Search

The current research highlighted the usage of serpentine clay to remove Nile red dye from an aqueous solution. At first serpentine clay minerals were analyzed by various analytical techniques like Fourier transform infrared spectroscopy (FTIR), X ray diffraction (XRD), and thermal gravimetric analysis (TGA) analysis. From the characterization results it was found that the clay was determined to be a separate group. Sorption studies investigated the impacts of adsorbent dosage, initial pH, initial dye concentration, and temperature on Nile red color elimination. From the test results it was found that the capacity of adsorption was seen to increase from 32.4 mg/g to a high value of 43.8 mg/g by raising the pH value from 2 to 6. Adsorption on serpentine clay decreased from 234.7 to 33.2 mg/g due to an increase in the adsorbent dosage. The removal capacity of Nile red dye increased from 12.2% to 88.5% with the rise in the adsorbent dosage. This rise in the Nile red dye removal may be observed due to the increase in the area as well as the pore volume of the surface. Experimental study was carried out to study the effect of initial concentration of adsorbate on adsorption at a pH of 6, adsorbent dosage of 3 g/L, and at a temperature of 28°C. The removal efficiency of the Nile red dye was reduced from 96.7% to 42.6%. To determine the temperature effect on the removal of Nile red dye by the clay, the initial pH value was set to 6, and the temperature was set at 28, 38, 48, and 58°C. Without reaching the equilibrium conditions, at a time of 30 min, the removal efficiency of dye rises from 60% to 81% due to the temperature rise. The experimental findings indicated that the adsorption of the dye on the clay followed the "Langmuir adsorption" isotherm rather than the Freundlich adsorption isotherm. Adsorption on clay minerals follows the pseudo‐second‐order adsorption kinetics compared to pseudo‐first‐order adsorption kinetics. [ABSTRACT FROM AUTHOR]

The outcomes of DFT‐based calculations are here reported to assess the applicability of two synthesized polypyridyl Ru(II) complexes, bearing ethynyl nile red (NR) on a bpy ligand, and two analogues, bearing modified‐NR, in photodynamic therapy. The absorption spectra, together with the non‐radiative rate constants for the S1 – Tn intersystem crossing transitions, have been computed for this purpose. Calculations evidence that the structural modification on the chromophore destabilizes the HOMO of the complexes thus reducing the H‐L gap and, consequently, red shifting the maximum absorption wavelength within the therapeutic window, up to 620 nm. Moreover, the favored ISC process from the bright state involves the triplet state closest in energy, which is also characterized by the highest SOC value and by the involvement of the whole bpy ligand bearing the chromophore in delocalising the unpaired electrons. These outcomes show that the photophysical behavior of the complexes is dominated by the chromophore. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have emerged as viable alternatives to toxic organic solvents. The most intriguing aspect of these solvents is perhaps the widely varying physicochemical properties emerging from the changes in the constituents that form DESs along with their composition. Based on the constituents, a DES can be hydrophilic/polar or hydrophobic/non-polar, rendering a vastly varying spectrum of polarity a possibility. DESs formed by mixing urea (U) with hydrated lanthanide salts, lanthanum nitrate hexahydrate (La : U), cerium nitrate hexahydrate (Ce : U), and gadolinium nitrate hexahydrate (Gd : U), respectively, exhibit very high polarity as manifested via the probe-reported empirical parameters of dipolarity/polarizability (π*). The highest π* of 1.70 exhibited by the DES (Gd : U) in a 1 : 2 molar ratio is unprecedented. The π* ranges from 1.50 to 1.70 for these DESs, which is almost the highest reported for any solvent system. The π* decreases with an increasing amount of urea in the DES; however, the anomalous trends in H-bond donating acidity (α) and H-bond accepting basicity (β) appear to be due to the hydrated water of the lanthanide salt. The emission band maxima of the fluorescence probe of the "effective" dielectric constant (εeff) of the solubilizing media, pyrene-1-carboxaldehyde (PyCHO), in salt-rich DESs reflect higher cybotactic region dipolarity than that offered by water. Probe Nile red aggregates readily in these DESs to form non-fluorescent H-aggregates, which is a characteristic of highly polar solvents. The behavior of probe pyranine also corroborates these outcomes as the (lanthanide salt : urea) DES system supports the formation of the deprotonated form of the probe in the excited state. The (lanthanide salt : urea) DES system offers solubilizing media of exceptionally high polarity, which is bound to expand their application potential. [ABSTRACT FROM AUTHOR]

