A Study of the Development of an Electrochemical Point-of-Care Urine Analysis Platform for Pathogen Screening

Abstract

To reduce the incidence of clinical complications and cost associated with Urinary Tract infections (UTIs), there is a need for the development of a low-cost and culture-free UTI diagnostic test with a rapid sample-to-answer time. The aim of this study is to develop an electrochemical assay for nucleic acid detection that is sensitive and specific. We sought to develop such system by creating an assay that combines low background signals with built-in amplification. In this work, gold disk macroelectrodes are used in conjunction with a bio-recognition layer to capture pathogen-related nucleic acids and then this event is translated into an electrochemical signal. At first DNA was used as the bio-recognition layer. However, to enhance the system’s limit-of-detection (LOD), we developed an assay based on the neutral bio-recognition layer, peptide nucleic acid (PNA). PNA produced a lower background signal compared to DNA and a LOD of 0.001 nanomolar. In order to take advantage of isothermal and low-temperature nucleic acid amplification towards further enhancing the system’s LOD, a new assay based on programmable strand displacement coupled with electrochemical readout was employed. The system employed target cycling to produce in-built amplification. With this assay a LOD of 0.5 nM was achieved. Further tuning of probe densities is required to realise lower LODs. These results illustrate how using PNA produces a lower background signal compared to DNA and that employing a programmable strand displacement assay introduces built amplification into a system. Future studies combining the two systems would be ideally suited for realising an assay that is sensitive and specific.