Direct quantification of solute diffusivity in porous, viscoelastic materials using Correlation Spectroscopy

Osteoarthritis (OA) is a disease which results in altered fluid flow and solute-matrix interactions in affected articular cartilage. We propose that quantification of these changes could be used as a diagnostic measure of OA, early on in disease progression. This study validates the use of Fluorescence Correlation Spectroscopy and Raster Image Correlation Spectroscopy to quantify the equilibrium diffusivity of solutes in agarose and cartilage. We also demonstrate diffusion attenuation with increased solute size and gel concentration. Lastly, we characterize diffusion in three zones of bovine articular cartilage. Future work, utilizing Spatiotemporal Image Correlation Spectroscopy, will be able to quantify load-induced solute convection in situ, which will allow further characterization of solute-matrix interactions and fluid flow in articular cartilage.