Polymer microgels are swollen macromolecular networks with a typical size of hundred of nanometers to several microns that show an extraordinary open and responsive architecture to different external stimuli, being therefore important candidates for nanobiotechnology and nanomedical applications such as biocatalysis, sensing and drug delivery. It is therefore crucial to understand the delicate balance of physical-chemical interactions between the polymer backbone and solvent molecules that to a high extent determine their responsivity. In particular, the co-nonsolvency effect of poly(N -isopropylacrylamide) in aqueous alcohols is highly discussed, and there is a disagreement between molecular dynamics (MD) simulations (from literature) of the preferential adsorption of alcohol on the polymer chains and the values obtained by several empirical methods that mostly probe the bulk solvent properties. It is our contention that the most efficacious method for addressing this problem requires a nanoscopic method that can be combined with spectroscopy and record fluorescence spectra and super-resolved fluorescence lifetime images of microgels labeled covalently with the solvatochromic dye Nile Red. By employing this approach, we could simultaneously resolve the structure of sub-micron size objects in the swollen and in the collapsed state and estimate the solvent composition inside of them in ▪–▪ mixtures for two very different polymer architectures. We found an outstanding agreement between the MD simulations and our results that estimate a co-solvent molar fraction excess of approximately 3 with a very flat profile in the lateral direction of the microgel.   • STED-FLIM resolves the structure and solvent composition in submicron-sized PNIPAM microgels in methanol-water mixtures. • Our methodology allows us to measure the distribution of protic solvents in complex liquid mixtures without the need of any calibration. • We found an outstanding agreement between our FLIM results and MD simulations (from literature) for the molar fraction excess of methanol. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) have emerged as viable alternatives to toxic organic solvents. The most intriguing aspect of these solvents is perhaps the widely varying physicochemical properties emerging from the changes in the constituents that form DESs along with their composition. Based on the constituents, a DES can be hydrophilic/polar or hydrophobic/non-polar, rendering a vastly varying spectrum of polarity a possibility. DESs formed by mixing urea (U) with hydrated lanthanide salts, lanthanum nitrate hexahydrate (La : U), cerium nitrate hexahydrate (Ce : U), and gadolinium nitrate hexahydrate (Gd : U), respectively, exhibit very high polarity as manifested via the probe-reported empirical parameters of dipolarity/polarizability (π*). The highest π* of 1.70 exhibited by the DES (Gd : U) in a 1 : 2 molar ratio is unprecedented. The π* ranges from 1.50 to 1.70 for these DESs, which is almost the highest reported for any solvent system. The π* decreases with an increasing amount of urea in the DES; however, the anomalous trends in H-bond donating acidity (α) and H-bond accepting basicity (β) appear to be due to the hydrated water of the lanthanide salt. The emission band maxima of the fluorescence probe of the “effective” dielectric constant (εeff) of the solubilizing media, pyrene-1-carboxaldehyde (PyCHO), in salt-rich DESs reflect higher cybotactic region dipolarity than that offered by water. Probe Nile red aggregates readily in these DESs to form non-fluorescent H-aggregates, which is a characteristic of highly polar solvents. The behavior of probe pyranine also corroborates these outcomes as the (lanthanide salt : urea) DES system supports the formation of the deprotonated form of the probe in the excited state. The (lanthanide salt : urea) DES system offers solubilizing media of exceptionally high polarity, which is bound to expand their application potential.

