Fluorescence Technique Research Articles

Spatial distribution, bioaccessibility, and human health implications of potentially toxic elements in mining-impacted topsoils in Obuasi Municipality of Ghana.

Potential toxic elements emanating from extracted ores during gold processing present occupational and unintentional health hazards in communities, the general populace, and the environment. This study investigated the concentrations and potential health effects of metal content in the topsoils of Obuasi municipality, which has been mined for gold over the past century. Surface topsoil samples, sieved to 250µm, were initially scanned for metals using x-ray fluorescence techniques, followed by confirmation via ICP-MS. In vitro bioaccessibility assays were conducted using standard methods. The geoaccumulation indices (Igeo) indicate high enrichment of As (Igeo = 6.28) and Cd (Igeo = 3.80) in the soils, especially in the eastern part of the municipality where illegal artisanal mining is prevalent. Additionally, the southern corridor, situated near a gold mine, exhibited significant levels of As and Mn. Results obtained for the total metal concentrations and contamination indices confirmed the elevation of the studied potential toxic elements in the Obuasi community. A hazard index value of 4.42 and 3.30 among children and adults, respectively, indicates that indigens, especially children, are susceptible to non-cancer health effects.

Characterization Of The Electrothermal Conversion Mechanisms Of A Plasma Actuator For Icing Control

The characterization of a new icing protection system, specifically a dielectric barrier discharge (DBD) plasma actuator, is conducted in this study. The system operates by establishing an AC high voltage between two electrodes arranged on opposite sides of a dielectric material. This setup generates a plasma on the dielectric surface, which in turn induces a significant temperature rise (about 30°C) in both the dielectric surface and the surrounding air. To gain a comprehensive understanding of the electrothermal conversion mechanisms involved in the discharge, a Planar Laser Induced Fluorescence technique is employed. Using a two-colour one-dye ratiometric method (PLIF2c1d), the technique provides measurements of the temperature evolution of an ice droplet deposited on the actuator during its melting process by the discharge. An annular actuator configuration is chosen to minimise the effect of the generated ionic wind and maintain the droplet in the discharge. A pyranine and sucrose solution is identified and temperature calibrated. The calibration process involves depositing a droplet of the solution in a temperature-controlled enclosure capable of reaching temperatures as low as -22°C. Through detailed spectral analysis, two specific detection spectral bands are selected for the imaging applications. These bands enable measurements of the ice temperature with a sensitivity of 7.61%/°C. The effects of laser light scattering by ice and fluorescence reabsorption are also investigated by varying the ice thickness. They are found to have limited influence on the fluorescence emission when the solution in ice form. Finally, the capacity of the technique is evaluated by measuring the ice temperature evolution during the melting induced by a plasma discharge. Droplets are deposited on two dielectric materials, namely PTFE and Sapphire, which possess distinct thermal and dielectric properties. Comparisons under varying plasma discharge power levels provide valuable insights into the optimization of DBD plasma actuators for effective icing protection.

Enzyme immunoassay system for serological diagnosis of hemorrhagic fever with renal syndrome based on inactivated purified Puumala virus (Hantaviridae: Orthohantavirus)

Hemorrhagic fever with renal syndrome (HFRS) is the most common zoonotic human viral disease in the Russian Federation. More than 98% of the HFRS cases are caused by Puumala orthohantavirus (PUU). Effective serological tests are required for laboratory diagnosis of HFRS. Construction of an enzyme immunoassay (ELISA) test system for detection of specific antibodies using standard antigen in the form of highly purified inactivated PUU virus as immunosorbent. Preparation of PUU virus antigen, designing the ELISA for detection of specific antibodies, developing parameters of the ELISA system, parallel titration of HFRS patients sera by fluorescent antibody technique (FAT) and the new ELISA. For the first time, ELISA based on purified inactivated PUU virus as standard antigen directly absorbed onto immunoplate was developed. Parallel titration of 50 samples from HFRS patients blood sera using FAT and the developed ELISA showed high sensitivity and specificity of this ELISA, with 100% concordance of testing results and significant level of correlation between the titers of specific antibodies in the two assays. The ELISA based on purified inactivated PUU virus as an immunosorbent can be effectively used for HFRS serological diagnosis and for mass seroepidemiological studies.

Spectral Characteristics of Water-Soluble Rhodamine Derivatives for Laser-Induced Fluorescence.

