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The similar transmission patterns and early symptoms of respiratory viral infections, particularly severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza (H1N1), and respiratory syncytial virus (RSV), pose substantial challenges in the diagnosis, therapeutic management, and handling of these infectious diseases. Multiplexed point-of-care testing for detection is urgently needed for prompt and efficient disease management. Here, we introduce an electrochemical paper-based analytical device (ePAD) platform for multiplexed and label-free detection of SARS-CoV-2, H1N1, and RSV infection using immobilized pyrrolidinyl peptide nucleic acid probes. Hybridization between the probes and viral nucleic acid targets causes changes in the electrochemical response. The resulting sensor offers high sensitivity and low detection limits of 0.12, 0.35, and 0.36 pM for SARS-CoV-2 (N gene), H1N1, and RSV, respectively, without showing any cross-reactivities. The amplification-free detection of extracted RNA from 42 nasopharyngeal swab samples was successfully demonstrated and validated against reverse-transcription polymerase chain reaction (range of cycle threshold values: 17.43-25.89). The proposed platform showed excellent clinical sensitivity (100 %) and specificity (≥97 %) to achieve excellent agreement (κ ≥ 0.914) with the standard assay, thereby demonstrating its applicability for the screening and diagnosis of these respiratory diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.) more...

A significant bottleneck exists for mass-production of ion-selective electrodes despite recent developments in manufacturing technologies. Here, we present a fully-automated system for large-scale production of ISEs. Three materials, including polyvinyl chloride, polyethylene terephthalate and polyimide, were used as substrates for fabricating ion-selective electrodes (ISEs) using stencil printing, screen-printing and laser engraving, respectively. We compared sensitivities of the ISEs to determine the best material for the fabrication process of the ISEs. The electrode surfaces were modified with various carbon nanomaterials including multi-walled carbon nanotubes, graphene, carbon black, and their mixed suspensions as the intermediate layer to enhance sensitivities of the electrodes. An automated 3D-printed robot was used for the drop-cast procedure during ISE fabrication to eliminate manual steps. The sensor array was optimized, and the detection limits were 10 -5  M, 10 -5  M and 10 -4  M for detection of K + , Na + and Ca 2+ ions, respectively. The sensor array integrated with a portable wireless potentiometer was used to detect K + , Na + and Ca 2+ in real urine and simulated sweat samples and results obtained were in agreement with ICP-OES with good recoveries. The developed sensing platform offers low-cost detection of electrolytes for point-of-care applications., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.) more...

3D printing technologies are an attractive for fabricating electrochemical sensors due to their ease of operation, freedom of design, fast prototyping, low waste, and low cost. We report the fabrication of a simple 3D-printed electrochemical sensing device for non-enzymatic detection of creatinine, an important indicator of renal function. To create the 3D-printed electrodes (3DE), carbon black/polylactic acid (CB/PLA) composite filament was used. The 3DE was activated using 0.5 M NaOH via amperometry prior to use to improve electrochemical performance. To give selectivity for creatinine, the activated 3DE was modified with a copper oxide nanoparticle-ionic liquid/reduced graphene oxide (CuO-IL/rGO) composite. The modified 3DE was characterized using microscopy and electrochemistry. Cyclic voltammetry and amperometry were used to evaluate sensor performance. The modified 3DE provided electrocatalytic activity towards creatinine without enzymes. Under optimal conditions, the modified 3DE directly coupled with a portable smartphone potentiostat exhibited the linear detection range of 0.5-35.0 mM, and the limit of detection was 37.3 μM, which is sufficient for detecting creatinine in human urine samples. Furthermore, the other physiological compounds present in human urine were not detected on the modified 3DE. Therefore, the modified 3DE could be a tool for effective creatinine screening in the urine., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.) more...

This work introduces a low-cost adhesive tape combined with a hydroxylamine/polyvinyl alcohol/polyethylene oxide (HA/PVA/PEO) blend film to fabricate novel devices for improving sensitivity of gold nanoparticle (AuNP)-based lateral flow immunoassays (LFIAs) via two platforms: (1) LFIA device with integrated gold enhancement and (2) LFIA device with two independent sample inlets. The detection of ferritin has been used for proof-of-concept. The adhesive tape inserted in the devices assists to separate two solutions independently flowing from two different inlets toward a nitrocellulose membrane. On-device gold enhancement was achieved by the enlargement of AuNPs via the catalytic reaction of KAuCl 4 and HA using the HA/PVA/PEO blend film easily prepared via a solution-casting technique, which could delay the flow of HA released from the film for 180s and improve storage stability of the device. Under optimal conditions evaluated by naked eyes, the gold enhancement (LOD = 0.5 ng/mL) and double-sample inlet (LOD = 2 ng/mL) devices exhibited 20-fold and fivefold higher sensitivity respectively than a conventional device, verifying the sensitivity improvement. Furthermore, the proposed device was successfully detected ferritin in human serum samples within 10 min via naked-eye observation, exhibiting rapidity and simplicity of use, and the capability to perform on-site assays., (© 2022. The Author(s).) more...

Background: The demand for point-of-care testing (POCT) devices has rapidly grown since they offer immediate test results with ease of use, makingthem suitable for home self-testing patients and caretakers. However, the POCT development has faced the challenges of increased cost and limited resources. Therefore, the paper substrate as a low-cost material has been employed to develop a cost-effective POCT device, known as "Microfluidic paper-based analytical devices (μPADs)". This device is gaining attention as a promising tool for medicinal diagnostic applications owing to its unique features of simple fabrication, low cost, enabling manipulation flow (capillarydriven flow), the ability to store reagents, and accommodating multistep assay requirements., Objective: This review comprehensively examines the fabrication methods and device designs (2D/3D configuration) and their advantages and disadvantages, focusing on updated μPADs applications for motif identification., Methods: The evolution of paper-based devices, starting from the traditional devices of dipstick and lateral flow assay (LFA) with μPADs, has been described. Patterned structure fabrication of each technique has been compared among the equipment used, benefits, and drawbacks. Microfluidic device designs, including 2D and 3D configurations, have been introduced as well as their modifications. Various designs of μPADs have been integrated with many powerful detection methods such as colorimetry, electrochemistry, fluorescence, chemiluminescence, electrochemiluminescence, and SER-based sensors for medicinal diagnosis applications., Conclusion: The μPADs potential to deal with commercialization in terms of the state-of-the-art of μPADs in medicinal diagnosis has been discussed. A great prototype, which is currently in a reallife application breakthrough, has been updated., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.) more...