Microfluidic Paper-Based Diagnostics: Revolutionizing Healthcare at the Point of Care

Dr. Semonti Nandi Faculty of Pharmacy, Kalinga University, Naya Raipur

semonti.nandi@kalingauniversity.ac.in

Microfluidic paper-based diagnostics (μPADs) are “lab-on-chip” devices that have revolutionized healthcare by introducing point-of-care tests that are “ASSURED- Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free, and Deliverable” as per World Health Organisation. The groundbreaking technological advancement has also led to portability and cost-efficiency in healthcare. μPAD innovations have led to their use in diagnostics, reaching remote locations that lack health infrastructure. Principles and Design of μPADs μPADs involve a paper-based platform in which microliters of fluid travel within the paper’s capillary network, facilitating various analytical processes. Papers used in μPADs should be evaluated for suitable surface chemistry, available surface area, fluid dynamics, porosity, pore size, and paper thickness. A basic paper chip is composed of a sampling zone where the test sample is loaded. The test sample then runs through the paper via capillary action. Another area within the chip is the detection zone, where the test sample combines with the analytical reagent to produce a detectable colour change. Hydrophilic channels are patterned on the paper by forming hydrophobic barriers. The papers are patterned using photolithography, plotting, inkjet etching, plasma etching, cutting, and wax printing. These hydrophilic channels impart directionality to the flow of fluids toward the reagent end. Detection of analytes on μPADs are based on colorimetry, electrochemistry, chemiluminescence, and electrochemiluminescence. Application of μPADs One of the most significant applications of μPADs is in disease diagnosis and health condition detection, particularly in resource-limited settings. These devices detect infectious diseases, chronic conditions, HIV, malaria, diabetes, and cancer. Common μPADs are pregnancy and glucose detection kits, and recently Feluda- a paper test strip for coronavirus was developed in India. Drug screening and drug identification were also successfully conducted using μPADs. In the food industry, μPADs find application in pesticide detection, additive detection (SO2), and quality inspection (amylose content in rice). In environmental monitoring, μPADs are used for heavy metal detection (Cd2+, Pb2+, Cu2+, and Hg2+) and substance detection (chlorine in water). Biological detection of proteins, nucleic acids, antibodies, biomacromolecules, etc., has been reported using μPADs. Clinistix was the first commercially available μPAD strip developed for detecting glucose. The first μPADs dipstick test for glucose quantification in urine was reported in the 1950s and commercialized during the 1960s. Major companies delivering in the commercial paper diagnostics market are: 1. Diagnostics For All 2. Kenosha C.V. 3. Navigene Genetic Science Pvt. Ltd. 4. BiognostiX 5. Micro Essential Laboratory 6. GVS Filter Technology 7. Alere Inc. 8. Bio-Rad Laboratories 9. Siemens Healthcare Limitations of μPADs The challenges in developing μPADs include sample preparation, chances for false-positive or false-negative results, and end-user friendly. Conclusions Microfluidic paper-based diagnostics are poised to revolutionize healthcare by providing rapid, cost-effective, and portable testing solutions at the point of care. With their wide range of applications, from disease diagnosis to environmental monitoring, μPADs can improve healthcare access and outcomes globally, particularly in resource-limited settings. References 1. Xin Tong, Lu Ga, Ruiguo Zhao and Jun Ai, Research progress on the applications of paper chips, RSC Advances, 2021, 11, 8793-8820. 2. Ali Kemal Yetisen, Muhammad Safwan Akram and Christopher R. Lowe, Paper-based microfluidic point-of-care diagnostic devices, Lab on a Chip, 2013,13, 2210-2251. 3. Andres W. Martinez, Scott T. Phillips, and George M. Whitesides, Diagnostics for the Developing World: Microfluidic Paper-Based Analytical Devices, Analytical Chemistry, 2010, 82, 1, 2010. 4. Abdollah Abdollahi-Aghdam, Mir Reza Majidi, Yadollah Omidi, Microfluidic paper-based analytical devices (μPADs) for fast and ultrasensitive sensing of biomarkers and monitoring of diseases, BioImpacts, 2018, 8, 4, 237-240. 5. https://www.databridgemarketresearch.com/reports/global-paper-diagnostics-market