We present a comprehensive fluorescence characterization of seven water-soluble rhodamine derivatives for applications in laser-induced fluorescence (LIF)techniques. Absorption and emission spectra for these dyes are presented over the visible spectrum of wavelengths (400 to 700nm). Their fluorescence properties were also investigated as a function of temperature for LIF thermometry applications. Rhodamine 110 depicted the least fluorescence emission sensitivity to temperature at -0.11%/°C, while rhodamine B depicted the most with a -1.55%/°C. We found that the absorption spectra of these molecules are independent of temperature, supporting the notion that the temperature sensitivity of their emission only comes from changes in quantum yield with temperature. Conversely, these rhodamine fluorophores showed no change in emission intensities with pH variations and are, therefore, not suitable tracers for pH measurements. Similarly, fluorescent lifetime, which is also a property sensitive to local environmental changes in temperature, pH, and ion concentration, measurements were conducted for these fluorophores. It was found that rhodamine B and kiton red 620 have shorter fluorescence timescales compared to those of the other five rhodamine dyes, making them least suitable for applications where temporal changes in emission are monitored. Lastly, we conducted experiments to assess the physicochemical absorption characteristics of these dyes' molecules into polydimethylsiloxane (PDMS), the most common material for microfluidic devices. Rhodamine B showed the highest diffusion into PDMS substrates as compared to the other derivative dyes.

Fast, portable and sensitive detection of group B streptococcus DNA using one-pot MIRA-CRISPR system with suboptimal PAM

The group B Streptococcus (GBS) can generate vertical transmission to infants during delivery, has been seriously threatening the health of infants. Rapid and accurate prenatal GBS diagnosis for pregnant women is a deterministic blueprint to avoid infant viruses. Here, we developed an extraction-free nucleic acid isothermal amplification/CRISPR-Cas12a cutting one-pot system for GBS diagnostic assay by using suboptimal protospacer adjacent motifs, effectively avoiding multiple handling steps and uncapping contamination. The GBS diagnosis assay based on a one-pot system was validated by using fluorescent technique and lateral flow assay strips, exhibited fantastic specificity, accuracy and sensitivity with a limit of detection of 32 copies per reaction (0.64 copies/μL). Moreover, a portable device was constructed and integrated with the one-pot system to realize the GBS detection without professional and scene restrictions, it showed excellent performance in clinical sample detection, which achieved optical and portable GBS detection for point-of-care testing or home-self testing.

An ultrasensitive fluorescence sensing platform for HCV detection based on the T7 isothermal amplification combined with aggregation-induced emission luminogens strategy

Hepatitis C virus infection constitutes a significant global public health concern. Fluorescence technique (FL) is a promising biosensor, however, many conventional dyes exhibit reduced fluorescence or no emission at high concentrations. To break through this shackle, an ultrasensitive AIE-based (aggregation-induced emission) FL sensing platform was developed for HCV detection by using the FLRNAs-based T7 isothermal transcription amplification RNA diagnosis combined with AIE luminogens (FTAR) strategy. In the FTAR strategy, the T7 transcription amplification process was responsible for the recognition of the target HCV and produced Pepper aptamer, which could form aggregates of nanoparticles with the HBC, an AIEgen, to produce high-intensity FL. The multi-integrated signal amplification strategy led to ultrasensitivity. Moreover, under the optimal experimental conditions, HCV could be assayed in the range of 100aM-100pM. The proposed strategy has been successfully applied in detecting HCV in clinical samples. In summary, this research was the first to utilize aptamer restriction of AIEgens internal rotation to achieve aggregation-induced emission and presented the successful development of a specific, sensitive and rapid FTAR assay for HCV diagnosis. The proposed FTAR platform with facile operation, short analysis time, low-cost as well as excellent quantification ability could provide a promising tool for point-of-care testing (POCT).

