Epigenetic inheritance of diet-induced and sperm-borne mitochondrial RNAs.

Spermatozoa harbour a complex and environment-sensitive pool of small non-coding RNAs (sncRNAs)1, which influences offspring development and adult phenotypes1-7. Whether spermatozoa in the epididymis are directly susceptible to environmental cues is not fully understood8. Here we used two distinct paradigms of preconception acute high-fat diet to dissect epididymal versus testicular contributions to the sperm sncRNA pool and offspring health. We show that epididymal spermatozoa, but not developing germ cells, are sensitive to the environment and identify mitochondrial tRNAs (mt-tRNAs) and their fragments (mt-tsRNAs) as sperm-borne factors. In humans, mt-tsRNAs in spermatozoa correlate with body mass index, and paternal overweight at conception doubles offspring obesity risk and compromises metabolic health. Sperm sncRNA sequencing of mice mutant for genes involved in mitochondrial function, and metabolic phenotyping of their wild-type offspring, suggest that the upregulation of mt-tsRNAs is downstream of mitochondrial dysfunction. Single-embryo transcriptomics of genetically hybrid two-cell embryos demonstrated sperm-to-oocyte transfer of mt-tRNAs at fertilization and suggested their involvement in the control of early-embryo transcription. Our study supports the importance of paternal health at conception for offspring metabolism, shows that mt-tRNAs are diet-induced and sperm-borne and demonstrates, in a physiological setting, father-to-offspring transfer of sperm mitochondrial RNAs at fertilization.

Polariton response in the presence of Brownian dissipation from molecular vibrations.

We study the elastic response of a stationarily driven system of a cavity field strongly coupled with molecular excitons, taking into account the main dissipation channels due to the finite cavity linewidth and molecular vibrations. We show that the frequently used coupled oscillator model fails in describing this response especially due to the non-Lorentzian dissipation of the molecules to their vibrations. Signatures of this failure are the temperature dependent minimum point of the polariton peak splitting, the uneven polariton peak height at the minimum splitting, and the asymmetric shape of the polariton peaks even at the experimentally accessed "zero-detuning" point. Using a rather generic yet representative model of molecular vibrations, we predict the polariton response in various conditions, depending on the temperature, molecular Stokes shift and vibration frequencies, and the size of the Rabi splitting. Our results can be used as a sanity check of the experiments trying to "prove" results originating from strong coupling, such as vacuum-enhanced chemical reaction rate.

Effect of molecular Stokes shift on polariton dynamics.

When the enhanced electromagnetic field of a confined light mode interacts with photoactive molecules, the system can be driven into the regime of strong coupling, where new hybrid light-matter states, polaritons, are formed. Polaritons, manifested by the Rabi split in the dispersion, have shown potential for controlling the chemistry of the coupled molecules. Here, we show by angle-resolved steady-state experiments accompanied by multi-scale molecular dynamics simulations that the molecular Stokes shift plays a significant role in the relaxation of polaritons formed by organic molecules embedded in a polymer matrix within metallic Fabry-Pérot cavities. Our results suggest that in the case of Rhodamine 6G, a dye with a significant Stokes shift, excitation of the upper polariton leads to a rapid localization of the energy into the fluorescing state of one of the molecules, from where the energy scatters into the lower polariton (radiative pumping), which then emits. In contrast, for excitonic J-aggregates with a negligible Stokes shift, the fluorescing state does not provide an efficient relaxation gateway. Instead, the relaxation is mediated by exchanging energy quanta matching the energy gap between the dark states and lower polariton into vibrational modes (vibrationally assisted scattering). To understand better how the fluorescing state of a molecule that is not strongly coupled to the cavity can transfer its excitation energy to the lower polariton in the radiative pumping mechanism, we performed multi-scale molecular dynamics simulations. The results of these simulations suggest that non-adiabatic couplings between uncoupled molecules and the polaritons are the driving force for this energy transfer process.

Constructing Large 2D Lattices Out of DNA-Tiles.

