Paper-Based Blood Typing Device That Reports Patient’s Blood Type “in Writing”

Rapid and easily identifiable blood typing on microfluidic cotton thread-based analytical devices

In this study, we present a novel swing-elution-based method to achieve rapid, cost-effective, and easily identifiable blood typing assays. Specifically, the method aims to swing the microfluidic cotton thread-based analytical devices (μCTADs) in PBS solution to effectively elute free red blood cells (RBCs) and allow large agglutinated RBCs to remain to precisely determine the blood type. In order to ensure an easily identifiable blood typing assay, fast swing mode needs to be used, and the elution time is evaluated to be >50 seconds. The created μCTADs have been used to successfully classify ABO and RhD blood types in 56 blood samples. Finally, in order to enhance the convenience and portability of blood typing, a blood-typing chip that utilizes a PBS liquid bridge to effectively elute the free RBCs is designed and fabricated based on the above swing-elution principle. Compared with the traditional wicking-elution methods that rely on the wicking effect to weakly elute the RBCs, our method possesses a stronger elution effect to remove the free RBCs inside the inter-fiber gaps or adhered to the fiber surface, resulting in effectively enhancing the identifiability of the elution results and minimizing user interpretation error. Given the simplicity of the blood typing method, we believe that our blood typing method has great potential to be widely applied in resource-limited and developing regions.

High-performance blood plasma separation based on a Janus membrane technique and RBC agglutination reaction

Separation of plasma which is full of various biomarkers is critical for clinical diagnosis. However, the point-of-care plasma separation often relies on microfluidic filtration membranes which are usually limited in purity, yield, hemolysis, extraction speed, hematocrit level, and protein recovery. Here, we have developed a high-performance plasma membrane separation technique based on a Janus membrane and red blood cell (RBC) agglutination reaction. The RBC agglutination reaction can form larger RBC aggregates to separate plasma from blood cells. Then, the Janus membrane, serving as a multipore microfilter to block large RBC aggregates, allows the plasma to flow from the hydrophobic side to its hydrophilic side spontaneously. As a result, the separation technique can extract highly-purified plasma (99.99%) from whole blood with an ultra-high plasma yield (∼80%) in ∼80 s. Additionally, the separation technique is independent of the hematocrit level and can avoid hemolysis.

Paper based analytical devices for blood grouping: a comprehensive review

The clinical importance of blood group (BG) antigens is related to their ability to induce immune antibodies that can cause hemolysis. Yet, ABO and D (Rh) are still considered to be the key antigens for healthy blood transfusion and secondary antigens are the next priority. Serological typing is the most widely used typing method. Rapid and accurate blood grouping plays an important role in some clinical conditions, rather than conventional techniques. Hence, developing a simple and economical model for rapid blood grouping would facilitate these tests. In recent decades, paper-based microfluidics such as μPADs has gained much interest in wide application areas such as point-of-care diagnostic. In this study, we evaluated μPADs that are performed for blood grouping and its recent progress. A comprehensive literature search was performed using databases including PUBMED, SCOPUS, Web of Science and Google Scholar. Keywords were blood grouping or typing, paper analytical device, rapid test, etc. After investigation of search results, 16 papers from 2010 to 2020 were included. Further information in detail was classified in Table 1. Generally, two principles for blood typing μPADs are introduced. The lateral chromatographic flow method and the vertical flow-through method that detects BG in a visual-based manner. To detect results with acceptable clarity many factors and challenges like paper, blood sample, buffer, Ab and RBC interaction and also μPADs stability need to be considered, which are discussed. In conclusion, the simplicity, stability, cheapness, portability and biocompatibility of μPADs for blood grouping confirming its utility and also they have the capability to robust, universal blood-grouping platform. Table 1 Summary of blood grouping tests using paper-based analytical devices Antigens Type of diagnosis Validation method Sample No Accuracy Action time Paper type Stability Sample dilution Buffer Ref A, B, Rh Forward volunteers records 5 - - Whatman No. 4 - 1/2 PBS* (Khan et al. 2010) A, B, Rh Forward gel assay test and conventional slide test 100 100% 1 min Whatman No. 4 and Kleeenex paper towel 7 Days in 4 °C 1/1 NSS (Al-Tamimi et al. 2012) A, B, Rh Forward gel card assay 99 100% 20 Sec + Washing Kleeenex paper towel - 1/1 NSS (Li et al. 2012) A, B, Rh Forward - - - - Kleeenex paper towel - 45/100 PSS (Li et al. 2013) A, B, Rh Forward gel card assay 98 100% 1.5 min Kleeenex paper towel - 85/100 PBS (Guan et al. 2014b) C, E, c, e, K, Jka, Jkb, M, N, S, P1, and Lea Forward gel card assay 266 100% - Kleeenex paper towel - 1/1 NSS (Li et al. 2014b) A, B, Rh Forward and Reverse conventional slide test 96 ≈ 91% 10 min Whatman No. 1 21 Days in 4 °C 1/2 NSS (Noiphung et al. 2015) C, c, E, e, K, k, Fya, Fyb, Jka, Jkb, M, N, S and s, P1, Lea and Leb Forward - 478 - - Kleeenex paper towel - 1/1 NSS, PBS (Then et al. 2015) A, B Forward and Reverse conventional slide test 76 100% 5-8 min Whatman No. 4 38 Days in 4 °C 1/4, 1/1 NSS (Songjaroen and Laiwattanapaisal 2016) D, K Forward volunteers records 210 - 7.5 min Kleenex paper towel - 1/1 NSS (Yeow et al. 2016) A, B, c, e, D, C, E, M, N, S, s, P1, Jka, Jkb, Lea, Leb, Fya, and Fyb Forward and Reverse gel card assay 3550 ≈100% 30 s Fiber glass and cotton linter 180 Days in 25 °C 45/100, 1/1 PBS (Zhang et al. 2017) A, B Forward conventional slide test 598 100% 3 min Whatman No. 113 14 Day in 4 °C 1/1 NSS (Songjaroen et al. 2018) A, B, Rh Forward conventional slide test - - 30 Sec + Washing Unrefined sisal paper - 1/2 NSS (Casals-Terré et al. 2019) A, B, Rh Forward - - - - Whatman No.1 - 1/1 NSS (Ansari et al. 2020) ABO & Rh Forward and Reverse conventional slide test - 100% Unrefined Eucalyptus papers - 1/2 NSS, PBS (Casals-Terré et al. 2020) A, B, Rh Forward - - - 30 Sec + Washing Whatman No. 4 modified with chitosan  ≥ 100 days in 25 °C 1/1 NSS (Parween et al. 2020) ^*phosphate buffer saline, normal saline solution.