Abstract Infrastructure is often a limiting factor in microplastics research impacting the production of scientific outputs and monitoring data. International projects are therefore required to promote collaboration and development of national and regional scientific hubs. The Commonwealth Litter Programme and the Ocean Country Partnership Programme were developed to support Global South countries to take actions on plastics entering the oceans. An international laboratory network was developed to provide the infrastructure and in country capacity to conduct the collection and processing of microplastics in environmental samples. The laboratory network was also extended to include a network developed by the University of East Anglia, UK. All the laboratories were provided with similar equipment for the collection, processing and analysis of microplastics in environmental samples. Harmonised protocols and training were also provided in country during laboratory setup to ensure comparability of quality-controlled outputs between laboratories. Such large networks are needed to produce comparable baseline and monitoring assessments.

Microplastics (MPs), typically defined as plastic fragments smaller than 5 mm, are pervasive in terrestrial and marine ecosystems. There is a need for rapid, portable, low-cost detection systems to assess health and environmental risks. Fluorescent tagging with Nile Red (NR) has emerged as a popular detection method, but variations in fluorescent emissions based on NR solvent, plastic polymer, excitation wavelength, and additives complicate standardization. In this study, seven plastic samples stained with acetone-based NR were analyzed using a fluorescent spectrometer to identify optimal emission peaks across UV-Vis excitation wavelengths. These findings aid in selecting appropriate excitation wavelengths and optical filters for future detection systems. Additionally, a straightforward polymer identification scheme was validated against field-collected plastic samples, whose material composition was confirmed via Fourier Transform Infrared Spectroscopy. This work contributes towards developing accessible microplastic detection technologies by characterizing the fluorescent properties of NR-stained plastics and enhancing the capability for effective environmental monitoring. Future research will expand the dataset to include diverse plastics with varying additives and weathering, and incorporate computer-vision tools for automated data processing and polymer identification. [ABSTRACT FROM AUTHOR]

Caenorhabditis elegans was recently shown to be a powerful model for studying and identifying probiotics with specific functions. Lactobacillus acidophilus CL1285, Lacticaseibacillus casei LBC80R, and Lacticaseibacillus rhamnosus CLR2, which are three bacteria that were marketed by Bio-K+, were evaluated using the nematode C. elegans to study fat accumulation, lifespan, and resistance to oxidative stress. Although the general effects of probiotics in terms of protection against oxidative stress were highlighted, the CL1285 strain had an interesting and specific feature, namely its ability to prevent fat accumulation in nematodes; this effect was verified by both the Oil Red and Nile Red methods. This observed phenotype requires daf-16 and is affected by glucose levels. In addition, in a daf-16- and glucose-dependent manner, CL1285 extended the lifespan of C. elegans; this effect was unique to CL1285 and not found in the other L. acidophilus subtypes in this study. Our findings indicate that L. acidophilus CL1285 impacts fat/glucose metabolism in C. elegans and provides a basis to further study this probiotic, which could have potential health benefits in humans and/or in mammals. [ABSTRACT FROM AUTHOR]

