In silico identification and synthesis of a multi-drug loaded MOF for treating tuberculosis.

Conventional drug delivery systems have been applied to a myriad of active ingredients but may be difficult to tailor for a given drug. Herein, we put forth a new strategy, which designs and selects the drug delivery material by considering the properties of encapsulated drugs (even multiple drugs, simultaneously). Specifically, through an in-silico screening process of 5109 MOFs using grand canonical Monte Carlo simulations, a customized MOF (referred as BIO-MOF-100) was selected and experimentally verified to be biologically stable, and capable of loading 3 anti-Tuberculosis drugs Rifampicin+Isoniazid+Pyrazinamide at 10% + 28% + 23% wt/wt (total > 50% by weight). Notably, the customized BIO-MOF-100 delivery system cleared naturally Pyrazinamide-resistant Bacillus Calmette-Guérin, reduced growth of virulent Erdman infection in macaque macrophages 10-100-fold compared to soluble drugs in vitro and was also significantly reduced Erdman growth in mice. These data suggest that the methodology of identifying-synthesizing materials can be used to generate solutions for challenging applications such as simultaneous delivery of multiple, small hydrophilic and hydrophobic molecules in the same molecular framework.

Silver Nanofilament Formation Dynamics in a Polymer-Ionic Liquid Thin Film by Direct-Write.

Silver nanofilament formation dynamics are reported for an ionic liquid (IL)-filled solid polymer electrolyte prepared by a direct-write process using a conductive atomic force microscope (C-AFM). Filaments are electrochemically formed at hundreds of xy locations on a ~40 nm thick polymer electrolyte, polyethylene glycol diacrylate (PEGDA)/[BMIM]PF6. Although the formation time generally decreases with increasing bias from 0.7 to 3.0 V, an unexpected non-monotonic maximum is observed ~ 2.0 V. At voltages approaching this region of inverted kinetics, IL electric double layers (EDLs) becomes detectable; thus, the increased nanofilament formation time can be attributed to electric field screening which hinders silver electro-migration and deposition. Scanning electron microscopy confirms that nanofilaments formed in this inverted region have significantly more lateral and diffuse features. Time-dependent formation currents reveal two types of nanofilament growth dynamics: abrupt, where the resistance decreases sharply over as little as a few ms, and gradual where it decreases more slowly over hundreds of ms. Whether the resistance change is abrupt or gradual depends on the extent to which the EDL screens the electric field. Tuning the formation time and growth dynamics using an IL opens the range of accessible resistance states, which is useful for neuromorphic applications.

Tuning the Gas Separation Performance of CuBTC by Ionic Liquid Incorporation.

The efficient separation of gases has industrial, economic, and environmental importance. Here, the gas separation performance of a metal organic framework (MOF) is enhanced by ionic liquid (IL) incorporation. One of the most commonly used ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), was incorporated into a commercially available MOF, CuBTC. Detailed characterization by combining spectroscopy with diffraction, electron microscopy, and thermal analysis confirmed that the structures were intact after incorporation. Adsorption isotherms of CH4, H2, N2, and CO2 in IL-incorporated CuBTC were experimentally measured and compared with those of pristine CuBTC. Consequently, ideal selectivities for CO2/CH4, CO2/N2, CO2/H2, CH4/N2, CH4/H2, and N2/H2 separations were calculated. The results showed that the CH4 selectivity of CuBTC over CO2, H2, and N2 gases becomes at least 1.5 times higher than that of pristine CuBTC upon the incorporation of IL. For example, the CH4/H2 selectivity of CuBTC increased from 26 to 56 at 0.2 bar when the IL loading was 30 wt %. These results show that the incorporation of ILs into MOFs can lead to unprecedented improvements in the gas separation performance of MOFs. The tunable physicochemical properties of ILs combined with a large number of possible MOF structures open up opportunities for the rational design of novel materials for meeting future energy challenges.