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Objectives. Analysis of oral fluid in children with congenital cleft palate and palate defect after uranoplasty. Purpose. To analyze oral fluid in children with congenital cleft palate and palate defect after uranoplasty to determine the levels of pro-inflammatory (IL-1β, IL-6, TNF-α) and anti-inflammatory (IL-4, IL-10) cytokines and secretory immunoglobulin sIgA and evaluate physico-chemical (salivation rate, kinematic viscosity, pH) and biochemical parameters (calcium, magnesium, phosphorus, protein) of mixed saliva. Methodology. The article presents the results of studying the parameters of the oral fluid of 109 children aged 6–12 years with congenital cleft palate and palate defect after uranoplasty and 50 practically healthy children of the same age. Results. Hyperstimulation of pro-inflammatory (IL-1β, IL-6, TNF-α) and anti-inflammatory (IL-4, IL-10) cytokines in the oral fluid and a decrease in the average level of secretory immunoglobulin sIgA. In children with congenital cleft palate and defects remaining after uranoplasty, there was a deviation in the physicochemical and biochemical parameters of the oral fluid, which are manifested by a decrease in the rate of salivation, an increase in its viscosity and a shift in pH to the acid side. In contrast to the group of children without dental pathology, children with cleft palate and defects after uranoplasty showed a decrease in the content of total protein, phosphorus and calcium in the mixed saliva and an increase in the content of magnesium. Conclusions. The obtained laboratory data indicate the presence of a local inflammatory process in the oral cavity and a decrease in local immunological anti-inflammatory factors. This should be taken into account for the development of methods for preoperative sanitation of the oral mucosa in children with congenital cleft palate and a palate defect after uranoplasty at the stage of preparation for reoperation.

In our article, we studied the concentration of immunoglobulins, the interleukin system and observed their changes before and after our patented treatment with a dressing based on "Placentol". The study material was the oral fluid of the patients. We observed 67 patients with a diagnosis of chronic generalized periodontitis of mild severity from 214 employees. The patients are workers of the limestone quarry. We revealed the occupational conditionality of the disease by chronic generalized periodontitis in workers of the limestone quarry, which turned out to be highly conditioned (that is, working conditions affect the condition of the periodontal). The results of the treatment pleased us, we achieved clinical improvement on the fourth visit. The work of the periodontal immune system is partly determined by the direction of the development of pathological processes in chronic inflammation. The main cause in the pathogenesis of chronic immunological inflammation can be a local disorder at the level of the mucosal system or small abnormalities at the systemic level. This task is complex and it is studied both from the immunological position and from the position of general pathology, taking into account the functioning of other homeostatic systems of the body. The article also provides information on the role of cytokines in the pathogenetic mechanisms of chronic inflammation in periodontal tissues, and how our patented treatment can enhance the oral immune system. Also, to carry out early diagnosis and prevention of periodontitis in limestone quarry workers, identifying their relative risk index and the etiological proportion of periodontitis incidence. The aim of our work is to study the changes in the parameters of the oral cavity immune system, under the influence of the treatment of the Placentol dressing, in the workers of the limestone quarry, and in the future to offer them our treatment.

The main limitation of the use of tip-enhanced Raman scattering (TERS) is due to the lack of reliable scanning probes. We present a simple procedure to manufacture TERS probes with highly reproducible characteristics that are reliable and provide sufficient enhancement. The procedure is based on the modification of conventional cantilevers of scanning probe microscopes by plasma etching, followed by the formation of a TERS enhancing region at the apex by deposition of colloidal nanoparticles by dielectrophoresis.

Subject. This review presents a modern literature review on the clinical manifestations of severe autoimmune disease — pemphigus vulgaris, chronic genetic determinate dermatosis — by the example of epidermolysis bullosa, dermatosis — lichen planus, acute immuno-mediated disease — multiforme exudative erythema. The goal is to conduct a systematic analysis of modern domestic and foreign literature to determine some features of the clinical manifestations of chronic dermatoses with lesions of the oral mucosa. Methodology. A review of the studies allows us to consider the etiology and pathogenesis of the development of these nosologies, approaches to modern classification, as well as an analysis of their clinical features with an emphasis on differential diagnosis. Results. It was noted that with combined damage to the skin and oral mucosa, the diagnosis of these dermatoses in patients does not present any particular difficulties. However, the significance of determining pathognomonic signs of damage to the oral mucosa with a particular dermatosis increases significantly with an isolated lesion of the oral mucosa, and when it is the primary and only manifestation of skin disease. Conclusions. Undoubtedly, the principle of continuity of the interested specialties among which are undoubted - dermatovenerologists, dentists, gastroenterologists, gynecologists, neuropsychiatrists, has great prospects in both diagnosis and complex treatment. Nevertheless, for their widespread use, the local and general treatment of these patients needs to be verified, solving urgent problems of introducing and adapting modern technologies for rapid prototyping them into practical healthcare, which together will allow significant progress in their diagnosis and prevention.

