Particle Diffusometry for Biomedical Applications
Abstract
With the rapid expansion of microfluidics in biomedical research, there is a need to develop quantitative measurement methods for biomolecular phenomena on-chip. Particle diffusometry is a quantitative visualization tool that calculates the Brownian motion of particles suspended in a solution. I present particle diffusometry as a method for rapid (~8 seconds), low-volume (3 μL) measurements of biomolecules on-chip using only a microscope, CCD camera, and correlation-based algorithm. This work discusses the fundamental characterization and applications of calculating particle size and solution viscosity.We first use particle diffusometry in particle sizing measurements. Specifically, we apply particle diffusometry to detect small biomolecular surface modifications on gold nanoparticles. Further, we design a novel gold nanoparticle-protein conjugation method by employing a popular “click chemistry” to covalently attach chemoenzymatically modified proteins onto nanoparticles. These results yield highly active proteins that can be combined with particle diffusometry for protein kinetics measurements.Particle diffusometry is also used to measure viscosity changes in biomolecular solutions. Specifically, we characterize the degradation and viscosity of protein-based biotherapeutics for pharmaceutical applications by measuring particle Brownian motion in the presence of insulin and monoclonal antibodies. We also fundamentally characterize the effect of DNA length, topology, and concentration on solution viscosity and apply this knowledge toward the detection of amplified pathogen DNA in solution. This is used to successfully measure the presence of V. cholerae, a waterborne pathogen, where its DNA is amplified from pathogen cells spiked into environmental water sources.Particle diffusometry is therefore a feasible method for size and viscosity measurements of biomolecular solutions. This approach can be used for both protein and nucleic acid research and even in the presence of complex sample matrices. Particle diffusometry facilitates rapid, non-destructive measurements of biomolecular phenomena; allowing the translation of particle diffusomtery in microfluidic devices for immunoassays, protein kinetics, biotherapeutic analytical measurements, and pathogen detection.
Degree
Ph.D.
Advisors
Kinzer-Ursem, Purdue University.
Subject Area
Mechanical engineering|Biomedical engineering
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