BME Ph.D. Defense: Alyse Krausz
Microfluidic Assay Development for Diagnosis and Monitoring of Chronic and Acute Conditions
WHEN: July 30, 2021 10:00 am-11:00 amADD TO CALENDAR
Diagnostic and monitoring devices based on protein biomarker measurements have the potential to inform courses of treatment in acute conditions and to help manage and prevent disease progression in chronic conditions. The importance of diagnostic and monitoring devices cannot be overstated as medicine is blind without them. However, prevalent conditions such as traumatic brain injury (TBI) and chronic kidney disease (CKD) lack adequate diagnostic and monitoring tools.
Assessment of TBI is typically done through neurological examination and neuroimaging techniques. While these methods can identify direct tissue damage to the brain, they cannot assess the secondary damage stemming from the initial injury. The primary tissue damage sets off a cascade of secondary injuries, such as neuronal cell death, blood brain barrier breakdown, edema, and upregulation of inflammatory markers. Protein biomarkers have been proposed as a way of monitoring the progression of secondary TBI injury and of providing more sensitive diagnostic measures when used in conjunction with imaging and physical examination. However, FDA authorized biomarkers, glial fibrillary acidic protein (GFAP) and ubiquitin c-terminal hydrolase L1 (UCH-L1), can currently only be measured in a hospital laboratory. Analyzing TBI biomarker data in field and pre-hospital settings would enable rapid diagnosis and delivery of care, so we developed a glass and silicon microfluidic device for quantification of TBI protein biomarkers via bead-based immunoassay. The device consists of a single channel with a variable height profile fabricated by slowly lowering a glass wafer into hydrofluoric acid. The device can capture and separate beads with diameters ranging from 1 to 5 micrometers. We also developed bead-based quantum dot-linked immunosorbent assays (QLISAs) for GFAP, interleukin-6 (IL-6), and interleukin-8 (IL-8) by conjugating appropriate antibodies to 2.8, 4.5, and 1 micrometer diameter beads, respectively. We used the variable height device to passively separate a mixture of assay beads with completed immunocomplexes into distinct bands where the diameter of the beads matched the height of the channel. The fluorescent intensity of each band was used to quantify a different biomarker concentration, resulting in a customizable brain injury barcode. By changing out the bead size and antibodies used for each immunoassay, the variable height device can keep pace with the developing field of TBI biomarker discovery and validation or be applied to biomarkers for another condition of interest.
We also developed an assay system to monitor CKD, which is one of the ten most common chronic conditions in adults aged 65 and older. Clinical guidelines currently recommend that the urinary albumin-to-creatinine ratio (ACR) be measured once a year to monitor disease progression. However, measuring the ACR at home can enable patients to self-identify the early signs of disease progression and consult their physicians, potentially leading to improved outcomes. We designed and analytically validated inexpensive, colorimetric assays for urinary albumin and creatinine intended to be used in a 3D-printed, disposable microfluidic device. Discrepancies between the results from the colorimetric albumin assay and the hospital albumin assay when clinical urine samples were tested highlight the importance of incorporating analytical validation as a checkpoint in the development of microfluidic monitoring systems.
Overall, this work presents a novel method of multiplexing immunoassays in microfluidic systems that can be applied to measure protein biomarkers for TBI or another condition of interest and highlights the importance of integrating assay design with microfluidic device design to promote clinical translation.
Date: Friday, July 30, 2021
Time: 10:00 AM
Zoom: https://umich.zoom.us/meeting/register/tJYpdu2rrjsqH9LM0c4DZ8bs8Uj0BdggOEeE (pre-registration required)
Chair: Dr. Mark Burns