A unified analytical technology based on the integration of scanning probe nanotomography and optical microscopy (SPNT–OM) is presented, and the potential of the technology is demonstrated by the example of a multiparameter analysis of encoded microspheres. The presented SPNT–OM technology can become a powerful tool for multimodal nanocharacterization of a wide range of microparticles, composites, and hybrid polymers.

Bacteria of different species, due to the peculiarities of their metabolism, have different abilities to counteract the formation of free radicals and oxidative stress. An indicator reflecting the development of oxidative processes is the antioxidant activity of nutrient media during the cultivation of bacteria. The aim of the study. Comparative evaluation of the antioxidant activity of nutrient media samples during the cultivation of P. aeruginosa and E. coli. Materials and methods. The antioxidant activity of nutrient media was assessed by recording iron-induced chemiluminescence. Spontaneous antioxidant activity of nutrient media samples, as well as their parameters under conditions of oxidative stress, were evaluated. Results. It is shown that the nutrient medium in which P. aeruginosa was cultivated has a greater antioxidant activity than the medium with E. coli. Conclusions. The results obtained may indicate a better ability of P. aeruginosa to counteract the formation of free radical agents compared to E. coli.

Polariton emission from optical cavities integrated with various luminophores has been extensively studied recently due to the wide variety of possible applications in photonics, particularly promising in terms of fabrication of low-threshold sources of coherent emission. Tuneable microcavities allow extensive investigation of the photophysical properties of matter placed inside the cavity by deterministically changing the coupling strength and controllable switching from weak to strong and ultra-strong coupling regimes. Here we demonstrate room temperature strong coupling of exciton transitions in CdSe/ZnS/CdS/ZnS colloidal quantum dots with the optical modes of a tuneable low-mode-volume microcavity. Strong coupling is evidenced by a large Rabi splitting of the photoluminescence spectra depending on the detuning of the microcavity. A coupling strength of 154 meV has been achieved. High quantum yields, excellent photostability, and scalability of fabrication of QDs paves the way to practical applications of coupled systems based on colloidal QDs in photonics, optoelectronics, and sensing., Comment: 14 pages, 3 figures

Resonant interaction between excitonic transitions of molecules and localized electromagnetic field allows the formation of hybrid light–matter polaritonic states. This hybridization of the light and the matter states has been shown to significantly alter the intrinsic properties of molecular ensembles placed inside the optical cavity. Here, we have observed strong coupling of excitonic transition in a pair of closely located organic dye molecules demonstrating an efficient donor-to-acceptor resonance energy transfer with the mode of a tuneable open-access cavity. Analysing the dependence of the relaxation pathways between energy states in this system on the cavity detuning, we have demonstrated that predominant strong coupling of the cavity photon to the exciton transition in the donor dye molecule can lead not only to an increase in the donor–acceptor energy transfer, but also to an energy shift large enough to cause inversion between the energy states of the acceptor and the mainly donor lower polariton energy state. Furthermore, we have shown that the polariton-assisted donor–acceptor chromophores' role reversal or “carnival effect” not only changes the relative energy levels of the donor–acceptor pair, but also makes it possible to manipulate the energy flow in the systems with resonant dipole–dipole interaction and direct energy transfer from the acceptor to the mainly donor lower polariton state. Our experimental data are the first confirmation of the theoretically predicted possibility of polariton-assisted energy transfer reversal in FRET systems, thus paving the way to new avenues in FRET-imaging, remote-controlled chemistry, and all-optical switching., This study was supported by the Ministry of Education and Science of the Russian Federation (grant no. 14.Y26.31.0011). I. N. acknowledges the support from the Ministry of Higher Education, Research and Innovation of the French Republic and the University of Reims Champagne-Ardenne. The part of the work devoted to the microresonator development and adaptation was supported by the Russian Science Foundation (grant no. 21-79-30048). Y. R. acknowledges the support from the Basque Government (grant no. IT1164-19).

Fast, sensitive, high-throughput detection of coronavirus antigens at physiologically relevant levels is essential for population screening that could prevent epidemics such as the current COVID-19 global pandemic. Optical methods based on surface-enhanced Raman scattering (SERS) spectroscopy are promising for this purpose because they ensure quick detection of even single biological molecules in a sample. For achieving such a high sensitivity, it is crucial to design SERS-active systems concentrating incident radiation into small sample volumes. Here, metal-dielectric cavities have been obtained through interaction of protein sulfhydryl groups with a SERS-active silver surface. The concentration of light in these cavities allows the differential detection of spike glycoprotein and nucleocapsid protein of SARS-COV-2, which are its key antigens, at physiologically relevant concentrations. The cavity Q-factor can be increased by additionally covering the dielectric protein film with a silver shell to form an ultrathin cavity, which provides an at least tenfold enhancement of the detection signal. The results could be used to design high-throughput systems for specific and sensitive detection of viral antigens and quick diagnosis of viral infections.