The predictable nature of deoxyribonucleic acid (DNA) interactions enables assembly of DNA into almost any arbitrary shape with programmable features of nanometer precision. The recent progress of DNA nanotechnology has allowed production of an even wider gamut of possible shapes with high-yield and error-free assembly processes. Most of these structures are, however, limited in size to a nanometer scale. To overcome this limitation, a plethora of studies has been carried out to form larger structures using DNA assemblies as building blocks or tiles. Therefore, DNA tiles have become one of the most widely used building blocks for engineering large, intricate structures with nanometer precision. To create even larger assemblies with highly organized patterns, scientists have developed a variety of structural design principles and assembly methods. This review first summarizes currently available DNA tile toolboxes and the basic principles of lattice formation and hierarchical self-assembly using DNA tiles. Special emphasis is given to the forces involved in the assembly process in liquid-liquid and at solid-liquid interfaces, and how to master them to reach the optimum balance between the involved interactions for successful self-assembly. In addition, we focus on the recent approaches that have shown great potential for the controlled immobilization and positioning of DNA nanostructures on different surfaces. The ability to position DNA objects in a controllable manner on technologically relevant surfaces is one step forward towards the integration of DNA-based materials into nanoelectronic and sensor devices.

Circulating ß cell-specific CD8+ T cells restricted by high-risk HLA class I molecules show antigen experience in children with and at risk of type 1 diabetes.

In type 1 diabetes (T1D), autoreactive cytotoxic CD8+ T cells are implicated in the destruction of insulin-producing ß cells. The HLA-B*3906 and HLA-A*2402 class I genes confer increased risk and promote early disease onset, suggesting that CD8+ T cells that recognize peptides presented by these class I molecules on pancreatic ß cells play a pivotal role in the autoimmune response. We examined the frequency and phenotype of circulating preproinsulin (PPI)-specific and insulin B (InsB)-specific CD8+ T cells in HLA-B*3906+ children newly diagnosed with T1D and in high-risk HLA-A*2402+ children before the appearance of disease-specific autoantibodies and before diagnosis of T1D. Antigen-specific CD8+ T cells were detected using human leucocyte antigen (HLA) class I tetramers and flow cytometry was used to assess memory status. In HLA-B*3906+ children with T1D, we observed an increase in PPI5-12 -specific transitional memory CD8+ T cells compared to non-diabetic, age- and HLA-matched subjects. Furthermore, PPI5-12 -specific CD8+ T cells in HLA-B*3906+ children with T1D showed a significantly more antigen-experienced phenotype compared to polyclonal CD8+ T cells. In longitudinal samples from high-risk HLA-A*2402+ children, the percentage of terminal effector cells within the InsB15-24 -specific CD8+ T cells was increased before diagnosis relative to samples taken before the appearance of autoantibodies. This is the first study, to our knowledge, to report HLA-B*3906-restricted autoreactive CD8+ T cells in T1D. Collectively, our results provide evidence that ß cell-reactive CD8+ T cells restricted by disease-associated HLA class I molecules display an antigen-experienced phenotype and acquire enhanced effector function during the period leading to clinical diagnosis, implicating these cells in driving disease.

Anti-Müllerian hormone and letrozole levels in boys with constitutional delay of growth and puberty treated with letrozole or testosterone.

