M.F. Smiechowski, E. Akkari
Guild BioSciences,
United States
Keywords: electrochemical biosensor, drug monitoring, patient adherence, pathogen detection, point-of-care
Summary:
Both prophylactic and active pharmacological treatments are tools used to control the spread of disease and improve community health. The efficacy of these treatments depends significantly on the individuals adhering to their dosing regimen, a process that can be challenging. Self-reporting metrics are not always reliable and more objective monitoring typically involves sending samples such as urine, plasma/blood, hair, or dried blood spots to outside labs for analysis. Leading to lost opportunities for patent support. Monitoring and responding to the performance of the treatment also requires collecting samples, sending them to an outside lab, and waiting for results. A low-cost, rapid, and easy-to-perform at-home or POC device would enable convenient in-person assessment of patient adherence and the performance of the treatment, and if necessary, a physician could initiate or recommend support programs based on results. Disposable, ready-to-use, aptamer-based electrodes for rapid and reliable quantification of viral RNA and antiretroviral drugs in blood samples were developed. When an RNA or drug target binds to its aptamer, changes in the aptamer's tertiary structure and the presence of the target change the interfacial properties of the electrode. These changes were monitored and quantified using electrochemical impedance spectroscopy. The limit of detection for viral RNA in plasma and blood was determined to be 100 copies/mL in a 50 µL sample. The limit of detection for the tested pharmaceuticals ranged from 200-900 ng/mL. The response of the signal to RNA in blood was found to be linear up to 400 RNA/mL, after which it plateaued as the sensor surface started to become saturated. A similar pattern was observed in the sensor response to drug-targets. A membrane-based system was evaluated for its ability to prepare the blood samples prior to the electrode surface. Various components such as anti-coagulants and electrolytes were dried on the membrane prior to its attachment to the electrode and are rehydrated following the addition of the blood sample. The membrane also serves to filter the cell components away from the electrode reducing the noise in measurements. The final test protocol was able to detect and quantify both viral RNA and a known target drug in 50 µL blood samples taking less than 5 minutes of hands-on time, and output results within 15 minutes of starting the test measurement.