ChemistryOpen 9(6), 641 - 648 (2020). doi:10.1002/open.201900276, The synthetic function‐spacer‐lipid (FSL) amphiphile biotin‐CMG‐DOPE is widely used for delicate ligation of living cells with biotin residues under physiological conditions. Since this molecule has an “apolar‐polar‐hydrophobic” gemini structure, the supramolecular organization is expected to differ significantly from the classical micelle. Its organization is investigated with experimental methods and molecular dynamics simulations (MDS). Although the linear length of a single biotin‐CMG‐DOPE molecule is 9.5 nm, the size of the dominant supramer globule is only 14.6 nm. Investigations found that while the DOPE tails form a hydrophobic core, the polar CMG spacer folds back upon itself and predominantly places the biotin reside inside the globule or planar layer. MDS demonstrates that, Published by Wiley-VCH-Verl., Weinheim

Functional organic polymer materials with an ability to change their surface topography in response to external contactless stimuli, like light irradiation, have attracted considerable attention. This work is devoted to the study of contactless control of the surface topography and the formation of the surface features in the amorphousized and liquid crystalline films of two azobenzene-containing polymers. The investigated polymers are side-chain polymethacrylates containing azobenzene chromophores with two lateral methyl substituents in ortho-positions and differing in the length of flexible spacer with six and ten methylene units. Two lateral methyl substituents at the azobenzene chromophore ensure high photoresponses of these polymeric samples in the whole visible spectral range. Irradiation of the polymethacrylate films by focused polarized light of green (532 nm) and red (633 nm) lasers induces a specific photodeformation of the film surface. In the case of the green light formation of circular “craters” with anisotropic borders was found, whereas for the red light highly asymmetric “hills” were observed. The possible mechanisms of the surface topography formation and their features are discussed.

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.

Studies of resonance interaction between matter and localized electromagnetic field in a cavity have recently attracted much interest because they offer the possibility of controllably modifying some of the fundamental material properties. However, despite the large number of such studies, these is no universal approach that would allow investigation of sets of different samples with wide variation of the main experimental parameters of the optical modes. In this work, the main optical parameters of a previously developed universal tunable microcavity cell, i.e., the Q factor and mode volume, as well as their dependence on the characteristics of cavity mirrors and spacing between them, are analyzed. The results obtained will significantly expand the scope of applications of resonance interaction between light and matter, including such effects as the enhancement of Raman scattering, long-range resonance nonradiative energy transfer, and modification of chemical reaction rates., This work was supported by the Ministry of Science and Higher Education of the Russian Federation,contract no. 4.Y26.31.0011.

A new experimental method for nanoscale measurements of the absorption spectra of single nanoobjects has been developed based on scanning near-field optical microspectroscopy (SNOM) and nanospectrophotometry (NSP). The main distinctive feature of the proposed SNOM-NSP technique consists in depositing a sample onto a coverglass followed by its probing in the total internal reflection spectroscopy mode. This approach allows the number of analyzed samples to be significantly increased and provides the possibility of combining measurements with other optical techniques. The proposed SNOM-NSP method has been successfully used for studying single plasmonic nanoparticles and their complexes with Rhodamine 6G dye.

Light-matter coupling between the molecular dipole transitions and a confined electromagnetic field provides the ability to control the fundamental properties of coupled matter. The use of tunable optical microcavities for electromagnetic field confinement allows one to affect the coupled state properties in a controllable manner, whereas the coupling strength in this system strongly depends on the transition dipole moment and a mode volume of the cavity. In this study we have demonstrated controllable emission of Rhodamine 6G organic molecules with relatively low and unoriented dipole moments in a strong coupling regime by placing them into a tunable Fabry-Perot microcavity.

Resonance interaction between a localized electromagnetic field and excited states in molecules paves the way to control fundamental properties of a matter. In this study, we encapsulated organic molecules with relatively low unoriented dipole moments in the polymer matrix, placed them in tunable optical microcavity and realized, for the first time, controllable modification of the broad photoluminescence (PL) emission of these molecules in strong coupling regime at room temperature. Notably, while in most previous studies it was reported that the single mode dominates in the PL signal (radiation of the so-called branch of the lower polariton), here we report on the observation of two distinct PL peaks, evolution of which has been followed as the microcavity mode is detuned from the excitonic resonance. A significant Rabi splitting estimated from the modified PL spectra was as large as 225 meV. The developed approach can be used both in fundamental research of resonant light-mater coupling and its practical applications in sensing and development of coherent spontaneous emission sources using a combination of carefully designed microcavity with a wide variety of organic molecules., Ministry of Education and Science of the Russian Federation (14.Y26.31.0011); Ministerio de Economiá y Competitividad (FIS2016.80174-P, PLASMOQUANTA).

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.

