Flexible Coordination Network Exhibiting Water Vapor-Induced Reversible Switching between Closed and Open Phases.

That physisorbents can reduce the energy footprint of water vapor capture and release has attracted interest because of potential applications such as moisture harvesting, dehumidification, and heat pumps. In this context, sorbents exhibiting an S-shaped single-step water sorption isotherm are desirable, most of which are structurally rigid sorbents that undergo pore-filling at low relative humidity (RH), ideally below 30% RH. Here, we report that a new flexible one-dimensional (1D) coordination network, [Cu(HQS)(TMBP)] (H2HQS = 8-hydroxyquinoline-5-sulfonic acid and TMBP = 4,4'-trimethylenedipyridine), exhibits at least five phases: two as-synthesized open phases, α ⊃ H2O and ß âŠƒ MeOH; an activated closed phase (γ); CO2 (δ ⊃ CO2) and C2H2 (ϵ ⊃ C2H2) loaded phases. The γ phase underwent a reversible structural transformation to α ⊃ H2O with a stepped sorption profile (Type F-IV) when exposed to water vapor at <30% RH at 300 K. The hydrolytic stability of [Cu(HQS)(TMBP)] was confirmed by powder X-ray diffraction (PXRD) after immersion in boiling water for 6 months. Temperature-humidity swing cycling measurements demonstrated that working capacity is retained for >100 cycles and only mild heating (<323 K) is required for regeneration. Unexpectedly, the kinetics of loading and unloading of [Cu(HQS)(TMBP)] compares favorably with well-studied rigid water sorbents such as Al-fumarate, MOF-303, and CAU-10-H. Furthermore, a polymer composite of [Cu(HQS)(TMBP)] was prepared and its water sorption retained its stepped profile and uptake capacity over multiple cycles.

Photo-responsive functional gold nanocapsules for inactivation of community-acquired, highly virulent, multidrug-resistant MRSA.

The indiscriminate and sporadic use of antibiotics has contributed to the emergence of drug resistance phenomenon in bacteria including but not limited to Staphylococcus aureus. These drug-resistant bacteria have been threatening safety in hospitals and adversely affecting human health. Here we report a strategy to design photo-stimulated theranostic nanoprobes against methicillin-resistant Staphylococcus aureus (MRSA) "superbug" USA300. The nanocapsule probe is based on gold nanorods (GNRs) coated with pegylated thiol, mPEG-SH, which has been further modified by adding successively a natural antibacterial compound such as curcumin, and a cell targeting deoxyribonucleic acid (DNA) aptamer. We have used this novel gold nanocapsules for near-infrared (NIR) photophysical stimulation against pathogenic bacteria. We have found that the novel nanocapsule blocks biofilm formation and kills bacteria by photothermal action that causes disruption of the bacterial cell wall and membrane. In this approach, multiple drug-resistant Staphylococcus aureus has been captured by these nanocapsules through DNA aptamer targeting. All of the trapped bacteria could be killed in 30 minutes during the NIR stimulation due to the combination of photothermal effect, the generation of reactive oxygen species (ROS) and a loss of transmembrane potential (Δψ). Importantly we did not notice any resistance developed against the photothermal treatment. This is remarkable from an anti-biofilm activity point of view. Importantly, these multifunctional nanocapsules have also shown a surface enhanced Raman spectroscopy (SERS) effect, which could be used to evaluate the success of the inactivation effect during treatment. These results indicate that nanocapsule-based photo treatment can be an alternative antibacterial strategy without contributing to antibiotic resistance, and thus can be used for both environmental and therapeutic applications.

Environmentally Friendly Enzyme Immobilization on MOF Materials.

Metal-organic framework (MOF) materials have revolutionized the applications of nanoporous materials. They can be potentially used in separation, storage, and catalysis, among other applications. Since their discovery in 1999 (Li et al. Nature 402:276-279, 1999; Chui Science 283:1148-1150, 1999), more than 20,000 new structures have been synthesized thanks in part to their high compositional versatility. However, only some of them are really stable in water (both in liquid and vapor phase), which limits their employment in other applications. Furthermore, biocatalysis field has been demanding a "universal support" able to encapsulate/immobilize any type of enzyme in a straightforward methodology and, simultaneously, capable of keeping the enzymatic catalytic activity. This requisite set has been a big challenge considering the drastic synthesis conditions required for most of the MOF materials. Thus, a compromise between the development of a well-formed material support and an acceptable enzymatic activity had to be achieved in order to obtain active biocatalysts, ideally prepared in just one step and under sustainable conditions. In this chapter, we describe the protocols about how to synthesize MOF materials in water, under mild conditions and almost instantaneously in the presence of enzymes. The most successful support of these sustainable MOFs was the semicrystalline Fe-BTC MOF material (like the commercial Basolite F300) allowing the development of efficient active biocatalysts (97% with respect to the free enzyme in the case of CALB lipase). Particularly, this enzyme support improves the benefits given by some other MOF-based supports also described in this chapter, like NH2-MIL-53(Al). Furthermore, we present the post-synthesis immobilization approach, which consists firstly in the synthesis or preparation of the respective MOF material (Fe-BTC or NH2-MIL-53(Al)), followed by an enzyme immobilization protocol. As reported in bibliography, MOFs as enzyme supports combine together more active biocatalysts with lower enzyme leaching when compared to other conventional materials. Moreover, MOFs prepared in non-aqueous media (for instance, N,N-dimethylformamide) can also trap enzymes in an otherwise adverse media. These facts bring these biocatalysts closer to industrial employment in even more demanding applications.

Silica nano supra-assembly for the targeted delivery of therapeutic cargo to overcome chemoresistance in cancer.

Cancer cells become resistant over the period to chemotherapeutic drugs and pose a challenging impediment for oncologists in providing effective treatment. Nanomedicine allows to overcome chemoresistance and is the focus of our investigation. Silica nanostructures have been highlighted as an interesting drug delivery platform in vitro and in vivo applications. Here we show the validity of nanomedicine approach for targeted chemotherapeutic cargo delivery to overcome chemoresistance in cancer cells both in vitro and in vivo. For demonstrating the concept, we functionalised ∼100 nm long porous silica nanoparticles (∼20 nm diameter ordered pore structure) by conjugating anticancer drug, cytochrome c enzyme and dual-function anticancer aptamer AS1411 in single supra-assembled nanocargos. The supra-assembly on the porous silica nanostructure allows for a high loading of catalytic enzyme cytochrome c, anticancer drug and aptamer. The silica supra-assembly is characterized by transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) surface area analysis. Conjugation of cargoes has been monitored at each step by UV-vis and Fluorescence spectroscopy. Finally, the constructed supra-assembled nanocarrier tested on chemoresistance colon cancer (HCT116) cells. A pH-responsive, intracellular theranostic cargo delivery has been achieved and the triple action of the nanocargo made an efficient killing of drug resistance colon cancer cells in vitro (∼ 92% cell death) through triplex therapy effects by supressing the P-glycoprotein (P-gp) level. Furthermore, in vivo animal toxicity studies demonstrated, the supra-assembled nanocargos have encouraging safety index to be used in cancer therapy and drug delivery applications.