Super-resolution (SR) microscopy is a cutting-edge method that can provide detailed structural information with high resolution. However, the thickness of the specimen has been a major limitation for SR methods, and large biological structures have posed a challenge. To overcome this, the key step is to optimise sample preparation to ensure optical homogeneity and clarity, which can enhance the capabilities of SR methods for the acquisition of thicker structures. Oocytes are the largest cells in the mammalian body and are crucial objects in reproductive biology. They are especially useful for studying membrane proteins. However, oocytes are extremely fragile and sensitive to mechanical manipulation and osmotic shocks, making sample preparation a critical and challenging step. We present an innovative, simple and sensitive approach to oocyte sample preparation for 3D STED acquisition. This involves alcohol dehydration and mounting into a high refractive index medium. This extended preparation procedure allowed us to successfully obtain a unique two-channel 3D STED SR image of an entire mouse oocyte. By optimising sample preparation, it is possible to overcome current limitations of SR methods and obtain high-resolution images of large biological structures, such as oocytes, in order to study fundamental biological processes. Lay Abstract: Super-resolution (SR) microscopy is a cutting-edge tool that allows scientists to view incredibly fine details in biological samples. However, it struggles with larger, thicker specimens, as they need to be optically clear and uniform for the best imaging results. In this study, we refined the sample preparation process to make it more suitable for SR microscopy. Our method includes carefully dehydrating biological samples with alcohol and then transferring them into a mounting medium that enhances optical clarity. This improved protocol enables high-resolution imaging of thick biological structures, which was previously challenging. By optimizing this preparation method, we hope to expand the use of SR microscopy for studying large biological samples, helping scientists better understand complex biological structures.
- Klíčová slova
- 3D STED, alcohol dehydration, high refractive index medium, large biological objects, oocyte, sample preparation, super‐resolution,
- MeSH
- ethanol chemie MeSH
- fluorescenční mikroskopie metody MeSH
- myši MeSH
- odběr biologického vzorku * metody MeSH
- oocyty * cytologie ultrastruktura MeSH
- refraktometrie metody MeSH
- zobrazování trojrozměrné * metody MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ethanol MeSH
Here we study the analytical performance of label-free optical biosensors with respect to analyte-induced refractive index changes that can be measured by a biosensor (refractive index resolution). We present an analytical model that interrelates the refractive index resolution and the parameters of the optical platform of a biosensor. We demonstrate that the figure of merit (FOM), which has been widely used to design optical platforms of label-free optical biosensors, is not an appropriate metric to guide the design or predict the performance of label-free optical biosensors. Therefore, we propose an extended definition of FOM that addresses its limitations. We confirm the validity of the proposed approach by both numerical simulations and experiments. Finally, we show that the analytical model of the refractive index resolution not only makes it possible to predict the performance of a biosensor but also provides strategies for achieving optimal performance.
- Klíčová slova
- Figure of merit, Label-free biosensing, Optical biosensors, Plasmonics, Refractive index resolution,
- MeSH
- biosenzitivní techniky * MeSH
- refraktometrie metody MeSH
- Publikační typ
- časopisecké články MeSH
Remote detection of hydrogen, without the utilization of electronic component or elevated temperature, is one of the hot topics in the hydrogen technology and safety. In this work, the design and realization of the optical fiber-based hydrogen sensor with unique characteristics are proposed. The proposed sensor is based on the gold-coated multimode fiber, providing the plasmon properties, decorated by the IRMOF-20 layer with high selectivity and affinity toward hydrogen. The IRMOF-20 layer was grown by a surface-assisted technique, and its formation and properties were studied using X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and Brunauer-Emmett-Teller techniques. Simultaneous ellipsometry results indicate the apparent changes of the refractive index of the IRMOF-20 layer due to hydrogen sorption. As results, the presence of hydrogen led to the pronounced changes of plasmon band wavelength position as well as its intensity increase. The proposed hydrogen sensors were favorably distinguished by a high response/recovery rate, excellent selectivity toward the hydrogen, very low temperature dependency, functionality at room or lower temperature, insensitivity toward the humidity, and the presence of CO2, CO, or NO2. Additionally, the proposed hydrogen sensor showed good reversibility, reproducibility, and long-term stability.
- Klíčová slova
- hydrogen detection, metal−organic framework, optical fiber, plasmon, surface grafting,
- MeSH
- optická vlákna * MeSH
- porézní koordinační polymery chemie MeSH
- refraktometrie přístrojové vybavení metody MeSH
- reprodukovatelnost výsledků MeSH
- vodík analýza MeSH
- zlato chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- porézní koordinační polymery MeSH
- vodík MeSH
- zlato MeSH
Spectropolarimetry of intact plant leaves allows to probe the molecular architecture of vegetation photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological information. In addition to the molecular signals due to the photosynthetic machinery, the cell structure and its arrangement within a leaf can create and modify polarization signals. Using Mueller matrix polarimetry with rotating retarder modulation, we have visualized spatial variations in polarization in transmission around the chlorophyll a absorbance band from 650 nm to 710 nm. We show linear and circular polarization measurements of maple leaves and cultivated maize leaves and discuss the corresponding Mueller matrices and the Mueller matrix decompositions, which show distinct features in diattenuation, polarizance, retardance and depolarization. Importantly, while normal leaf tissue shows a typical split signal with both a negative and a positive peak in the induced fractional circular polarization and circular dichroism, the signals close to the veins only display a negative band. The results are similar to the negative band as reported earlier for single macrodomains. We discuss the possible role of the chloroplast orientation around the veins as a cause of this phenomenon. Systematic artefacts are ruled out as three independent measurements by different instruments gave similar results. These results provide better insight into circular polarization measurements on whole leaves and options for vegetation remote sensing using circular polarization.
