Paper-Based Devices for Virus Detection in Water

Viral infections are global health concerns that can cause high infection and mortality rates, as of the example from SARS-CoV-2 pandemic. Although conventional methods, e.g., polymerize chain reaction (PCR), can provide reliable and robust detection results, they are often time- and cost-consuming, limiting their application in resource-poor settings. Recently, paper-based devices, as a new biosensing technique, have emerged as a promising tool to conventional methods for pathogen detection including bacteria and virus. In this chapter, we provide a comprehensive introduction and insights on the development of paper-based devices for the pathogen detection in water. Firstly, the substrate materials and fabrication methods for paper-based devices are introduced. Engineering assay onto paper-based devices for virus detection is subsequently discussed for the rapid and on-site monitoring. We also compare the strengths and drawbacks between paper-based devices and the conventional analytical methods for virus detection, including culture method, biochemical test, immune assay, and molecular method. This chapter also discusses the feasibility of paper-based devices for point-of-use detection in water matrix, and the challenges and prospects of paper-based devices in water and environmental monitoring. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Label free electrochemical DNA biosensor for COVID-19 diagnosis.

The COVID-19 pandemic has significantly increased the development of the development of point-of-care (POC) diagnostic tools because they can serve as useful tools for detecting and controlling spread of the disease. Most current methods require sophisticated laboratory instruments and specialists to provide reliable, cost-effective, specific, and sensitive POC testing for COVID-19 diagnosis. Here, a smartphone-assisted Sensit Smart potentiostat (PalmSens) was integrated with a paper-based electrochemical sensor to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A disposable paper-based device was fabricated, and the working electrode directly modified with a pyrrolidinyl peptide nucleic acid (acpcPNA) as the biological recognition element to capture the target complementary DNA (cDNA). In the presence of the target cDNA, hybridization with acpcPNA probe blocks the redox conversion of a redox reporter, leading to a decrease in electrochemical response correlating to SARS-CoV-2 concentration. Under optimal conditions, a linear range from 0.1 to 200 nM and a detection limit of 1.0 pM were obtained. The PNA-based electrochemical paper-based analytical device (PNA-based ePAD) offers high specificity toward SARS-CoV-2 N gene because of the highly selective PNA-DNA binding. The developed sensor was used for amplification-free SARS-CoV-2 detection in 10 nasopharyngeal swab samples (7 SARS-CoV-2 positive and 3 SARS-CoV-2 negative), giving a 100% agreement result with RT-PCR.

Rapid SARS-CoV-2 testing with duplexed recombinase polymerase amplification and a bacteriophage internal control

Without global mass vaccination, COVID-19 will continue to infect and cause serious illness, disproportionately in low- and middle-income countries. Point-of-care and home-based nucleic acid amplification tests (NAATs) are valuable tools to control COVID-19 transmission. Here we present a rapid isothermal NAAT for duplexed detection of SARS-CoV-2 and an MS2 bacteriophage internal control. This assay amplifies RNA in less than 15 minutes, utilizes a low temperature of 39°C, and has fluorescence or visual lateral flow readout. This positions our assay for use in low-cost paper-based nucleic acid diagnostic devices for ultrasensitive and reliable COVID-19 detection in POC or home-based settings. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.

Non-invasive detection of COVID-19 using a microfluidic-based colorimetric sensor array sensitive to urinary metabolites.

A colorimetric sensor array designed on a paper substrate with a microfluidic structure has been developed. This array is capable of detecting COVID-19 disease by tracking metabolites of urine samples. In order to determine minor metabolic changes, various colorimetric receptors consisting of gold and silver nanoparticles, metalloporphyrins, metal ion complexes, and pH-sensitive indicators are used in the array structure. By injecting a small volume of the urine sample, the color pattern of the sensor changes after 7 min, which can be observed visually. The color changes of the receptors (recorded by a scanner) are subsequently calculated by image analysis software and displayed as a color difference map. This study has been performed on 130 volunteers, including 60 patients infected by COVID-19, 55 healthy controls, and 15 cured individuals. The resulting array provides a fingerprint response for each category due to the differences in the metabolic profile of the urine sample. The principal component analysis-discriminant analysis confirms that the assay sensitivity to the correctly detected patient, healthy, and cured participants is equal to 73.3%, 74.5%, and 66.6%, respectively. Apart from COVID-19, other diseases such as chronic kidney disease, liver disorder, and diabetes may be detectable by the proposed sensor. However, this performance of the sensor must be tested in the studies with a larger sample size. These results show the possible feasibility of the sensor as a suitable alternative to costly and time-consuming standard methods for rapid detection and control of viral and bacterial infectious diseases and metabolic disorders.

A colorimetric electronic tongue for point-of-care detection of COVID-19 using salivary metabolites.

The monitoring of profile concentrations of chemical markers in saliva samples can be used to diagnose COVID-19 patients, and differentiate them from healthy individuals. Here, this purpose is achieved by designing a paper-based colorimetric sensor with an origami structure, containing general receptors such as pH-sensitive organic dyes, Lewis donors or acceptors, functionalized nanoparticles, and ion metal complexes. The color changes taking place in the receptors in the presence of chemical markers are visually observed and recorded with a digital instrument. Different types and amounts of the chemical markers provide the sensor with a unique response for patients (60 samples) or healthy (55 samples) individuals. These two categories can be discriminated with 84.3% accuracy. This study evidences that the saliva composition of cured and healthy participants is different from each other with accuracy of 85.7%. Moreover, viral load values obtained from the rRT-PCR method can be estimated by the designed sensor. Besides COVID-19, it may possible to simultaneously identify smokers and people with kidney disease and diabetes using the specified electronic tongue. Due to its high efficiency, the prepared paper device can be employed as a rapid detection kit to detect COVID-19.