Recently, photofluidization and mass-transfer effects have gained substantial interest because of their unique abilities of photocontrolled manipulation with material structure and physicochemical properties. In this work, the surface topographies of amorphous, nematic, and crystalline films of an azobenzene-containing bent-core (banana-shaped) compound were studied using a special experimental setup combining polarizing optical microscopy and atomic force microscopy. Spin-coating or rapid cooling of the samples enabled the formation of glassy amorphous or nematic films of the substance. The effects of UV and visible-light irradiation on the surface roughness of the films were investigated. It was found that UV irradiation leads to the fast isothermal transition of nematic and crystalline phases into the isotropic phase. This effect is associated with E-Z photoisomerization of the compound accompanied by a decrease of the anisometry of the bent-core molecules. Focused polarized visible-light irradiation (457.9 nm) results in mass-transfer phenomena and induces the formation of so-called "craters" in amorphous and crystalline films of the substance. The observed photofluidization and mass-transfer processes allow glass-forming bent-core azobenzene-containing substances to be considered for the creation of promising materials with photocontrollable surface topographies. Such compounds are of principal importance for the solution of a broad range of problems related to the investigation of surface phenomena in colloid and physical chemistry, such as surface modification for chemical and catalytic reactions, predetermined morphology of surfaces and interfaces in soft matter, and chemical and biochemical sensing.

The 2nd International Symposium on Physics, Engineering and Technologies for Biomedicine , Moscow, Russia, 10 Oct 2017 - 14 Oct 2017; KnE Energy 3(2), 519 - 527 (2018). doi:10.18502/ken.v3i2.1860, Targeted drug delivery is one of the most promising tasks of nanomedicine, as this is a real way to increase the effectiveness of therapeutic effects against many diseases. In this regard, the development of new inexpensive highly effective stimulating and non-immunogenic drug delivery systems (DDS) is of great importance. In this work new molecular candidates were proposed and studied for the creation of such systems based on the use of new compounds, neoglycolipids. It is shown that these compounds are capable of self-association in aqueous solutions and can serve as potential carriers of drug compounds with targeted delivery determined by their terminal groups (in particular, glycans). The processes of their associates formation and features of their structure are investigated. The results show that these self-organizing nanoscale systems can be used as a basis for developing new drug delivery systems., Published by Knowledge E, Dubai

A simple approach of preparation of advanced fluorescent polyethylene (PE) composites containing the high concentration of CdSe/ZnS quantum dots (QDs) was elaborated. The method is based on the infiltration of concentrated solution of QDs in octadecene into the films of porous stretched PE. A developed technique allowed one to introduce high concentration of QDs (15 wt%) into the polymer films. The composite films possess very bright fluorescence, high thermal stability, flexibility, and good mechanical properties. An annealing of the films enables to collapse porous structure and obtain stable, flexible, highly fluorescent, and transparent composite films. The developed approach enables to prepare materials promising for applications in optoelectronics and photonics.

International audience; The interaction of semiconductor quantum dots and silver nanoparticles (AgNPs) with bacteriorhodopsin (BR), a membrane protein contained in the purple membrane (PM) of Halobacterium salinarum, is studied. It is shown that both types of nanoparticles are adsorbed efficiently on the surface of the purple membranes, modulating the parameters of the bacteriorhodopsin photocycle. Electrostatic interactions are found to be the main cause of the effect of nanoparticles on the bacteriorhodopsin photocycle. These results explain our earlier data on the “fixation” of the bacteriorhodopsin photocycle for protein molecules trapped after incubation of the purple membranes with silver nanoparticles near the location of the “hot spots” of the effect of surface-enhanced Raman scattering (SERS). It is demonstrated that exposure of silver nanoparticles with bacteriorhodopsin in SERS-active regions lowers the amount of bacteriorhodopsin molecules involved in phototransformations.

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; Unique properties of nanohybrid composites based on different types of porous polymer matrices doped with fluorescent nanoparticles (quantum dots, QDs) are determined by the combination of the mechanical properties of the host matrix (flexibility, chemical stability, etc.) and a high luminescence intensity and extreme stability of QDs. Here, we report on the preparation, optical and microstructural characterization of a nanoporous stretched polypropylene matrix embedded with CdSe/ZnS QDs as fluorescent dopants at a high concentration. The microstructure and optical properties of two types films based on QD-polymer composites and liquid crystals are described. The distribution of QDs in the composite films and their morphology was determined. The annealing of the nanoporous composite films leads to shrinking of the pores and encapsulation of QDs, which results in a domain-like structure. The resulting flexible, stable and highly luminescent materials may be applied to obtain the highly luminescent diodes, the light converter devices and the display systems.

Using a novel experimental method combining of polarizing optical microscopy (POM) and atomic force microscopy (AFM), the surface topography and optical properties of chiral- photochromic LC systems were studied. For this purpose, a mixture of cholesteric cyclosiloxanes with azobenzene-containing dopant was prepared. Correlations between the features of surface topography of mixture films and POM images of planarly oriented texture were found. Polarized light action (532 nm) leads to the formation of partially aligned surface structure features. The observed photooptical effects are associated with E-Z, Z-E isomerization cycles of azobenzene groups, anisotropic cooperative photoinduced rotational diffusion and directional mass-transport of chromophores and mesogens in the films.