STUDY QUESTION: Does treatment of constitutional delay of growth and puberty (CDGP) in boys with aromatase inhibitor letrozole (Lz) or conventional low-dose testosterone (T) have differing effects on developing seminiferous epithelium? SUMMARY ANSWER: Anti-Müllerian hormone (AMH) declined similarly in both treatment groups, and the two Sertoli cell-derived markers (AMH and inhibin B (iB)) exhibited differing responses to changes in gonadotrophin milieu. WHAT IS KNOWN ALREADY: Boys with CDGP may benefit from puberty-inducing medication. Peroral Lz activates gonadotrophin secretion, whereas intramuscular low-dose T may transiently suppress gonadotrophins and iB. STUDY DESIGN, SIZE, DURATION: Sera of 28 boys with CDGP who participated in a randomised, controlled, open-label trial at four paediatric centres in Finland between August 2013 and January 2017 were analysed. The patients were randomly assigned to receive either Lz (2.5 mg/day) (n = 15) or T (1 mg/kg/month) (n = 13) for 6 months. PARTICIPANTS/MATERIALS, SETTING, METHODS: The 28 patients were at least 14 years of age, showed first signs of puberty, wanted medical attention for CDGP and were evaluated at 0, 3, 6 and 12 months of visits. AMH levels were measured with an electrochemiluminescence immunoassay and Lz levels with liquid chromatography coupled with tandem mass spectrometry. MAIN RESULTS AND THE ROLE OF CHANCE: AMH levels decreased in both treatment groups during the 12-month follow-up (P < 0.0001). Between 0 and 3 months, the changes in gonadotrophin levels (increase in the Lz group, decrease in the T group) correlated strongly with the changes in levels of iB (FSH vs iB, r = 0.55, P = 0.002; LH vs iB, r = 0.72, P < 0.0001), but not with the changes in AMH (P = NS). At 12 months, AMH levels did not differ between the groups (P = NS). Serum Lz levels (range, 124-1262 nmol/L) were largely explained by the Lz dose per weight (at 3 months r = 0.62, P = 0.01; at 6 months r = 0.52, P = 0.05). Lz levels did not associate with changes in indices of hypothalamic-pituitary-gonadal axis activity or Sertoli cell markers (in all, P = NS). LIMITATIONS, REASONS FOR CAUTION: The original trial was not blinded for practical reasons and included a limited number of participants. WIDER IMPLICATIONS OF THE FINDINGS: In early puberty, treatment-induced gonadotrophin stimulus was unable to counteract the androgen-mediated decrease in AMH, while changes in iB levels were associated with changes in gonadotrophin levels. AMH decreased similarly in both groups during the treatment, reassuring safety of developing seminiferous epithelium in both treatment approaches. Since a fixed dose of Lz induced variable serum Lz levels with a desired puberty-promoting effect in all boys, more research is needed to aim at a minimal efficient dose per weight. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Academy of Finland, the Foundation for Pediatric Research, the Emil Aaltonen Foundation, Sigrid Juselius Foundation and Helsinki University Hospital Research Funds. The authors have nothing to disclose. TRIAL REGISTRATION NUMBER: NCT01797718.

Influence of Fano resonance on SERS enhancement in Fano-plasmonic oligomers.

Plasmonic oligomers can provide profound Fano resonance in their scattering responses. The sub-radiant mode of Fano resonance can result in significant near-field enhancement due to its light trapping capability into the so-called hotspots. Appearance of these highly localized hotspots at the excitation and/or Stokes wavelengths of the analytes makes such oligomers promising SERS active substrates. In this work, we numerically and experimentally investigate optical properties of two disk-type gold oligomers, which have different strength and origin of Fano resonance. Raman analysis of rhodamine 6G and adenine with the presence of the fabricated oligomers clearly indicates that an increment in the strength of Fano resonance can improve the Raman enhancement of an oligomer significantly. Therefore, by suitable engineering of Fano lineshape, one can achieve efficient SERS active substrates with spatially localized hotspots.

Surface Characteristics Control the Attachment and Functionality of (Chimeric) Avidin.

The physical adsorption (physisorption) of proteins to surfaces is an important but incompletely understood factor in many biological processes and is of increasing significance in bionanotechnology as well. Avidin is an important protein because of strong avidin-biotin binding, which has been exploited in numerous applications. We have undertaken thorough experimentation on the physisorption of avidin, to chemically different flat surfaces of Si and graphite and also to the curved version of the latter, on multiwalled carbon nanotubes (MWNTs) of different diameters. The difference in the behavior of avidin on Si versus graphite is drastic; on Si, avidin deposits as single globular tetrameric units and maintains functionality, whereas on graphite, it forms irregular networks of two-layer thick filaments, where the first layer has lost its biological activity. On MWNTs, avidin also deposits as one-dimensional formations, or stripes, but these appear to order in a perpendicular arrangement to the MWNT axis. A better understanding of protein-surface interactions is essential for the development of robust and reliable methods for biofunctionalization of materials. This work also provides insights into the importance of the nanoscale surface architecture.

Serum carotenoid and tocopherol concentrations and risk of asthma in childhood: a nested case-control study.

