Point of care testing for infectious diseases

Signal amplification strategies for paper-based analytical devices

Advanced "lab-on-a-chip" to detect viruses - Current challenges and future perspectives.

Nucleic acid amplification technology (NAAT) has assumed a critical position in disease diagnosis in recent times and contributed significantly to healthcare. Application of these methods has resulted in a more sensitive, accurate and rapid diagnosis of infectious diseases than older traditional methods like culture-based identification. NAAT such as the polymerase chain reaction (PCR) is widely applied but seldom available to resource-limited settings. Isothermal amplification (IA) methods provide a rapid, sensitive, specific, simpler and less expensive procedure for detecting nucleic acid from samples. However, not all of these IA techniques find regular applications in infectious diseases diagnosis. Disease diagnosis and treatment could be improved, and the rapidly increasing problem of antimicrobial resistance reduced, with improvement, adaptation, and application of isothermal amplification methods in clinical settings, especially in developing countries. This review centres on some isothermal techniques that have found documented applications in infectious diseases diagnosis, highlighting their principles, development, strengths, setbacks and imminent potentials for use at points of care.

https://www.dovepress.com/getfile.php?fileID=56039

Current and Future Perspectives on Isothermal Nucleic Acid Amplification Technologies for Diagnosing Infections.

The emergence of a novel coronavirus, SARS-CoV-2, has highlighted the need for rapid, accurate, and point-of-care diagnostic testing. As of now, there is not enough testing capacity in the world to meet the stated testing targets, which are expected to skyrocket globally for broader testing during reopening This review focuses on the development of lab-on-chip biosensing platforms for diagnosis of COVID-19 infection. We discuss advantages of utilizing lab-on-chip technologies in response to the current global pandemic, including their potential for low-cost, rapid sample-to-answer processing times, and ease of integration into a range of healthcare settings. We then highlight the development of magnetic, colorimetric, plasmonic, electrical, and lateral flow-based lab-on-chip technologies for the detection of SARS-CoV-2, in addition to other viruses. We focus on rapid, point-of-care technologies that can be deployed at scale, as such devices could be promising alternatives to the current gold standard of reverse transcription-polymerase chain reaction (RT-PCR) diagnostic testing. This review is intended to provide an overview of the current state-of-the-field and serve as a resource for innovative development of new lab-on-chip assays for COVID-19 detection.

/pdf/scalable-covid-19-detection-enabled-by-lab-on-chip-2ttxog3yjd.pdf

Scalable COVID-19 Detection Enabled by Lab-on-Chip Biosensors.

The recent Zika virus (ZIKV) outbreak has prompted the need for field-ready diagnostics that are rapid, easy-to-use, handheld, and disposable while providing extreme sensitivity and specificity. To meet this demand, we developed a wax-printed paper microfluidic chip utilizing reverse transcription loop-mediated isothermal amplification (RT-LAMP). The developed simple and sensitive ZIKV assay was demonstrated using undiluted tap water, human urine, and diluted (10%) human blood plasma. Paper type, pore size, and channel dimension of various paper microfluidic chips were investigated and optimized to ensure proper filtration of direct-use biological samples (tap water, urine, and plasma) during capillary action-driven flow. Once ZIKV RNA has flowed and reached to a detection area of the paper microfluidic chip, it was excised for the addition of an RT-LAMP mixture with a pH indicator, then placed on a hot plate at 68 °C. Visible color changes from successful amplification were observed in 15 minutes and quantified by smartphone imaging. The limit of detection was as low as 1 copy/μL. The developed platform can also be used for identifying other flaviviruses, such as Chikungunya virus (CHIKV) and Dengue virus (DENV), and potentially other quickly transmitted virus pathogens, towards field-based diagnostics.

/pdf/simpler-faster-and-sensitive-zika-virus-assay-using-icxxjmi6l3.pdf

Simpler, Faster, and Sensitive Zika Virus Assay Using Smartphone Detection of Loop-mediated Isothermal Amplification on Paper Microfluidic Chips

https://doi.org/10.1016/j.bios.2022.114192

Smartphone-based sensitive detection of SARS-CoV-2 from saline gargle samples via flow profile analysis on a paper microfluidic chip

https://onlinelibrary.wiley.com/doi/pdf/10.1002/mds3.10085

The future of microbiome analysis: Biosensor methods for big data collection and clinical diagnostics

Abstract Saliva specimens have drawn interest for diagnosing respiratory viral infections due to their ease of collection and decreased risk to healthcare providers. However, rapid and sensitive immunoassays have not yet been satisfactorily demonstrated for such specimens due to their viscosity and low viral loads. Using paper microfluidic chips and a smartphone-based fluorescence microscope, we developed a highly sensitive, low-cost immunofluorescence particulometric SARS-CoV-2 assay from clinical saline gargle samples. We demonstrated the limit of detection of 10 ag/μL. With easy-to-collect saline gargle samples, our clinical sensitivity, specificity, and accuracy were 100%, 86%, and 93%, respectively, for n = 27 human subjects with n = 13 RT-qPCR positives.

/pdf/sensitive-smartphone-based-sars-cov-2-detection-from-rqbscggd.pdf

Sensitive, smartphone-based SARS-CoV-2 detection from clinical saline gargle samples

Investigation of the potential adverse effects of chemicals and drugs is essential during the drug development process. In vitro cell model systems have been developed over the past years towards such toxicity investigation. 96-well plate is the common platform for screening drug toxicity due to its simplicity. However, this platform only offers 2D cell culture environment and lacks the flow of solutions, which fails to provide the suitable environment for the cells to adequately metabolize the drugs, for the media to replenish, and for the metabolites and wastes to be removed. Microfluidic chips populated with human or animal cells, known as organ-on-a-chip (OOC), can reconcile many issues of in vitro cell models, such as the lack of extracellular matrix and flow as well as the species difference. However, OOC can be complicated to fabricate and operate. To bridge this gap, we utilized paper as a primary substrate for OOC, considering its fibrous structure that can mimic natural extracellular matrix, as well as a syringe pump and filter that are commonly available in most laboratories. Paper microfluidic model was designed and fabricated by wax printing on nitrocellulose paper, seeded and proliferated with liver cells (primary rat hepatocytes and HepG2 cells), and two paper substrates were stacked together to complete the paper model. To this paper-based liver cell model, the following drugs were added: Phenacetin (pain reliever and fever reducer), Bupropion (antidepressant), Dextromethorphan (antidepressant), and phosphate-buffered saline (PBS) as a control, all under a physiologically relevant flow rate. The combination of these drugs with Fluconazole (antifungal drug) was also investigated. Cell count, cell morphology, protein production, and urea secretion after drug treatment confirmed that the model successfully predicted toxicity within 40 minutes. This simple, paper-based liver cell model provided enhanced and faster cell response to drug toxicity and showed comparable or better behavior than the cells cultured in conventional 2D in vitro models.

Patarajarin Akarapipad

Papers

Simpler, Faster, and Sensitive Zika Virus Assay Using Smartphone Detection of Loop-mediated Isothermal Amplification on Paper Microfluidic Chips

Smartphone-based sensitive detection of SARS-CoV-2 from saline gargle samples via flow profile analysis on a paper microfluidic chip

The future of microbiome analysis: Biosensor methods for big data collection and clinical diagnostics

Sensitive, smartphone-based SARS-CoV-2 detection from clinical saline gargle samples

Simple Paper-based Liver Cell Model for Drug Screening