International audience; The effect of silver nanoparticles (AgNPs) that are adsorbed on the surface of the purple membranes of Halobacterium salinarium bacteria on the optical properties and functional peculiarities of the lightsensitive protein bacteriorhodopsin (BR) has been demonstrated for the first time. Two mechanisms of the effect of AgNPs on the protein photocycle have been demonstrated using Raman scattering, giant Raman scattering, flash photolysis, and atomic force microscopy. It has been shown that the nanoparticles in the immediate spatial vicinity of BR fix its photocycle at the stage where it was at the moment of interaction with the nanoparticles. At greater distances, which reach three radii of an AgNPs, they have a weaker effect on BR, under which it retains the ability to be involved in the photocycle, however, has its parameters significantly changed. Thus, in the case of wild-type BR the photocycle accelerates and for the BR-D96N mutant it becomes slower. The data that are obtained could be of significance for creation of such optoelectronic hybrid systems with BR, where the parameters of its photocycle can be controlled using NPs. The results of the study may also be used in the field of nanobioengineering research, which is directed to creation of unique materials with controlled properties for recording and storage of information, energy transformation, and identification and characterization of trace amounts of analytes.

International audience; A new experimental approach to multiparametric three-dimensional (3D) investigation of a broad class of composite nanostructural materials is developed on the basis of scanning near-field optical nanotomography (SNONT). Using this method, it is possible to simultaneously study the optical properties, 3D morphology, and distribution of the mechanical and electrical properties of the same region of a sample. The proposed method combines features of the confocal and near-field optical microspectroscopy (fluorescence and Raman spectroscopy) with a lateral resolution of up to 50 nm and scanning-probe microscopy. The possibility of studying the volume distribution of optical, morphological, electrical, and mechanical characteristics of a material with nanoscale resolution is related to the probing of sequential layers at a step of up to 20 nm and a total Z-scan depth of up to 3 mm. In particular, the SNONT method has been used to study a liquid-crystalline polymer doped with fluorescent nanocrystals.

International audience; We have developed a facile approach to engineering ratiometric sensors nano-thermosensors (NTSs) with a core/shell structure. A layer of “smart” thermosensitive poly(N-vinylcaprolactam) doped with quantum dots (QDs) with the emission wavelength λem shell makes it possible to obtain fluorescence emission depending on temperature. QDs with a different emission wavelength λem core incorporated in the NTS core emit a reference signal which allows ratiometric temperature measurements to be performed within a nanoscale volume. It has been shown that an NTS has a high temperature sensitivity if long-wavelength QDs are located in the core of the sensor, whereas the temperature-sensitive shell contains short-wavelength QDs (λem core > λem shell). An optimally selected thermosensitive polymer has allowed us to design NTSs operating in the physiological temperature range.

International audience; Interaction of silver nanoparticles (AgNPs) with purple membranes (PM) has been studied using atomic force microscopy and optical spectroscopy. It was shown that AgNPs alter the photocycle of the bacteriorhodopsin (BRh) molecules located in SERS-active spots. AgNPs suppresses the photocycle by “freezing” the state of retinal in which BRh has bound AgNPs. Outside SERS-active spots, BRh molecules retain the capacity for carrying out the photocycle but with shorter lifetimes of its photointermediate states. Thus, the AgNPs may affect the BRh photocycle through its acceleration in the regions of weak AgNPs-PM interaction or by the photocycle freezing in the SERS-active spots.

Novel glass-forming photoactive cholesteric mixtures doped with CdSe quantum dots were prepared and studied. The photooptical and fluorescent properties of these materials were studied. The possibility of phototuning of circularly polarised emission using ultraviolet irradiation was demonstrated.

Laser-induced luminescence of multilayer structures based on the solids of CdSe and CdSe/ZnS nanocrystals, different organic semiconductors and on the layers of organic semiconductors with embedded nanocrystals has been investigated. Drastic decrease of luminescence quantum yield is observed in the films of CdSe nanocrystals on organic semiconductors compared to those on optical glasses. The luminescence of the nanocrystals in the matrices of organic semiconductors and in multilayer structures is shown to be suppressed. The effects observed are explained by the transfer of photogenerated carriers from the nanocrystals to the molecules of organic semiconductors. The presence of the charge transfer is confirmed by a drastic increase in the conductivity (by 2 – 4 orders of magnitude) and in photovoltaic effect at the presence of CdSe and CdSe/ZnS nanocrystals in the structures under investigation. The prospects of using the multilayer structures for development new materials for solar cells are discussed.

The photophysical properties of solutions and films with relatively high concentrations of CdSe/ZnS nanoparticles are studied in the presence of the visible laser irradiation in a wide range of power densities. The short-wavelength wing detected in the photoluminescence spectra of the solutions of quantum dots is due to the selective laser excitation of small-size nanoparticles. A comprehensive analysis of the anti-Stokes photoluminescence of the nanoparticles in solutions and films indicates the thermal mechanism of this phenomenon. The dimensional quantization effect, narrow spectra, and a relatively high luminescence yield are retained in the films with a high nanoparticle concentration. The luminescence spectra of the films remain unchanged when the laser flux density increases to 1 × 106 W/cm2. The effect of the laser radiation on the nanoparticle films is studied at the flux densities exceeding the damage threshold (5 × 106–1 × 109 W/cm2).

