Presenter: Erin Kim

Faculty Sponsor: Sang Hyun Lee

School: UMass Amherst

Research Area: Biomedical Engineering

Session: Poster Session 6, 4:15 PM - 5:00 PM, 163, C18

ABSTRACT

Biofilm in porous environments plays an important role in ecological and biomedical systems, yet conventional microfluidic platforms often rely on simple two-dimensional (2D) channel geometries that do not capture the structural complexity and flow tortuosity of natural porous media. To address this limitation, I developed microfluidic chips incorporating both 2D patterned cylinders (1000 μm × 500 μm x 500 μm) and three-dimensional (3D) architectures composed of repeating hemispherical features (1000 μm × 500 μm × 500 μm) fabricated using a biocompatible 3D‑printing resin. The goal of this work was to compare biofilm formation and quorum sensing (QS), which regulates biofilm formation, signal dynamics under geometrically distinct microenvironments.

Green fluorescence protein (GFP)-tagged Pseudomonas aeruginosa, a clinically relevant QS-active strain known to form biofilms through C4-HSL and 3-oxo-C12-HSL N‑acylhomoserine lactones (AHLs) QS signal molecules was chosen as our model bacterium and injected via a syringe pump at a fixed rate. Extracellular QS signal levels were quantified using the AHLs-responsive reporter strain Agrobacterium tumefaciens A136 (Ti−)(pCF218)(pCF372), which expresses β-galactosidase upon detecting a broad range of AHLs. Biofilm formation and spatial distribution was then quantified and compared in 2D and 3D geometries. In addition, flow simulations were conducted to assess the velocity field and shear stress in the considered structures by solving Navier-Stokes equation in COMSOL.

Through this work, I aim to highlight the importance of microenvironmental architecture in shaping biofilm proliferation and QS activity. The developed 3D patterned microchip provides a more realistic platform for studying biofilm behavior and may support future investigations into suppressing biofilm growth.