Photoluminescent peptide nanotubes are synthesized in an in situ incorporation of lanthanide complexes into peptide nanotubes through a self‐assembly process. We found that peptide nanotubes and photosensitizer molecules exhibited a high synergistic effect on the enhancement of lanthanide photoluminescence through a cascaded energy‐transfer mechanism.

Graphene, an sp 2 -bonded carbon sheet with a thickness of single atom, has recently received attention from materials scientists because of its unique qualities, which include excellent thermal and mechanical properties and electrical conductivity resulting from long-range π -conjugation. [1][2][3][4][5] While graphene was originally developed for nanoelectronics applications, [ 1 , 6 , 7 ] research interests in graphene are continuously expanding to other fi elds. [ 1 , 2 ] For example, graphene is considered to be an adequate reinforcing component for composite materials. [ 3 , 5 , 8 , 9 ] However, hybridization or interaction of graphene with biominerals has so far been rarely reported. Biomineralization is the process that gives rise to small and large inorganic-based structures in biological systems, and it often results in sophisticated materials having elaborate morphologies, excellent mechanical and optical properties, and vital biological functions. [10][11][12][13] Thus, the convergence of the study of graphene with biomineralization is expected to widen the horizons of material science.We have successfully incorporated graphene and graphene oxide (GO) sheets into the crystals of the two most abundantly studied biominerals found in the hard tissues of invertebrates and vertebrtates: calcium carbonate [14][15][16] and calcium phosphate. [ 17 , 18 ] As illustratived in Scheme 1 , we used GO sheets for the synthesis of a graphene-CaCO 3 hybrid fi lm, which then underwent a transformation into graphene-incorporated hydroxyapaptite [Ca 10 (PO 4 ) 6 (OH) 2 ; HAp]. By applying CO 2 gas to a mixture of GO and CaCl 2 , we obtained spherical CaCO 3 vaterite microspheres that were wrapped and interconnected by a GO network. After the reduction of GO-CaCO 3 composite, we fabricated a conductive, biocompatible, and bone-bioactive hybrid fi lm that consisted of CaCO 3 microspheres interconnected with a graphene network. When incubated in simulated body fl uid (SBF), the graphene-CaCO 3 hybrid fi lm was transformed to graphene-incorporated bone HAp crystals. We further found that osteoblast cells adhered well and proliferated on the graphene-HAp composite.We prepared GO sheets from pristine graphite according to the modifi ed Hummers method. [19][20][21] Atomic force microscopy (AFM) analysis showed that single-layered GO sheets approximately 1.06 nm thick were successfully attained from pristine graphite (Scheme 1 ), which is in agreement with previous reports. [21][22][23] The characteristics of GO sheets were further confi rmed using X-ray diffraction (XRD) measurements ( Figure S1, Supporting Information). After introducing CO 2 gas into a solution containing exfoliated GO and CaCl 2 , followed by fi ltering and drying the resultant suspension, we synthesized a rigid, Scheme 1 . Illustration of GO/graphene-CaCO 3 hybrid material synthesis and its conversion to GO/graphene-hydroxyapatite (HAp) composites. The steps describe a) CO 2 mineralization to CaCO 3 in the presence of GO sheets and CaCl 2 , b) GO/graphe...

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We report the results of equilibrium molecular dynamics (EMD) simulations of diffusion and sorption isotherms of CO2 and CH4 molecules in polyetherimide (PEI). Amorphous PEI structures are generated by MD simulations and energy minimizations, and are characterized by their density, glass transition temperature, and the radial distribution function. The self-diffusivities of CH4 and CO2 in the polymer are estimated by EMD simulations. The simulations indicate oscillatory motion of the molecules inside the temporal cavities of the polymer and hopping from one cavity to another in the PEI matrix as the mechanism of gas transport in the polymer. The accessible free volume of the polymer is calculated with the use of a probe molecule. It exhibits strong temporal fluctuations which indicates the existence of correlations between these fluctuations and those in the excess chemical potential of the gases. The solubility coefficients of the gases, calculated by the test particle insertion method, and the single gas sorption isotherms, are within the reported range of the experimental values. The computed self-diffusivities D of the gases differ from the experimental data by about one order of magnitude, although the range of the experimental values for D is quite large. We also compute the sorption isotherms for binary gas mixtures of CO2 and CH4 in the polymer.

We report a versatile and facile route for highly sensitive detection of analytes through coupling the enlargement of gold nanoparticles with fluorescence quenching. The fluorescence intensity of dye molecules (e.g., fluorescein or rhodamine B) significantly decreased with the increasing concentration of reducing agents, such as hydrogen peroxide and hydroquinone. The sensitivity for the detection of reducing agents was much higher than that of other methods based on the absorbance measurement of enlarged gold nanoparticles or quantum-dot-enzyme hybridization. We could successfully detect acetylthiocholine with the detection limit of several nanomolar concentration using an enzymatic reaction by acetylcholine esterase, a key route for the detection of toxic organophosphate compounds. The fluorescence quenching approach described in this report requires only a simple addition of fluorescence dye to the reaction solution without any chemical modification. The strategy of fluorescence quenching coupled with nanoparticle growth would provide a new horizon for the development of highly sensitive optical biosensors.