Fluorescent labeling of micro/nanoplastics for biological applications with a focus on “true-to-life" tracking

The increased environmental presence of micro-/nanoplastics (MNPLs) and the potential health risks associated with their exposure classify them as environmental pollutants with special environmental and health concerns. Consequently, there is an urgent need to investigate the potential risks associated with secondary MNPLs. In this context, using “true-to-life” MNPLs, resulting from the laboratory degradation of plastic goods, may be a sound approach. These non-commercial secondary MNPLs must be labeled to track their presence/journeys inside cells or organisms. Because the cell internalization of MNPLs is commonly analyzed using fluorescence techniques, the use of fluorescent dyes may be a sound method to label them. Five different compounds comprising two chemical dyes (Nile Red and Rhodamine-B), one optical brightener (Opticol), and two industrial dyes (Amarillo Luminoso and iDye PolyPink) were tested to determine their potential for such applications. Using commercial standards of polystyrene nanoplastics (PSNPLs) with an average size of 170nm, different characteristics of the selected dyes such as the absence of impact on cell viability, specificity for plastic staining, no leaching, and lack of interference with other fluorochromes were analyzed. Based on the overall data obtained in the wide battery of assays performed, iDye PolyPink exhibited the most advantages, with respect to the other compounds, and was selected to effectively label “true-to-life” MNPLs. These advantages were confirmed using a proposed protocol, and labeling titanium-doped PETNPLs (obtained from the degradation of milk PET plastic bottles), as an example of “true-to-life” secondary NPLs. These results confirmed the usefulness of iDye PolyPink for labeling MNPLs and detecting cell internalization. Environmental ImplicationsEnvironmental micro-/nanoplastics (MNPLs) are emerging pollutants of special concern, and determining their potential risks is essential. Although a large dataset has been obtained using pristine nano-polystyrene, it is not considered representative of the secondary MNPLs present in the environment. Consequently, obtaining true-to-life MNPLs resulting from the laboratory degradation of plastic goods seems to be an appropriate alternative to fill this gap. Notably, the use of such noncommercial MNPLs requires labeling to confirm their cell/tissue internalization. Although different dyes have been proposed for this purpose, there is a lack of comparative studies showing the advantages and disadvantages of each dye. In this study, after using a wide variety of assays to demonstrate their advantages and disadvantages, iDye PolyPink was proposed as the most suitable dye for labeling secondary MNPLs in studies aimed at identifying their internalization. Such labeling can be used in both in vivo/in vitro models to determine potential environmental and health hazards.

Fluorescent labeling of micro/nanoplastics for biological applications with a focus on “true-to-life" tracking

The increased environmental presence of micro-/nanoplastics (MNPLs) and the potential health risks associated with their exposure classify them as environmental pollutants with special environmental and health concerns. Consequently, there is an urgent need to investigate the potential risks associated with secondary MNPLs. In this context, using “true-to-life” MNPLs, resulting from the laboratory degradation of plastic goods, may be a sound approach. These non-commercial secondary MNPLs must be labeled to track their presence/journeys inside cells or organisms. Because the cell internalization of MNPLs is commonly analyzed using fluorescence techniques, the use of fluorescent dyes may be a sound method to label them. Five different compounds comprising two chemical dyes (Nile Red and Rhodamine-B), one optical brightener (Opticol), and two industrial dyes (Amarillo Luminoso and iDye PolyPink) were tested to determine their potential for such applications. Using commercial standards of polystyrene nanoplastics (PSNPLs) with an average size of 170 nm, different characteristics of the selected dyes such as the absence of impact on cell viability, specificity for plastic staining, no leaching, and lack of interference with other fluorochromes were analyzed. Based on the overall data obtained in the wide battery of assays performed, iDye PolyPink exhibited the most advantages, with respect to the other compounds, and was selected to effectively label “true-to-life” MNPLs. These advantages were confirmed using a proposed protocol, and labeling titanium-doped PETNPLs (obtained from the degradation of milk PET plastic bottles), as an example of “true-to-life” secondary NPLs. These results confirmed the usefulness of iDye PolyPink for labeling MNPLs and detecting cell internalization.

OH radical and Cl atom initiated Reactions of Methyl n-propyl ether: Kinetics and Atmospheric Implications

Oxygenated volatile organic compounds (OVOCs) are emitted into the atmosphere via biological processes, oxidation of hydrocarbons, evaporation of oxygenated solvents or fuels and incomplete combustion of hydrocarbon-fueled sources. In the troposphere, the degradation mechanisms of these VOCs are triggered by oxidising agents like Cl atoms and OH radicals. In the present work, the kinetics were investigated for the reactions of methyl n-propyl ether (MPE) with OH radicals and Cl atoms using pulsed laser photolysis-laser induced fluorescence and relative rate techniques, respectively, in the range of 278 – 363 K. No significant temperature-dependence was observed for the reaction of MPE with OH radicals, whereas a slight negative temperature-dependence was asserted in the Cl reaction. The rate coefficients were also determined computationally at the CCSD(T)/aug-cc-pVDZ//M06-2X/6-311+G(d,p) and CCSD(T)/6-31+G(d,p)//BHandHLYP/6-31+G(d,p) level of theories over 250 – 400 K for the OH- and Cl-initiated reactions of MPE, respectively. The Arrhenius expressions for the title reactions determined are: cm3 molecule-1 s-1 and cm3 molecule-1 s-1. The rate coefficients were estimated using SAR and compared to the experimentally and computationally determined kinetic data. The products formed in the reactions were detected using the GC-MS. The atmospheric lifetimes of MPE were estimated, accounting for the rate coefficients of both reactions. The impacts of MPE emissions on the atmosphere are discussed using important atmospheric parameters.