BACKGROUND: The antioxidant hypothesis regarding the risk of asthma in childhood has resulted in inconsistent findings. Some data indicate that the role of antioxidants in childhood asthma risk may have a critical time window of effect, but only a well-designed longitudinal cohort study can clarify this hypothesis. OBJECTIVE: To study the longitudinal associations between serum carotenoid and tocopherol concentrations during the first 4 years of life and asthma risk by the age of 5 years. METHODS: Based on a case-control design nested within a Finnish birth cohort, 146 asthma cases were matched to 270 controls on birth time, sex, genetic risk, and birth place. Non-fasting blood samples were collected at the ages of 1, 1.5, 2, 3, and 4 years and serum carotenoids and tocopherols were analysed. Parents reported the presence and age at start of persistent doctor-diagnosed asthma in the child at the age of 5 years. Data analyses were conducted using generalized estimating equations. RESULTS: We did not find strong associations between serum carotenoids and tocopherols and the risk of asthma based on age-specific and longitudinal analyses. Both lower and higher quarters of α-carotene and γ-tocopherol increased the risk of asthma. CONCLUSIONS: The current findings do not support the suggestion that the increased prevalence of asthma may be a consequence of decreased intake of antioxidant nutrients. Moreover, we did not confirm any critical time window of impact of antioxidants on asthma risk. Replication of these findings in similar longitudinal settings will strengthen this evidence base.

Toward Single Electron Nanoelectronics Using Self-Assembled DNA Structure.

DNA based structures offer an adaptable and robust way to develop customized nanostructures for various purposes in bionanotechnology. One main aim in this field is to develop a DNA nanobreadboard for a controllable attachment of nanoparticles or biomolecules to form specific nanoelectronic devices. Here we conjugate three gold nanoparticles on a defined size TX-tile assembly into a linear pattern to form nanometer scale isolated islands that could be utilized in a room temperature single electron transistor. To demonstrate this, conjugated structures were trapped using dielectrophoresis for current-voltage characterization. After trapping only high resistance behavior was observed. However, after extending the islands by chemical growth of gold, several structures exhibited Coulomb blockade behavior from 4.2 K up to room temperature, which gives a good indication that self-assembled DNA structures could be used for nanoelectronic patterning and single electron devices.

Compensated reduction in Leydig cell function is associated with lower semen quality variables: a study of 8182 European young men.

STUDY QUESTION: Is the Leydig cell function of young European men associated with semen quality? SUMMARY ANSWER: Compensated reduction in Leydig cell function, defined as increased LH concentration combined with adequate testosterone production is associated with lower semen quality. WHAT IS ALREADY KNOWN: Semen quality of young European men shows a heterogeneous pattern. Many have sperm counts below and in the lower WHO reference where there nevertheless is a significant risk of subfecundity. Little is known about differences in Leydig cell function between men with semen quality below and within the WHO reference range. STUDY DESIGN, SIZE AND DURATION: A coordinated, cross-sectional population-based study of 8182 men undertaken in 1996-2010. PARTICIPANTS, SETTING AND METHOD: Young men (median age 19.1 years) were investigated in centres in Denmark, Estonia, Finland, Germany Latvia, Lithuania, and Spain. The men originated from the general populations, all were young, almost all were unaware of their fecundity and each provided a semen and blood sample. Associations between semen parameters and serum levels of testosterone and luteinising hormone (LH), calculated free testosterone, and ratios between serum testosterone and LH were determined. MAIN RESULT AND ROLE OF CHANCE: Serum testosterone levels were not associated with sperm concentrations, total sperm counts, or percentage of motile or morphologically normal spermatozoa. There was an inverse association between the semen parameters and serum LH levels, and accordingly a positive association to testosterone/LH ratio and calculated-free-testosterone/LH ratio. LIMITATIONS, REASON FOR CAUTION: The size of the study mitigates the intra-individual variability concern. The distinction between different sub-categories of sperm motility and sperm morphology is subjective despite training. However, inter-observer variation would tend towards non-differential misclassification and would decrease the likelihood of detecting associations between reproductive hormone levels and semen variables, suggesting that the presented associations might in reality be even stronger than shown. Although we adjusted for confounders, we cannot of course exclude that our results can be skewed by selection bias or residual confounding. WIDER IMPLICATIONS OF THE FINDINGS: Compensated reduction in Leydig cell function, defined as increased LH concentration combined with adequate testosterone production is associated with lower semen quality. This is apparent even within the WHO reference range of semen quality. It is unknown whether impaired Leydig cell function in young men may confer an increased risk of acquired testosterone deficiency later in life. STUDY FUNDING/COMPETING INTERESTS: Support from The Research Fund of Rigshospitalet (grant no. R42-A1326) to N.J. made this study possible. The background studies of young men have been supported economically by several grants. ITALIC! Denmark: The European Union (contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603 and most recently FP7/2007-2013, DEER Grant agreement no. 212844), The Danish Research Council (grants nos. 9700833 2107-05-0006), The Danish Agency for Science, Technology and Innovation (Grant no. 271070678), Rigshospitalet (Grant no. 961506336), The University of Copenhagen (Grant no. 211-0357/07-3012), The Danish Ministry of Health and the Danish Environmental Protection Agency, A.P. Møller and wife Chastine McKinney Møllers foundation, and Svend Andersens Foundation. ITALIC! Finland: European Union (contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT- 2002-00603 and most recently FP7/2008-2012, DEER Grant agreement no. 212844), The Academy of Finland, Turku University Hospital Funds, Sigrid Juselius Foundation. ITALIC! Estonia, Latvia and Lithuania: European Union (QLRT-2001-02911), the Estonian Science Foundation, grant number 2991, Lithuanian Foundation for Research, Organon Agencies B.V. and the Danish Research Council, grant no. 9700833. ITALIC! Germany: European Union (contract numbers QLK4-CT-2002-00603). ITALIC! Spain: European Commission QLK4-1999-01422. M.F. received support from the Spanish Ministry of Science and Innovation (Program Ramon y Cajal). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. None of the authors have any competing interests to declare.

