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MoS2 nanosheets (NSs) are novel 2D nanomaterials (NMs) with potential uses in many areas, and therefore oral exposure route to MoS2 NSs is plausible. Currently, MoS2 NSs are considered as biocompatible NMs, but there is lacking of systemic investigations to study the interactions of MoS2 NSs with intestinal cells. In this study, we exposed the 3D Caco-2 spheroids to MoS2 NSs or MoS2 powders (denoted as MoS2-bulk), and investigated the potential adverse effects of MoS2-materials based on transcriptomics and lipidomics analysis. As expected, both MoS2 NSs and MoS2-bulk were dose-dependently internalized into 3D Caco-2 spheroids but did not induce cytotoxicity, membrane disruption or decrease of thiols. However, the Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes (KEGG) analysis indicated that nutrient absorption and metabolism was decreased. One of the most significantly decreased KEGG pathways is fat digestion and absorption (map04975), and Western blotting analysis further showed that fatty acid binding protein 1 and apolipoprotein A1, key proteins involved in fat digestion and absorption, were down-regulated by MoS2 NSs or MoS2-bulk. In addition, BODIPY 493/503 staining suggested that exposure to MoS2 NSs and MoS2-bulk decreased lipid levels in the spheroids. However, lipidomics data indicated that MoS2 materials only decreased 8 lipid classes, including lysophosphatidylcholine, lysodimethylphosphatidylethanolamine, N-acylethanolamine, ceramide phosphoethanolamines, gangliosides, lysosphingomyelin and sulfatide, whereas most of the lipid classes were indeed increased. In addition, MoS2 NSs was more potent to decrease the lipid classes compared with MoS2-bulk. Combined, the results from this study showed that MoS2 NSs and bulk materials were non-cytotoxic but altered lipid profiles in 3D Caco-2 spheroids.

Malus hupehensis is an extensively used apple rootstock in China. In the current study, M. hupehensis seedlings were treated with exogenous 2.2 µm 6-benzyladenine (6-BA) so as to investigate the mechanism by which 6-BA affects lateral root development. The results indicate that 6-BA treatment promotes elongation and thickening of both root and shoot in M. hupehensis, but reduces the number of lateral roots, as well as reducing the auxin level after 6-BA treatment. Moreover, MhAHK4, MhRR1 and MhRR2 were also significantly up-regulated in response to 6-BA treatment. Expression levels of auxin synthesis- and transport-related genes, such as MhYUCCA6, MhYUCCA10, MhPIN1 and MhPIN2, were down-regulated, which corresponds with lower auxin levels in the 6-BA-treated seedlings. A negative regulator of auxin, MhIAA3, was induced by 6-BA treatment, leading to reduced expression of MhARF7 and MhARF19 in 6-BA-treated seedlings. As a result, expression of MhWOX11, MhWOX5, MhLBD16 and MhLBD29 was blocked, which in turn inhibited lateral root initiation. In addition, a lower auxin level decreased expression of MhRR7 and MhRR15, which repressed expression of key transcription factors associated with root development, thus inhibiting lateral root development. In contrast, 6-BA treatment promoted secondary growth (thickening) of the root by inducing expression of MhCYCD3;1 and MhCYCD3;2. Collectively, the changes in hormone levels and gene expression resulted in a reduced number of lateral roots and thicker roots in 6-BA-treated plants.

Indium (In)-based halide perovskites are desirable for next-generation phosphors and emitting devices, due to their broad emission, nontoxicity, and oxidization avoidance capabilities. However, the...

Flexible solar cells represent a unique field in which hybrid perovskites may find complementary application to silicon solar cells. However, significant challenges in the fabrication of electron transport layers and hole transport layers at low temperatures have been imposed for perovskite solar cells since flexible substrates typically cannot withstand high processing temperatures (>150 °C). In this study, a low-temperature (140 °C) processed SnO2 layer was adopted as the electron transport layer in perovskite solar cells on a flexible PEN (polyethylene naphthalate) substrate, and a fullerene derivative with a carboxylic group (CPTA) that modified the interface between SnO2 and MAPbI3 was found to significantly improve the device performance. The beneficial effects of interface modification on increasing the carrier selectivity to electrons were elucidated, which resulted in a power conversion efficiency of 18.36% for the solar cells under simulated AM1.5 sunlight. The flexible solar cell still retained 75% of its initial efficiency after 500 cycles of bending with a curvature radius of 5 mm. The MAPbI3 solar cells were stable under ambient air conditions (25 °C, 30% relative humidity), and 87% of the initial efficiencies were retained for the unencapsulated devices after 46 days of storage in ambient air.

