Affordable technologies for point-of-care diagnostics

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.2022-05-15T00:00:00

Electrochemical strategy for low-cost viral detection

Sexually transmitted infections, including the human immunodeficiency virus (HIV) and the human papillomavirus (HPV), disproportionally impact those in low-resource settings. Early diagnosis is essential for managing HIV. Similarly, HPV causes nearly all cases of cervical cancer, the majority (90%) of which occur in low-resource settings. Importantly, infection with HPV is six times more likely to progress to cervical cancer in women who are HIV-positive. An inexpensive, adaptable point-of-care test for viral infections would make screening for these viruses more accessible to a broader set of the population. Here, we report a novel, cost-effective electrochemical platform using gold leaf electrodes to detect clinically relevant viral loads. We have combined this platform with loop-mediated isothermal amplification and a CRISPR-based recognition assay to detect HPV. Lower limits of detection were demonstrated down to 104 total copies of input nucleic acids, which is a clinically relevant viral load for HPV DNA. Further, proof-of-concept experiments with cervical swab samples, extracted using standard extraction protocols, demonstrated that the strategy is extendable to complex human samples. This adaptable technology could be applied to detect any viral infection rapidly and cost-effectively.R01 EB029795 - NIBIB NIH HHSPublished versio

Electricity, chemistry and biomarkers: an elegant and simple package

Electrochemical sensors to measure biomarkers from complex samples are a tried and tested technology with large untapped potential for addressing important public health needs

Perspective—Electrochemical Sensors for Neurotransmitters and Psychiatrics: Steps toward Physiological Mental Health Monitoring

Therapeutic monitoring of neurotransmitters (NTs) and psychiatric medications is essential for the diagnosis and treatment of mental illness. However, in-vivo monitoring of NTs in humans as well as continuous physiological monitoring of psychiatrics have yet to be realized. In pursuit of this goal, there has been a plethora of work to develop electrochemical sensors for both in-vivo NT monitoring as well as in-vitro detection of psychiatric medications. We review these sensors here while discussing next steps needed to achieve concurrent, continuous physiological monitoring of NTs and psychiatric medications as part of a closed-loop feedback system that guides medication administration.</jats:p

Recent advances in gold electrode fabrication for low-resource setting biosensing

Conventional gold electrode fabrication is too costly and laborious for implementation in low-resource settings (LRS). We review affordable, simple alternative fabrication methods, highlighting gold leaf electrodes, for LRS applications.</jats:p

Bioelectrochemical platforms to study and detect emerging pathogens

Abstract The ongoing SARS-CoV-2 pandemic has emphasized the importance of technologies to rapidly detect emerging pathogens and understand their interactions with hosts. Platforms based on the combination of biological recognition and electrochemical signal transduction, generally termed bioelectrochemical platforms, offer unique opportunities to both sense and study pathogens. Improved bio-based materials have enabled enhanced control over the biotic–abiotic interface in these systems. These improvements have generated platforms with the capability to elucidate biological function rather than simply detect targets. This advantage is a key feature of recent bioelectrochemical platforms applied to infectious disease. Here, we describe developments in materials for bioelectrochemical platforms to study and detect emerging pathogens. The incorporation of host membrane material into electrochemical devices has provided unparalleled insights into the interaction between viruses and host cells, and new capture methods have enabled the specific detection of bacterial pathogens, such as those that cause secondary infections with SARS-CoV-2. As these devices continue to improve through the merging of hi-tech materials and biomaterials, the scalability and commercial viability of these devices will similarly improve. Graphic Abstrac

Surface Requirements for Optimal Biosensing with Disposable Gold Electrodes

Electrochemical biosensors are promising technologies for detection and monitoring in low-resource settings due to their potential for easy use and low-cost instrumentation. Disposable gold screen-printed electrodes (SPEs) are popular substrates for these biosensors, but necessary dopants in the ink used for their production can interfere with biosensor function and contribute to the heterogeneity of these electrodes. We recently reported an alternative disposable gold electrode made from gold leaf generated using low-cost, equipment-free fabrication. We have directly compared the surface topology, biorecognition element deposition, and functional performance of three disposable gold electrodes: our gold leaf electrodes and two commercial SPEs. Our leaf electrodes significantly outperformed the SPEs for reproducible and effective biosensing in a DNase I assay and are nearly an order of magnitude less expensive than the SPEs. Therefore, these electrodes are promising for further development as point-of-care diagnostics, especially in low-resource settings