Genetic susceptibility to type 1 diabetes in childhood - estimation of HLA class II associated disease risk and class II effect in various phases of islet autoimmunity.

OBJECTIVE: The HLA-DR/DQ region remains the major determinant of susceptibility to type 1 diabetes (T1D) despite the more than 50 risk affecting loci outside human leukocyte antigen (HLA) region that have been identified. We aimed at developing a simple risk estimation based on HLA class II genotyping, which was also tested by analyzing HLA class II effect on the autoantibody seroconversion and further progression to diabetes. SUBJECTS AND METHODS: A total of 2991 trio families with a diabetic child from the Finnish Pediatric Diabetes Register were genotyped and the risk contributed by each DR-DQ haplotype calculated through transmission analysis. The genotype risk was estimated based on the summary effect of haplotypes. Genotype grouping was further tested in a subcohort of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study RESULTS: The summary effect of haplotypes was generally seen in genotypes, while the expected synergistic effect of DR3-DQ2 and DR4-DQ8 (DRB1*04:03 excluded) combination was also clear in the T1D risk association analysis. This highest risk DR/DQ genotype was found in 21.6% of patients and 2.0% of controls, odds ratio (OR) = 13.2 (10.1-17.2), whereas the lowest risk genotype contained only 0.8% of patients and 28.0% of controls, OR = 0.02 (0.01-0.03). In the subcohort from the DIPP study the risk grades correlated clearly with seroconversion for islet autoantibodies and T1D development. In contrast, DR/DQ risk groups did not associate with the progression rate from advanced autoimmunity to clinical diabetes. CONCLUSIONS: Class II HLA genotype groups improve the estimation of T1D risk. Class II effect is limited to the early phase of the disease process characterized by seroconversion for islet autoantibodies.

Dielectrophoretic trapping of multilayer DNA origami nanostructures and DNA origami-induced local destruction of silicon dioxide.

DNA origami is a widely used method for fabrication of custom-shaped nanostructures. However, to utilize such structures, one needs to controllably position them on nanoscale. Here we demonstrate how different types of 3D scaffolded multilayer origamis can be accurately anchored to lithographically fabricated nanoelectrodes on a silicon dioxide substrate by DEP. Straight brick-like origami structures, constructed both in square (SQL) and honeycomb lattices, as well as curved "C"-shaped and angular "L"-shaped origamis were trapped with nanoscale precision and single-structure accuracy. We show that the positioning and immobilization of all these structures can be realized with or without thiol-linkers. In general, structural deformations of the origami during the DEP trapping are highly dependent on the shape and the construction of the structure. The SQL brick turned out to be the most robust structure under the high DEP forces, and accordingly, its single-structure trapping yield was also highest. In addition, the electrical conductivity of single immobilized plain brick-like structures was characterized. The electrical measurements revealed that the conductivity is negligible (insulating behavior). However, we observed that the trapping process of the SQL brick equipped with thiol-linkers tended to induce an etched "nanocanyon" in the silicon dioxide substrate. The nanocanyon was formed exactly between the electrodes, that is, at the location of the DEP-trapped origami. The results show that the demonstrated DEP-trapping technique can be readily exploited in assembling and arranging complex multilayered origami geometries. In addition, DNA origamis could be utilized in DEP-assisted deformation of the substrates onto which they are attached.

