Tailoring Nanocrystalline Metal–Organic Frameworks as Fluorescent Dye Carriers for Bioimaging

Challenges exist in taking advantage of dye molecules for reliable and reproducible molecular probes in biomedical applications. In this study, we show how to utilize the dye molecules for bioimaging within protective carriers of nanocrystalline metal–organic frameworks (nMOFs) particles. Specifically, Resorufin and Rhodamine-6G having different molecular sizes were encapsulated within close-fitting pores of nMOF-801 and nUiO-67 particles, respectively. The resulting nanocrystalline particles have high crystallinity, uniform size, and morphology and preserve enhanced photoluminescence properties with exceptional stabilities in biomedical environment. The samples are further functionalized with a targeting agent and successfully work for fluorescence imaging of FL83B (human hepatocyte cell) and HepG2 (human hepatocellular carcinoma) without cytotoxicity

Network of Heterogeneous Catalyst Arrays on the Nitrogen-Doped Graphene for Synergistic Solar Energy Harvesting of Hydrogen from Water

Combination of different nanoparticles has been suggested as a promising approach to realize advanced functionalities for many applications. Herein, we report a new method to make uniform sized nanoparticle arrays in a network by arranging a micelle monolayer in an ordered fashion on the conductive nitrogen-doped graphene (NG). Moreover, coarrangement of two different arrays using both metal and metal oxide nanoparticles on the conductive graphene is found to result in the synergistic and cooperative photocatalytic activity for production of hydrogen from water using solar energy, with the excellent performance attributed to efficient electron transfer from one nanoparticle through the conductive NG to the other nanoparticle in a single-layer network. Consequently, this work suggests a promising solution to design high-performance catalysts in a network of different nanoparticle arrays on thin and flexible conductive substrates

Supercapacitors of Nanocrystalline Metal–Organic Frameworks

The high porosity of metal–organic frameworks (MOFs) has been used to achieve exceptional gas adsorptive properties but as yet remains largely unexplored for electrochemical energy storage devices. This study shows that MOFs made as nanocrystals (nMOFs) can be doped with graphene and successfully incorporated into devices to function as supercapacitors. A series of 23 different nMOFs with multiple organic functionalities and metal ions, differing pore sizes and shapes, discrete and infinite metal oxide backbones, large and small nanocrystals, and a variety of structure types have been prepared and examined. Several members of this series give high capacitance; in particular, a zirconium MOF exhibits exceptionally high capacitance. It has the stack and areal capacitance of 0.64 and 5.09 mF cm^–2, about 6 times that of the supercapacitors made from the benchmark commercial activated carbon materials and a performance that is preserved over at least 10000 charge/discharge cycles

Nanocrystalline Titanium Metal–Organic Frameworks for Highly Efficient and Flexible Perovskite Solar Cells

Flexible perovskite solar cells (PSCs) have attracted considerable attention due to their excellent performance, low-cost, and great potential as an energy supplier for soft electronic devices. In particular, the design of charge transporting layers (CTLs) is crucial to the development of highly efficient and flexible PSCs. Herein, nanocrystalline Ti-based metal–organic framework (nTi-MOF) particles are synthesized to have <i>ca</i>. 6 nm in diameter. These are then well-dispersed in alcohol solvents in order to generate electron transporting layers (ETLs) in PSCs under ambient temperatures using a spin-coating process. The electronic structure of nTi-MOF ETL is found to be suitable for charge injection and transfer from the perovskite to the electrodes. The combination of a [6,6]-phenyl-C₆₁-butyric acid (PCBM) into the nTi-MOF ETL provides for efficient electron transfer and also suppresses direct contact between the perovskite and the electrode. This results in impressive power conversion efficiencies (PCEs) of 18.94% and 17.43% for rigid and flexible devices, respectively. Moreover, outstanding mechanical stability is retained after 700 bending cycles at a bending radius (<i>r</i>) of 10 mm

Copper Nanocrystals Encapsulated in Zr-based Metal–Organic Frameworks for Highly Selective CO₂ Hydrogenation to Methanol

We show that the activity and selectivity of Cu catalyst can be promoted by a Zr-based metal–organic framework (MOF), Zr₆O₄(OH)₄(BDC)₆ (BDC = 1,4-benzenedicarboxylate), UiO-66, to have a strong interaction with Zr oxide [Zr₆O₄(OH)₄(−CO₂)₁₂] secondary building units (SBUs) of the MOF for CO₂ hydrogenation to methanol. These interesting features are achieved by a catalyst composed of 18 nm single Cu nanocrystal (NC) encapsulated within single crystal UiO-66 (Cu⊂UiO-66). The performance of this catalyst construct exceeds the benchmark Cu/ZnO/Al₂O₃ catalyst and gives a steady 8-fold enhanced yield and 100% selectivity for methanol. The X-ray photoelectron spectroscopy data obtained on the surface of the catalyst show that Zr 3d binding energy is shifted toward lower oxidation state in the presence of Cu NC, suggesting that there is a strong interaction between Cu NC and Zr oxide SBUs of the MOF to make a highly active Cu catalyst

Visualization 1: In vivo photothermal treatment by the peritumoral injection of macrophages loaded with gold nanoshells

The xenograft tumor mass was illuminated using a NIR laser at an irradiance of 1 W/cm2 for 2 minutes Originally published in Biomedical Optics Express on 01 January 2016 (boe-7-1-185