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Fully Integrated Modular and Mixed-Scale Systems for Processing the Molecular Cargo of Liquid Biopsy Markers
Childers, Katie
Childers, Katie
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Abstract
Precision medicine is the concept of delivering the right treatment, to the right patient, at the right time. However, accessibility to precision medicine is still a major challenge. The field of distributive medicine aims to rectify this by creating biomedical solutions that increase access to health care. One way is through the development of in vitro diagnostic (IVD) tests. The COVID-19 pandemic highlighted the need for rapid diagnostic tools that could be easily adapted for a specific disease and mass produced to be accessible and deployable both at-home and at the point-of-need. However, infectious disease is not the only area in which accessible diagnostic tools would be highly impactful. Screening, diagnostics, prognostics, monitoring response to therapy, and recurrence are all examples where there is a need for accessible IVD tests.
Both the biochemical assay development and engineering design of IVD tests is dependent on their use-case, that is where they will be used and by whom. In general, the goal of IVD testing is to decrease time to treatment and reduce the cost per test. However, to also increase distribution, IVD tests should be designed to be operated at the point-of-need with limited training. Additionally, accessible IVD tests should target biomarkers in samples that are minimally to non- invasive in nature, like blood or saliva also known as liquid biopsies. Circulating tumor cells, microRNAs, extracellular vesicles (EVs), or proteins are all examples of liquid biopsy biomarkers. Analysis of these biomarkers normally requires a trained operator to run expensive and laborious laboratory procedures making these tests not conducive to distributive medicine.
We are developing a diagnostic platform that selectively isolates disease-specific biomarkers from liquid biopsies and performs the downstream analysis all within a single autonomous system. This integrated and mixed-scale fluidic system combines multiple devices to complete a multi-step diagnostic assay. Our system consists of a thermoplastic universal fluidic motherboard containing valve seats, fluidic channels, interconnects, and mixers to direct fluid, introduce reagents, and connect multiple devices together to perform the assay. Attached to the motherboard are thermoplastic task-specific micro/nanofluidic modules each optimized to perform a single processing step within a multi-step assay. What sets this system apart from the current IVD literature is that all the modules are interchangeable allowing for the system to adapt for various diagnostic assays, such as capturing circulating tumor cells or EVs then performing mRNA profiling, protein analysis, or sequencing on the particular marker.
In this work, several aspects of this universal molecular processing platform were studied. A microfluidic module for upstream isolation of bio-nanoparticles from liquid biopsies is first presented. The module used a surface-bound aptamer to target and isolate SARS-CoV-2 virus particles from saliva with a 94% recovery. Another module consisted of a nanofluidic for the downstream processing of the molecular cargo of liquid biopsy markers using a label-free approach even at the single-molecule level. This unique module, which consisted of two in-plane nanopores in series with an intervening flight tube was studied using COMSOL Multiphysics. A novel model for the ion distribution between the two in-plane nanopores was presented and the importance of geometry, surface, and salt concentration were delineated.
To fluidically connect these modules together, mechanically actuated thermoplastic valves using an elastomeric cyclic olefin copolymer membrane were characterized. The membrane/substrate bond was demonstrated to withstand high burst pressure (~10 psi or ~50 psi) using a novel in situ bonding method. These valves were integrated into three different systems to successfully control the fluid: a 2-module system for SARS-CoV-2 screening, a 3-module system for immunophenotyping circulating leukemia cells, and the six-module universal motherboard for identifying ischemic and hemorrhagic strokes. The system could select stroke-associated EVs, harvest total RNA from the lysed EVs, and expression profile the exo-mRNA to diagnose ischemic or hemorrhagic stroke at the point-of-need. Here we demonstrated control of fluid flow through the six modules and motherboard. The components were housed within a 6” × 6” × 12” platform. An electrical control box and a user-interfacing program controlled the electronics and allowed for design of automated workflows. The end result was a compact, deployable system accessible in rural areas and operated by users with minimal training.
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Date
2025-05-31
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University of Kansas
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This item contains archived web content.
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Childers_ku_0099D_20100.pdf
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- Embargoed until 2027-05-31
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Keywords
Bioengineering, Biomedical engineering, Nanotechnology, COVID-19, Integrated Systems, Microfluidics, Nanofluidics, Stroke, Thermoplastics