The application of highly ordered TiO 2 nanotube arrays (NTAs) for energy storage devices such as supercapacitors has been attractive and of great interest owing to their large surface area and greatly improved charge-transfer pathways compared to those of nonoriented structures. Modification of the semiconductor nature of TiO 2 is important for its application in constructing high-performance supercapacitors. Hence, the present study demonstrates a novel method involving fabrication of self-doped TiO 2 NTAs by a simple cathodic polarization treatment on the pristine TiO 2 NTAs to achieve improved conductivity and capacitive properties of TiO 2 . The self-doped TiO 2 NTAs at −1.4 V (vs SCE) exhibited 5 orders of magnitude improvement on carrier density and 39 times enhancement in capacitance compared to those of the pristine TiO 2 NTAs. Impedance analysis based on a proposed simplified transmission line model proved that the enhanced capacitive behavior of the self-doped TiO 2 NTAs was due to a decrease of charge-transport resistance through the solid material. Moreover, the MnO 2 species was introduced onto the TiO 2 NTAs by an impregnation−electrodeposition method, and the optimal specific capacitance achieved (1232 F g −1 ) clearly confirmed the suitability of self-doped TiO 2 NTAs as effective current collector materials for supercapacitors.

Because of their exotic electronic properties and abundant active sites, two-dimensional (2D) materials have potential in various fields. Pursuing a general synthesis methodology of 2D materials and advancing it from the laboratory to industry is of great importance. This type of method should be low cost, rapid and highly efficient. Here, we report the high-yield synthesis of 2D metal oxides and hydroxides via a molten salts method. We obtained a high-yield of 2D ion-intercalated metal oxides and hydroxides, such as cation-intercalated manganese oxides (Na0.55Mn2O4·1.5H2O and K0.27MnO2·0.54H2O), cation-intercalated tungsten oxides (Li2WO4 and Na2W4O13), and anion-intercalated metal hydroxides (Zn5(OH)8(NO3)2·2H2O and Cu2(OH)3NO3), with a large lateral size and nanometre thickness in a short time. Using 2D Na2W4O13 as an electrode, a high performance electrochemical supercapacitor is achieved. We anticipate that our method will enable new path to the high-yield synthesis of 2D materials for applications in energy-related fields and beyond.

Iron oxides nanoparticles tailored for magnetic particle imaging (MPI) have been synthesized, and their MPI signal intensity is three-times that of commercial MPI contrast (Ferucarbotran, also called Vivotrax) and seven-times that of MRI contrast (Feraheme) at the same Fe concentration. MPI tailored iron oxide nanoparticles were encapsulated with semiconducting polymers to produce Janus nanoparticles that possessed optical and magnetic properties for MPI and fluorescence imaging. Janus particles were applied to cancer cell labeling and in vivo tracking, and as few as 250 cells were imaged by MPI after implantation, corresponding to an amount of 7.8 ng of Fe. Comparison with MRI and fluorescence imaging further demonstrated the advantages of our Janus particles for MPI-super sensitivity, unlimited tissue penetration, and linear quantitativity.

Organic solid-state luminescence switching (SLS) materials with the ability to reversibly switch the luminescence by altering the mode of molecular packing without changing the chemical structures of their component molecules have attracted considerable interest in recent years. In this work, we design and synthesize a new class of 2,7diphenylfluorenone derivatives (compounds 1−6) that exhibit prominent aggregation-induced emission (AIE) properties with high solid-state fluorescence quantum yields (29−65%). Among them, 2,7-bis(4-methoxyphenyl)-9H-fluoren-9-one (2) and 2,7-bis(4-ethylphenyl)-9H-fluoren-9-one ( 6) display reversible stimuli-responsive solid-state luminescence switching. Compound 2 transforms between red and yellow crystals (the emission wavelength switches between 601 and 551 nm) under the stimuli of temperature, pressure, or solvent vapor. Similarly, compound 6 exhibits SLS behavior, with luminescence switching between orange (571 nm) and yellow (557 nm). Eight X-ray single-crystal structures, characterization of the photophysical properties, powder X-ray diffraction, and differential scanning calorimetry provide insight into the structure−property relationships of the solid-state fluorescence behavior. The results indicate that the variable solid-state luminescence of the fluorenone derivatives is attributed to the formation of different excimers in different solid phases. Additionally, the stimuli-responsive reversible phase transformations of compounds 2 and 6 involve a structural transition between π−π stacking-directed packing and hydrogen bond-directed packing. The results also demonstrate the feasibility of our design strategy for new solid-state luminescence switching materials: introduction of both π−π stacking and hydrogen bonding into an AIE structure to obtain a metastable solid/crystalline state luminescence system.

