating process closely monitored, real-time PCR testing in reaction chambers proceeded smoothly, and the results show similar quantification cycle values to those of traditional test sets. Scanning electron microscope (SEM) and atomic force microscopy (AFM) images showed that the surface of the reaction chamber was smoothly coated, illustrating the promising coating and isolating properties. Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-optical emission spectrometer (ICP-OES) showed that no metal ions escaped from the metal to the chip surface. Fourier-transform infrared spectroscopy (FTIR) was used to check the surface chemical state before and after tests, and the unchanged infrared absorption peaks indicated the unreacted, antifouling surface. The limit of detection (LOD) of at least two copies can be obtained in this chip.
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Precise detection involving droplets based on functional surfaces is promising for the parallelization and miniaturization of platforms and is significant in epidemic investigation, analyte recognition, environmental simulation, combinatorial chemistry, etc. However, a challenging and considerable task is obtaining mutually independent droplet arrays without cross-contamination and simultaneously avoiding droplet evaporation-caused quick reagent loss, inaccuracy, and failure. Herein, a strategy to generate mutually independent and hardly-volatile capsular droplet arrays using innovative mosaic patterned surfaces is developed. The evaporation suppression of the capsular droplet arrays is 1712 times higher than the naked droplet. The high evaporation suppression of the capsular droplet arrays on the surfaces is attributed to synergistic blocking of the upper oil and bottom mosaic gasproof layer. The scale-up of the capsular droplet arrays, the flexibility in shape, size, component (including aqueous, colloidal, acid, and alkali solutions), liquid volume, and the high-precision hazardous substance testing proves the concept's high compatibility and practicability. The mutually independent capsular droplet arrays with amazingly high evaporation suppression are essential for the new generation of high-performance open-surface microfluidic chips used in COVID-19 diagnosis and investigation, primary screening, in vitro enzyme reactions, environmental monitoring, nanomaterial synthesis, etc.
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The Coronavirus disease 2019 (COVID-19) outbreak has urged the establishment of a global-wide rapid diagnostic system. Current widely-used tests for COVID-19 include nucleic acid assays, immunoassays, and radiological imaging. Immunoassays play an irreplaceable role in rapidly diagnosing COVID-19 and monitoring the patients for the assessment of their severity, risks of the immune storm, and prediction of treatment outcomes. Despite of the enormous needs for immunoassays, the widespread use of traditional immunoassay platforms is still limited by high cost and low automation, which are currently not suitable for point-of-care tests (POCTs). Microfluidic chips with the features of low consumption, high throughput, and integration, provide the potential to enable immunoassays for POCTs, especially in remote areas. Meanwhile, luminescence detection can be merged with immunoassays on microfluidic platforms for their good performance in quantification, sensitivity, and specificity. This review introduces both homogenous and heterogenous luminescence immunoassays with various microfluidic platforms. We also summarize the strengths and weaknesses of the categorized methods, highlighting their recent typical progress. Additionally, different microfluidic platforms are described for comparison. The latest advances in combining luminescence immunoassays with microfluidic platforms for POCTs of COVID-19 are further explained with antigens, antibodies, and related cytokines. Finally, challenges and future perspectives were discussed.
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The spread of microorganisms in the air, especially pathogenic microorganisms, seriously affects people's normal life. Therefore, the analysis and detection of airborne microorganisms is of great importance in environmental detection, disease prevention and biosafety. As an emerging technology with the advantages of integration, miniaturization and high efficiency, microfluidic chips are widely used in the detection of microorganisms in the environment, bringing development vitality to the detection of airborne microorganisms, and they have become a research highlight in the prevention and control of infectious diseases. Microfluidic chips can be used for the detection and analysis of bacteria, viruses and fungi in the air, mainly for the detection of Escherichia coli, Staphylococcus aureus, H1N1 virus, SARS-CoV-2 virus, Aspergillus niger, etc. The high sensitivity has great potential in practical detection. Here, we summarize the advances in the collection and detection of airborne microorganisms by microfluidic chips. The challenges and trends for the detection of airborne microorganisms by microfluidic chips was also discussed. These will support the role of microfluidic chips in the prevention and control of air pollution and major outbreaks.
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Rapid, sensitive, quantitative and patient-friendly diagnostic tools have yet to be developed for COVID-19 continued monitoring at the point-of-care. Here, we present an instrument-free capillary microfluidic chip coupled to a lateral flow module that is compatible with a smartphone application for quantitative detection of SARS-CoV-2 from saliva samples. The microfluidic chip is fully autonomous, and performs aliquoting, sample metering, and sequential delivery of reagents. The limit of detection is 0.07 ng/mL for recombinant nucleocapsid protein in saliva. This rapid antigen test provides results in less than 1 hour, without sacrificing analytical sensitivity. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.
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The SARS-CoV-2 pandemic has elevated the development of novel diagnostic solutions, including rapid nucleic acid amplification tests (NAATs), to a global priority to meet the high demand for accurate, timely viral detection and diagnosis. However, ubiquitously implemented NAATs, such as polymerase chain reaction (PCR), consume hours of testing. We report a field-forward instrument capable of ultra-fast real-time PCR for amplification-based nucleic acid detection in a custom-designed microfluidic chip. Prudent selection and unconventional positioning of thermal cyclers relative to the microfluidic chip and a fluorescent detector permit ultra-fast simultaneous amplification and detection, with 40 cycles complete in under 10 minutes. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.
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We will present a microfluidic assay to detect SARS-CoV-2 RNA from nasopharyngeal swab samples. Our method leverages isotachophoresis (ITP) to integrate sample preparation, RT-LAMP, and CRISPR-based nucleic acid detection in an automatable chip. For the first time, we use ITP to purify, pre-concentrate and isothermally amplify target nucleic acids into a ~1 µL reaction volume on-chip. The device then transitions LAMP amplicons into an on-chip zone containing Cas12-gRNA complexes and reporter molecules to measure target-activated CRISPR activity. We will use our method to automatically detect COVID-19 from nasopharyngeal swab samples. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.
ABSTRACT
Nucleic acid amplification detection is one of the most widely used molecular diagnostic techniques in recent years, which can rapidly and efficiently amplify the characteristic nucleotide sequences of pathogenic bacteria in the diagnosis of infectious diseases, it has been widely used in clinical diagnosis, disease screening and other fields. In this work, we report a micro-cavity digital PCR for rapid detection of pathogens on a silicon-based microfluidic chip. The device has the advantages of high flux, no pumping, rapid reaction, quantification and high sensitivity. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.
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Fast point-of-use detection of, for example, early-stage zoonoses, e.g., Q-fever, bovine tuberculosis, or the Covid-19 coronavirus, is beneficial for both humans and animal husbandry as it can save lives and livestock. The latter prevents farmers from going bankrupt after a zoonoses outbreak. This paper describes the development of a fabrication process and the proof-of-principle of a disposable DNA amplification chip with an integrated heater. Based on the analysis of the milling process, metal adhesion studies, and COMSOL MultiPhysics heat transfer simulations, the first batch of chips has been fabricated and successful multiple displacement amplification reactions are performed inside these chips. This research is the first step towards the development of an early-stage zoonoses detection device. Tests with real zoonoses and DNA specific amplification reactions still need to be done.