Radiation shielding parameterizations of FeSO4, CuSO4, NiSO4 and ZnSO4 Compounds: using (XRF) technique & Monte Carlo FLUKA approach

The mass attenuation coefficient (MAC) for different sulphate compounds can be estimated by using the Energy Dispersive X-ray Fluorescence (EDXRF), also known as X-ray Fluorescence (XRF) technique. The X-ray photons emitted have different energies depending on incident photon energy, atomic weight, and molecular structure of tested material. The excitation energy of the gamma rays source with 59.53 keV was obtained by using 241Am (40 µci). The (MAC) for sulphate compounds of a different element (Fe, Ni, Cu, Zn) have been calculated by measuring the intensity difference for kα in pure elements and their compounds. The determined results showed that the maximum value for (µm) was in FeSO4. These results are consistent with the theoretical value obtained by the XCOM software in addition to investigating the wide energy response of photon interaction with the introduced compounds using the FLUKA Monte Carlo simulation software. The mass attenuation coefficient (MAC) of these compounds is numerically evaluated in the energy range 0.015-15 MeV using the FLAIR code. The computed (µm) is used to generate significant radiation protection factors such as the linear attenuation coefficient (LAC), half-layer value (HVL), effective (Zeff), and equivalent (Zeq) atomic number. For studying the shielding effectiveness and efficiency, for fast and thermal neutron radiation, the removal cross-section ƩR was given.

“Hearts of gold” (Cuori d'oro): The case study of the leather corami of Palazzo Chigi in Ariccia

In this work we present the results obtained by different technical analysis in order to perform the characterization of the chromatic richness, the employed materials and the iconographic elements of different fragments of decorated and gilded leather corami coming from the archive of Palazzo Chigi of Ariccia (Rome) and employed, during the 17th century, as wallcoverings. Different microscopic and spectroscopic analyses have been performed by means of Ion Beam Analysis (IBA) and Macro Area X-Ray Fluorescence (MA-XRF) techniques available at the INFN LABEC ion beam laboratory in Florence and the Scanning Electron Microscopy-Energy Dispersive X-ray Analysis (SEM-EDX) of the Superconductivity Laboratory of the ENEA Frascati Research Center. The results aim to provide the scholar information about the manufacturing process and the materials employed for the production of these peculiar artefacts, also in order to plan the best and most appropriate conservation protocol. In particular, thanks to the SEM-EDX analysis it has been possible to characterize the layered structure of the samples and, specifically, the interface between the leather of the substrate, the metal foil of the so called meccatura and between these and the overlying pictorial layer. The IBA and MA-XRF techniques has helped in characterizing the painting palette employed while IBA has allowed to determine the conservation condition of the silver layer with the hypothesis of the incorporation of the silver leaf into the organic compound of the mecca as its main deterioration phenomena. These complementary techniques provide, therefore, a comprehensive understanding of the materials and iconographic elements of these leather-based artefacts, which is essential for their preservation and restoration as well as they contribute to a better understanding of the deterioration processes they incur.

A hydrogel sensor based on cellulose nanofiber/polyvinyl alcohol with colorimetric-fluorescent bimodality for non-invasive detection of urea in sweat

