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Creatinine is one of many markers used to investigate kidney function. This paper describes a low-cost enzymatic paper-based analytical device (enz-PAD) for determining urine creatinine. The disposable dead volumes of creatinine enzyme reagents from an automatic analyser cassette were utilised. Whatman No. 3 paper was cut into long rectangular shapes (4×40 mm 2 ) on which the enzyme reagents, R1 and R2, were adsorbed in two consecutive regions. The assay was performed by immersing test strips into urine samples contained in microwells to allow creatinine in the sample to react with immobilised active ingredients and, then, traverse via capillary action to the detection area where chromogen products accumulated. The method is based on hydrogen peroxide (H 2 O 2 ) formation via creatinine conversion using creatininase, creatinase, and sarcosine oxidase. The liberated H 2 O 2 reacts with 4-aminophenazone and 2,4,6-triiodo-3-hydroxybenzoic acid to form quinoneimine with a pink-red colour at the detection zone. The linear range of the creatinine assay was 2.5–25 mg dL −1 ( r 2 =0.983), and the detection limit was 2.0 mg dL −1 . The colorimetric enz-PAD for the creatinine assay was highly correlated with a conventional alkaline picrate method when real urine samples were evaluated ( r 2 =0.977; n =40). This simple and nearly zero-cost paper-based device provides a novel alternative method for screening urinary creatinine and will be highly beneficial for developing countries. [ABSTRACT FROM AUTHOR]

We propose a new, paper-based analytical device (PAD) for blood typing that allows for the simultaneous determination of ABO and Rh blood groups on the same device. The device was successfully fabricated by using a combination of wax printing and wax dipping methods. A 1:2 blood dilution was used for forward grouping, whereas whole blood could be used for reverse grouping. A 30% cell suspension of A-cells or B-cells was used for haemagglutination on the reverse grouping side. The total assay time was 10 min. The ratio between the distance of red blood cell movement and plasma separation is the criterion for agglutination and indicates the presence of the corresponding antigen or antibody. The proposed PAD has excellent reproducibility in that the same blood groups, namely A, AB, and O, were reported by using different PADs that were fabricated on the same day ( n =10). The accuracy for detecting blood group A ( n =12), B ( n =13), AB ( n =9), O ( n =14), and Rh ( n =48) typing were 92%, 85%, 89%, 93%, and 96%, respectively, in comparison with the conventional slide test method. The haematocrit of the sample affects the accuracy of the results, and appropriate dilution is suggested before typing. In conclusion, this study proposes a novel method that is straightforward, time-saving, and inexpensive for the simultaneous determination of ABO and Rh blood groups, which is promising for use in developing countries. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel platform of paper-based microfluidic devices for glucose assay from whole blood sample was established that incorporates plasma isolation methods. [•] Dumbbell shaped μPADs was fabricated to obtain the uniform plasma separation and reproducible electrochemical signals. [•] Two pieces of VF2 membranes combined with Whatman No. 1 paper using wax-dipping fabrication method to form a dumbbell shaped μPAD. [•] Conventional Prussian blue-modified screen printed electrode (PB-SPEs) was placed underneath the middle part of a dumbbell shaped μPAD. [Copyright &y& Elsevier]

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently administered over-the-counter medicines to treat fever, pain and control inflammation. However, their overdose can cause detrimental effects in the human body, whereas uncontrollable disposable into ecosystems pose significant environmental concerns. Electrochemical (bio) sensors overcome the limitations of traditional detection approaches and provide immense potential for sensitive, selective, efficient, and low-cost detection of pharmaceuticals in complex media. This review presents an overview of the current state-of-the-art progress in electrochemical (bio) sensors utilizing nanoscale materials (e.g., metal/metal oxides nanoparticles, carbonaceous materials, and conducting polymers) as electrode modifiers that target NSAIDs. Special attention is paid to different electrode fabrication strategies, sensor/analyte interactions, and analysis of real-world samples. Besides, experimental conditions and some analytical parameters including linear concentration range, detection limit, detection method, etc., are compiled and compared. Finally, this review concludes by discussing future prospects, challenges, and possibilities in designing next-generation advanced sensing devices. [Display omitted] • Recent development in electrochemical (bio) sensors for NSAIDs determination is reviewed. • Electrode fabrication methods and different sensing strategies are presented. • Clinical and environmental applications are critically discussed. • Current challenges and future research directions are also discussed. [ABSTRACT FROM AUTHOR]

Point-of-care testing (POCT) for uropathogen detection and chemical screening has great benefits for the diagnosis of urinary tract infections (UTIs). The goal of this study was to develop a portable and inexpensive paper-based analytical device (PAD) for cultivating bacteria in situ and rapidly testing for nitrite on the same device. The PAD was fabricated using a wax printing technique to create a pattern on Whatman No. 1 filter paper, which was then combined with a cotton sheet to support bacterial growth. Nitrite detection was based on the principle of the Griess reaction, and a linear detection range of 0-1.6 mg/dL (R2 = 0.989) was obtained. Scanning electron microscopy (SEM) analysis demonstrated that the bacteria were able to grow and formed a cluster on the cellulose fibres within 2 hours. The enzyme β-glucuronidase, which is specifically produced by Escherichia coli, was able to convert the pre-immobilized 5-bromo-4-chloro-3-indolyl-β-D-glucuronide sodium salt (X-GlcA), a colourless substrate, generating a blue colour. Under optimum conditions, the proposed device allowed bacterial concentrations in the range of 104-107 colony forming units (CFU)/mL to be quantified within 6 hours. Moreover, the use of this device enables the identification of E. coli pathogens with selectivity in real urine samples. In conclusion, the PAD developed in this study for UTI screening provides a rapid, cost-effective diagnostic method for use in remote areas. [ABSTRACT FROM AUTHOR]

Both the ABO and Rhesus (Rh) blood groups play crucial roles in blood transfusion medicine. Herein, we report a simple and low-cost paper-based analytical device (PAD) for phenotyping red blood cell (RBC) antigens. Using this Rh typing format, 5 Rh antigens on RBCs can be simultaneously detected and macroscopically visualized within 12 min. The proposed Rh phenotyping relies on the presence or absence of hemagglutination in the sample zones after immobilizing the antibodies targeting each Rh antigen. The PAD was optimized in terms of filter paper type, antibodies, and distance of the visualization zone. In this study, the optimal conditions were Whatman filter paper Grade 4; anti-D, –C, -E, -c, and -e antibodies; RBC suspension of 30%; and a visualization zone of 1 cm above the sample zone. The accuracy of simultaneously phenotyping the five Rh RBC antigens in the blood samples (n = 4692) was 99.19%, comparable with the accuracy of the gold-standard tube method used by blood bank laboratories in several regions of Thailand. Furthermore, decision making based on this method can be assisted by deep learning. After implementing a two-stage objective detection algorithm (YOLO v4-tiny) and classification model (DenseNet-201), the ambiguous images (n = 48) were interpreted with 100% accuracy. The PAD integrated with customized-region convolutional neural networks can reduce the interpretation discrepancies in RBC antigen phenotyping in any laboratory. [Display omitted] • Five Rh antigens typing PADs combined with deep learning algorithm for an assisted human-decision. • Rh antigens typing PADs were tested with real blood samples and compared with the standard tube method. • Dataset of photographs following Rh PADs testing were trained and evaluated by the in-house deep learning platform CiRA CORE. • Misinterpretation caused by weak or ambiguous reactions was solved by the CiRA CORE platform. [ABSTRACT FROM AUTHOR]