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Improving the performance, reproducibility, and stability of Sn‐based perovskite solar cells (PSCs) with n–i–p structures is an important challenge. Spiro‐OMeTAD [2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)9,9′‐spirobifluorene], a hole transporting material (HTM) with n–i–p structure, requires the oxygen exposure after addition of Li‐TFSI [Lithium bis(trifluoromethanesulfonyl)imide] as a dopant to increase the hole concentration. In Sn‐based PSC, Sn2+ is easily oxidized to Sn4+ under such a condition, resulting in a sharp decrease in efficiency. Herein, a formamidinium tin triiodide (FASnI3)‐based PSCs fabricated using DPI‐TPFB [4‐Isopropyl‐4′‐methyldiphenyliodonium tetrakis(pentafluorophenyl)borate] instead of Li‐TFSI are reported as a dopant in Spiro‐OMeTAD. The DPI‐TPFB enables the fabrication of PSCs with an efficiency of up to 10.9%, the highest among FASnI3‐based PSCs with n–i–p structures. Moreover, ≈80% of the initial efficiency is maintained even after 1,597 h under maximum power point tracking conditions. In particular, the encapsulated device does not show any decrease in efficiency even after holding for 50 h in the 85 °C/85% RH condition. The high efficiency and excellent stability of PSCs prepared by doping with DPI‐TPFB are attributed to not only increasing electrical conductivity by acting as a Lewis acid, but also stabilizing Sn2+ through coordination with Sn2+ on the surface of FASnI3. [ABSTRACT FROM AUTHOR]

Cancer cells have the capacity to synthesize nanoparticles (NPs). The detailed mechanism of this process is not very well documented. We report the mechanism of biomineralization of aqueous gold chloride into NPs and microplates in the breast-cancer cell line MCF7. Spherical gold NPs are synthesized in these cells in the presence of serum in the culture media by the reduction of HAuCl 4 . In the absence of serum, the cells exhibit gold microplate formation through seed-mediate growth albeit slower reduction. The structural characteristics of the two types of NPs under different media conditions were confirmed using scanning electron microscopy (SEM); crystallinity and metallic properties were assessed with transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). Gold-reducing proteins, related to cell stress initiate the biomineralization of HAuCl 4 in cells (under serum free conditions) as confirmed by infrared (IR) spectroscopy. MCF7 cells undergo irreversible replicative senescence when exposed to a high concentration of ionic gold and conversely remain in a dormant reversible quiescent state when exposed to a low gold concentration. The latter cellular state was achievable in the presence of the rho/ROCK inhibitor Y-27632. Proteomic analysis revealed consistent expression of specific proteins under serum and serum-free conditions. A high-throughput proteomic approach to screen gold-reducing proteins and peptide sequences was utilized and validated by quartz crystal microbalance with dissipation (QCM-D). Statement of significance Cancer cells are known to synthesize gold nanoparticles and microstructures, which are promising for bioimaging and other therapeutic applications. However, the detailed mechanism of such biomineralization process is not well understood yet. Herein, we demonstrate that cancer cells exposed to gold ions (grown in serum/serum-free conditions) secrete shock and stress-related proteins with specific gold-binding/reducing polypeptides. Cells undergo reversible senescence and can recover normal physiology when treated with the senescence inhibitor depending on culture condition. The use of mammalian cells as microincubators for synthesis of such particles could have potential influence on their uptake and biocompatibility. This study has important implications for in-situ reduction of ionic gold to anisotropic micro-nanostructures that could be used in-vivo clinical applications and tumor photothermal therapy. [ABSTRACT FROM AUTHOR]

Abstract: Nature manufactures biological systems in three dimensions with precisely controlled spatiotemporal profiles on hierarchical length and time scales. In this article, we review 3D patterning of biological systems on synthetic platforms for neuropharmacological applications. We briefly describe 3D versus 2D chemical and topographical patterning methods and their limitations. Subsequently, an overview of introducing a third dimension in neuropharmacological research with delineation of chemical and topographical roles is presented. Finally, toward the end of this article, an explanation of how 3D patterning has played a pivotal role in relevant fields of neuropharmacology to understand neurophysiology during development, normal health, and disease conditions is described. The future prospects of organs‐on‐a‐‐like devices to mimic patterned blood–brain barrier in the context of neurotherapeutic discovery and development for the prioritization of lead candidates, membrane potential, and toxicity testing are also described. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1369–1382, 2018. [ABSTRACT FROM AUTHOR]

