Translucency and Color Stability of a Simplified Shade Nanohybrid Composite after Ultrasonic Scaling and Air-Powder Polishing

We aimed to assess the influence of professional dental prophylaxis on the translucency and color stability of a novel simplified shade nanohybrid composite material. Sixty composite disks (5 mm in diameter and 2 mm thick) of light (n = 30) and dark (n = 30) shades were prepared. The specimens were randomly divided into the following three groups (n = 10) according to the prophylaxis procedure used: ultrasonic scaling, air-powder polishing with sodium bicarbonate, and controls. The specimens were submitted to translucency and color analysis based on the CIELab system. Two measurements were performed before and after 48-h storage in coffee. Translucency values of untreated light and dark specimens were 9.15 ± 0.38 and 5.28 ± 1.10, respectively. Airpowder polishing decreased the translucency of the light composite specimens. Storage in coffee resulted in color changes (∆E) ranging between 2.69 and 12.05 and a mean translucency decrease ranging between −0.88 and −6.91. The samples in the light group tended to exhibit greater staining; the treatment method had no effect on ∆E. It can be concluded that light-shade composite restorations are more prone to translucency and color changes resulting from air-powder polishing and contact with staining media. However, further research using other composites and powders is required

Label-free characterization of white blood cells using fluorescence lifetime imaging and flow-cytometry: molecular heterogeneity and erythrophagocytosis [Invited]

Article reporting the results of blood cell characterization using label-free fluorescence imaging techniques and flow-cytometry. Autofluorescence parameters of different cell types – white blood cells, red blood cells, erythrophagocytic cells – are assessed and analyzed in terms of molecular heterogeneity and possibilities of differentiation between different cell types in vitro and in vivo

Single-Fiber Diffuse Reflectance Spectroscopy and Spatial Frequency Domain Imaging in Surgery Guidance: A Study on Optical Phantoms

Diffuse reflectance spectroscopy (DRS) and imaging are increasingly being used in surgical guidance for tumor margin detection during endoscopic operations. However, the accuracy of the boundary detection with optical techniques may depend on the acquisition parameters, and its evaluation is in high demand. In this work, using optical phantoms with homogeneous and heterogeneous distribution of chromophores mimicking normal and pathological bladder tissues, the accuracy of tumor margin detection using single-fiber diffuse reflectance spectroscopy and spatial frequency domain imaging was evaluated. We also showed how the diffuse reflectance response obtained at different spatial frequencies with the spatial frequency domain imaging technique could be used not only to quantitatively map absorption and scattering coefficients of normal tissues and tumor-like heterogeneities but also to estimate the tumor depth localization. The demonstrated results could be helpful for proper analysis of the DRS data measured in vivo and for translation of optical techniques for tumor margin detection to clinics

Assessment of the Europium(III) Binding Sites on Albumin Using Fluorescence Spectroscopy

Intrinsic fluorescence quenching of bovine serum albumin (BSA) and europium­(III) luminescence in BSA complexes were investigated. The number of BSA binding sites (<i>n</i>) and equilibrium constant (<i>K</i>_eq) values were determined from both measurements provided qualitatively different results. While the modified Stern–Volmer relation for BSA fluorescence quenching gave <i>n</i> = 1 at pH 4.5 and pH 6, two sets of binding sites were determined from Eu³⁺ luminescence with <i>n</i>₁ = 2, <i>n</i>₂ = 4 at pH 6 and <i>n</i>₁ = 1, <i>n</i>₂ = 2 at pH 4.5. The model explaining the discrepancy between the results obtained by these fluorescent approaches was suggested, and the limitations in application of the “log–log” Stern–Volmer plots in analysis of binding processes were discussed

Probing Red Blood Cell Membrane Microviscosity Using Fluorescence Anisotropy Decay Curves of the Lipophilic Dye PKH26

Red blood cell (RBC) aggregation and deformation are governed by the molecular processes occurring on the membrane. Since several social important diseases are accompanied by alterations in RBC aggregation and deformability, it is important to develop a diagnostic parameter of RBC membrane structural integrity and stability. In this work, we propose membrane microviscosity assessed by time-resolved fluorescence anisotropy of the lipophilic PKH26 fluorescent probe as a diagnostic parameter. We measured the fluorescence decay curves of the PKH26 probe in the RBC membrane to establish the optimal parameters of the developed fluorescence assay. We observed a complex biphasic profile of the fluorescence anisotropy decay characterized by two correlation times corresponding to the rotational diffusion of free PKH26, and membrane-bounded molecules of the probe. The developed assay allowed us to estimate membrane microviscosity &eta;m in the range of 100&ndash;500 cP depending on the temperature, which paves the way for assessing RBC membrane properties in clinical applications as predictors of blood microrheological abnormalities