The concentration of urea in sweat serves as a valuable indicator of an individual's overall health. In this study, we present a novel hydrogel sensor (BAF-CPu), based on cellulose nanofiber and polyvinyl alcohol, designed to achieve non-invasive in situ and highly sensitive detection of urea in sweat by combining the dual-mode response of colorimetric and ratiometric fluorescence techniques. The bright red fluorescent gold‑copper bimetallic nanoclusters and green fluorescent fluorescein isothiocyanate-modified cellulose nanofibers endowed BAF-CPu with proportional fluorescence responsive properties. Under the catalytic action of urease, the hydrolysis of urea raises the pH, resulting in diminished red fluorescence along with enhanced green fluorescence, and the fluorescence color of BAF-CPu changes from red to green. Moreover, BAF-CPu hydrogel encapsulates pH-responsive bromothymol blue (BTB), which changes from yellow to blue in the presence of urea. Importantly, BAF-CPu absorbs sweat by adhering directly to the skin surface, avoiding the complicated sampling process and improving the maneuverability of the detection process. With both ratiometric fluorescence and colorimetric modes, BAF-CPu is not only able to detect sweat in situ, but also can reduce the interference of the complex sweat environment on the urea detection, and realize the high sensitivity detection of urea in sweat.

Dieback of royal poinciana (Delonix regia) trees induced by Alternaria tenuissima and its impact on photochemical efficiency of Photosystem II.

In Hafr Al Batin, Saudi Arabia, poinciana (Delonix regia) trees are afflicted by dieback disease, manifesting symptoms that can lead to complete defoliation and, ultimately, the demise of trees in advanced stages. To investigate the dieback symptoms, samples were collected from branches at the transition zone, subjected to surface sterilization, and then plated onto potato dextrose agar. Identification of fungal isolates involved the assessment of colony and spore morphology, as well as PCR amplification and sequencing of the internal transcribed spacer (ITS) gene regions. The predominant fungus isolated was Alternaria tenuissima. Confirming its pathogenicity to poinciana plants, detached stems and decapitated mature plants were inoculated with this fungus. Chlorophyll a fluorescence quenching and polyphasic fluorescence induction kinetics were conducted to assess the photochemical and nonphotochemical processes of Photosystem II (PSII) in stem barks affected by dieback. The dieback disease significantly reduced chlorophyll content, potentially hindering PSII performance in terms of maximum photochemical efficiency, quantum yield, electron flux, and photoprotection. These findings suggest that compromised photochemistry and photoprotection render poinciana trees inoculated by dieback less efficient in utilizing light energy and more susceptible to photoinhibition. Additionally, this study implies the use of non-invasive chlorophyll fluorescence techniques as a phenotyping tool for assessing photoprotective and photoinhibitory responses of stems to dieback stress.

FLUORESCENT DIAGNOSTIC METHOD AS A TOOL FOR COMPREHENSIVE EVALUATION OF THE HYGIENE OF NATURAL TEETH AND FIXED DENTAL PROSTHESIS CONSTRUCTIONS

This study focuses on the critical need for an oral care, especially when using fixed bridge prostheses. The analysis and impact of insufficient care for oral hygiene on the development of dental diseases and the need to develop effective methods for its assessment have been carried out. The research consists of the improvement of fluorescent diagnostics in orthopedic dentistry, as well as, in the development of an index for the assessment of the hygiene of natural teeth and fixed denture structures based on an in vivo experiment. This aims to improve the diagnosis of the condition of the oral cavity in patients with fixed prostheses, contributing to the improvement of the quality of their orthopedic treatment. Materials and methods: The use of fluorescent diagnostics with Rhodamine G dye allows to identify the presence of dental deposits under the influence of ultraviolet light. The technique involves treating teeth and dentures with a solution that enhances the visibility of dental plaque under ultraviolet light. Research results: The obtained research data confirm the high efficiency of the fluorescent technique in the detection of dental deposits, both on natural teeth and on the surfaces of fixed prostheses. Digital analysis allows you to visualize the specific graphic characteristics of the biofilm, which facilitates the adaptation of an individual approach. Conclusions: The conducted study demonstrates that the improved fluorescent method was extremely effective in determining the state of oral hygiene, effective both for the analysis of natural teeth and fixed prostheses. The proposed method allows you to determine the hygienic condition in detail, makes a significant contribution to the prevention of dental diseases and improves the optimization of medical interventions. The technique is easy to use, and the corresponding software is available for dentists. Further expansion of observations for the use of this technique in patients with a different orthopedic spectrum of needs is expected.

Exoscopic versus Microscopic Surgery in 5-ALA-Guided Resection of High-Grade Gliomas.

