[Visualization analysis of microfluidics research status]

Microfluidics is the science and technology to manipulate small amounts of fluids in micro/nano-scale space. Multiple modules could be integrated into microfluidic device, and due to its advantages of microminiaturization and controllability, microfluidics has drawn extensive attention since its birth. In this paper, the literature data related to microfluidics research from January 1, 2006 to December 31, 2021 were obtained from Web of Science Core Collection database. CiteSpace 5.8.R3 software was used for bibliometrics analysis, so as to explore the research progress and development trends of microfluidics research at home and abroad. Based on the analysis of 50 129 articles, it could be seen that microfluidics was a hot topic of global concern, and the United States had a certain degree of authority in this field. Massachusetts Institute of Technology and Harvard University not only had a high number of publications, but also had strong influence and extensive cooperation network. Combined with ultrasonic, surface modification and sensor technology, researchers constructed paper-based microfluidic, droplet microfluidic and digital microfluidic platforms, which were applied in the field of immediate diagnosis, nucleic acid and circulating tumor cell analysis of in vitro diagnosis and organ-on-a-chip. China was one of the countries with a high level of research in the field of microfluidics, while the industrialization of high-end products needed to be improved. As people's demand for disease risk prediction and health management increased, promoting microfluidic technological innovation and achievement transformation is of great significance to safeguard people's life and health.

An enzymatic nucleic acid vertical flow assay

Vertical flow assays have been developed in recent years addressing limitations of the lateral flow assays, including limited multiplexing capability, quantitation, and hook effect. In the present study, the first passive paper-based vertical flow assay is developed for the detection of the nucleic acid target. Horseradish peroxidase was used as an enzymatic tracer with a high potential for signal amplification. In order to achieve the best signal-to-noise ratio, different parameters of paper-based assays were optimized. The sample is heat denatured and hybridized with a specific probe to form a dual-labeled hybridization complex. A small volume of diluted sample, 12 µl, can be analyzed within 6 min on the assay in a sandwich format. Assay specificity was evaluated by testing different unrelated samples, and also, 1.7 nM was obtained as the limit of detection (LOD) using the 0 + 3SD method, which is equivalent to 8.5 fmol of double-stranded DNA in the 12 µl sample volume. The linear range of 3-194 nM with a 0.978 correlation coefficient was obtained according to the calibration curve. The developed assay was evaluated with 45 hepatitis B virus clinical plasma samples, and the result showed 100% consistency of the assay with the real-time PCR benchmark. In the present study, we sought to develop a mere detection system for nucleic acid targets, and to investigate the possibility of using enzyme reporter in a passive vertical flow assay.

Type-I Interferon assessment in 45 minutes using the FilmArray® PCR platform in SARS-CoV-2 and other viral infections

Low concentrations of type‐I interferon (IFN) in blood seem to be associated with more severe forms of Coronavirus disease 2019 (COVID‐19). However, following the type‐I interferon response (IR) in early stage disease is a major challenge. We evaluated detection of a molecular interferon signature on a FilmArray® system, which includes PCR assays for four interferon stimulated genes. We analyzed three types of patient populations: (i) children admitted to a pediatric emergency unit for fever and suspected infection, (ii) ICU‐admitted patients with severe COVID‐19, and (iii) healthcare workers with mild COVID‐19. The results were compared to the reference tools, that is, molecular signature assessed with Nanostring® and IFN‐α2 quantification by SIMOA® (Single MOlecule Array). A strong correlation was observed between the IR measured by the FilmArray®, Nanostring®, and SIMOA® platforms (r‐Spearman 0.996 and 0.838, respectively). The FilmArray® panel could be used in the COVID‐19 pandemic to evaluate the IR in 45‐min with 2 min hand‐on‐time at hospitalization and to monitor the IR in future clinical trials.

Characterization and Separation of Cancer Cells with a Wicking Fiber Device

Current cancer diagnostic methods lack the ability to quickly, simply, efficiently, and inexpensively screen cancer cells from a mixed population of cancer and normal cells. Methods based on biomarkers are unreliable due to complexity of cancer cells, plasticity of markers, and lack of common tumorigenic markers. Diagnostics are time intensive, require multiple tests, and provide limited information. In this study, we developed a novel wicking fiber device that separates cancer and normal cell types. To the best of our knowledge, no previous work has used vertical wicking of cells through fibers to identify and isolate cancer cells. The device separated mouse mammary tumor cells from a cellular mixture containing normal mouse mammary cells. Further investigation showed the device separated and isolated human cancer cells from a heterogeneous mixture of normal and cancerous human cells. We report a simple, inexpensive, and rapid technique that has potential to identify and isolate cancer cells from large volumes of liquid samples that can be translated to on-site clinic diagnosis.

Six years of INSTAND e. V. sIgE proficiency testing: An evaluation of in vitro allergy diagnostics

Background

Even though allergies are an important health issue, wide manufacturer-dependent differences in the detected amounts of allergen-specific IgE (sIgE) have repeatedly been found. These discrepancies hinder diagnostics and research into clinically significant cutoff points for life-threatening symptoms.

Methods

To evaluate whether the reported differences have led to changes in diagnostic testing, we analyzed data from six years of round robin testing (RRT, also known as proficiency testing) at the Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien e.V.  (Society for Promoting Quality Assurance in medical Laboratories) for the important allergen sources bee venom, wasp venom, and birch pollen. The results of the four main suppliers of in vitro diagnostic sIgE testing were compared in a pseudo-anonymized form using overlay images of box plot graphs for the semiquantitative data and allergen class results. Coefficients of variation (CV) were obtained to study the development of interlaboratory comparability.

Results

We found that the large differences between the manufacturer collectives remained constant between January 2010 and April 2015 without any real improvement. The CVs were good for two of the four analyzed suppliers, one was marginal and one above the quality level of 20%.

Conclusion

The numerous publications that have found discrepancies in the sIgE results of the different suppliers did not change the status quo within the last six years. Unfortunately, this is unlikely to change until there is a characterized standard material with known values of sIgE.

A novel delivery platform based on Bacteriophage MS2 virus-like particles

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Here we reviewed Bacteriophage MS2 virus-like particles, including introduction to their structure, their potential as a delivery platform, and their expected use in medicine and other fields.

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Bacteriophage MS2 virus-like particles represent the novel delivery platform.

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Bacteriophage MS2 virus-like particles possess promising application prospect.

Our objective here is to review the novel delivery platform based on Bacteriophage MS2 virus-like particles (VLPs), including introduction to their structure, their potential as a delivery platform, and their expected use in medicine and other fields. Bacteriophage MS2 VLPs are nanoparticles devoid of viral genetic material and can self-assemble from the coat protein into an icosahedral capsid. As a novel delivery platform, they possess numerous features that make them suitable and attractive for targeted delivery of RNAs or DNAs, epitope peptides, and drugs within the protein capsid. In short, as a novel delivery platform, MS2 VLPs are suitable for delivery of targeted agents and hold promise for use in diagnostics, vaccines, and therapeutic modalities.