Human adipose-derived stem cells (hASCs) show great potential for healing bone defects. Bone morphogenetic protein-2 (BMP-2) has been reported to stimulate their osteogenic differentiation both in vitro and in vivo. Here, methacrylated gelatin (GelMA) hydrogels were evaluated as a system to deliver BMP-2 to encapsulated hASCs from two different donors, and BMP-2 delivered from the hydrogels was compared to BMP-2 presented exogenously in culture media. GelMA hydrogels were shown to provide sustained, localized presentation of BMP-2 due to electrostatic interactions between the growth factor and biomaterial after an initial burst release. Both donors exhibited similar responses to the loaded and exogenous growth factor; BMP-2 from the hydrogels had a statistically significant effect on hASC osteogenic differentiation compared to exogenous BMP-2. Expression of alkaline phosphatase was accelerated, and cells in hydrogels with loaded BMP-2 deposited more calcium at one, two, and four weeks than cells without BMP-2 or with the growth factor presented in the media. There were no statistically significant differences in calcium content between groups with 25, 50, or 100 µg/mL loaded BMP-2, suggesting that using a lower growth factor dose may be as effective as a higher loading amount in this system. Taken together, these findings suggest that controlled delivery of BMP-2 from the GelMA enhances its osteogenic bioactivity compared to free growth factor presented in the media. Thus, the GelMA system is a promising biomaterial for BMP-2-mediated hASC osteogenesis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1387-1397, 2016.

A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.The isolation and characterization of aquatic dissolved organic matter (DOM) in both limnological and oceanic environments has been the focus of a number of studies (Aiken et al.

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Sequential deposition of the active layer in organic solar cells (OSCs) is favorable to circumvent the existing drawbacks associated with controlling the microstructure in bulk‐heterojunction (BHJ) device fabrication. However, how the processing solvents impact on the morphology during sequential deposition processes is still poorly understood. Herein, high‐efficiency OSCs are fabricated by a sequential blade coating (SBC) through optimization of the morphology evolution process induced by processing solvents. It is demonstrated that the device performance is highly dependent on the processing solvent of the upper layer. In situ morphology characterizations reveal that an obvious liquid–solid phase separation can be identified during the chlorobenzene processing of the D18 layer, corresponding to larger phase separation. During chloroform (CF) processing of the D18 layer, a proper aggregation rate of Y6 and favorable intermixing of lower and upper layers results in the enhanced crystallinity of the acceptor. This facilitates efficient exciton dissociation and charge transport with an inhibited charge recombination in the D18/CF‐based devices, contributing to a superior performance of 17.23%. These results highlight the importance of the processing solvent for the upper layer in the SBC strategy and suggest the great potential of achieving optimized morphology and high‐efficiency OSCs using the SBC strategy.

Ordered porous gold/titanium dioxide (Au/TiO2) hybrid nanostructured films are specifically interesting in large-scale applications using localized surface plasmon resonances (LSPRs) and surface-enhanced Raman scattering (SERS). Deposition of Au nanoparticles via sputter deposition is one of the promising technologies to establish optically active sites at low cost in combination with nanostructured TiO2 films. In this work, we investigate the optical response of sputter-deposited Au/TiO2 nanohybrid thin films with a focus on the plasmonic response and application as molecular sensors. The LSPR peak red shifts with an increasing thickness of deposited Au. The Raman intensity of deposited molecules, probed with rhodamine 6G (R6G), depends on the deposited gold thickness. It has its maximum at an effective Au thickness of 3.4 nm. To elucidate the origin of this behavior, we apply in situ grazing-incidence small-angle X-ray scattering (GISAXS) to investigate the growth kinetics of Au on a TiO2 template during sputter deposition. On the basis of time-resolved GISAXS, the growth characteristics of sputter-deposited Au on a TiO2 template with a final effective Au layer thickness around the percolation threshold is described with the well-known four-stage model of nucleation and cluster formation, diffusion-mediated growth, adsorption-mediated growth, and grain growth. The maximum in SERS intensity is corroborated by the existence and optimal size of hot spots in the narrow space occurring between the sputter-deposited Au clusters, on staying below the percolation threshold. On the basis of the growth laws extracted, we give a guideline for tailoring the ordered porous Au/TiO2 nanohybrid thin films for SERS sensor applications.

