Paper Number
PO3 

Session
Poster Session

Title
Rheological enhancement of artificial sputum medium

Presentation Date and Time
October 11, 2017 (Wednesday) 6:30

Track / Room
Poster Session / Cripple Creek Ballroom

Authors (Click on name to view author profile)

1. Tan, Mingyang (Oregon State University, CBEE)
2. Mao, Yating (Oregon State University, CBEE)
3. Walker, Travis W. (Oregon State University, CBEE)

Author and Affiliation Lines (in printed abstract book)
Mingyang Tan, Yating Mao, and Travis W. Walker
CBEE, Oregon State University, Corvallis, OR 97331

Speaker / Presenter 
Tan, Mingyang

Text of Abstract
Microscopic rheology enables the characterization of the microenvironment of biofluids, such as sputum from cystic fibrosis (CF) patients. As noninvasive collection of mucus for fundamental research is difficult without contamination, we have created a synthetic biofluid alternative that is a combination of artificial sputum medium (ASM) and xanthan gum (XG). The macroscopic rheological study of ASM showed that the storage and loss moduli are at least two orders of magnitude lower than those values of CF sputum, and the microscopic rheology showed that ASM is a purely-viscous fluid. The addition of XG provides a tunable parameter to the synthetic recipe that enables rheological properties that are mechanically consistent with real sputum. Probe particles that were suspended in a media of ASM and XG displayed a subdiffusive behavior at short time scales with a diffusive exponent that decreased with an increase in concentration of XG. At long time scales, particles that were suspended in ASM+XG with a concentration of XG of 0.1% to 0.4% displayed diffusive behavior. While in more concentrated samples (0.5% and 1.0%), the particles were constrained inside local elastic cages. The elastic and viscous moduli that were obtained via the generalized Stokes-Einstein relation (GSER) showed consistently lower moduli than the values that were obtained from rotational rheometry. The discrepancy suggests that the solutions of XG have a hierarchical structure that better represents the weakly associated microstructure of mucus that is found in real sputum.