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The technological application of sensitized upconversion based on triplet-triplet annihilation (TTA) requires the transition from systems operating in liquid solutions to solid-state materials. Here, we demonstrate that the high upconversion efficiency reported in hyper-cross-linked nanoparticles does not originate from residual mobility of the embedded dyes as it happens in soft hosts. The hyper-reticulation from one side blocks the dyes in fixed positions, but on the other one, it suppresses the nonradiative spontaneous decay of the triplet excitons, reducing intramolecular relaxations. TTA is thus enabled by an unprecedented extension of the triplet lifetime, which grants long excitons diffusion lengths by hopping among the dye framework and gives rise to high upconversion yield without any molecular displacement. This finding paves the way for the design of a new class of upconverting materials, which in principle can operate at excitation intensities even lower than those requested in liquid or in rubber hosts.

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We present a simple and rapid procedure for producing polymer-coated substrates that can be easily functionalized by ion-chelating proteins. The procedure consists of depositing 18 nm metal-chelating cyclam-modified polymer nanoparticles (cyclam-nps) onto a conductive substrate (an Indium Tin Oxide (ITO) electrode) from an aqueous dispersion of Cu(2+)-loaded cyclam-nps while being subjected to a direct current (DC) field. The density of deposited nps as measured by AFM is shown to be in direct correlation to the concentration of nps in the dispersion with deposition of the particles taking less than 5 s. Because of the functionalization of the nps with cyclam groups, they can be used as anchoring sites for 6-Histidine (6-His) tagged proteins through complexation with divalent metal ions. In this work 6-His Green Fluorescent Protein (6-His GFP) is used as a model protein. The characterization by fluorescence microscopy clearly shows that the protein affinity was ion dependent and that the 6-His GFP density can be controlled by np density, which is itself easily tunable. AFM observations confirmed the immobilization of 6-His GFP onto cyclam-nps and its subsequent removal by treatment with ethylenediaminetetraacetic acid (EDTA).

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Herein, we report an easy preparation of azide-coated polystyrene-based nanoparticles (15 nm in diameter) and their surface functionalization via CuAAC with fluorophores in water. Resultant dual fluorescent nanoparticles coated with dansyl and pH-sensitive fluorescein moieties as the donor/acceptor FRET pair show a ratiometric response to pH upon excitation at a single wavelength.

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Azobenzene-coated polymer nanoparticles in the 16-nm-diameter range act as phototriggered nanomotors combining photo to kinetic energy conversion with optical control through light intensity gradients. The grafted dyes act as molecular propellers: their photoisomerization supplies sufficient mechanical work to propel the particles in an aqueous medium toward the intensity minima with velocities of up to 15 µm/s. It is shown that nanoparticles can be driven over tens of micrometers by translating the intensity gradients in the plane. The analysis of the particles motion demonstrates the decisive role of photoisomerization in the transport with a measured driving force that is 3 to 4 orders of magnitude higher than optical forces.

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Core-shell type dual fluorescent nanoparticles (NPs) in the 16 nm diameter range with a selective ligand (cyclam) attached to the surface and two fluorophores--9,10-diphenyl-anthracene (donor, D) and pyrromethene PM 567 (acceptor, A)--embedded within the polymer core were synthesized and their fluorescent and copper-sensing properties were studied and compared to single D-doped and A-doped NPs. The acceptor (A) and donor (D) dyes were chosen to allow two sequential Förster resonance energy transfer (FRET) processes from D to A and from the encapsulated dyes to copper complexes that form at the surface and act as quenchers. NPs with different D/A loads were readily obtained by two consecutive entrapments of the dyes. Dual NPs present tunable fluorescence emission that is dependent on the doping ratio. FRET from D to A results in sensitized emission from A upon excitation of D, with FRET efficiencies reaching 80 % at high acceptor loads. A 9-fold amplification of the signal of A is observed at high D-to-A ratios. Single- and dual-dye-doped NPs were used to detect the presence of cupric ions in water by using the quenching of fluorescence as a transduction signal. In accordance with the spectral overlaps and the values of the critical distance (R0) of D- and A-copper complex pairs, the acceptor is much more sensitive than the donor. In dual fluorescent NPs, the sensitized emission of A is efficiently attenuated whereas the remaining emission of D is much less affected, allowing the detection of copper in a ratiometric manner upon excitation at a single (D) wavelength. Dual-dye-doped NPs with the highest acceptor loads (23 A-per-NP) were found to be the most sensitive for the detection of copper over a wide range of concentrations (20 nM to 8.5 microM). Owing to its great convenience and modularity, the cascade FRET strategy based on dual fluorescent NPs holds great promise for the design of various sensing nanodevices.

