Boosting the in situ encapsulation of proteins with MIL-100(Fe): the role of strong Lewis acid centers

Encapsulation of biomolecules using Metal-Organic Frameworks (MOFs) to form stable biocomposites has been demonstrated a valuable strategy for their preservation and controlled release, which has been however restricted to specific electrostatic surface conditions. We present a general in situ strategy that promotes the spontaneous MOF growth onto a broad variety of proteins, for the first time, regardless of their surface nature. We demonstrate that MOFs based on cations exhibiting considerable inherent acidity such as MIL-100(Fe) enable biomolecule encapsulation, including alkaline proteins previously inaccesible by the welldeveloped in situ encapsulation with azolate-based MOFs. In particular, MIL-100(Fe) scaffold permits effective encapsulation of proteins with very distinct surface nature, retaining their activity and allowing triggered release under biocompatible conditions. This general strategy will enable an ample use of biomolecules in desired biolotechnological applications.