We report the performance of perovskite solar cells (PSCs) with an electron transport layer (ETL) consisting of a SnO2 thin film obtained by electrochemical deposition. The surface morphology and thickness of the electrodeposited SnO2 films were closely related to electrochemical process conditions, i.e., the applied voltage, bath temperature, and deposition time. We investigated the performance of PSCs based on the SnO2 films. Remarkably, the experimental factors that are closely associated with the photovoltaic performance were strongly affected by the SnO2 ETLs. Finally, to enhance the photovoltaic performance, the surfaces of the SnO2 films were modified slightly by TiCl4 hydrolysis. This process improves charge extraction and suppresses charge recombination.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-2247-x) contains supplementary material, which is available to authorized users.

Crystalline metal–organic frameworks (MOFs) are extensively used in areas such as gas storage and small-molecule drug delivery. Although Cu-BTC (1, MOF-199, BTC: benzene-1,3,5-tricarboxylate) has versatile applications, its NO storage and release characteristics are not amenable to therapeutic usage. In this work, micro-sized Cu-BTC was prepared solvothermally and then processed by ball-milling to prepare nano-sized Cu-BTC (2). The NO storage and release properties of the micro- and nano-sized Cu-BTC MOFs were morphology dependent. Control of the hydration degree and morphology of the NO delivery vehicle improved the NO release characteristics significantly. In particular, the nano-sized NO-loaded Cu-BTC (NO⊂nano-Cu-BTC, 4) released NO at 1.81 µmol·mg−1 in 1.2 h in PBS, which meets the requirements for clinical usage. The solid-state structural formula of NO⊂Cu-BTC was successfully determined to be [CuC6H2O5]·(NO)0.167 through single-crystal X-ray diffraction, suggesting no structural changes in Cu-BTC upon the intercalation of 0.167 equivalents of NO within the pores of Cu-BTC after NO loading. The structure of Cu-BTC was also stably maintained after NO release. NO⊂Cu-BTC exhibited significant antibacterial activity against six bacterial strains, including Gram-negative and positive bacteria. NO⊂Cu-BTC could be utilized as a hybrid NO donor to explore the synergistic effects of the known antibacterial properties of Cu-BTC.

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The excessive initial corrosion rate of Mg is a critical limitation in the clinical application of biodegradable Mg implants because the device loses its fixation strength before the fractured bone heals. This study suggests a new approach to overcome this hurdle by accelerating tissue regeneration instead of delaying the implant biodegradation. As angiogenesis is an essential process in early bone regeneration, a Mg implant coated with electrospun nanofibers containing nitric oxide (NO), which physiologically promotes angiogenesis, is designed. The integrated device enables adjustable amounts of NO to be stored on the NO donor-conjugated nanofiber coating, stably delivered, and released to the fractured bone tissue near the implanted sites. An in vitro corrosion test reveals no adverse effect of the released NO on the corrosion behavior of the Mg implant. Simultanously, the optimal concentration level of NO released from the implant significantly enhances tube network formation of human umbilical vein endothelial cells (HUVECs) without any cytotoxicity problem. This indicates that angiogenesis can be accelerated by combining NOreleasing nanofibers with a Mg implant. With its proven feasibility, the proposed approach could be a novel solution for the initial stability problem of biodegradable Mg implants, leading to successful bone fixation.

Metal−organic frameworks (MOFs) are potential exogenous scaffolds for therapeutic nitric oxide (NO) delivery because they can store drug or bioactive gas molecules within pores or on active metal sites. Herein, we employed a Cu-MOF coordinated with glutarate (glu) and 1,2-bis(4-pyridyl)ethane (bpa) to obtain NO-loaded Cu-MOF (NO⊂Cu-MOF). NO loading transformed the space group of Cu-MOF from monoclinic C2/c to triclinic P-1 through nonclassical hydrogen bonding with glu and bpa. Cu-MOF showed good stability in deionized water and phosphate-buffered saline. NO⊂Cu-MOF released up to 1.10 μmol mg −1 NO over 14.6 h at 37 °C, which is suitable for therapeutic applications. NO⊂Cu-MOF showed moderate biocompatibility with L-929 cells and significant anticancer activity against HeLa cells, suggesting an apoptosis-mediated cell death mechanism. These insights into NO bonding modes with Cu-MOF that enable controlled NO release can inspire the design of functional MOFs as hybrid NO donors for drug delivery.