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In the past decade correlative microscopy, which combines the potentials of different types of high-resolution microscopies with a variety of optical microspectroscopy techniques, has been attracting increasing attention in material science and biological research. One of outstanding solutions in this area is the combination of scanning probe microscopy (SPM), which provides data on not only the topography, but also the spatial distribution of a wide range of physical properties (elasticity, conductivity, etc.), with ultramicrotomy, allowing 3D multiparametric examination of materials. The combination of SPM and ultramicrotomy (scanning probe nanotomography) is very appropriate for characterization of soft multicompound nanostructurized materials, such as polymer matrices and microstructures doped with different types of nanoparticles (magnetic nanoparticles, quantum dots, nanotubes, etc.), and biological materials. A serious problem of this technique is a lack of chemical and optical characterization tools, which may be solved by using optical microspectroscopy. Here, we report the development of an instrumental approach to combining confocal microspectroscopy and 3D scanning probe nanotomography in a single apparatus. This approach retains all the advantages of SPM and upright optical microspectroscopy and allows 3D multiparametric characterization using both techniques. As the first test of the system developed, we have performed correlative characterization of the morphology and the magnetic and fluorescent properties of fluorescent magnetic microspheres doped with a fluorescent dye and magnetic nanoparticles. The results of this study can be used to obtain 3D volume images of a specimen for most high-resolution near-field scanning probe microscopies: SNOM, TERS, AFM-IR, etc. This approach will result in development of unique techniques combining the advantages of SPM (nanoscale morphology and a wide range of physical parameters) and high-resolution optical microspectroscopy (nanoscale chemical mapping and optical properties) and allowing simultaneous 3D measurements.

Hybrid composites of polymers with fluorescent nanoparticles are unique materials combining good mechanical properties of the host polymer matrices and luminescent properties of the embedded nanoparticles. Here, we report on the optical characterization of novel inorganic–organic hybrid composites based on nanoporous polypropylene (PP) as a polymer matrix and quantum dots (QDs) as a fluorescent inorganic component. The first type of the composite films is prepared by absorption of CdSe/ZnS QDs onto the porous structure of the PP films, followed by annealing at 170 °C, i.e., above the melting point of the PP. The second type of the composite films is obtained by filling of porous QD–PP composites with a nematic liquid crystalline (LC) mixture. Both types of composites are characterized by low light scattering, which makes it possible to study their optical properties by absorbance and fluorescence spectroscopies. TEM and confocal fluorescence microscopy have been used to analyze the aggregation of QDs in composites of different types. It has been shown that introduction of QDs into PP with a low draw ratio decreases the degree of alignment of LC molecules embedded into the pores of QD–PP composite films.

For the first time, AFM study of laser induced surface deformation and crater (holes) formation in liquid crystalline (LC) azobenzene-containing photochromic polymer systems was performed. Special set up including combination of polarizing optical, atomic force microscopies and a possibility of irradiation with a highly focused laser beam (532 nm) was used for these investigations. Films of the nematic azobenzene-containing polyacrylate polymer and the cholesteric mixture prepared by doping of this polymer with the chiral dopant were investigated. Focused laser beam irradiation results in the crater formation formed due to a mass-transfer outside center of beam. Depth of these craters lies in the range of tens of nanometers and increases by prolongation of irradiation time. It is found that this phenomenon takes place only for thick (5–10 μm) films, whereas these phenomena do not take place for the thin spin-coated films. For nematic and cholesteric films the rate of the crater formation, their depth and diameter are the same; that means the chirality of the systems has no influence on kinetics and the depth of photoinduced craters. It is shown, that for the nonaligned LC-films no preferable directed mass transport nearby photoinduced holes was found, but in the case of the uniaxially aligned nematic polymer films the mass-transport occurs only in direction along LC-director and does not depend on the laser polarization direction.

International audience; Bis-netropsins (bis-Nts) are efficient catalytic inhibitors of human DNA topoisomerase I (top I). These DNA minor groove binders are considered to serve as suppressors of top I-linked DNA breaks, which is generally believed to be related to their affinity to DNA. In this study, it was found that bis-Nts exhibit sequence-specificity of suppression of the strong top I-specific DNA cleavage sites and that this sequence-specificity is determined by differential ligand-induced structural alterations of DNA. Raman scattering analysis of bis-Nts interactions with double-stranded oligonucleotides, each containing the site of specific affinity to one of bis-Nts and a distinctly located top I degenerate consensus, demonstrated that bis-Nts induce not only structural changes in duplex DNA at their loading position, but also conformational changes in a distant top I-specific DNA cleavage site. The ability to alter the DNA structure correlates with the anti-top I inhibitory activities of the ligands. In addition, DNA structural alterations induced by bis-Nts were shown to be responsible for modulation of the camptothecin (CPT)-mediated DNA cleavage by top I. This effect is expressed in the bis-Nts-induced enhancement of some of the CPT-dependent DNA cleavage sites as well as in the CPT-induced enhancement of some of the top I-specific DNA cleavage sites suppressed by bis-Nts in the absence of CPT.