Abstract: Although antimony sulfoiodide (SbSI) exhibits very interesting properties including high photoconductivity, ferroelectricity, and piezoelectricity, it is not applied to solar cells. Meanwhile, SbSI is predominantly prepared as a powder using a high‐temperature, high‐pressure system. Herein, the fabrication of solar cells utilizing SbSI as light harvesters is reported for the first time to the best of knowledge. SbSI is prepared by solution processing, followed by annealing under mild temperature conditions by a reaction between antimony trisulfide, which is deposited by chemical bath deposition on a mesoporous TiO2 electrode and antimony triiodide, under air at a low temperature (90 °C) without any external pressure. The solar cells fabricated using SbSI exhibit a power conversion efficiency of 3.05% under standard illumination conditions of 100 mW cm−2. [ABSTRACT FROM AUTHOR]

Despite the large body of experimental work recently on biohybrid microsystems, few studies have focused on theoretical modeling of such systems, which is essential to understand their underlying functioning mechanisms and hence design them optimally for a given application task. Therefore, this study focuses on developing a mathematical model to describe the 3D motion and chemotaxis of a type of widely studied biohybrid microswimmer, where spherical microbeads are driven by multiple attached bacteria. The model is developed based on the biophysical observations of the experimental system and is validated by comparing the model simulation with experimental 3D swimming trajectories and other motility characteristics, including mean squared displacement, speed, diffusivity, and turn angle. The chemotaxis modeling results of the microswimmers also agree well with the experiments, where a collective chemotactic behavior among multiple bacteria is observed. The simulation result implies that such collective chemotaxis behavior is due to a synchronized signaling pathway across the bacteria attached to the same microswimmer. Furthermore, the dependencies of the motility and chemotaxis of the microswimmers on certain system parameters, such as the chemoattractant concentration gradient, swimmer body size, and number of attached bacteria, toward an optimized design of such biohybrid system are studied. The optimized microswimmers would be used in targeted cargo, e.g., drug, imaging agent, gene, and RNA, transport and delivery inside the stagnant or low‐velocity fluids of the human body as one of their potential biomedical applications. [ABSTRACT FROM AUTHOR]

The considerable morbidity associated with hospitalized patients and clinics in developed countries due to biofilm formation on biomedical implants and surgical instruments is a heavy economic burden. An alternative to chemically treated surfaces for bactericidal activity started emerging from micro/nanoscale topographical cues in the last decade. Here, we demonstrate a putative antibacterial surface using copper nanowhiskers deposited by molecular beam epitaxy. Furthermore, the control of biological response is based on hydrophobic pinning of water droplets in the Wenzel regime, causing mechanical injury and cell death. Scanning electron microscopy images revealed the details of the surface morphology and non-contact mode laser scanning of the surface revealed the microtopography-associated quantitative parameters. Introducing the bacterial culture over nanowhiskers produces mechanical injury to cells, leading to a reduction in cell density over time due to local pinning of culture medium to whisker surfaces. Extended culture to 72 hours to observe biofilm formation revealed biofilm inhibition with scattered microcolonies and significantly reduced biovolume on nanowhiskers. Therefore, surfaces patterned with copper nanowhiskers can serve as potential antibiofilm surfaces. The topography-based antibacterial surfaces introduce a novel prospect in developing mechanoresponsive nanobiomaterials to reduce the risk of medical device biofilm-associated infections, contrary to chemical leaching of copper as a traditional bactericidal agent. [ABSTRACT FROM AUTHOR]

We provide a comparative analysis of protein adsorption, primary human cell behavior, and biofilm formation on modified titanium substrates of either micro-, nano-, or hybrid micro/nano-scale feature sizes. While studies revealed that nano-scale structures initially decreased the attachment and spreading of both human fibroblasts (hDFs) and mesenchymal stem cells (hMSCs), hMSC differentiation studies revealed that hybrid structures promoted the highest levels of osteogenic gene expression and attenuated biofilm formation by Staphylococcus epidermidis. Taken together, this novel approach of generating a hybrid topographical feature results in a potential implant material capable of enhanced dermal cell adhesion and osteogenic differentiation while limiting biofilm accumulation. [ABSTRACT FROM AUTHOR]

The formation of CH3NH3PbI3 (MAPbI3) from its precursors is probably the most significant step in the control of the quality of this semiconductor perovskite material, which is highly promising for photovoltaic applications. Here we investigated the transformation of spin coated PbI2 films to MAPbI3 using a reaction with MAI in vapor phase, referred to as vapor assisted solution process (VASP). The presence of a mesoporous TiO2 scaffold on the substrate was found to speed up reaction and led to complete conversion of PbI2, while reaction on glass substrates was slower, with some PbI2 remaining even after prolonged reaction time. Based on data from UV-visible spectroscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, the formation of an X-ray amorphous intermediate phase is proposed, which is identified by an increasing absorption from 650 to 500 nm in the absorption spectrum. This feature disappears upon long reaction times for films on planar substrates, but persists for films on mesoporous TiO2. Poor solar cell performance of planar VASP prepared devices was ascribed to PbI2 remaining in the film, forming a barrier between the perovskite layer and the compact TiO2/FTO contact. Good performance, with efficiencies up to 13.3%, was obtained for VASP prepared devices on mesoporous TiO2. [ABSTRACT FROM AUTHOR]