Background: Glioma surgery has been remarkably enhanced in the past 2 decades, with improved safety and limited but improved life expectations. The fluorescence-guided resection of high-grade gliomas (HGGs) plays a central role in this sense, allowing a greater extent of resection (EOR). The introduction of exoscopic-guided surgery may be considered in implementing fluorescence techniques over traditional microscopes. We present the application and the advantages of exoscopic-guided surgery compared to microscopic surgery in tumor resection guided by 5-ALA fluorescence in patients with HGGs. Methods: Ten consecutive patients underwent surgery for HGG resection. The surgery was performed via an exoscopic-guided procedure (Olympus ORBEYE) and after the oral administration of Gliolan 5 h before the procedure. During surgery, the procedure shifted to using a microscopic (Kinevo 900, Zeiss) view. The intensity of the fluorescence under the two different procedures was subjectively measured in different picture samples during the surgery on a 1 to 5 (from minimum to maximum) scale. The brightness of the surgical field and the detailing of the anatomy were also analyzed comparatively. Results: Among the ten patients, the histopathological diagnosis was an high-grade glioma in all cases. In nine cases, it was possible to achieve gross total resection. There was no perioperative mortality. The median fluorescence intensity, on a scale of 1-5, was 4.5 in the exoscope group and 3.5 in the microscope group (p < 0.01). Conclusions: The exoscopic-guided surgery adds advantages to traditional fluorescence-guided surgery with 5-aminolevulinic acid. Beyond the important advantage of low cost and the possibility to perform collaborative surgeries, it adds a plain and continuous visualization of the tumor and offers advantages in the surgical field of fluorescence-guided glioma surgery compared to the microscopic-guided one.

Insulin amyloid fibril formation reduction by tripeptide stereoisomers.

Insulin fibrillation is a problem for diabetic patients that can occur during storage and transport, as well as at the subcutaneous injection site, with loss of bioactivity, inflammation, and various adverse effects. Tripeptides are ideal additives to stabilise insulin formulations, thanks to their low cost of production and inherent cytocompatibility. In this work, we analysed the ability of eight tripeptide stereoisomers to inhibit the fibrillation of human insulin in vitro. The sequences contain proline as β-breaker and Phe-Phe as binding motif for the amyloid-prone aromatic triplet found in insulin. Experimental data based on spectroscopy, fluorescence, microscopy, and calorimetric techniques reveal that one stereoisomer is a more effective inhibitor than the others, and cell live/dead assays confirmed its high cytocompatibility. Importantly, in silico data revealed the key regions of insulin engaged in the interaction with this tripeptide, rationalising the molecular mechanism behind insulin fibril formation reduction.

Multimodal 2D and 3D microscopic mapping of growth cartilage by computational imaging techniques – a short review including new research

Being able to image the microstructure of growth cartilage is important for understanding the onset and progression of diseases such as osteochondrosis and osteoarthritis, as well as for developing new treatments and implants. Studies of cartilage using conventional optical brightfield microscopy rely heavily on histological staining, where the added chemicals provide tissue-specific colours. Other microscopy contrast mechanisms include polarization, phase- and scattering contrast, enabling non-stained or ‘label-free’ imaging that significantly simplifies the sample preparation, thereby also reducing the risk of artefacts. Traditional high-performance microscopes tend to be both bulky and expensive. Computational imaging denotes a range of techniques where computers with dedicated algorithms are used as an integral part of the image formation process. Computational imaging offers many advantages like 3D measurements, aberration correction and quantitative phase contrast, often combined with comparably cheap and compact hardware. X-ray microscopy is also progressing rapidly, in certain ways trailing the development of optical microscopy. In this study, we first briefly review the structures of growth cartilage and relevant microscopy characterization techniques, with an emphasis on Fourier ptychographic microscopy (FPM) and advanced x-ray microscopies. We next demonstrate with our own results computational imaging through FPM and compare the images with hematoxylin eosin and saffron (HES)-stained histology. Zernike phase contrast, and the nonlinear optical microscopy techniques of second harmonic generation (SHG) and two-photon excitation fluorescence (TPEF) are explored. Furthermore, X-ray attenuation-, phase- and diffraction-contrast computed tomography (CT) images of the very same sample are presented for comparisons. Future perspectives on the links to artificial intelligence, dynamic studies and in vivo possibilities conclude the article.