In this paper, bovine serum albumin served as the initial materials for preparing a kind of cyan-emitting fluorescent protein nanoparticles (BSA NPs). The BSA NPs were further adopted as a template to synthesize protein nanoparticles-stabilized silver nanoclusters (BSA NPs@Ag NCs) that offered two well-separated fluorescence emission peaks respectively at 470 nm and 670 nm. Dopamine could specifically induce the fluorescence enhancement at 470 nm and the fluorescence quenching at 670 nm of BSA NPs@Ag NCs. Moreover, cupric ions could cause the fluorescence quenching at 670 nm of BSA NPs@Ag NCs just with a negligible impact on the fluorescence intensity at 470 nm. The BSA NPs@Ag NCs can serve as a ratiometric probe for detection of dopamine and cupric ions.

In spite of great progress in the surface modification of semiconductor photoelectrodes, the role of the metal oxide cocatalyst on photoelectrochemical (PEC) performance is still not well understood. In this study, ferrihydrite (Fh) as a novel cocatalyst was decorated on a wormlike nanoporous BiVO4 photoanode. A surface kinetics study of Fh/BiVO4 by intensity-modulated photocurrent spectroscopy (IMPS) evidences the primary role of Fh on PEC performance enhancement, varying with the loading of Fh. It was found that dispersed Fh nanoparticles accelerate hole transfer for water oxidation, but the resulting photoanode suffers from poor stability. The thick layers of Fh address the stability of the electrode by suppressing surface charge recombination but result in reduced hole transfer rates. Modification of a BiVO4 film with optimally thick layers of discrete nanoflakes effectively reduces charge recombination without compromising stability, leading to a high AM 1.5 G photocurrent of 4.78 mA/cm2 at 1.23 V ve...

Polyphenols as typical food components can influence the colloidal properties and internalization of nanomaterials (NMs) into mammalian cells. Recently, we found that 3-hydroxyflavone (H3) promoted intracellular Zn ions in ZnO nanoparticle (NP) exposed Caco-2 and HepG2 cells. However, it is unclear if H3 could affect the internalization of metal-based NMs with different morphologies. This study investigated the influence of H3 on colloidal aspects of Ag NPs and Ag nanoflakes (NFs) as well as the internalization of Ag NMs into THP-1 macrophages. 3-Hydroxyflavone at 50 μM promoted the solubility and altered hydrodynamic size, polydispersity index, and ζ potential of Ag NPs and Ag NFs, which indicated that H3 could affect the colloidal stability of Ag NMs. Only H3 but not Ag NMs significantly decreased mitochondrial activities of THP-1 macrophages. The internalization of Ag NMs was markedly increased due to the presence of H3. 3-Hydroxyflavone also exhibited antioxidative properties as it reduced intracellular reactive oxygen species and promoted the activities of ABC transporters as it reduced retention of Calcein in Ag NM-exposed THP-1 macrophages. We concluded that H3 promoted the internalization of Ag NMs into macrophages probably by altering the colloidal stability of Ag NMs and consequently NM-macrophage interactions.

CdSe quantum dots (QDs) were attached to single crystal ZnO(0001) and ZnO(1100) substrates using capping groups, 4-mercaptobenzoic acid, 2-mercaptoacetic acid, 3-mercaptopropionic acid, 8-mercaptooctanoic acid, and 11-mercaptoundecanoic acid, as bifunctional linker molecules. The spectral response and photosensitization yields of the adsorbed QDs were studied with photocurrent spectroscopy. Atomic force microscopy (AFM) was used to verify the surface structure of the ZnO crystals and to examine the coverage and arrangement of the QDs on the single crystal surface. The inner-sphere aqueous redox couple Sx(2-)/S(2-), often used as a regenerator for chalcogenide-based QDs, as well as outer-sphere redox couples such as ferrocene, were able to regenerate the photoexcited CdSe QDs and suppress their photocorrosion. Differences in the binding of the QDs to different ZnO crystal faces are also reported.