Antiviral action of a functionalized plastic surface against human coronaviruses.

Viruses may persist on solid surfaces for long periods, which may contribute to indirect transmission. Thus, it is imperative to develop functionalized surfaces that will lower the infectious viral load in everyday life. Here, we have tested a plastic surface functionalized with tall oil rosin against the seasonal human coronavirus OC43 as well as severe acute respiratory syndrome coronavirus 2. All tested non-functionalized plastic surfaces showed virus persistence up to 48 h. In contrast, the functionalized plastic showed good antiviral action already within 15 min of contact and excellent efficacy after 30 min over 90% humidity. Excellent antiviral effects were also observed at lower humidities of 20% and 40%. Despite the hydrophilic nature of the functionalized plastic, viruses did not adhere strongly to it. According to helium ion microscopy, viruses appeared flatter on the rosin-functionalized surface, but after flushing away from the rosin-functionalized surface, they showed no apparent structural changes when imaged by transmission electron microscopy of cryogenic or negatively stained specimens or by atomic force microscopy. Flushed viruses were able to bind to their host cell surface and enter endosomes, suggesting that the fusion with the endosomal membrane was halted. The eluted rosin from the functionalized surface demonstrated its ability to inactivate viruses, indicating that the antiviral efficacy relied on the active leaching of the antiviral substances, which acted on the viruses coming into contact. The rosin-functionalized plastic thus serves as a promising candidate as an antiviral surface for enveloped viruses.IMPORTANCEDuring seasonal and viral outbreaks, the implementation of antiviral plastics can serve as a proactive strategy to limit the spread of viruses from contaminated surfaces, complementing existing hygiene practices. In this study, we show the efficacy of a rosin-functionalized plastic surface that kills the viral infectivity of human coronaviruses within 15 min of contact time, irrespective of the humidity levels. In contrast, non-functionalized plastic surfaces retain viral infectivity for an extended period of up to 48 h. The transient attachment on the surface or the leached active components do not cause major structural changes in the virus or prevent receptor binding; instead, they effectively block viral infection at the endosomal stage.

Thermal disorder prevents the suppression of ultra-fast photochemistry in the strong light-matter coupling regime.

Strong coupling between molecules and confined light modes of optical cavities to form polaritons can alter photochemistry, but the origin of this effect remains largely unknown. While theoretical models suggest a suppression of photochemistry due to the formation of new polaritonic potential energy surfaces, many of these models do not account for the energetic disorder among the molecules, which is unavoidable at ambient conditions. Here, we combine simulations and experiments to show that for an ultra-fast photochemical reaction such thermal disorder prevents the modification of the potential energy surface and that suppression is due to radiative decay of the lossy cavity modes. We also show that the excitation spectrum under strong coupling is a product of the excitation spectrum of the bare molecules and the absorption spectrum of the molecule-cavity system, suggesting that polaritons can act as gateways for channeling an excitation into a molecule, which then reacts normally. Our results therefore imply that strong coupling provides a means to tune the action spectrum of a molecule, rather than to change the reaction.

Direct optical measurement of light coupling into planar waveguide by plasmonic nanoparticles.

Coupling of light into a thin layer of high refractive index material by plasmonic nanoparticles has been widely studied for application in photovoltaic devices, such as thin-film solar cells. In numerous studies this coupling has been investigated through measurement of e.g. quantum efficiency or photocurrent enhancement. Here we present a direct optical measurement of light coupling into a waveguide by plasmonic nanoparticles. We investigate the coupling efficiency into the guided modes within the waveguide by illuminating the surface of a sample, consisting of a glass slide coated with a high refractive index planar waveguide and plasmonic nanoparticles, while directly measuring the intensity of the light emitted out of the waveguide edge. These experiments were complemented by transmittance and reflectance measurements. We show that the light coupling is strongly affected by thin-film interference, localized surface plasmon resonances of the nanoparticles and the illumination direction (front or rear).

Strong coupling between surface plasmon polaritons and ß-carotene in nanolayered system.

