Elucidating molecular oxygen adsorption in ZIF-8 through integrated experimental and computational studies

Abstract

Oxygen delivery remains a critical challenge in biomedical applications, particularly where controlled and localized oxygen supplementation is required. In this study, Zeolitic Imidazolate Framework-8 (ZIF-8) was investigated as a biocompatible model metal–organic framework to understand molecular oxygen adsorption and release through an integrated experimental and computational approach. Experimental adsorption measurements showed an oxygen uptake of approximately 0.9 mmol g⁻¹, while oxygen-release studies in deoxygenated PBS indicated concentration-dependent but partial reoxygenation under aqueous conditions. Grand Canonical Monte Carlo (GCMC) and molecular dynamics simulations further identified preferential adsorption regions and highlighted differences between pore-confined and surface-accessible oxygen behavior. Breakthrough experiments and adsorption kinetic models (Thomas, Yoon-Nelson, and Adam-Bohart) supported the observed oxygen adsorption trend. Preliminary in vitro studies in A549 cells suggested acceptable short-term biological compatibility under the tested conditions. Overall, the results position ZIF-8 not as high-capacity systemic oxygen carrier, but as a mechanistically informative and biocompatible proof-of-concept platform for understanding oxygen adsorption, confinement, and localized release in MOF-based biomedical systems.