Rationale of Drug Encapsulation and Release from Biocompatible Porous Metal-Organic Frameworks

A joint experimental and computational systematic exploration of the driving forces that govern (i) encapsulation of active ingredients (solvent, starting material dehydration, drug/material ratio, immersion time, and several consecutive impregnations) and (i) its kinetics of delivery (structure, polarity, ...) was performed using a series of porous biocompatible metal-organic frameworks (MOFs) that bear different topologies, connectivities, and chemical compositions. The liporeductor cosmetic caffeine was selected as the active molecule. Its encapsulation is a challenge for the cosmetic industry due to its high tendency to crystallize leading to poor loadings (<5 wt %) and uncontrolled releases with a subsequent low efficiency. It was evidenced that caffeine entrapping reaches exceptional payloads up to 50 wt %, while progressive release of this cosmetic agent upon immersion in the simulated physiological media (phosphate buffer solution pH = 7.4 or distilled water pH = 6.3, 37 degrees C) occurred mainly depending on the degree of MOF stability, caffeine mobility, and MOF-caffeine interactions. Thus, MIL-100 and UiO-66 appear as very promising carriers for topical administration of caffeine with both spectacular cosmetic payloads and progressive releases within 24 h.