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A simple synthesis of polymer core-dendrimer shell nanoparticles (NPs) in the 15-20-nm-diameter range is presented. Amine-terminated polypropyleneimine (PPI) dendrimers DAB-dendri-(NH(2))(4) and DAB-dendri-(NH(2))(16) (DAB4 and DAB16) are covalently attached to the surface of primary polystyrene-based NPs bearing reactive chlorobenzyl groups produced by microemulsion polymerization in the presence of a cationic surfactant. The grafting readily proceeds under mild conditions and leads to translucent aqueous suspensions of core-shell-type NPs with a high density of peripheral amine groups that have been characterized relative to their size and chemical composition. The dendritic shell acts as a protective ionizable outer layer and provides an improvement of the colloidal stability in neutral and acidic media. The metal-binding capacity of the PPI dendrimers is retained, and spectrophotometric titrations show that the dendrimer-grafted NPs can trap a large number of Cu(2+) ions (more than 900 Cu per NP-DAB16). These properties make them potentially valuable templates for the elaboration of hybrid nanomaterials. The reactivity of the external amine groups is used to link covalently azobenzene chromophores (disperse Red 1 residues) through aza-Michael addition in aqueous suspension. This simple method gives access to colored NPs with high dye contents in the outer layer (up to 1000-1500 dye molecules per NP), which indicates that dendrimer-functionalized NPs are valuable building blocks for the construction of multifunctional nanomaterials.

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The title compound, C(61)H(68)F(8)O(2)S(2), is a photochromic liquid crystal based on diaryl-ethene as photoswitchable unit. The F atoms connected to the benzene rings are disordered over two positions; the site-occupation factors refined to 0.830 (3)/0.170 (3). The mol-ecule adopts a photo-active anti-parallel conformation and the distance between the two reactive C atoms of the thio-phene rings is 3.448 (3) Å. The dihedral angles between the central cyclo-pentene ring and the adjacent thio-phene rings are 43.56 (3) and 48.58 (3)°. These structural elements exhibit a suitable geometry for photochromic behaviour in the crystalline state.

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Latex nanoparticles functionalized with cyclam (1,4,8,11-tetraazacyclotetradecane), a copper chelator, have been doped with a fluorescent dye (BODIPY derivative: 4,4-difluoro-8-(2',4',6'-trimethyl)phenyl-2,6-diethyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene). The bulky, hydrophobic fluorophore dissolves within the nanoparticles' polymer core up to a concentration of about 88.4 micromol g(-1). At this concentration the fluorescence yield is about 0.80. Adding Cu2+ ions to the solution decreases the fluorescence because of the energy transfer between the dye and the violet copper cyclam complexes. The response is fast: 90% of the quenching occurs within 1 s. The Cu2+ detection threshold is of 1 nanomolar. No interferences were observed with zinc and nickel ions.

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A fluorescent sensor for Cu(2+) at the nanomolar level in water has been designed by associating a BODIPY fluorophore and a selective ligand (cyclam) in ultrafine polymer nanoparticles.

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A straightforward grafting of a polycationic phosphorus-containing dendritic shell onto polystyrene nanoparticles leads to dendronized nanoparticles showing unique behavior.

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New functional thermoreversible metal complexing surfactants consisting of a chelating amino acid residue grafted to the tip of a nonionic surfactant [alkyl poly(oxyethylene) CiEj] or in a branched position are studied. Nonionic surfactants are thermoreversible and exhibit a clouding phenomenon associated with phase separation of micelles. The functional molecules retain both the surface-active properties and the characteristic thermoreversible behavior. Because of the hydrophilic contribution of the chelating group (acetyl lysine), the cloud point and the area at the air-water interface are higher for functional surfactants than for nonionic precursors. These new surfactants have efficient complexing properties toward metal ions and are more efficient than the mixture of the corresponding nonionic surfactant and the acetyl lysine ligand solubilized in micelles. This reveals the synergistic effect obtained by the covalent link between the two functions. Addition of a bulky group on classical amphiphilic structures modifies markedly the packing constraints at the origin ofmicellar structures. Small-angle X-ray or neutron scattering results, modeled jointly on the absolute scale, demonstrate the influence of unrecognized lithium nitrate (LiNO3) as well as specifically recognized uranyl nitrate [UO2(NO3)2] salts on micellar structure and phase boundaries. The determination of the micellar shape variations induced by a recognized salt, that is, a decrease of the polar headgroup, allows the rationalization of uncommon synergistic effects on the cloud point variation: increase with lithium nitrate, no decrease in the presence of uranyl nitrate, and a very large decrease when these two salts are present together.

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New reactive-surfactants, N-alkylglucosylacrylamides and N-alkylglucosylmethacrylamides, are easily prepared in two steps from glucose without protection. The complete structural analysis of these compounds by 1D and 2D NMR spectroscopy shows the existence of a rotational isomerism that is strongly dependent on the steric hindrance of the carbonyl substituent: whatever the alkyl chain length, both endo and exo rotamers are observed for N-alkylglucosylacrylamides 1 while the endo rotamer is the sole species observed in the case of N-alkylglucosylmethacrylamides 2. For acrylamido derivatives 1, the exo-endo equilibrium is solvent-dependent: the endo isomer is favored in polar nonaqueous solvents (endo-exo isomeric ratio R = 70/30) while the equilibrium is shifted toward the exo rotamer in protic acidic medium (R = 50/50 in water and 80/20 in acidic medium). An intramolecular hydrogen bond is assumed to be responsible for the increased stability of the endo rotamer. Furthermore, for tetra-O-acetylated derivatives the exo rotamer becomes favored in aprotic solvents. Surface tension measurements demonstrate that N-octyl- to -tetradecyl-substituted compounds 1 and 2 are surfactants with critical micelle concentrations ranging from 1.2 x 10(-2) to 1.7 x 10(-5) mol/L.