N-heterocyclic carbenes (NHCs) were demonstrated to be efficient catalysts for the Staudinger reaction of ketenes with N-tosyl, N-benzyloxycarbonyl, or N-tert-butoxycarbonyl imines. Chiral NHC 8b, conveniently prepared from L-pyroglutamic acid, catalyzed the reactions of arylalkylketenes with a variety of N-tert-butoxycarbonyl arylimines to give the corresponding cis-beta-lactams in good yields with good diastereoselectivities and excellent enantioselectivities (up to 99% ee). Two possible catalytic pathways, initiated by the addition of NHC to ketenes or imines, were discussed.

Graphene oxides with different surface charges were fabricated from carboxylated graphene oxide by chemical modification with amino- (-NH2), poly-m-aminobenzene sulfonic acid- (-NH2/-SO3H), or methoxyl- (-OCH3) terminated functional groups. The chemically functionalized graphene oxides and the carboxylated graphene oxide were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, UV-Vis spectrometry, ζ potential measurements, field emission scanning electron microscopy, and contact angle analyses. Subsequently, the resulting graphene oxides were used as substrates for culturing primary rat hippocampal neurons to investigate neurite outgrowth and branching. The morphological features of neurons that directly reflect their potential capability in synaptic transmission were characterized. The results demonstrate that the chemical properties of graphene oxide can be systematically modified by attaching different functional groups that confer known characteristics to the substrate. By manipulating the charge carried by the functionalized graphene oxides, the outgrowth and branching of neuronal processes can be controlled. Compared with neutral, zwitterionic, or negatively charged graphene oxides, positively charged graphene oxide was found to be more beneficial for neurite outgrowth and branching. The ability to chemically modify graphene oxide to control neurite outgrowth could be implemented clinically, especially in cases wherein long-term presence of outgrowth modulation is necessary.

Photodynamic therapy (PDT) is a noninvasive and light-activated method for cancer treatment. Two of the vital parameters that govern the efficiency of PDT are the light irradiation to the photosensitizer and visual detection of the selective accumulation of the photosensitizer in malignant cells. Herein, we prepared an integrated nanoplatform for targeted PDT and imaging of cancer cells using folic acid and horseradish peroxidase (HRP)-bifunctionalized semiconducting polymer dots (FH-Pdots). In the FH-Pdots, meta-tetra(hydroxyphenyl)-chlorin (m-THPC) was used as photosensitizer to produce cytotoxic reactive oxygen species (ROS); fluorescent semiconducting polymer poly[2-methoxy-5-((2-ethylhexyl)oxy)-p-phenylenevinylene] was used as light antenna and hydrophobic matrix for incorporating m-THPC, and amphiphilic Janus dendrimer was used as a surface functionalization agent to conjugate HRP and aminated folic acid onto the surface of FH-Pdots. Results indicated that the doped m-THPC can be simultaneously excited by the on-site luminol-H2O2-HRP chemiluminescence system through two paths. One is directly through chemiluminescence resonance energy transfer (CRET), and the other is through CRET and subsequent fluorescence resonance energy transfer. In vitro PDT and specificity studies of FH-Pdots using a standard transcriptional and translational assay against MCF-7 breast cancer cells, C6 glioma cells, and NIH 3T3 fibroblast cells demonstrated that cell viability decreased with increasing concentration of FH-Pdots. At the same concentration of FH-Pdots, the decrease in cell viability was positively relevant with increasing folate receptor expression. Results from in vitro fluorescence imaging exhibited that more FH-Pdots were internalized by cancerous MCF-7 and C6 cells than by noncancerous NIH 3T3 cells. All the results demonstrate that the designed semiconducting FH-Pdots can be used as an integrated nanoplatform for targeted PDT and on-site imaging of cancer cells.

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