Concentration-dependent diffusion of unlabeled protein within an in vitro hyaluronic acid matrix

Antonio C F Dos Santos1, Adib Ahmadzadegan2, Eduardo Ximenes1

  • 1Department of Agricultural and Biological Engineering, Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, Indiana, USA.

Diffusion and movement of subcutaneously injected biologics and high-concentration immunoglobulin G (IgG) therapeutics away from the injection site and through the subcutaneous (SC) tissue may be concentration dependent. This possibility was confirmed by in situ measurement of diffusion coefficients of unlabeled bovine IgG in phosphate-buffered saline within an in vitro hyaluronic acid matrix that represents the SC electrostatic environment. Diffusion decreased from 2.67 to 0.05 × 10-7  cm2 /s when IgG concentration increased from 25 to 73 mg/mL. The results demonstrated that in situ detection of unlabeled proteins within an in vitro SC environment provides another useful tool for the preclinical characterization of injectable biologics.