Pericapillary Edema Assessment by Means of the Nailfold Capillaroscopy and Laser Scanning Microscopy

Edema, i.e., fluid accumulation in the interstitial space, accompanies numerous pathological states of the human organism, including heart failure (HF), inflammatory response, and lymphedema. Nevertheless, techniques for quantitative assessment of the edema&rsquo;s severity and dynamics are absent in clinical practice, and the analysis is mainly limited to physical examination. This fact stimulates the development of novel methods for fast and reliable diagnostics of fluid retention in tissues. In this work, we focused on the possibilities of two microscopic techniques, nailfold video capillaroscopy (NVC) and confocal laser scanning microscopy (CLSM), in the assessment of the short-term and long-term cutaneous edema. We showed that for the patients with HF, morphological parameters obtained by NVC&mdash;namely, the apical diameter of capillaries and the size of the perivascular zone&mdash;indicate long-term edema. On the other hand, for healthy volunteers, the application of two models of short-term edema, venous occlusion, and histamine treatment of the skin, did not reveal notable changes in the capillary parameters. However, a significant reduction of the NVC image sharpness was observed in this case, which was suggested to be due to water accumulation in the epidermis. To verify these findings, we made use of CLSM, which provides the skin structure with cellular resolution. It was observed that for the histamine-treated skin, the areas of the dermal papillae become hyporefractive, leading to the loss of contrast and the lower visibility of capillaries. Similar effect was observed for patients undergoing infusion therapy. Collectively, our results reveal the parameters can be used for pericapillary edema assessment using the NVC and CLSM, and paves the way for their application in a clinical set-up

Fluorescence Lifetime and Intensity of Thioflavin T as Reporters of Different Fibrillation Stages: Insights Obtained from Fluorescence Up-Conversion and Particle Size Distribution Measurements

Thioflavin T (ThT) assay is extensively used for studying fibrillation kinetics in vitro. However, the differences in the time course of ThT fluorescence intensity and lifetime and other physical parameters of the system, such as particle size distribution, raise questions about the correct interpretation of the aggregation kinetics. In this work, we focused on the investigation of the mechanisms, which underlay the difference in sensitivity of ThT fluorescence intensity and lifetime to the formation of protein aggregates during fibrillation by the example of insulin and during binding to globular proteins. The assessment of aggregate sizes and heterogeneity was performed using dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Using the sub-nanosecond resolution measurements, it was shown that the ThT lifetime is sensitive to the appearance of as much as a few percent of ThT bound to the high-affinity sites that occur simultaneously with an abrupt increase of the average particle size, particles concentration, and size heterogeneity. The discrepancy between ThT fluorescence intensity and a lifetime can be explained as the consequence of a ThT molecule fraction with ultrafast decay and weak fluorescence. These ThT molecules can only be detected using time-resolved fluorescence measurements in the sub-picosecond time domain. The presence of a bound ThT subpopulation with similar photophysical properties was also demonstrated for globular proteins that were attributed to non-specifically bound ThT molecules with a non-rigid microenvironment

First 24-Membered Macrocyclic 1,10-Phenanthroline-2,9-Diamides—An Efficient Switch from Acidic to Alkaline Extraction of <i>f</i>-Elements

A reaction of acyl chlorides derived from 1,10-phenanthroline-2,9-dicarboxylic acids with piperazine allows the preparation of the corresponding 24-membered macrocycles in good yield. The structural and spectral properties of these new macrocyclic ligands were thoroughly investigated, revealing promising coordination properties towards f-elements (Am, Eu). It was shown that the prepared ligands can be used for selective extraction of Am(III) from alkaline–carbonate media in presence of Eu(III) with an SFAm/Eu up to 40. Their extraction efficiency is higher than calixarene-type extraction of the Am(III) and Eu(III) pair. Composition of macrocycle–metal complex with Eu(III) was investigated by luminescence and UV-vis spectroscopy. The possibility of such ligands to form complexes of L:Eu = 1:2 stoichiometry is revealed