Aakanksha Gubbala

All Publications

• Phase field model for viscous inclusions in anisotropic networks. Soft matter Gubbala, A., Jena, A. M., Arnold, D. P., Takatori, S. C. 2025

  Abstract

  The growth of viscous two-dimensional lipid domains in contact with a viscoelastic actin network was recently shown to exhibit unusual lipid domain ripening due to the geometry and anisotropy of the actin network [Arnold & Takatori. Langmuir. 40, 26570-26578 (2024)]. In this work, we interpret previous experimental results on lipid membrane-actin composites with a theoretical model that combines the Cahn-Hilliard and Landau-de Gennes liquid crystal theory. In our model, we incorporate fiber-like characteristics of actin filaments and bundles through a nematic order parameter, and elastic anisotropy through cubic nematic gradients. Numerical simulations qualitatively agree with experimental observations, by reproducing the competition between the thermodynamic forces that coarsen lipid domains versus the elastic forces generated by the surrounding actin network that resist domain coarsening. We observe a decrease in the growth of domain sizes, finding R(t) talpha with alpha < 1/4 for different actin network stiffnesses, in sharp contrast to the t1/3 scaling for diffusive growth of domains in the absence of the actin network. Our findings may serve as a foundation for future developments in modeling elastic ripening in complex systems.

  View details for DOI 10.1039/d5sm00478k

  View details for PubMedID 40692432

• Dynamic swarms regulate the morphology and distribution of soft membrane domains PHYSICAL REVIEW E Gubbala, A., Arnold, D. P., Jena, A., Anujarerat, S., Takatori, S. C. 2024; 110 (1): 014410

  Abstract

  We study the dynamic structure of lipid domain inclusions embedded within a phase-separated reconstituted lipid bilayer in contact with a swarming flow of gliding filamentous actin. Passive circular domains transition into highly deformed morphologies that continuously elongate, rotate, and pinch off into smaller fragments, leading to a dynamic steady state with ≈23× speedup in the relaxation of the intermediate scattering function compared with passive membrane domains driven by purely thermal forces. To corroborate experimental results, we develop a phase-field model of the lipid domains with two-way coupling to the Toner-Tu equations. We report phase domains that become entrained in the chaotic eddy patterns, with oscillating waves of domains that correlate with the dominant wavelengths of the Toner-Tu flow fields.

  View details for DOI 10.1103/PhysRevE.110.014410

  View details for Web of Science ID 001275918000011

  View details for PubMedID 39160984

• Active Surface Flows Accelerate the Coarsening of Lipid Membrane Domains PHYSICAL REVIEW LETTERS Arnold, D. P., Gubbala, A., Takatori, S. C. 2023; 131 (12): 128402

  Abstract

  Phase separation of multicomponent lipid membranes is characterized by the nucleation and coarsening of circular membrane domains that grow slowly in time as ∼t^{1/3}, following classical theories of coalescence and Ostwald ripening. In this Letter, we study the coarsening kinetics of phase-separating lipid membranes subjected to nonequilibrium forces and flows transmitted by motor-driven gliding actin filaments. We experimentally observe that the activity-induced surface flows trigger rapid coarsening of noncircular membrane domains that grow as ∼t^{2/3}, a 2x acceleration in the growth exponent compared to passive coalescence and Ostwald ripening. We analyze these results by developing analytical theories based on the Smoluchowski coagulation model and the phase field model to predict the domain growth in the presence of active flows. Our Letter demonstrates that active matter forces may be used to control the growth and morphology of membrane domains driven out of equilibrium.

  View details for DOI 10.1103/PhysRevLett.131.128402

  View details for Web of Science ID 001102941000002

  View details for PubMedID 37802933