A spectrophotometer-based diffusivity assay reveals that diffusion hindrance of small molecules in extracellular matrix gels used in 3D cultures is dominated by viscous effects

- Diffusion hindrance in extracellular matrix (ECM) gels used in 3D cultures is investigated.
- A cost-effective and simple spectrophotometer-based diffusivity assay is introduced, and complemented with FRAP and AFM measurements.
- Diffusion hindrance is largely controlled by the enhanced ECM viscosity.
- Unassembled ECM macromolecules may control ECM viscosity.
- Dense (but not sparse) ECM gels are suitable tissue surrogates in terms of diffusion.