Dibenzothiophene Bridged Bis‐Bodipy and Bis‐Metal Dipyrrin Complexes

AbstractDibenzothiophene (DBT) bridged bis‐dipyrromethane was synthesized by treating readily available 4,6‐di(p‐formylphenyl) dibenzothophene with pyrrole under acid catalyzed conditions. The DBT bridged bis‐dipyrromethane was further oxidized with DDQ to afford the DBT bridged bis‐dipyrrin which was used as a ligand to prepare DBT bridged bis‐BODIPY, bis‐Ni(II) dipyrrin and bis‐Pd(II) dipyrrin complexes by treating the ligand with BF3 ⋅ Et2O, Ni(acac)2 and Pd(acac)2 respectively under mild reaction conditions. The DBT‐bridged bis‐BODIPY and bis‐metal dipyrrin complexes were thoroughly characterized and studied by HR‐MS, 1D &amp; 2D NMR, absorption, fluorescence, cyclic voltammetry and DFT techniques. The bis‐BODIPY and bis‐Pd(II) dipyrrin showed highly intense absorption band at ~500 nm along with one low intense absorption band at 340 nm whereas the bis‐Ni(II) dipyrrin complex showed slightly broadened blue shifted high intense band at 490 nm along with one additional band at 426 nm. The bis‐BODIPY was fluorescent with fluorescence band at 524 nm and quantum yield of 0.031 whereas bis‐M(II) dipyrrin complexes were nonfluorescent. DFT optimized structures revealed that the BODIPY units are more planar with the dibenzophene moiety in bis‐BODIPY with an angle of ∼5.68°. However, in 3‐Pd and 3‐Ni, the M(II)‐dipyrrin units are much more deviated from the dibenzothiophene plane with an angle of 12.81°–14.23°.

Chromogenic recognition of Cr(III) and Cu(II) using a novel Schiff base and “turn-on” fluorescent detection of CO32− by its reduced scaffold in aqueous media

An upsurge of severe toxic inorganic ionic species in water arising due to anthropogenic activities, has caused global concern and detection of such harmful contaminants is a matter of supreme importance. In this regard, a novel trans-1,2-diaminocyclohexane containing Schiff base N,N′-di(4-acetamidophenylmethylene)-1,2-cyclohexanediamine (1) and its reduced scaffold N,N’-di(4-acetamidophenylmethyl)-1,2-cyclohexanediamine (2) have been synthesized and characterized by FT-IR and 1H & 13C-NMR while the structures of both 1 and 2 have been determined by X-ray single crystal diffraction analysis. The detection response of 1 and 2 have been investigated toward same set of analytes and found to be entirely different both in absorption and emission studies. Compound 1 selectively and very sensitively detects Cr3+ and Cu2+via hydrolytic rupture of >C=N- bond as indicated by ratiometric change and emergence of an isosbestic point in UV-vis analysis. Further, the kinetic studies clearly suggested rapid hydrolysis of 1 (< 3.0 mins) in the presence of Cr3+ whereas it requires ∼1.0 h for complete hydrolysis with Cu2+. In contrast, the recognition of Cr3+ and Cu2+ not be observed through fluorescence technique. Moreover, 2 remains silent toward Cr3+/Cu2+ in UV-vis analysis, however, it selectively recognizes CO32− through ‘turn-on’ fluorescence output in the background presence of several tested cations and anions. Job's plot and mass analysis suggested 1:2 (CO32−: 2) binding stoichiometry between CO32− and 2. Remarkably, the present findings demonstrate entirely different functionality of a Schiff base and its reduced form in presence of same analytes. The main objective of this report is to illustrate that how a subtle structural change of a molecule governs the analyte detection ability.

Does dental material type influence bacterial adhesion under the same polishing conditions? Direct observation using a fluorescent staining technique: An in vitro study.

Highly polished 3, 4, and 5 mol% yttria-stabilized zirconia and CAD/CAM composite resin samples were prepared, and the influence of surface roughness (Ra and Sa, 21 areas/group), wettability (contact angle and surface energy, 3 samples/group), and surface chemical composition (2 samples/group) on single-strain bacterial adhesion models (Porphyromonas gingivalis, Streptococcus oralis, Streptococcus sanguinis, Streptococcus gordonii, and Streptococcus mutans) were compared via fluorescent staining with graphical analysis (21 areas/group). Statistical analysis was performed using the Shapiro-Wilk test followed by one-way analysis of variance with Tukey's test or the Kruskal-Wallis test with Dunn's test (α=0.05) and linear regression. For dental zirconia with the same surface roughness, the yttria content did not significantly influence the initial bacterial adhesion. However, higher bacterial adhesion was detected for the composite resin owing to its high C, O, and Si contents. There was no correlation between surface energy and bacterial adhesion for any bacterial strain (p<0.005).