Ultrastructural studies of contusive spinal cord injury (SCI) in mammals have shown that the most prominent acute changes in white matter are periaxonal swelling and separation of myelin away from their axon, axonal swelling, and axonal spheroid formation. However, the underlying cellular and molecular mechanisms that cause periaxonal swelling and the functional consequences are poorly understood. We hypothesized that periaxonal swelling and loss of connectivity between the axo-myelinic interface impedes neurological recovery by disrupting conduction velocity, and glial to axonal trophic support resulting in axonal swelling and spheroid formation. Utilizing in vivo longitudinal imaging of Thy1YFP+ axons and myelin labeled with Nile red, we reveal that periaxonal swelling significantly increases acutely following a contusive SCI (T13, 30 kdyn, IH Impactor) versus baseline recordings (laminectomy only) and often precedes axonal spheroid formation. In addition, using longitudinal imaging to determine the fate of myelinated fibers acutely after SCI, we show that ∼73% of myelinated fibers present with periaxonal swelling at 1 h post SCI and ∼ 51% of those fibers transition to axonal spheroids by 4 h post SCI. Next, we assessed whether cation-chloride cotransporters present within the internode contributed to periaxonal swelling and whether their modulation would increase white matter sparing and improve neurological recovery following a moderate contusive SCI (T9, 50 kdyn). Mechanistically, activation of the cation-chloride cotransporter KCC2 did not improve neurological recovery and acute axonal survival, but did improve chronic tissue sparing. In distinction, the NKKC1 antagonist bumetanide improved neurological recovery, tissue sparing, and axonal survival, in part through preventing periaxonal swelling and disruption of the axo-myelinic interface. Collectively, these data reveal a novel neuroprotective target to prevent periaxonal swelling and improve neurological recovery after SCI.

Abstract The ubiquitous presence of plastic brought on by the extensive use of plastic products calls for efficient and rapid plastic detection methods to detect and evaluate pollution. The commonly used Nile red dye takes many hours and is expensive while also not equally efficient across all the common plastic waste. To address this, we investigated the staining efficiency and optimized the ratio of a combined Coomassie brilliant blue and Methylene blue dye. In the optimisation process, Methanol-based Coomassie and Methylene blue dyes effectively stained the Polyethylene Terephthalate (PET), Polypropylene (PP), Polystyrene (PS), Linear Low-Density Polyethylene (LLDPE), Low-Density Polyethylene (LDPE), and Linear Low-Density Polyethylene (HDPE) plastics without compromising the plastic's integrity. Image analysis showed a generally better staining efficacy compared to Nile red. Through systematic experimentation, we identified specific optimal ratios of Coomassie (C) brilliant blue: Methylene (M) blue for various plastics: 5:5 (mass) for PVC, 7:3 (mass) for PET, and 8:2 (mass) for PP, LDPE, and HDPE. Additionally, the ratio of 10:0 (mass) was found suitable for PS and LLDPE. Given the cost-effectiveness, efficiency, and accessibility of the blue dyes in labs, the optimized ratio of the blue dyes makes it suitable for large-scale plastic staining across the six tested types of plastic, replacing Nile red.

The ubiquitous presence of plastic brought on by the extensive use of plastic products calls for efficient and rapid plastic detection methods to detect and evaluate pollution. The commonly used Nile red dye takes many hours and is expensive while also not equally efficient across all the common plastic waste. To address this, we investigated the staining efficiency and optimized the ratio of a combined Coomassie brilliant blue and Methylene blue dye. In the optimisation process, Methanol-based Coomassie and Methylene blue dyes effectively stained the Polyethylene Terephthalate (PET), Polypropylene (PP), Polystyrene (PS), Linear Low-Density Polyethylene (LLDPE), Low-Density Polyethylene (LDPE), and Linear Low-Density Polyethylene (HDPE) plastics without compromising the plastic's integrity. Image analysis showed a generally better staining efficacy compared to Nile red. Through systematic experimentation, we identified specific optimal ratios of Coomassie (C) brilliant blue: Methylene (M) blue for various plastics: 5:5 (mass) for PVC, 7:3 (mass) for PET, and 8:2 (mass) for PP, LDPE, and HDPE. Additionally, the ratio of 10:0 (mass) was found suitable for PS and LLDPE. Given the cost-effectiveness, efficiency, and accessibility of the blue dyes in labs, the optimized ratio of the blue dyes makes it suitable for large-scale plastic staining across the six tested types of plastic, replacing Nile red. [ABSTRACT FROM AUTHOR]

