Paper Number
SM13                         My Program 

Session
Polymer Solutions, Melts and Blends

Title
Microrheology of biosynthetic composites of DNA and NaPSS

Presentation Date and Time
October 20, 2025 (Monday) 4:05

Track / Room
Track 3 / Coronado + DeVargas

Authors (Click on name to view author profile)

  1. Safi Samghabadi, Farshad (University of Houston)
  2. McGovern, Ashlee D. (University of San Diego)
  3. Robertson-Anderson, Rae M. (University of San Diego, Physics and Biophysics)
  4. Conrad, Jacinta C. (University of Houston, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Farshad Safi Samghabadi1, Ashlee D. McGovern2, Rae M. Robertson-Anderson2 and Jacinta C. Conrad1
1Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204; 2Physics and Biophysics, University of San Diego, San Diego, CA 92110

Speaker / Presenter 
Conrad, Jacinta C.

Keywords
bio-fluid dynamics; biomaterials; biorheology; polymer blends; polymer solutions

Text of Abstract
We engineer entangled bio-synthetic polyelectrolyte composites with judiciously matched critical concentrations that are tunable via solution conditions. We show that biological DNA polymers and synthetic sodium poly(styrene sulfonate) (PSS) polymers of comparable coil size in low salt conditions interpenetrate to form macroscopically miscible solutions across the dilute to semidilute to entangled regimes. Whereas PSS dynamics are highly dependent on salt concentration, DNA dynamics are largely insensitive, allowing for independent tuning of the critical concentration for entanglements. For all composites containing DNA (i.e., for DNA fractions wDNA > 0), the DNA entanglement concentration dictates the crossover from semidilute to entangled dynamics. The dynamic data on long and short time scales can be collapsed using the entanglement concentration in both low and high salt conditions, indicating that DNA entanglements appear to govern the crossover between dynamical regimes. In the entangled regime, the scaling behavior for the zero-shear viscosity monotonically transitions from the prediction for polyelectrolytes to that for neutral polymers as wDNA increases and is surprisingly insensitive to salt concentration for wDNA > 0 composites. We observe similar collapse in the short-time limit, where the composites exhibit shear-thinning and anomalous transport behavior in the entangled regime. By combining biological and synthetic polyelectrolytes we are able to span from semidilute to entangled regimes and from polyelectrolyte to neutral polymer behavior, with independent tuning knobs governing these transitions. The design principles can be leveraged for designing miscible blends with greater dynamic range and responsiveness.