Low-cost In Vitro Diagnostic Technologies

Abstract

This chapter introduces current trends in low-cost in vitro diagnostic technologies for resource-limited settings around the world. To date, the focus of diagnostics research has been to expand and support the healthcare system by both alleviating cost burden and enhancing the quality of life for individuals in underdeveloped regions. To reach such goals, a suitable in vitro diagnostic device for resource-limited settings should be affordable, sensitive, specific, user-friendly, rapid, robust, functionable without additional instrumentation, and easily deliverable to end users. Employing cellulose-based materials, i.e., paper, thread, and cotton, to build diagnostic devices is considered a promising approach to tackling today’s diagnostic challenges. Such tools overcome resource-limited area issues such as the lack of medical infrastructure that hinder routine medical examination. Because cellulose products are inexpensive, ubiquitous, portable, and disposable (incineration), provide inherent capillary action, and are readily compatible with current technologies (e.g., wax printing and surface modification technologies), cellulose-based diagnostics offer immense potential as WHO-aligned, highly sensitive, and highly specific alternatives to conventional, “gold standard” methods. Of the low-cost in vitro diagnostic technologies currently employing cellulose-based materials, paper-based analytical devices (PADs) are the most prevalent diagnostic platform for disease detection. PADs, which require defining reaction areas by creating hydrophobic boundaries onto and into paper via screen-printing, immersing, photolithography-like techniques, origami, and curing/engraving techniques, provide reagent–sample-saving measures and can function as high-throughput platforms for disease diagnostics. Currently, PADs have been used to indicate the presence or levels of specific biomarkers (e.g., DNAs, RNAs, and protein/antigens from pathogens or metabolic products of cell) in buffer systems or biofluid samples (e.g., urine, serum) through the use of colorimetric, fluorescence, chemiluminescence, electrochemiluminescence (ECL), electrochemical, and surface-enhanced Raman spectroscopy detection methods. In addition to paper, thread and cotton are popular cellulose-based materials that have been repeatedly validated as diagnostic application platforms that align their methodology easily with previously established approaches using paper. In summary, low-cost in vitro diagnostic technologies benefit resource-limited settings and provide specific, accurate, precise, and rapid detection results comparable to standard, clinical diagnoses.