Paper-based analytical devices for point-of-care blood tests

Blood can be a window to health, and as a result, is the most intensively studied human biofluid. Blood tests can diagnose diseases, monitor therapeutic drugs, and provide information about the health of an individual. Rapid response blood tests are becoming increasingly essential, especially when subsequent treatment is required. Toward this need, paper-based devices have been excellent tools for performing blood tests due to their ability to conduct rapid and low-cost diagnostics and analyses in a non-laboratory environment. In this Perspective, we review recent advances in paper-based blood tests, particularly focusing on the specific techniques and assays applied. Additionally, we discuss the future of these paper-based devices, such as how the signal intensity can be enhanced and how the in situ synthesis of nanomaterials can be used to improve the sensitivity, functionality, and operational simplicity. With these advances, paper-based devices are becoming increasingly valuable tools for point-of-care blood tests in various practical scenarios.

Microfluidic Paper-Based Analytical Devices for Colorimetric Detection of Lactoferrin

Lactoferrin is an abundant glycoprotein in human body fluids and is known as a biomarker for various diseases. Therefore, point-of-care testing (POCT) for lactoferrin is of interest. Microfluidic paper-based analytical devices (µPADs) have gained a lot of attention as next-generation POCT device candidates, due to their inexpensiveness, operational simplicity, and being safely disposable. This work presents a colorimetric sensing approach for quantitative lactoferrin analysis. The detection mechanism takes advantage of the high affinity of lactoferrin to ferric ions (Fe3+). Lactoferrin is able to displace an indicator from a colorimetric 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-Fe3+ complex, resulting in a color change. A 5-Br-PADAP-Fe3+ complex was encapsulated into water-dispersible poly(styrene- block-vinylpyrrolidone) particles, whose physical entrapment in the cellulosic fiber network results in the immobilization of the complex to the paper matrix. The complex-encapsulating particles showed a color change response in accordance with lactoferrin concentration. Both color intensity-based paper well plates and distance readout-based µPADs are demonstrated. Color intensity-based devices allowed quantitative analysis of lactoferrin concentrations with a limit of detection of 110 µg/mL, using a smartphone and a color readout app. On the other hand, distance readout-based µPADs showed changes of the length of colored sections in accordance with lactoferrin concentration. In summary, we successfully developed both colorimetric intensity-based paper wells and distance-based µPADs for lactoferrin detection. This work demonstrates a user-friendly colorimetric analysis platform for lactoferrin without requiring lab equipment and expensive antibodies.

Paper-based inkjet-printed microfluidic analytical devices

Rapid, precise, and reproducible deposition of a broad variety of functional materials, including analytical assay reagents and biomolecules, has made inkjet printing an effective tool for the fabrication of microanalytical devices. A ubiquitous office device as simple as a standard desktop printer with its multiple ink cartridges can be used for this purpose. This Review discusses the combination of inkjet printing technology with paper as a printing substrate for the fabrication of microfluidic paper-based analytical devices (μPADs), which have developed into a fast-growing new field in analytical chemistry. After introducing the fundamentals of μPADs and inkjet printing, it touches on topics such as the microfluidic patterning of paper, tailored arrangement of materials, and functionalities achievable exclusively by the inkjet deposition of analytical assay components, before concluding with an outlook on future perspectives.

Patterned paper sensors printed with long-chain DNA aptamers

There is growing interest in developing printable paper sensors to enable rapid testing of analytes for environmental, food safety, and clinical applications. A major challenge is to find suitable bioinks that are amenable to high-speed printing and remain functional after printing. We report on a simple and effective approach wherein an aqueous ink composed of megadalton-sized tandem repeating structure-switching DNA aptamers (concatemeric aptamers) is used to rapidly create patterned paper sensors on filter paper by inkjet printing. These concatemeric aptamer reporters remain immobilized at the point of printing through strong adsorption but retain sufficient segmental mobility to undergo structure switching and fluorescence signaling to provide both qualitative and quantitative detection of small molecules and protein targets. The convenience of inkjet printing allows for the patterning of internally referenced sensors with multiplexed detection, and provides a generic platform for on-demand printing of sensors even in remote locations.