International audience; An instrumental system and the corresponding experimental technique for multiparametric nanoscale 3D characterization of a wide range of composite nanomaterials have been developed. This system makes it possible to obtain 3D data on the chemical composition of a material by optical methods in the confocal and near-field optical microspectroscopy modes (fluorescence and Raman) with a lateral resolution up to 50 nm, as well as data on the 3D morphology and spatial distribution of mechanical, electrical, and other characteristics of the material in the scanning probe microscopy mode with a resolution of about 10 nm on the X and Y axes and several angstroms on the Z axis, for a single area of the sample (100 μm × 100 μm × 3 mm). The nanoscale 3D pattern of the distribution of these characteristics is obtained by sequentially examining nanomaterial layers at a step of 20 nm along the Z axis and a total depth of Z-scanning of 3 mm.

The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 106 W/cm2. The laser action on the nanoparticle films is studied at intensities (5 × 106−1 × 109 W/cm2) higher than the damage threshold.

Topotecan (TPT), a water-soluble derivative of camptothecin (inhibitor of human DNA topoiomerase I), has found wide application in cancer chemotherapy. The central problem in using topotecan is the presence of lactone rings in its molecules, which undergo hydrolysis at a physiological pH yielding an inactive and even toxic form of the drug. The analysis of Raman spectra of TPT in H2O and D2O solutions made it possible to assign the spectral bands to the vibrations of particular molecular groups. Spectral features indicative of the opening of the lactone rings of the TPT molecules, deprotonation of the hydroxyl groups in their quinoline fragments, and of possible participation of the hydroxyl and carbonyl groups in H bonding are found. The data obtained are necessary to study the molecular mechanisms of TPT-DNA interaction and the formation of ternary complexes between TPT, DNA, and DNA topoisomerase I.

The interaction of topotecan (TPT), antitumor inhibitor of human DNA topoisomerase I, with calf thymus DNA was studied by surface-enhanced Raman scattering (SERS) spectroscopy. The SERS spectra of TPT are found to depend on its concentration in solution, which is associated with the dimerization of TPT. The spectral signatures of dimerization are identified. It is shown that binding to DNA induces the formation of TPT dimers. The formation of DNA-TPT-TPT-DNA complexes is considered as one of the possible mechanisms of human DNA topoisomerase I inhibition.

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.

We employed Raman and circular dichroism (CD) spectroscopy to probe the molecular structure of 68-kDa recombinant human DNA topoisomerase I (TopoI) in solution, in a complex with a 16-bp DNA fragment containing a camptothecin-enhanced TopoI cleavage site, and in a ternary complex with this oligonucleotide and topotecan. Raman spectroscopy reveals a TopoI secondary structure transition and significant changes in the hydrogen bonding of the tyrosine residues induced by the DNA binding. CD spectroscopy confirms the Raman data and identifies a DNA-induced (>7%) decrease of the TopoI α helix accompanied by at least a 6% increase of the β structure. The Raman DNA molecular signatures demonstrated a bandshift that is expected for a net change in the environment of guanine C6O groups from pairing to solvent exposure. The formation of a ternary cleavage complex with TopoI, DNA, and topotecan as probed by CD spectroscopy reveals neither additional modifications of the TopoI secondary structure nor of the oligonucleotide structure, compared to the TopoI–oligonucleotide complex. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 369–375, 2002

International audience; We present a new concept of a combined scanning probe microscope (SPM)/ultramicrotome apparatus. It enables “slice-and-view” scanning probe nanotomography measurements and 3D reconstruction of the bulk sample nanostructure from series of SPM images after consecutive ultrathin sections. The sample is fixed on a flat XYZ scanning piezostage mounted on the ultramicrotome arm. The SPM measuring head with a cantilever tip and a laser-photodiode tip detection system approaches the sample for SPM measurements of the block-face surface immediately after the ultramicrotome sectioning is performed. The SPM head is moved along guides that are also fixed on the ultramicrotome arm. Thereby, relative dysfunctional displacements of the tip, the sample, and the ultramicrotome knife are minimized. The design of the SPM head enables open frontal optical access to the sample block-face adapted for high-resolution optical lenses for correlative SPM/optical microscopy applications. The new system can be used in a wide range of applications for the study of 3D nanostructures of biological objects, biomaterials, polymer nanocomposites, and nanohybrid materials in various SPM and optical microscopy measuring modes.

Camptothecin (CPT) and its clinically important antitumor derivative topotecan (Tpt) were traditionally described as unique antitumor compounds exhibiting no affinity toward DNA alone or DNA topoisomerase I (top1) alone but interacting with both the enzyme and the DNA within the so-called ternary cleavable complexes. We present here the first experimental data on the molecular structure and geometry of TptDNA complexes in solution. Tpt interacts with DNA within the DNA minor groove and demonstrates the preferential binding to GC-rich DNA. The flow linear dichroism (FLD) spectra show that the Tpt binds DNA only in lactone form and its chromophore forms the angle nearly 55° with the DNA long axis. Induced circular dichroism (CD) data independently confirm conclusions about Tpt preferable orientation drawn from the FLD experiments. The Raman spectroscopy data confirm the FLD and CD results and further demonstrate direct interactions of Tpt lactone ring with dG. The capability of Tpt to bind DNA in the minor groove of GC-rich DNA regions must be taken into account when considering molecular structure of ternary cleavable complexes of CPTs, DNA, and top1 in solution.