This study investigated spectral laser-induced fluorescence signals of dyes in fuels for automotive and aerospace applications under low temperatures and cryogenic conditions down to 183 K. For this purpose, a fluorescence chamber was developed based on cooling with liquid nitrogen. The design enabled a minimal inner chamber temperature of 153 K. Furthermore, the applicability of two-color LIF for liquid thermometry was evaluated under these conditions. The temperature determination was based on the temperature-sensitive fluorescence intensity ratio of the special dyes doped into the fuels determined in suitable spectral regions, which represented common bandpass filters. For this purpose, the fluorescence signals of the dye doped into the gasoline and jet fuel surrogate isooctane were tested as well as blends of isooctane and the ethanol biofuels E20 (comprising 80 vol.% isooctane and 20 vol.% ethanol), E40, and E100. Additionally, a realistic multi-component fuel Jet A-1 mixed with a suitable fluorescence dye was investigated. E100 was doped with Eosin-Y, and the remaining fuels were doped with Nile red. Temperature-dependent spectral LIF intensities were recorded in the range of 183 K–293 K, which simulate extreme environments for aerospace and automotive applications. Frozen fuel–dye mixtures cause significant extinction effects and prevent sufficient signal detection at low and cryogenic temperatures, defining the detection limit. A temperature decrease led to a spectral shift in the emission peaks of E100 doped with Eosin-Y toward shorter wavelengths, while the spectra of mixtures doped with Nile red were shifted toward longer wavelengths. The suggested bandpass filters produced the temperature-sensitive intensity ratio (the average over the temperature interval) of the dyes with the largest sensitivity for Jet A-1 (5.2%/K), followed by E100 (4.95%/K), E40 (4.07%/K), E20 (3.23%/K), and isooctane (3.07%/K), even at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) have been extensively studied as drug delivery systems due to their favorable characteristics, including biocompatibility, high loading efficiency, and pH-responsive release. However, the current research predominantly focuses on LDHs as carriers for various anionic drugs, while there are only limited reports on LDHs as carriers for hydrophobic drugs. In this study, we successfully achieved the loading of a hydrophobic drug mimic, Nile red (NR), into LDHs using sodium dodecyl sulfate (SDS) as an intermediate storage medium. Furthermore, we optimized the experimental methods and varied the SDS/NR molar ratio to optimize this intercalation system. With an increase in the SDS/NR molar ratio from 2/1 to 32/1, the loading efficiency of LDH-SDS-NR for NR initially increased from 1.32% for LDH-SDS-NR_2/1 to 4.46% for LDH-SDS-NR_8/1. Then, the loading efficiency slightly decreased to 3.64% for LDH-SDS-NR_16.8/1, but then increased again to 6.31% for LDH-SDS-NR_32/1. We believe that the established method and the obtained results in this study broaden the application scope of LDHs as delivery systems for hydrophobic drugs and contribute to the further expansion of the application scope of LDHs. [ABSTRACT FROM AUTHOR]

The fast, affordable, and standardized detection of microplastics (MP) remains one of the biggest challenges in MP research. Comparable data are essential for appropriate risk assessments and the implementation of laws and limit values. The fluorescent staining of MP in environmental samples is a possible solution to this problem. This study investigates the optimization of a sample preparation process (hydrogen peroxide digestion) and the staining process (temperature, concentration, time, surfactants as staining aids) for using a specifically developed fluorescent dye for MP detection. The optimization is performed by comparing the sample preparation process and staining of MP from different polymers and natural particles. Further, the suitability of the optimized process for the detection of fluoropolymers and tire abrasion was tested. The results show that the optimized method (increased temperature and optimized stain concentration) can detect microplastics reliably with a total sample preparation and measurement time of 2.5–3 h per sample, reaching recovery rates of 93.3% (polypropylene) to 101.7% (polyester). Moreover, two of the three tested fluoropolymers could be detected reliably. Tire abrasion could not be detected with the here presented method, as the black color leads to strong quenching. A long-term study measuring the MP pollution in the effluent of a municipal wastewater treatment plant compared the optimized and original processes and confirmed the stability of the improved method for routine measurements and contamination control. [ABSTRACT FROM AUTHOR]

