Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

A Low-Cost Microfluidic-Based Detection Device for Rapid Identification and Quantification of Biomarkers-Based on a Smartphone

The sensitive and rapid detection of microsamples is crucial for early diagnosis of diseases. The short response times and low sample volume requirements of microfluidic chips have shown great potential in early diagnosis, but there are still shortcomings such as complex preparation processes and high costs. We developed a low-cost smartphone-based fluorescence detection device (Smartphone-BFDD) without precision equipment for rapid identification and quantification of biomarkers on glass capillary. The device combines microfluidic technology with RGB image analysis, effectively reducing the sample volume to 20 μL and detection time to only 30 min. For the sensitivity of the device, we constructed a standard sandwich immunoassay (antibody-antigen-antibody) in a glass capillary using the N-protein of SARS-CoV-2 as a biological model, realizing a low limit of detection (LOD, 40 ng mL^-1). This device provides potential applications for different biomarkers and offers wide use for rapid biochemical analysis in biomedical research.

Multifunctional Portable System Based on Digital Images for In-Situ Detecting of Environmental and Food Samples

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.

Systematic Review and Meta-Analysis of the Diagnostic Accuracy of Mobile-Linked Point-of-Care Diagnostics in Sub-Saharan Africa

Mobile health devices are emerging applications that could help deliver point-of-care (POC) diagnosis, particularly in settings with limited laboratory infrastructure, such as Sub-Saharan Africa (SSA). The advent of Severe acute respiratory syndrome coronavirus 2 has resulted in an increased deployment and use of mHealth-linked POC diagnostics in SSA. We performed a systematic review and meta-analysis to evaluate the accuracy of mobile-linked point-of-care diagnostics in SSA. Our systematic review and meta-analysis were guided by the Preferred Reporting Items requirements for Systematic Reviews and Meta-Analysis. We exhaustively searched PubMed, Science Direct, Google Scholar, MEDLINE, and CINAHL with full text via EBSCOhost databases, from mHealth inception to March 2021. The statistical analyses were conducted using OpenMeta-Analyst software. All 11 included studies were considered for the meta-analysis. The included studies focused on malaria infections, Schistosoma haematobium, Schistosoma mansoni, soil-transmitted helminths, and Trichuris trichiura. The pooled summary of sensitivity and specificity estimates were moderate compared to those of the reference representing the gold standard. The overall pooled estimates of sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of mobile-linked POC diagnostic devices were as follows: 0.499 (95% CI: 0.458–0.541), 0.535 (95% CI: 0.401–0.663), 0.952 (95% CI: 0.60–1.324), 1.381 (95% CI: 0.391–4.879), and 0.944 (95% CI: 0.579–1.538), respectively. Evidence shows that the diagnostic accuracy of mobile-linked POC diagnostics in detecting infections in SSA is presently moderate. Future research is recommended to evaluate mHealth devices’ diagnostic potential using devices with excellent sensitivities and specificities for diagnosing diseases in this setting.

Paper-based nucleic acid amplification tests for point-of-care diagnostics

There has been a recent resurgence in the use of paper as a substrate for developing point-of-care medical diagnostic tests, possibly triggered by expiring patents published in the 1990s. A hallmark of this resurgence has been the development of advanced shapes and structures made from paper to conduct multi-step fluidic operations using the wicking action of porous materials. Such devices indicate a distinct improvement over lateral flow immunoassays, which are restricted to conducting one-step operations. New developments in paper-based diagnostic devices have triggered interest in the development of paper-based point-of-care nucleic acid amplification tests (NAATs). NAATs can identify extremely low levels of specific nucleic acid sequences from clinical samples and are the most sensitive of all available tests for infectious disease diagnosis. Because traditional PCR-based NAATs require expensive instruments, the development of portable paper-based NAAT's has become an exciting field of research. This article aims to review and analyse the current state of development of paper-based NAATs. We project paper-based NAATs as miniaturized chemical processes and shed light on various schemes of operation used for converting the multiple steps of the chemical processes into paper microfluidic devices. We conclude by elaborating on the challenges that must be overcome in the near future so that progress can be made towards the development of fully functional and commercial paper-based NAATs.

Advances in paper-analytical methods for pharmaceutical analysis

Paper devices have many advantages over other microfluidic devices. The paper substrate, from cellulose to glass fiber, is an inexpensive substrate that can be readily modified to suit a variety of applications. Milli- to micro-scale patterns can be designed to create a fast, cost-effective device that uses small amounts of reagents and samples. Finally, well-established chemical and biological methods can be adapted to paper to yield a portable device that can be used in resource-limited areas (e.g., field work). Altogether, the paper devices have grown into reliable analytical devices for screening low quality pharmaceuticals. This review article presents fabrication processes, detection techniques, and applications of paper microfluidic devices toward pharmaceutical screening.

Portable devices and mobile instruments for infectious diseases point-of-care testing

INTRODUCTION

Rapidity, simplicity, and portability are highly desirable characteristics of tests and devices designed for performing diagnostics at the point of care (POC), either near patients managed in healthcare facilities or to offer bioanalytical alternatives in external settings. By reducing the turnaround time of the diagnostic cycle, POC diagnostics can reduce the dissemination, morbidity, and mortality of infectious diseases and provide tools to control the global threat of antimicrobial resistance. Areas covered: A literature search of PubMed and Google Scholar, and extensive mining of specialized publications, Internet resources, and manufacturers' websites have been used to organize and write this overview of the challenges and requirements associated with the development of portable sample-to-answer diagnostics, and showcase relevant examples of handheld devices, portable instruments, and less mobile systems which may or could be operated at POC. Expert commentary: Rapid (<1 h) diagnostics can contribute to control infectious diseases and antimicrobial resistant pathogens. Portable devices or instruments enabling sample-to-answer bioanalysis can provide rapid, robust, and reproducible testing at the POC or close from it. Beyond testing, to realize some promises of personalized/precision medicine, it will be critical to connect instruments to healthcare data management systems, to efficiently link decentralized testing results to the electronic medical record of patients.