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The correct interpretation of the result from a point-of-care device is crucial for an accurate and rapid diagnosis to guide subsequent treatment. Lateral flow tests (LFTs) use a well-established format that was designed to simplify the user experience. However, the LFT device architecture is inherently limited to detecting analytes that can be captured by molecular recognition. Microfluidic paper-based analytical devices (μPADs), like LFTs, have the potential to be used in diagnostic applications at the point of care. However, μPADs have not gained significant traction outside of academic laboratories, in part, because they have often demonstrated a lack of homogeneous shape or color in signal outputs, which consequently can lead to inaccurate interpretation of results by users. Here, we demonstrate a new class of μPADs that form colorimetric signals at the interfaces of converging liquid fronts (i.e., lines) to control where colorimetric signals are formed without relying on capture techniques. We demonstrate our approach by developing assays for three classes of analytes—an ion, an enzyme, and a small molecule—to measure using iron(III), acetylcholinesterase, and lactate, respectively. Additionally, we show these devices have the potential to support multiplexed assays by generating multiple lines in a common readout zone. These results highlight the ability of this new paper-based device architecture to aid the interpretation of assays that create soluble products by using flow to constrain those colorimetric products in a familiar, line-format output. [ABSTRACT FROM AUTHOR]

The article demonstrates the utility of lateral microscopy for correlating cell surface biomarker expression levels with quantitative descriptions of cell morphology. SUP-T1 and CEM CD4+ cells, both of which express similar levels of CD4, experienced average changes in contact angle which are not statistically different from one another on surfaces coated in anti-CD4.The lateral microscopy approach offers a more reproducible and quantitative alternative to evaluate adhesion compared to commonly used wash assays and can be extended to many additional immunophenotyping applications to identify cells of interest within heterogeneous populations.

The article describes a density-based method for removing contaminants, including microorganisms and nonviable cells, from mammalian cell cultures using an aqueous two-phase system (ATPS). The effectiveness of the method in model contaminated cultures of both adherent (HeLa) and suspension (HL-60 II) mammalian cells contaminated with bacteria (E. coli) and yeast (S. cerevisiae), is tested. By removing unwanted cells, desired cell populations can be recovered, and cultures which would otherwise need to be discarded can continue to be used.

A multichannel air displacement pipet with reconfigurable channels for nonstandard liquid handling applications, is developed.Using the pipet, complex paper-based microfluidic devices can be fabricated without requiring multiple, time-consuming motions with a single-channel pipet or device designs limited to the configurations of traditional multichannel pipets. The reconfigurable pipet supports the advancement of custom analytical tools with nonstandard liquid handling requirements and provides an ergonomic alternative to commercial equipment for developers of paper-based devices.

In the wake of the COVID‐19 global pandemic, self‐administered microsampling tools have reemerged as an effective means to maintain routine healthcare assessments without inundating hospitals or clinics. Finger‐stick collection of blood is easily performed at home, in the workplace, or at the point‐of‐care, obviating the need for a trained phlebotomist. While the initial collection of blood is facile, the diagnostic or clinical utility of the sample is dependent on how the sample is processed and stored prior to transport to an analytical laboratory. The past decade has seen incredible innovation for the development of new materials and technologies to collect low‐volume samples of blood with excellent precision that operate independently of the hematocrit effect. The final application of that blood (i.e., the test to be performed) ultimately dictates the collection and storage approach as certain materials or chemical reagents can render a sample diagnostically useless. Consequently, there is not a single microsampling tool that is capable of addressing every clinical need at this time. In this review, we highlight technologies designed for patient‐centric microsampling blood at the point‐of‐care and discuss their utility for quantitative sampling as a function of collection material and technique. In addition to surveying methods for collecting and storing whole blood, we emphasize the need for direct separation of the cellular and liquid components of blood to produce cell‐free plasma to expand clinical utility. Integrating advanced functionality while maintaining simple user operation presents a viable means of revolutionizing self‐administered microsampling, establishing new avenues for innovation in materials science, and expanding access to healthcare. [ABSTRACT FROM AUTHOR]

The article describes the development of a multiplexed, patterned paper immunoassay for the detection of biomarkers of malaria and dengue fever : malaria HRP2, malaria pLDH, and dengue NS1 type 2. It demonstrates the analytical performances of paper-based assays for each biomarker and shows that there is no significant difference in performance between the multiplexed immunoassay and those immunoassays performed in singleplex. The results suggest multiplex paper-based devices can be an essential component of diagnostic assays used at the point-of-care.

The article provides a method to produce hybrid gradients in apparent density by combining aqueous multiphase (AMPS) and magnetic levitation (MagLev) systems. The mixtures of objects with large differences in density can be separated and analyzed by combining these two approaches. The results suggest that combining steps in density with gradients in density can enable new classes of separations based on density.