Mott–Schottky analysis is used to determine the band edge positions for ZnO single crystals in acetonitrile electrolytes. The band alignment between ZnO and PbS QDs suggests that electron injection can occur for PbS quantum dots (QDs) over a wide range of sizes. Sensitization of ZnO single crystal electrodes with PbS QDs is then demonstrated using ferrocene/ferrocenium as the regenerator (hole acceptor). The largest 5.5 nm QDs are sensitizing the ZnO out to 1580 nm or 0.84 eV, to our knowledge the longest wavelength sensitization measured for any oxide semiconductor. The driving force for the hole transfer from the 5.5 nm PbS QDs with a band gap of 0.84 eV using ferrocene/ferrocenium regenerator in acetonitrile is found to be close to zero, which may result in a high open circuit voltages for QDs sensitized solar cells (QDSSCs) with a spectral response extending well into the infrared.

Carriers generated inside semiconductors during photocatalytic processes are highly energetic and can locally drive reactions that are otherwise difficult or impossible through thermally driven catalysis. However, a model photocatalytic system with high activity and long-term stability is still lacking. Based on surface charge-induced activation, we designed a photocatalytic system of dehydrogenation of methanol and a high activity (95% photon-to-hydrogen efficiency at 405 nm) and long-term durability (still being active after operation for a week) was achieved. The presence of NiCl2 inside the system dramatically changes the adsorption behaviors of reactants and products on catalytic centers and leads to great enhancements in both the catalytic activity and long-term durability of the photocatalyst. This work highlights the importance of electronic property of the surface of catalytic centers for designing efficient and stable photocatalytic systems for solving energy and environment problems.

Understanding interfacial loss and the ways to improving interfacial property is critical to fabricate highly efficient and reproducible perovskite solar cells (PSCs). In SnO2 -based PSCs, nonradiative recombination sites at the SnO2 -perovskite interface lead to a large potential loss and performance variation in the resulting photovoltaic devices. Here, a novel SnO2 -in-polymer matrix (i.e., polyethylene glycol) is devised as the electron transporting layer to improve the film quality of the SnO2 electron transporting layer. The SnO2 -in-polymer matrix is fabricated through spin-coating a polymer-incorporated SnO2 colloidal ink. The polymer is uniformly dispersed in SnO2 colloidal ink and promotes the nanoparticle disaggregation in the ink. Owing to polymer incorporation, the compactness and wetting property of SnO2 layer is significantly ameliorated. Finally, photovoltaic devices based on Cs0.05 FA0.81 MA0.14 PbI2.55 Br0.45 perovskite sandwiched between SnO2 and Spiro-OMeTAD layer are fabricated. Compared with the averaging power conversion efficiency of 16.2% with 1.2% deviation for control devices, the optimized devices exhibit an improved averaging efficiency of 19.5% with 0.25% deviation. The conception of polymer incorporation in the electron transporting layer paves a way to further increase the performance of planar perovskite solar cells.

Adventitious roots (AR) play an important role in the vegetative propagation of apple rootstocks. The potential role of hormone, wounding, and sugar signalling pathways in mediating AR formation has not been adequately explored and the whole co-expression network in AR formation has not been well established in apple. In order to identify the molecular mechanisms underlying AR formation in &lsquo, T337&rsquo, apple rootstocks, transcriptomic changes that occur during four stages of AR formation (0, 3, 9 and 16 days) were analyzed using high-throughput sequencing. A total of 4294 differentially expressed genes were identified. Approximately 446 genes related to hormones, wounding, sugar signaling, root development, and cell cycle induction pathways were subsequently selected based on their potential to be involved in AR formation. RT-qPCR validation of 47 genes with known functions exhibited a strong positive correlation with the RNA-seq data. Interestingly, most of the candidate genes involved in AR formation that were identified by transcriptomic sequencing showed auxin-responsive expression patterns in an exogenous Indole-3-butyric acid (IBA)-treatment assay: Indicating that endogenous and exogenous auxin plays key roles in regulating AR formation via similar signalling pathways to some extent. In general, AR formation in apple rootstocks is a complex biological process which is mainly influenced by the auxin signaling pathway. In addition, multiple hormones-, wounding- and sugar-signaling pathways interact with the auxin signaling pathway and mediate AR formation in apple rootstocks.