Tin perovskite solar cells (PSCs) are considered promising candidates to promote lead‐free perovskite photovoltaics. However, their power conversion efficiency (PCE) is limited by the easy oxidation of Sn2+ and low quality of tin perovskite film. Herein, an ultra‐thin 1‐carboxymethyl‐3‐methylimidazolium chloride (ImAcCl) layer is used to modify the buried interface in tin PSCs, which can induce multifunctional improvements and remarkably enhance the PCE. The carboxylate group (CO) and the hydrogen bond donor (NH) in ImAcCl can interact with tin perovskites, thus significantly suppressing the oxidation of Sn2+ and reducing the trap density in perovskite films. The interfacial roughness is reduced, which contributes to a high‐quality tin perovskite film with increased crystallinity and compactness. In addition, the buried interface modification can modulate the crystal dimensionality, favoring the formation of large bulk‐like crystals instead of low‐dimensional ones in tin perovskite films. Therefore, the charge carrier transport is effectively promoted and the charge carrier recombination is suppressed. Eventually, tin PSCs show a remarkably enhanced PCE from 10.12% to 12.08%. This work highlights the importance of buried interface engineering and provides an effective way to realize efficient tin PSCs.

Single-crystalline niobium pentoxide nanowires (NWs) of length 10−15 μm and diameter 100−200 nm are synthesized by thermal oxidation of niobium substrates in a mild vacuum (3−10 mbar). Amorphous Al 2 O 3 shells of varying thicknesses (10, 30, 40, and 50 nm) are deposited on top of the wires using atomic layer deposition. Bending tests of the uncoated Nb 2 O 5 NWs and the Nb 2 O 5 /Al 2 O 3 core−shell NWs are carried out inside a scanning electron microscope using a micromanipulator with a force measurement tip. The experimental deflection curves are modeled with Euler−Bernoulli (E−B) beam theory, and the Young's modulus is manipulated to determine the best fit. The Nb 2 O 5 NWs with no shell are determined to have a Young's modulus of 67 ± 10 GPa, which agrees with the published data on Nb 2 O 5 thin films. For core−shell NWs, only small deflections of the wires with 10 and 30 nm thick shells can be fitted with the E−B model when utilizing constant Young's modulus values of 67 GPa for the Nb 2 O 5 core and about 160 GPa for the Al 2 O 3 shell. When allowing for a change in the Young's modulus of the Al 2 O 3 shell, the Young's modulus is determined to be at 120 ± 10 GPa for 10 nm and 145 ± 12 GPa for 30 nm at the highest applied load. For thicknesses of 40 nm and 50 nm, we observed a reduced but constant 120 ± 11 and 111 ± 10 GPa, respectively. Such behavior may result from structural disordering of the amorphous Al 2 O 3 through reducing fractions of the densely packed polyhedra, while the fractions of the loosely packed polyhedra increase as a result of the increasing strain or the fabrication process. The increased disorder is associated with increased average interatomic spacing. Thus, the atomic bonding force and also the Young's modulus decrease.

Slot‐die coating is a promising upscaling fabrication method to promote commercialization in the field of organic solar cells. Herein, the nonfullerene active layer blend of a conjugated polymer PffBT4T‐2OD and a small molecule acceptor EH‐IDTBR, which is printed out of the nonhalogenated solvent 1,2,4‐trimethylbenzene, is studied. The film formation kinetics of the active layer PffBT4T‐2OD:EH‐IDTBR is probed in terms of the temporal evolutions in morphology as well as molecular conformation and aggregation as revealed by in situ grazing‐incidence small angle X‐ray scattering and UV–vis spectroscopy during the film printing process. A five‐regime mesoscale domain growth process is observed in the active layer from the liquid state to the final dry state. The solvent evaporation‐induced domain growth is accompanied with molecular stacking in a distinct J‐type aggregation of the acceptor and a slight H‐type aggregation of the donor molecules. The printed active layers exhibit an edge‐on dominated PffBT4T‐2OD and a face‐on dominated EH‐IDTBR crystallite structure. Compared to the neat PffBT4T‐2OD and EH‐IDTBR films, in the active layer, the crystallite structure deviates slightly in lattice spacing.