Article publicat sota la llicència AuthorChoice de l'American Chemical Society: https://pubs.acs.org/userimages/ContentEditor/1404932937291/authorchoice_form.pdf We present a route toward a radical improvement in solar cell efficiency using resonant energy transfer and sensitization of semiconductor metal oxides with a light-harvesting quantum dot (QD)/bacteriorhodopsin (bR) layer designed by protein engineering. The specific aims of our approach are (1) controlled engineering of highly ordered bR/QD complexes; (2) replacement of the liquid electrolyte by a thin layer of gold; (3) highly oriented deposition of bR/QD complexes on a gold layer; and (4) use of the Forster resonance energy transfer coupling between bR and QDs to achieve an efficient absorbing layer for dye-sensitized solar cells. This proposed approach is based on the unique optical characteristics of QDs, on the photovoltaic properties of bR, and on state-of-the-art nanobioengineering technologies. It permits spatial and optical coupling together with control of hybrid material components on the bionanoscale. This method paves the way to the development of the solid-state photovoltaic device with the efficiency increased to practical levels.

Hybrid materials formed by semiconductor quantum dots and J-aggregates of cyanine dyes provide a unique combination of enhanced absorption in inorganic constituents with large oscillator strength and extremely narrow exciton bands of the organic component. The optical properties of dendrite structures with fractal dimension 1.7-1.8, formed from J-aggregates integrated with CdTe quantum dots (QDs), have been investigated by photoluminescence spectroscopy and fluorescence lifetime imaging microscopy. Our results demonstrate that (i) J-aggregates are coupled to QDs by Förster-type resonant energy transfer and (ii) there are energy fluxes from the periphery to the centre of the structure, where the QD density is higher than in the periphery of the dendrite. Such an anisotropic energy transport can be only observed when dendrites are formed from QDs integrated with J-aggregates. These QD/J-aggregate hybrid systems can have applications in light harvesting systems and optical sensors with extended absorption spectra. © The Royal Society of Chemistry 2013., This research was supported by the ETORTEK 2011–2013 project “nanoIKER” from the Department of Industry of the Basque Government and by the Ministry of Education and Science of the Russian Federation Contract no. 8842 and 11.G34.31.0050. Financial support from the Portuguese Foundation for Science and Technology (FCT) and FEDER through Projects PTDC-FIS-113199-2009 and PEst-C/FIS/UI0607/2011 is gratefully acknowledged.

International audience; Combination of 3D structural analysis with optical characterization of the same sample area on the nanoscale is a highly demanded approach in nanophotonics, materials science, and quality control of nanomaterial. We have developed a correlative microscopy technique where the 3D structure of the sample is reconstructed on the nanoscale by means of a “slice-and-view” combination of ultramicrotomy and scanning probe microscopy (scanning probe nanotomography, SPNT), and its optical characteristics are analyzed using microspectroscopy. This approach has been used to determine the direct quantitative relationship of the 3D structural characteristics of nanovolumes of materials with their microscopic optical properties. This technique has been applied to 3D structural and optical characterization of a hybrid material consisting of cholesteric liquid crystals doped with fluorescent quantum dots (QDs) that can be used for photochemical patterning and image recording through the changes in the dissymmetry factor of the circular polarization of QD emission. The differences in the polarization images and fluorescent spectra of this hybrid material have proved to be correlated with the arrangement of the areas of homogeneous distribution and heterogeneous clustering of QDs. The reconstruction of the 3D nanostructure of the liquid crystal matrix in the areas of homogeneous QDs distribution has shown that QDs do not perturb the periodic planar texture of the cholesteric liquid crystal matrix, whereas QD clusters do perturb it. The combined microspectroscopy–nanotomography technique will be important for evaluating the effects of nanoparticles on the structural organization of organic and liquid crystal matrices and biomedical materials, as well as quality control of nanotechnology fabrication processes and products.