Hybrid (organic–inorganic) lead trihalide perovskites have attracted much attention in recent years due to their exceptionally promising potential for application in solar cells. Here a controlled one-step method is presented where PbCl2 is combined with three equivalents methylammonium halide (MAX, with X = I and/or Br) in polar solvents to form MAPb(I1−xBrx)3 perovskite films upon annealing in air at 145 °C. The procedure allows for a linear increment of the semiconductor bandgap from 1.60 eV to 2.33 eV by increasing the Br content. A transition from a tetragonal to a cubic structure is found when the Br fraction is larger than 0.3. X-ray photoelectron spectroscopy investigations shows that the increase of Br content is accompanied by a shift of the valence band edge to lower energy. Simultaneously, the conduction band moves to higher energy, but this shift is less pronounced. Time-resolved single-photon counting experiments of the perovskite materials on mesoporous TiO2 show faster decay kinetics for Br containing perovskites, indicative of improved electron injection into TiO2. Interestingly, kinetics of MAPbI2.7Br0.3Cly on TiO2 scaffold became faster after prolonged excitation during the measurement. In solar cell devices, MAPbI2.7Br0.3Cly yielded best performance, giving more than 14% power conversion efficiency when used in combination with an n-type contact consisting of fluorine-doped tinoxide glass coated with dense TiO2 and a mesoporous Al2O3 scaffold, and a p-type contact, spiro-MeOTAD/Ag. [ABSTRACT FROM AUTHOR]

With [RuII(bpyMeP)2tpphzPtCl2]2+ (4) a molecular photocatalyst has been synthesized for visible-light-driven H2-evolution. It contains the ligand bpyMeP (4,4′-bis(diethyl-(methylene)-phosphonate)-2,2′-bipyridine) with phosphate ester groups as precursors for the highly potent phosphonate anchoring groups, which can be utilized for immobilization of the catalyst on metal–oxide semiconductor surfaces. The synthesis was optimized with regard to high yields, bpyMeP was fully characterized and a solid-state structure could be obtained. Photophysical studies showed that the photophysical properties and the localization of the excited states are not altered compared to similar Ru-complexes without anchoring group precursors. (4) was even more active in homogenous catalysis experiments than [RuII(tbbpy)2tpphzPtCl2]2+ (6) with tbbpy (4,4′-bis(tbutyl)-2,2′-bipyridine) as peripheral ligands. After hydrolysis (4) was successfully immobilized on NiO, suggesting that an application in photoelectrosynthesis cells is feasible. [ABSTRACT FROM AUTHOR]

Organic–inorganic halide perovskite(OIHP) compounds arevery interesting materials for device application in, for example,solar cells, electro-optics, and electronic circuits. In this report,we investigated OIHPs reported as CH3NH3PbI3–xClx(MAPbI3–xClx)and CH3NH3PbI3(MAPbI3) prepared from solution on mesoporous TiO2/glass substrates.A long-term conversion from disordered to more crystalline OIHPs wasobserved for both types of samples from XRD patterns over 5 weeks.The conversion rate to more crystalline OIHPs could be increased byincreasing the temperature of the sample. SEM analyses of the twotypes of OIHPs show remarkably different surface microstructures.The X-ray diffractograms suggest that both samples are dominated bythe similar crystal structure, although the preferential orientationfor the crystal structure is different. Moreover, the results suggestthat the material reported as MAPbI3–xClxis a combination of MAPbI3and MAPbCl3. The crystal structure and exact natureof the material is important for the understanding and optimizationof devices, and the possibility for enhanced crystallinity of theOIHPs shown in this report will therefore be important for furtherimprovement and understanding of the devices. [ABSTRACT FROM AUTHOR]

Abstract: Encapsulation of horseradish peroxidase (HRP) inside a peptide nanotube (PNT) was demonstrated and its activity was measured. Enzyme assay verified that 0.16μg of the enzymes were encapsulated in 1mg of PNTs. The encapsulation was also verified with TEM, UV–vis spectroscopy, and FTIR. The activity of the encapsulated HRP was examined for thermal stability, long-term storage stability, and resistance to a denaturant. They showed good storage stability, retaining its activity up to 90%, while the free HRP lost 50% of its activity over the course of 18days. At 55°C, the encapsulated HRP activity remained 20% higher than that of the free HRP. With the denaturant, guanidinium hydrochloride (GdmHCl), the encapsulated HRP activity was maintained around 10% higher than the free HRP. This result proves that the encapsulation of HRP inside the PNT may be an effective way to keep the enzyme activity stable in various environments. [Copyright &y& Elsevier]

