Leveraging magnetic resonance imaging to assess biocompatible scaffolds diffusion and flow-driven perfusion for lab-on-a-chip systems.

Biocompatible scaffolds play a crucial role in creating 3D in vitro models for precision medicine. Understanding liquid transport dynamics is essential for ensuring timely delivery of nutrients, drugs or imaging agents to cells embedded within the scaffold. Therefore, it is imperative to thoroughly characterise the physical properties of these scaffolds. In this study, we leverage nuclear magnetic resonance imaging (MRI) to examine the diffusivity and flow-driven perfusion properties of commonly used cryogels and hydrogels. We used deuterium oxide (i.e. heavy water) as a contrast agent to monitor the reduction in proton concentration from water within the scaffolds due to molecular motion. By analysing pixel intensity in MRI images, we extract information on the diffusion speed and liquid passage efficacy of these materials. This approach allowed us to investigate passive water diffusion in a carboxymethyl cellulose cryogel and polyethylene glycol diacrylate hydrogel. The diffusion rates differed by 50% between the two scaffolds by direct comparison of their diffusion coefficients. Furthermore, we measured their flow-driven perfusion properties in a PDMS microfluidic chip.