Point-of-Care Diagnostic Device Development for Multiplexed Detection of Infectious Diseases

Abstract

The COVID-19 pandemic highlighted major weaknesses in the global healthcare system for patient accessibility to diagnostics. The pandemic led to a significant increase in demand for respiratory disease testing to facilitate treatment and limit transmission, demonstrating in the process that most existing test options in centralized facilities were too complex and expensive to perform in point-of-care settings. While laboratory-based nucleic acid amplification test (NAAT) assays remained the gold standard of clinical diagnosis, their reliance on complex equipment, cold-chain storage, and trained personnel initially limited their accessibility to testing in well-equipped labs and kept them out of low-resource or home environments. As transmission of SARS-CoV-2 led to national lockdown orders around the world, remote and home testing for infectious pathogens emerged as the new standard in patient care and clinical research. There was a major demand for multi-disease detection tools that could be implemented in point-of-care or home settings and could readily be adapted for new variants or different diseases entirely. In this thesis, I explored the design and development of multiple integrated point-of-care devices to perform simultaneous detection of multiple infectious diseases from a single patient sample. First, we demonstrated a point-of-care, paper-based rapid analysis device that could simultaneously detect multiple viral RNAs (for COVID-19 and influenza A) that had been spiked onto a commercial nasal swab. This compact and affordable device, enabled by novel valving innovations, not only enabled fast, sensitive detection of both SARS-CoV-2 and influenza A viruses from a single sample, but also opened the possibility for simple applications in other nucleic acid-based detection systems. Next, we adapted the multiplexing UbiNAAT platform for screening of two sexually transmitted illnesses (gonorrhea & chlamydia) in vaginal lysate samples from female clinical patients. We demonstrated the device’s compatibility with different assays and sample types, while incorporating additional processing steps for clinical sample treatment. The results highlighted the UbiNAAT’s potential for multiplexed screening of clinical samples across a multitude of infectious diseases. Lastly, we explored the development of an at-home testing platform for early-stage HIV using fingerstick blood samples. Toward this end, a novel point-of-care device with onboard plasma separation, chemical lysis, target concentration, isothermal amplification, and an innovative pull-tab valving system was integrated alongside extensive assay development for fluorescence and colorimetric detection. In future work, we anticipate that the findings and technologies developed in this thesis could be employed for a multitude of other targets, sample types, and detection systems that may enable large-scale, sensitive point-of-care testing.