In the last decade, 1D semiconductor nanostructures attracted much attention due to their potential applications in electronics, optoelectronics, sensor, and biotechnology. Among various synthetic strategies, the electrochemical method is a relatively simple and effective way to prepare 1D semiconductor nanostructures. Moreover, electrochemical methods can afford precise processes for controlling the compositions and morphologies of the nanostructured materials. In this review, we present a systematic description of the electrochemical synthesis of oriented and hierarchical quasi-1D semiconducting nanostructures. The main contents containing: (1) electrodeposition of materials in hard porous membranes templates with 1D pore geometry or under assistance of the capping reagents for oriented nanowires/nanorods film; (2) multi-step template replication methods, two-step synthetic strategy and anodization methods for uniform nanotube arrays; (3) electrochemical synthetic strategies for complex hierarchical nanostructured films. Additionally, we give a brief introduction about the applications of these quasi-1D semiconducting nanostructures.

α-Fe2O3thin film photoanodes for solar water splitting were prepared by spray pyrolysis ofFe(AcAc)3. The donor density in theFe2O3films could be tuned between1017–1020 cm-3by doping with silicon. By depositing a 5 nmSnO2interfacial layer between theFe2O3films and the transparent conducting substrates, both the reproducibility and the photocurrent can be enhanced. The effects of Si doping and the presence of theSnO2interfacial layer were systematically studied. The highest photoresponse is obtained forFe2O3doped with 0.2% Si, resulting in a photocurrent of 0.37 mA/cm2at 1.23 VRHEin a 1.0 M KOH solution under 80 mW/cm2AM1.5 illumination.

BiVO4 has shown great potential as a semiconductor photoanode for solar water splitting. Significant improvements made during recent years allowed researchers to obtain a photocurrent density of up to 4.0 mA cm(-2) (AM1.5 sunlight illumination, 1.23 VRHE bias). For further improvements of the BiVO4 photoelectrodes, a deep understanding of the processes occurring at the BiVO4-H2O interface is crucial. Employing an electrochemical loading and removal process of NiOx, we show here that carrier recombination at this interface strongly affects the photocurrents. The removal of NiOx species by electrochemical treatment in a phosphate electrolyte leads to significantly increased photocurrents for BiVO4 photoelectrodes. At a bias of 1.23 VRHE, the Incident Photon-to-Current Efficiency (IPCE) at 450 nm reaches 43% for the passivated BiVO4 electrode under back side illumination. A model incorporating heterogeneity of NiOx centers on the BiVO4 surface (OER catalytic centers, recombination centers, and passivation centers) is proposed to explain this improved performance.

Electrocatalysts that are stable and highly active at low overpotential (η) under mild conditions as well as cost-effective and scalable are eagerly desired for potential use in photo- and electro-driven hydrogen evolution devices. Here the fabrication and characterization of a super-active and robust Cu-CuxO-Pt nanoparticulate electrocatalyst is reported, which displays a small Tafel slope (44 mV dec-1) and a large exchange current density (1.601 mA cm-2) in neutral buffer solution. The catalytic current density of this catalyst film reaches 500 mA cm-2 at η = -390 ± 12 mV and 20 mA cm-2 at η = -45 ± 3 mV, which are significantly higher than the values displayed by Pt foil and Pt/C electrodes in neutral buffer solution and even comparable with the activity of Pt electrode in 0.5 m H2SO4 solution.

Comparison of the UV–vis absorption spectra of CdSe quantum dots (QDs) capped with various mercaptocarboxylic acid capping ligands reveals that only 4-mercaptobenzoic acid (MBzA) capping ligands lower the apparent optical band gap. We propose that the delocalization of the excitons in the CdSe QDs is extended onto the ligands via electronic coupling to the π system of the 4-mercaptobenzoic acid molecules through the Cd–S bond. Furthermore, we demonstrate that the electronic coupling between the QDs and the (MBzA) thiol ligands is influenced by the strength of the Cd–S bond that can be changed by protonating the S atom.

The direct conversion of solar energy into hydrogen represents an attractive but challenging alternative for photo-voltaic solar cells. Several metal oxide semiconductors are able to split water into hydrogen and oxygen upon illumination, but the efficiencies are still (too) low. The operating principles of photo-electrochemical devices for water splitting, their main bottlenecks, and the various device concepts will be reviewed. Materials properties play a key role, and the advantages and pitfalls of the use of interfacial layers and dopants will be discussed. Special attention will be given to recent progress made in the synthesis of nanostructured metal oxides with high aspect ratios, such as nanowire arrays, which offers new opportunities to develop efficient photo-active materials for solar water splitting.