Tin sulfide (SnS) is one of the most promising solar cell materials, as it is abundant, environment friendly, available at low cost, and offers long‐term stability. However, the highest efficiency of the SnS solar cell reported so far remains at 4.36% even using the expensive atomic layer deposition process. This study reports on the fabrication of SnS solar cells by a solution process that employs rapid thermal treatment for few seconds under Ar gas flow after spin‐coating a precursor solution of SnCl2 and thiourea dissolved in dimethylformamide onto a nanostructured thin TiO2 electrode. The best‐performing cell exhibits power conversion efficiency (PCE) of 3.8% under 1 sun radiation conditions (AM1.5G). Moreover, secondary treatment using SnCl2 results in a significant improvement of 4.8% in PCE, which is one of the highest efficiencies among SnS‐based solar cells, especially with TiO2 electrodes. The thin film properties of SnS after SnCl2 secondary treatment are analyzed using grazing‐incidence wide‐angle X‐ray scattering, and high‐resolution transmittance electron microscopy. [ABSTRACT FROM AUTHOR]

Swimming microorganisms have been shown to be useful for the propulsion of microrobotic devices due to their self‐powered motion. Up to now, mainly bacteria, e.g., magnetotactic bacteria (MTB), are investigated as biohybrid microrobots. But biocompatibility studies of MTB regarding medical utilizations are still lacking. Moreover, MTB require special culture conditions for their stability, which also might limit their usage for biomedical applications. Herein, a cytocompatible, highly motile microswimmer is presented from a microalga, Chlamydomonas reinhardtii, which has the capacity to carry large loads. C. reinhardtii cells are magnetized by incorporating terbium. The following analyses reveal an induced magnetic moment of a magnetized C. reinhardtii cell of 1.6 × 10−11 emu, comparable to its counterparts used as magnetotactic microrobots. The magnetized algae are able to align to the field lines of an applied uniform magnetic field, guiding them to swim in a directional motion. In addition, C. reinhardtii cells and human cells show mutual biocompatibility, indicating that the algae cells are noncytotoxic. Furthermore, the magnetized microalgae reported here are easy to track in the human body by luminescence imaging tools due to their innate autofluorescence performance and photoluminescence of the incorporated Tb3+. Thus, terbium‐incorporated microalgae are promising candidates for magnetically steerable biohybrid microrobots. Magnetotactic microalgae are facilely generated by accumulation of magnetic terbium ions inside the living cells. The fast swimming algae can be controlled magnetically, they align passively to magnetic field lines and swim actively towards the magnets. They have fluorescence properties due to the lanthanide terbium and show mutual biocompatibility with mammal cells. The reported magnetotactic microalgae display promising candidates for microrobotic devices. [ABSTRACT FROM AUTHOR]

In view of the possible replacement of toxic lead perovskites in solar cells by a less toxic electrode material, Bi-based perovskites A3Bi2I9 (A: MeNH3, Cs) are synthesized by reaction of metallic Cs or MeNH3I with BiI3 in a 7:3 DMF/DMSO mixture. [ABSTRACT FROM AUTHOR]

We report a hybrid dye system, in which two dyes are linked linearly by a metal–O–metal linkage, for dye sensitized solar cells (cell-NcSn-N719). Tin(IV) 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (NcSn) was adsorbed on a SnO2 surface by a Sn(p)–O–Sn(n) linkage, where Sn(p) and Sn(n) stand for a Sn atom on a Sn nanoparticle surface and that at the center of NcSn, respectively. cis-Diisothiocyanato-bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II) bis(tetrabutylammonium), known as N719, was bonded to NcSn by a –Sn(n)–O–CO– linkage. The incident photon to photocurrent efficiency (IPCE) curve of cell-NcSn-N719 suggested that electrons are injected from both N719 and NcSn to SnO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The use of bacterial cells as agents of medical therapy has a long history. Research that was ignited over a century ago with the accidental infection of cancer patients has matured into a platform technology that offers the promise of opening up new potential frontiers in medical treatment. Bacterial cells exhibit unique characteristics that make them well-suited as smart drug delivery agents. Our ability to genetically manipulate the molecular machinery of these cells enables the customization of their therapeutic action as well as its precise tuning and spatio-temporal control, allowing for the design of unique, complex therapeutic functions, unmatched by current drug delivery systems. Early results have been promising, but there are still many important challenges that must be addressed. We present a review of promises and challenges of employing bioengineered bacteria in drug delivery systems and introduce the biohybrid design concept as a new additional paradigm in bacteria-based drug delivery. [ABSTRACT FROM AUTHOR]