Origin of the High Variability in Sol-Gel Phase Transitions: The Agar Gelation Model

Area of Science:

• Soft Matter Physics
• Materials Science
• Biophysics

Background:

• Sol-gel phase transitions are complex, far-from-equilibrium processes with poorly understood origins and limited reproducibility.
• Quantifying variability in these transitions is crucial for understanding their fundamental nature and potential applications.

Purpose of the Study:

• To investigate the thermally induced sol-gel transition of agar and quantify its variability.
• To differentiate between experimental, intrinsic, and nonergodic sources of variability.
• To establish a quantitative framework for characterizing variability in phase transitions.

Main Methods:

• Utilized turbidimetry to monitor the sol-gel transition of agar under thermal induction.
• Applied a phenomenological model to extract kinetic parameters from 96 independent replicates.
• Compared variability in agar gelation with an enzymatic reaction to isolate contributions.

Main Results:

• Agar gelation exhibited significantly higher variability (CV ≈ 16%) compared to experimental error (1-2%) and nonergodic contributions (≈2%).
• The majority of variability originates from intrinsic process dynamics, particularly during the early stages of gelation.
• Stochastic nucleation and network formation pathways lead to divergent kinetic trajectories.

Conclusions:

• Variability in agar gelation is an intrinsic hallmark, not a measurement artifact.
• The inherent stochasticity limits the predictive power of deterministic models, especially at smaller scales.
• The developed quantitative framework can be applied to other complex biological and soft matter systems.