In this article we experimentally demonstrate the strong coupling between surface plasmon polaritons (SPP) and the S(2) state of ß-carotene. The SPPs are excited by prism coupling technique on a thin silver film with ß-carotene embedded in a polymer layer on top of that. Rabi splittings with energies 80 and 130 meV are observed in the recorded dispersion relations. Both coupled oscillator model and transfer matrix method are used to fit the experimental results. The scattered radiation of the propagating strongly coupled SPP-S(2) hybrids is collected and an increase of the low energy splitting to 120 meV is observed compared to the reflectivity data. In addition, we performed molecule excitation by laser and analyzed the emission patterns revealing clear surface plasmon coupled fluorescence of ß-carotene. By increasing the concentration of ß-carotene we are able to collect also surface plasmon coupled Raman scattering. This study substantially extends the SPP-molecular excitation strong coupling studies to biomolecules, and energy transfer and coupling properties of excited states of carotenoids.

Elongation and plasmonic activity of embedded metal nanoparticles following heavy ion irradiation.

Shape modification of embedded nanoparticles by swift heavy ion (SHI) irradiation is an effective way to produce nanostructures with controlled size, shape, and orientation. In this study, randomly oriented gold nanorods embedded in SiO2 are shown to re-orient along the ion beam direction. The degree of orientation depends on the irradiation conditions and the nanorod's initial size. SHI irradiation was also applied to modify spherical metallic nanoparticles embedded in Al2O3. The results showed that they elongate due to the irradiation comparably to those embedded in SiO2. Metallic nanostructures embedded in dielectric matrices can exhibit localized surface plasmon (LSP) modes. The elongated nanoparticles investigated by means of dark-field spectroscopy showed two discrete peaks which correspond to longitudinal and transverse modes.

Creation of ordered 3D tubes out of DNA origami lattices.

Hierarchical self-assembly of nanostructures with addressable complexity has been a promising route for realizing novel functional materials. Traditionally, the fabrication of such structures on a large scale has been achievable using top-down methods but with the cost of complexity of the fabrication equipment versus resolution and limitation mainly to 2D structures. More recently bottom-up methods using molecules like DNA have gained attention due to the advantages of low fabrication costs, high resolution and simplicity in an extension of the methods to the third dimension. One of the more promising bottom-up techniques is DNA origami due to the robust self-assembly of arbitrarily shaped nanostructures with feature sizes down to a few nanometers. Here, we show that under specific ionic conditions of the buffer, the employed plus-shaped, blunt-ended Seeman tile (ST) origami forms elongated, ordered 2D lattices, which are further rolled into 3D tubes in solution. Imaging structures on a surface by atomic force microscopy reveals ribbon-like structures, with single or double layers of the origami lattice. Further studies of the double-layered structures in a liquid state by confocal microscopy and cryo-TEM revealed elongated tube structures with a relatively uniform width but with a varying length. Through meticulous study, we concluded that the assembly process of these 3D DNA origami tubes is heavily dependent on the concentration of both mono- and divalent cations. In particular, nickel seems to act as a trigger for the formation of the tubular assemblies in liquid.

Semen quality and reproductive hormone levels in men from Southern Spain.

In North European countries, a significant difference in semen quality among young men has been shown. Men from the western countries, Denmark, Germany and Norway, have lower semen quality than men from the eastern countries Finland, Estonia and Lithuania. Similarly, men in the western countries have a higher risk of testicular cancer. According to the testicular dysgenesis syndrome (TDS) concept that suggests a link between risk of impaired semen quality and increased risk of testicular cancer, Spanish men would be expected to have a semen quality at a normal level because of their very low testis cancer risk. We therefore investigated 273 men from the Almeria region in the Southern Spain to test this hypothesis. The men delivered semen samples, underwent physical examinations, had a blood sample drawn and provided information on lifestyle and reproductive health parameters. The investigations took place from November 2001 to December 2002. Adjusting for effects of confounders, the median sperm concentration and total sperm count were 62 (95% confidence interval 47-82) million/mL and 206 (153-278) million, respectively. The median numbers of motile and morphologically normal spermatozoa assessed according to strict criteria were 59% (57-62%) and 9.4% (8.6-10.0%), respectively. The median total testosterone and calculated free androgen index were 28 nm (26-30) and 95 (88-103), respectively. Assuming that the investigated men, to a large extent, are representative of the population of young men the Southern Spain, the results show that these have normal semen quality and reproductive hormone levels as expected in a population with a low incidence of testicular cancer.