Organic nanofibers embedding stimuli-responsive threaded molecular components

While most of the studies on molecular machines have been performed in solution, interfacing these supramolecular systems with solid-state nanostructures and materials is very important in view of their utilization in sensing components working by chemical and photonic actuation. Host polymeric materials, and particularly polymer nanofibers, enable the manipulation of the functional molecules constituting molecular machines, and provide a way to induce and control the supramolecular organization. Here, we present electrospun nanocomposites embedding a self-assembling rotaxane-type system that is responsive to both optical (UV-visible light) and chemical (acid/base) stimuli. The system includes a molecular axle comprised of a dibenzylammonium recognition site and two azobenzene end groups, and a dibenzo[24]crown-8 molecular ring. The dethreading and rethreading of the molecular components in nanofibers induced by exposure to base and acid vapors, as well as the photoisomerization of the azobenzene end groups, occur in a similar manner to what observed in solution. Importantly, however, the nanoscale mechanical function following external chemical stimuli induces a measurable variation of the macroscopic mechanical properties of nanofibers aligned in arrays, whose Young's modulus is significantly enhanced upon dethreading of the axles from the rings. These composite nanosystems show therefore great potential for application in chemical sensors, photonic actuators and environmentally responsive materials.Comment: 39 pages, 16 figure

Synthesis and characterisation of fluorescently doped mesoporous nanoparticles for two-photon excitation.

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Functionalization of two-photon dye-doped mesoporous silica nanoparticles with folic acid. Cytotoxicity studies with folate receptor positive cancer cells.

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Mesoporous silica nanoparticles combining two-photon excited fluorescence and magnetic properties

A new approach to the synthesis of multifunctional nanoparticles was developed by using covalent anchoring of cyano-bridged coordination polymer Ni2+/[Fe(CN)6]3- to the surface of two-photon dyedoped mesoporous silica nanoparticles. The obtained hybrid nanoparticles were studied by infrared (IR) spectroscopy, nitrogen adsorption (BET), X-ray diffraction, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), luminescence, and magnetic analysis. The synthesis leads to homogeneously dispersed uni-shaped nanoparticles of around 100 nm in length that are coated with cyano-bridged metallic coordination polymer nanoparticles. These hybrid nanoparticles combine effective two-photon excited fluorescence, porosity, high transverse nuclear relaxivity values (i.e. the magnetic resonance imaging efficiency) and superparamagnetic properties

Identification of MRC2 and CD209 receptors as targets for photodynamic therapy of retinoblastoma using mesoporous silica nanoparticles

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