Coarse-Grained Insights into Insulin Aspart Adsorption on Plasticized Poly(vinyl chloride) (PVC) Surfaces

Insulin aspart, a biomacromolecule essential for diabetes treatment, is known to interact with polymer-based drug delivery systems. Plasticized poly(vinyl chloride) (PVC) materials, widely used in medical infusion tubing, contribute significantly to insulin aspart loss due to adsorption. However, experimental studies alone cannot distinguish the individual contributions of plasticizers and the PVC matrix in this process. To address this, we employed coarse-grained molecular dynamics (Martini 3) simulations to investigate protein-surface interactions over extended time scales, providing deeper insights into adsorption mechanisms. Our results revealed a strong preference for insulin aspart adsorption onto PVC regions rather than plasticizers, explaining the experimentally observed lack of adsorption differences between plasticized and nonplasticized PVC surfaces. Additionally, we explored the formation of the insulin aspart adsorption layer for both monomeric and hexameric forms, further characterizing the thermodynamics of the adsorption process.