As lipogenic yeasts are becoming increasingly harnessed as biofactories of oleochemicals, the availability of efficient protocols for the determination and optimization of lipid titers in these organisms is necessary. In this study, we optimized a quick, reliable, and high-throughput Nile red-based lipid fluorometry protocol adapted for oleaginous yeasts and validated it using different approaches, the most important of which is using gas chromatography coupled to flame ionization detection and mass spectrometry. This protocol was applied in the optimization of the concentrations of ammonium chloride and glycerol for attaining highest lipid titers in Rhodotorula toruloides NRRL Y-6987 and Yarrowia lipolytica W29 using response surface central composite design (CCD). Results of this optimization showed that the optimal concentration of ammonium chloride and glycerol is 4 and 123 g/L achieving a C/N ratio of 57 for R. toruloides, whereas for Y. lipolytica, concentrations are 4 and 139 g/L with a C/N ratio of 61 for Y. lipolytica. Outside the C/N of 33 to 74 and 45 to 75, respectively, for R. toruloides and Y. lipolytica, lipid productions decrease by more than 10%. The developed regression models and response surface plots show the importance of the careful selection of C/N ratio to attain maximal lipid production. Key points: • Nile red (NR)-based lipid fluorometry is efficient, rapid, cheap, high-throughput. • NR-based lipid fluorometry can be well used for large-scale experiments like DoE. • Optimal molar C/N ratio for maximum lipid production in lipogenic yeasts is ~60. [ABSTRACT FROM AUTHOR]

The calcifying cells of corals are responsible for skeleton formation, a process that is the basis for reef building. Their cell biology is therefore of primary interest, but current knowledge is limited because direct in vivo investigation of this cell type is challenging. Studies at the growing edge of laterally extending coral colonies allow for direct observations of actively calcifying cells in living samples. In the current study, we used this approach to study lipid droplets, which are considered storage organelles that fuel cells for physiological processes. Using the fluorescent lipid probe Nile Red and in vivo confocal microscopy, we observed lipid droplets in calcifying cells of the coral Stylophora pistillata and we suggest that they play a key role in coral calcification. [ABSTRACT FROM AUTHOR]

The fast, affordable, and standardized detection of microplastics (MP) remains one of the biggest challenges in MP research. Comparable data are essential for appropriate risk assessments and the implementation of laws and limit values. The fluorescent staining of MP in environmental samples is a possible solution to this problem. This study investigates the optimization of a sample preparation process (hydrogen peroxide digestion) and the staining process (temperature, concentration, time, surfactants as staining aids) for using a specifically developed fluorescent dye for MP detection. The optimization is performed by comparing the sample preparation process and staining of MP from different polymers and natural particles. Further, the suitability of the optimized process for the detection of fluoropolymers and tire abrasion was tested. The results show that the optimized method (increased temperature and optimized stain concentration) can detect microplastics reliably with a total sample preparation and measurement time of 2.5–3 h per sample, reaching recovery rates of 93.3% (polypropylene) to 101.7% (polyester). Moreover, two of the three tested fluoropolymers could be detected reliably. Tire abrasion could not be detected with the here presented method, as the black color leads to strong quenching. A long-term study measuring the MP pollution in the effluent of a municipal wastewater treatment plant compared the optimized and original processes and confirmed the stability of the improved method for routine measurements and contamination control.

