The Design and Development of Novel Methods to Improve Sensitivity of Current Infectious Disease Diagnostics

Abstract

Several diagnostics employ sandwich immunoassays for the detection of various infectious diseases. While some of these strategies fail to produce sensitive diagnoses for use in the field, enhancements to commercially available tactics can improve detection to prevent the development of entirely new point-of-care (POC) platforms. Quantitative analysis of commercial devices points to inherent inefficiencies in the current format. In order to improve sensitivity, every aspect of a diagnostic, including capture, detection strategies with reporter elements, signal generation, and signal readout is explored. To replace the traditional capture antibody on a test line, the use of a cationic polymer was investigated for the detection of circulating anodic antigen, a biomarker for schistosomiasis. This on-paper strategy was applied to both lateral flow assays and vertical flow through devices. The integration of an electrostatic binding strategy demonstrates a method to increase stability of the assay and enhance the number of binding sites to improve capture in just 100 µL of sample. A large volume device was developed to further enhance the limit of detection for the capture strategy. Additional work focused on a novel signal amplification strategy for improved detection strategies. Nanoparticles conjugated to a detection antibody provide access to a signal amplification scheme with a more stable reporter element to make immunoassays more field deployable. Acid dissolution of the nanoparticle results in hundreds to thousands of signal-producing metal ions, which can be detected by a sensitive and specific fluorescent probe. Research efforts then centralized around the application of smartphones as surveillance tools to control and map the spread of disease. The use and usability of a web-application, MyCOVIDKey, was investigated to assist COVID-19 contact tracing efforts. Ultimately, the work described in this dissertation centralizes around enhancing components to current POC infectious disease devices.