Nanostructures of MIL-100 were synthesized and used as a drug delivery platform for two members of the Tetracycline family. Doxycycline monohydrate (DOX) and Tetracycline hydrochloride (TC) were loaded separately on nano-MIL-100 (nanoparticles of drug@carrier were abbreviated as DOX@MIL-100 and TC@MIL-100). Characterizations were carried out using FT-IR, XRD, BET, DLS, and SEM. The FT-IR spectra revealed that the drugs were loaded into the framework of the carrier. The XRD patterns of DOX@MIL-100 and TC@MIL-100 indicated that no free DOX or TC were present. It could be concluded that the drugs are well dispersed into the pores of nano-MIL-100. The microporosity of the carrier was confirmed by BJH data. BET analysis showed a reduction in the free surface for both DOX@MIL-100 and TC@MIL-100. The release of TC and DOX was investigated, and it was revealed that MIL-100 mediated the drug solubility in water, which in turn resulted in a decrease in the release rate of TC (accelerating in DOX case) without lowering the total amount of released drug. After 48 h, 96 percent of the TC was sustain released, which is an unprecedented amount in comparison with other methods.

Combined therapies emerge as an interesting tool to overcome limitations of traditional pharmacological treatments (efficiency, side effects). Among other materials, metal-organic frameworks (MOFs) offer versatilities for the accommodation of multiple and complementary active pharmaceutical ingredients (APIs): accessible large porosity, availability of functionalization sites, and biocompatibility. Here, we propose topical patches based on water-stable and biosafe Fe carboxylate MOFs (MIL-100 and MIL-127), the biopolymer polyvinyl alcohol (PVA) and two co-encapsulated drugs used in skin disorders (azelaic acid (AzA) as antibiotic, and nicotinamide (Nic) as anti-inflammatory), in order to develop an advanced cutaneous combined therapy. Exceptional MOF drug contents were reached (total amount 77.4 and 48.1 wt.% for MIL-100 and MIL-127, respectively), while an almost complete release of both drugs was achieved after 24 h, adapted to cutaneous delivery. The prepared cutaneous PVA-MOF formulations are safe and maintain the high drug-loading capacity (total drug content of 38.8 and 24.2 wt.% for MIL-100 and MIL-127, respectively), while allowing a controlled delivery of their cargoes, permeating through the skin to the active target sites. The total amount of drug retained or diffused through the skin is within the range (Nic), or even better (AzA) than commercial formulations. The presented results make these drug combined formulations promising candidates for new cutaneous devices for skin treatment.

In its crystal structure the one-dimensional coordination polymer [Ag₄(O₂C(CF₂)₂CF₃)₄(TMP)₃]_n (1) (TMP = 2,3,5,6-tetramethylpyrazine) adopts a zig-zag arrangement in which pairs of silver(I) centres bridged by two fluorocarboxylate ligands are linked alternately via one or two neutral TMP ligands. This material can reversibly absorb/desorb small alcohols (ROH) in single-crystal-to-single-crystal transformations, despite the lack of porosity in the crystals, to yield a related material of formula [Ag₄(O₂C(CF₂)₂CF₃)₄(TMP)₃(ROH)₂]_n (1-ROH). The absorption process includes coordination of the alcohol to silver(I) centres and, in the process, insertion of the alcohol into one-quarter of the Ag–O bonds of coordination polymer. When in place, the alcohol molecule is also supported by formation of an O–H⋯O hydrogen bond to the now partially dissociated carboxylate group. The reverse process leading to desorption of the alcohol takes place upon mild heating to regenerate 1. Upon further heating, 1 can release molecules of TMP into the vapour phase resulting in a separate chemical and structural transformation to yield a two-dimensional layered material of composition [Ag₄(O₂C(CF₂)₂CF₃)₄(TMP)₂]_n (2). This new transformation occurs via dissociation of Ag–N bonds upon ligand release and formation of new Ag–O bonds. The whole series of transformations has been followed in situ by single-crystal and/or powder X-ray diffraction and studied by thermogravimetric analysis. As a mechanistic probe to explore transport within formally nonporous 1, gravimetric CO₂ gas sorption/desorption has been conducted. It is proposed that transport of small molecules occurs through the fluorous layers in the crystal.