Microplastics (MPs), typically defined as plastic fragments smaller than 5 mm, are pervasive in terrestrial and marine ecosystems. There is a need for rapid, portable, low-cost detection systems to assess health and environmental risks. Fluorescent tagging with Nile Red (NR) has emerged as a popular detection method, but variations in fluorescent emissions based on NR solvent, plastic polymer, excitation wavelength, and additives complicate standardization. In this study, seven plastic samples stained with acetone-based NR were analyzed using a fluorescent spectrometer to identify optimal emission peaks across UV-Vis excitation wavelengths. These findings aid in selecting appropriate excitation wavelengths and optical filters for future detection systems. Additionally, a straightforward polymer identification scheme was validated against field-collected plastic samples, whose material composition was confirmed via Fourier Transform Infrared Spectroscopy. This work contributes towards developing accessible microplastic detection technologies by characterizing the fluorescent properties of NR-stained plastics and enhancing the capability for effective environmental monitoring. Future research will expand the dataset to include diverse plastics with varying additives and weathering, and incorporate computer-vision tools for automated data processing and polymer identification.

AbstractPlastic pollution in the environment has become a much-discussed issue worldwide. In recent decades, the contamination of all environments has become increasingly evident, in particular, that of water is highly concerning. Ingestion by different animal species under natural conditions has also been demonstrated. Among these is the Talitrid Amphipod Cryptorchestia garbinii, which lives on the banks of the internal waterways and lakes’ shorelines. As detritivores species, it is very exposed to microplastics that can be ingested, probably mistaking them for food. Aiming to highlight the microplastic ingestion and the role of this species as an entry point for the food web, we analyzed 80 specimens from 4 sites along the shores of Garda Lake, one of the first lakes in Italy to be studied for this type of contamination. The microplastics ingested were observed and quantified through the Nile Red staining method. We were able to verify the presence of ingested microplastics in all the samples analyzed and, therefore, in the food web. This species could serve as valuable natural models of plastic exposure. Microplastic sentinel species can be used as a proxy for environmental exposure and ecosystem monitoring tools to quantify and assess the impacts of microplastic contamination.

[Display omitted] • Oxidizing reagents are the most prevalent and exhibit a high recovery rate. • The recycling and composting processes significantly impact the generation of microplastics. • Studies prove microplastic leakage from landfills into surrounding environment. • Acid rain can intensify microplastic dispersion from unmanaged ash piles. • Closed loop device proposed to enhance microplastic extraction efficiency. Numerous studies have reported the presence of microplastics (MPs) in waste collection and disposal systems. However, current scientific studies on measuring MP occurrence in a waste management context are not comparable due to a lack of standardized methodologies. Consequently, the impact of MPs on ecosystems and human health remains largely unclear. To address the inconsistencies, present in published studies, this review thoroughly examines sample preparation techniques for transfer stations, landfill leachate, recycling, compost, and incineration ash samples. Furthermore, various analytical approaches such as flotation, filtration, and organic matter digestion, as well as morphological categorization, identification, and quantification, are subsequently rigorously assessed. The benefits and limitations of each methodology are evaluated to facilitate the development of accurate and effective methods for detecting and characterizing nanoplastics. Recent research suggests that plastic recycling and composting facilities are the primary environmental sources of microplastic pollution among different waste treatment methods. The most prevalent microplastic types discovered in waste management were polyethylene (PE) and polypropylene (PP), with fragment and fiber being the most frequently reported morphologies. The review highlights a number of tactics that could be integrated into the methodology development for detecting microplastics in waste management systems (WMS), ultimately leading to better consistency and reliability of data across different studies. In essence, this will advance our comprehension of potential risks associated with microplastics. [ABSTRACT FROM AUTHOR]

Large molecules of dyes or other substances can act as nano-adsorbents in aqueous surfactant solutions and, being coated with surfactant molecules, they resemble surfactant micelles with a solubilizate. These micelle-like particles were called protomicelles (or, more precisely, adsorption protomicelles, as in this paper). Their formation does not require a critical micelle concentration (CMC) and begins immediately when a surfactant is added to a solution. In this spectrophotometric study of Nile red (NR) in aqueous solutions of nonanoic acid (NOA), the first case where protomicelles were more important than micelles was demonstrated. It was shown that NR solubilization in both premicellar and micellar solutions proceeds through protomicelles rather than through NOA micelles. In the theoretical part of the paper, on the basis of the chemical potential of the nano-adsorbent, it was proved that the addition of a surfactant to a solution always increases the solubility of the nano-adsorbent. The dependence of adsorption on the curvature of the nano-adsorbent surface was considered, and it was shown that the adsorption equations for flat surfaces are applicable to curved surfaces with high accuracy. [ABSTRACT FROM AUTHOR]