Combination of nanometer-scale 3D structural analysis with optical characterization of the same material is a challenging task. Its results may be important for nanophotonics, materials science, and quality control. We have developed a new technique for complementary high-resolution structural and optical characterization followed by optical spectroscopic and microscopic measurements accompanied by reconstruction of the 3D structure in the same area of the sample. The 3D structure is reconstructed by combination of ultramicrotomic and SPM techniques allowing the study of the 3D distribution of implanted nanoparticles and their effect on the matrix structure. The combination of scanning probe nanotomography (SPN) and optical microspectroscopy makes it possible to direct estimate how the 3D structural characteristics of materials affect their macroscopic optical properties. The technique developed has been applied to the engineering of materials made from cholesteric liquid crystals and fluorescent quantum dots (QDs). These materials permit photochemical patterning and image recording through the changes in the dissymmetry factor of circular polarization of QD emission. The differences in the polarisation images and morphological characteristics of the liquid crystal matrix have proved to be correlated with the arrangement of the areas of homogeneous distribution and nonhomogeneous clustering of QDs. The reconstruction of the 3D structure of the liquid crystal matrix in the areas of homogeneous QD distribution has shown that QDs embedded into cholesteric liquid crystal matrices do not perturb their periodic planar texture. The combined optical/SPM/ultramicrotome technique will be indispensable for evaluating the effects of inorganic nanoparticles on the organisation of organic and liquid crystal matrices, biomedical materials, cells, and tissues.

Novel types of electro- and photoactive quantum dot-doped cholesteric materials have been engineered. UV-irradiation or electric field application allows one to control the degree of circular polarization and intensity of fluorescence emission by prepared quantum dot-doped liquid crystal films.

International audience; Ordered structures in the form of quasi-nanowires were obtained from CdSe/ZnS fluorescent semiconductor nanoparticles of spherical (quantum dots) or rodlike (quantum rods) form by their electrostatic deposition on DNA molecules with subsequent stretching of the molecules on a solid substrate. Positively charged nanoparticles were fixed along the negatively charged backbones of DNA molecules by electrostatic interactions in an aqueous solution of a mixture of DNA with quantum particles at different stoichiometric ratios. Strands of single DNA molecules with quantum particles fixed along them were immobilized and stretched on hydrophobic surfaces using the molecular combing technique. It is shown that, by varying the nanoparticle charge and the stoichiometry of complexes of DNA with particles, it is possible to create fluorescent structures with predetermined morphology and properties.

International audience; Topotecan (TPT), a water-soluble derivative of camptothecin, is a potent antitumor poison of human DNA topoisomerase I (top1) that stabilizes the cleavage complex between the enzyme and DNA. The role of the recently discovered TPT affinity to DNA remains to be defined. The aim of this work is to clarify the molecular mechanisms of the TPT–DNA interaction and to propose the models of TPT–DNA complexes in solution in the absence of top1. It is shown that TPT molecules formdimers with a dimerization constant of (4.0 +/- 0.7) X 10^3 M^-1 and the presence of DNA provokes more than a 400-fold increase of the effective dimerization constant. Flowlinear dichroism spectroscopy accompanied by circular dichroism, fluorescence, andsurface-enhanced Raman scattering experiments provide evidence that TPT dimers areable to bind DNA by bridging different DNA molecules or distant DNA structural domains. This effect may provoke modification of the intrinsic geometry of the cruciform DNA structures, leading to the appearance of new crossover points that serve as the sites of the top1 loading position. The data presume the hypothesis of TPT-mediated modulation of top1–DNA recognition before ternary complex formation.

International audience; Monodispersed semiconductor nanocrystals or quantum dots (QDs) specifically immobilized on the surface of purple membranes (PMs) containing bacteriorhodopsin (bR) can harvest light in the UV to blue region, which cannot be absorbed efficiently by the PMs alone, and transfer the harvested energy to the retinal chromophores of bR via highly efficient Förster resonance energy transfer (FRET). CdTe or CdSe/ZnS QDs with a quantum yield as high as 70% have been used to estimate different parameters characterizing the improvement of the bR biological function caused by nanocrystals. AFM examination has shown that the most FRET-efficient QD–PM hybrid structures are characterized by the highest level of QD ordering; hence, AFM imaging of bR–PM hybrid materials provides the basis for optimization of the assembly design in order to engineer bio-hybrid structures with advanced optical and photovoltaic properties. Oriented bR-containing proteoliposomes tagged with QDs at a QD-to-bR molar ratio of up to 1:5 have been engineered and used to analyze the photoresponse, with the bR proton pumping considerably increased. Finally, the kinetics of the potential/current generation in films of oriented bR containing or not containing QDs have been analyzed. Incorporation of QDs resulted in an increase in the potential/current generation rate and in an almost fourfold increase in the rate of M-form formation. Thus, the improvement of the bR native function by QDs may be caused by two reasons: an extension of the range of utilized light and an increase in the rate of the bR photocycle.

International audience; Optical materials based on cholesteric liquid crystals (LCs) doped with fluorescent CdSe/ZnS quantum dots (QDs) have been developed and demonstrated to have a wide photonic band gap. It has been shown that the fluorescence emission of QDs embedded in LCs is circularly polarized and that the dissymmetry factor of this polarization may be optically or electrically controlled via conformational changes in the helical structure of the LC matrix. The possibility of photochemical patterning or image recording using these materials has been demonstrated; the recorded information can be read through changes in the dissymmetry factor of circular polarization of QDs emission. The developed photo- and electro-active materials with a controlled degree of fluorescence circular polarization may be used as on-demand single photon sources in photonics, optoelectronics, and quantum cryptography, as well as for development of nanophotonic systems capable of low-threshold lasing.