Affordable technologies for point-of-care diagnostics
Embargo Date
2022-05-15
OA Version
Citation
Abstract
Affordable, point-of-care diagnostics are needed for disease monitoring in low-
resource settings (LRS). Gold-standard laboratory tests require expensive benchtop
equipment, which limits their widespread use. In this work, I developed low-cost
technologies for the transduction of two independent types of biosensors. In the first
part of my work, I developed inexpensive gold leaf electrodes that can be used to build
electrochemical biosensors; I use these electrodes to detect clinically relevant viral loads
human papillomavirus (HPV) from clinical samples. In the next part of my work, I built an
optical setup using off-the-shelf parts for the inexpensive detection of a fluorescent
progesterone biosensor; next, I translated this solution-based progesterone biosensor
into a paperfluidic format for inexpensive point-of-care testing.
The first technology I developed were gold leaf electrodes as a cheaper
alternative to conventional gold electrodes. Gold electrodes are commonly used as
substrates for biosensors due to the ease of surface modification through the self-
assembly of thiolated molecules. However, conventional gold electrodes are often costly
and laborious to fabricate, rendering them inappropriate for many applications in low-
resource settings. Here, I developed the first integrated, three-electrode biosensor
fabricated using pure gold leaf, an inexpensive and widely available material; each
device uses only $0.16 worth of gold. Importantly, my fabrication scheme does not
require any specialized equipment or clean room space, enabling my fabrication process
to be carried out anywhere it is needed. As a proof of concept of this platform,
electrodes were modified with DNA for CRISPR-based detection of clinically relevant
viral loads (1.2 x 104 total copies) of HPV 18 DNA that had been extracted from clinical
samples.
Next, I developed a benchtop optical device using inexpensive-off-the shelf parts
for fluorescent detection of a transcription-factor based biosensor. This transcription-
factor based biosensor detected progesterone as a model target. This optical device
worked as well as a multi-thousand dollar plate reader. Next, I adapted the solution-
based progesterone biosensor to a paper-based biosensor for the affordable and
portable progesterone monitoring. This device had a lower limit of detection of 27 nM,
which is a clinically relevant level of progesterone in both cows and premenopausal
women.