ENGINEERING SAMPLE-TO-ANSWER TESTS FOR SIMPLIFIED WHOLE-BLOOD DIAGNOSTIC PLATFORMS FOR THE DETECTION OF CLINICALLY RELEVANT BIOMARKERS ACROSS MEDICAL APPLICATIONS

Abstract

The field of diagnostics has advanced significantly in recent decades, particularly in blood-based testing, which provides critical insight into physiological status, disease progression, and therapeutic response. However, these tests typically require expensive infrastructure and trained personnel, restricting access to well-equipped settings. This limitation underscores the need for affordable, rapid, and accessible detection methods. Point-of-care tests (POCTs) offer a promising solution, yet many existing systems remain impractical for resource-limited environments or time-sensitive applications, especially for blood-based diagnostics. This is largely due to reliance on manual sample preparation and reagent handling, which limits usability outside of laboratory settings. In this dissertation, I present a series of sample-to-answer diagnostic platforms designed to address these challenges by enabling direct detection of analytes in whole blood across multiple clinical applications. First, I introduce the Portable Histone Assay Technology (PHAST), a device and assay for detecting circulating histones, which are associated with increased risk of multiple organ failure, a condition that currently lacks a reliable predictive biomarker. Second, I have developed a simplified, laboratory-based quantitative assay for measuring blood lead levels (BLL), reducing reliance on the current gold standard of inductively coupled plasma mass spectrometry (ICP-MS). Third, I have translated this assay into a point-of-care format to enable rapid, low-cost screening in pediatric populations, eliminating the need for specialized equipment and lengthy processing times. Finally, I propose an assay for the direct detection of circulating cell-free DNA from Borrelia burgdorferi in whole blood samples, targeting improved diagnosis of Lyme disease, the most common vector-borne disease in the United States. Collectively, these platforms eliminate the need for extensive sample preparation by operating directly in whole blood or through selective target capture. By simplifying workflows and reducing technical barriers, these systems improve accessibility across diverse settings, with the potential to significantly enhance diagnostic reach and patient outcomes.