- Klíčová slova
- Chlorophyll a, Chloroplast, Circular dichroism, Mueller matrix polarimetry, Photosynthesis,
- MeSH
- algoritmy * MeSH
- fotosyntéza * MeSH
- kukuřice setá růst a vývoj metabolismus MeSH
- listy rostlin růst a vývoj metabolismus MeSH
- počítačové zpracování obrazu metody MeSH
- polarizační mikroskopie metody MeSH
- refraktometrie metody MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The spectrophotometric method and the electron microscope have been used to determine the distribution function of Ag@Fe3O4 nanoparticles by sizes and to measure their complex refractive index. These particles have been synthesized as acomponent of magnetically controlled drugs with antibacterial properties. The algorithm of processing the results of the experiment has been designed to measure the sizes of nanoparticles (1-100 nm).Key words: nanoparticle sizes measuring spectrum attenuation.
- MeSH
- antibakteriální látky farmakologie MeSH
- kovové nanočástice * MeSH
- refraktometrie MeSH
- stříbro * farmakologie MeSH
- železnaté sloučeniny * farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- antibakteriální látky MeSH
- ferrous oxide MeSH Prohlížeč
- stříbro * MeSH
- železnaté sloučeniny * MeSH
The complex index of refraction in the spectral range of 0.74 to 4.5 eV is studied by variable-angle spectroscopic ellipsometry in ferroelectric K0.5Na0.5NbO3 films. The 20-nm-thick cube-on-cube-type epitaxial films are grown on SrTiO3(001) and DyScO3(011) single-crystal substrates. The films are transparent and exhibit a significant difference between refractive indices Δn = 0.5 at photon energies below 3 eV. The energies of optical transitions are in the range of 3.15-4.30 eV and differ by 0.2-0.3 eV in these films. The observed behavior is discussed in terms of lattice strain and strain-induced ferroelectric polarization in epitaxial perovskite oxide films.
- MeSH
- organické látky chemie MeSH
- oxidy chemie MeSH
- povrchové vlastnosti MeSH
- refraktometrie MeSH
- sloučeniny vápníku chemie MeSH
- spektrální analýza MeSH
- titan chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- organické látky MeSH
- oxidy MeSH
- perovskite MeSH Prohlížeč
- sloučeniny vápníku MeSH
- titan MeSH
We experimentally characterized a birefringent side-hole microstructured fiber in the visible wavelength region. The spectral dependence of the group and phase modal birefringence was measured using the methods of spectral interferometry. The phase modal birefringence of the investigated fiber increases with wavelength, but its positive sign is opposite to the sign of the group modal birefringence. We also measured the sensing characteristics of the fiber using a method of tandem spectral interferometry. Spectral interferograms corresponding to different values of a physical parameter were processed to retrieve the spectral phase functions and to determine the spectral dependence of polarimetric sensitivity to strain, temperature and hydrostatic pressure. A negative sign of the polarimetric sensitivity was deduced from the simulation results utilizing the known modal birefringence dispersion of the fiber. Our experimental results show that the investigated fiber has a very high polarimetric sensitivity to hydrostatic pressure, reaching -200 rad x MPa(-1) x m(-1) at 750 nm.
- MeSH
- analýza selhání vybavení MeSH
- design vybavení MeSH
- dvojitý lom MeSH
- manometrie přístrojové vybavení metody MeSH
- měniče * MeSH
- poréznost MeSH
- refraktometrie přístrojové vybavení metody MeSH
- technologie optických vláken přístrojové vybavení MeSH
- testování materiálů MeSH
- tlak MeSH
- vyrobené materiály analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.
- MeSH
- analýza selhání vybavení MeSH
- design vybavení MeSH
- diamant chemie MeSH
- krystalizace MeSH
- nanočástice chemie MeSH
- nanotechnologie přístrojové vybavení MeSH
- povrchová plasmonová rezonance přístrojové vybavení MeSH
- refraktometrie přístrojové vybavení MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- diamant MeSH
In computational Fourier optics, computer generated holography, etc., coherent light propagation calculation between parallel planes is the essential task. A proper calculation discretization in the off-axis case leads to big memory demands in order to avoid aliasing errors. The proposed method typically cuts down the memory demands one hundred times. The principle of the method is based on the observation that there is a close correspondence between the reconstruction process (opposite of the sampling process) and prefiltering of the convolution kernel.
We present a concept of suppression of the influence of variations of the refractive index of air in displacement measuring interferometry. The principle is based on referencing of wavelength of the coherent laser source in atmospheric conditions instead of traditional stabilization of the optical frequency and indirect evaluation of the refractive index of air. The key advantage is in identical beam paths of the position measuring interferometers and the interferometer used for the wavelength stabilization. Design of the optical arrangement presented here to verify the concept is suitable for real interferometric position sensing in technical practice especially where a high resolution measurement within some limited range in atmospheric conditions is needed, e.g. in nanometrology.
- MeSH
- atmosféra MeSH
- design vybavení MeSH
- interferometrie přístrojové vybavení metody normy MeSH
- lasery MeSH
- nanotechnologie přístrojové vybavení metody normy MeSH
- refraktometrie přístrojové vybavení metody normy MeSH
- teoretické modely * MeSH
- vzduch * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
