This article describes a 3D microfluidic paper-based analytical device that can be used to conduct an enzyme-linked immunosorbent assay (ELISA). The device comprises two parts: a sliding strip (which contains the active sensing area) and a structure surrounding the sliding strip (which holds stored reagents—buffers, antibodies, and enzymatic substrate—and distributes fluid). Running an ELISA involves adding sample (e.g. blood) and water, moving the sliding strip at scheduled times, and analyzing the resulting color in the sensing area visually or using a flatbed scanner. We demonstrate that this device can be used to detect C-reactive protein (CRP)—a biomarker for neonatal sepsis, pelvic inflammatory disease, and inflammatory bowel diseases—at a concentration range of 1–100 ng/mL in 1000-fold diluted blood (1–100 µg/mL in undiluted blood). The accuracy of the device (as characterized by the area under the receiver operator characteristics curve) is 89% and 83% for cut-offs of 10 ng/mL (for neonatal sepsis and pelvic inflammatory disease) and 30 ng/mL (for inflammatory bowel diseases) CRP in 1000-fold diluted blood respectively. In resource-limited settings, the device can be used as a part of a kit (containing the device, a fixed-volume capillary, a pre-filled tube, a syringe, and a dropper); this kit would cost ~ $0.50 when produced in large scale (>100,000 devices/week). This kit has the technical characteristics to be employed as a pre-screening tool, when combined with other data such as patient history and clinical signs.

Development of a set of C•G-to-G•C transversion base editors from CRISPRi screens, targetlibrary analysis, and machine learningThe MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. CitationKoblan, Luke W. et al. "Development of a set of C•G-to-G•C transversion base editors from CRISPRi screens, target-library analysis, and machine learning." Nature Biotechnology (June 2021): dx.

An inexpensive at-home quantitative analysis activity was developed for the determination of glucose in unknown samples using paper-based microfluidic devices. All of the materials and reagents for the activity fit in a small kit that was mailed to students. The only items students needed to supply were water and a smartphone. Microgram quantities of glucose were dried down in microcentrifuge tubes and included in the kit so that students could prepare external standards. Student results distinguished between two different concentrations of glucose that served as unknown samples. The combination of paper-based devices and dried-down microgram quantities of reagents provides a foundation for the development of other at-home or in-person experiments.

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