Bovine oocytes and blastocysts produced in vitro are frequently of lower quality and less cryotolerant than those produced in vivo, and greater accumulation of lipids in the cytoplasm has been pointed out as one of the reasons. In human adipocytes cGMP signaling through the activation of PKG appears to be involved in lipid metabolism, and components of this pathway have been detected in bovine cumulus-oocyte complexes (COCs). The aim of this study was to investigate the influence of this pathway on the lipid content in oocytes and expression of PLIN2 (a lipid metabolism-related gene) in cumulus cells. COCs were matured in vitro for 24 h with different stimulators of cGMP synthesis. The activation of soluble guanylyl cyclase (sGC) by Protoporphyrin IX reduced lipid content (22.7 FI) compared to control oocytes (36.45 FI; P 0.05). When the PKG inhibitor KT5823 was associated with Protoporphyrin IX, its effect was reversed and lipid contents increased (52.71 FI; P

In recent years, the utilization of flow cytometry for quantitative microplastic analysis has gained prominence. However, the current methods have some drawbacks that need to be improved. The present study aims to enhance the flow cytometry detection protocols for Nile red (NR) stained microplastics, facilitating distinct microplastic and nanoplastic enumeration. By elevating dimethyl sulfoxide (DMSO) concentration to 20%–30% within the solution, NR solubility improved and agglomeration reduced. The analysis of 26 replicates of polystyrene (PS) liquid samples through four distinct dot plots highlighted the superior accuracy of dot plots integrating yellow fluorescence. Through systematic staining of varying NR concentrations across three microplastic liquid samples (polyethylene terephthalate, polyethylene, and polypropylene), the optimal staining concentration was determined to be 15–20 μg/mL. The distributions of agglomerated NR and NR stained PS under two scenarios—dissolved NR and partially agglomerated NR—were compared. Results showed their distinct distributions within the side scatter versus yellow fluorescence dot plot. Counting results from gradient-diluted PS liquid samples revealed a microplastic detection lower limit of 104 particles/mL, with an optimal concentration range of 105–106 particles/mL. Flow cytometric assessment of PS microspheres spanning 150 nm to 40 μm indicated a 150 nm particle size detection minimum. Our investigation validated the efficacy of NR staining and subsequent flow cytometry analysis across eleven types of microplastics. Separation and concentration of microplastics (1.0–50.0 μm) and nanoplastics (0.2–1.0 μm) were achieved via sequential sieving through 50, 1.0, and 0.2 μm filter membranes. We used a combination of multiple filtration steps and flow cytometry to analyze microplastics and nanoplastics in nine simulated water samples. Our results showed that the combined amount of microplastics (1.0–50.0 μm) and nanoplastics (0.2–1.0 μm) after filtration had a ratio of 0.80–1.19 compared to the total microplastic concentration before filtration. This result confirms the practicality of our approach. By enhancing flow cytometry-based microplastic and nanoplastic detection protocols, our study provides pivotal technical support for research concerning quantitative toxicity assessment of microplastic and nanoplastic pollution.

Cysteine (Cys) is a significant biological mercaptan that achieves key roles in several important physiological processes, such as reversible redox homeostasis in living organisms. Abnormal levels of Cys in the human body are directly related to many diseases. In this work, we constructed a sensitive sensor (Cys-NR) by connecting a Cys recognition group to a Nile red derivative. Due to photo-induced electron transfer (PET), the Cys-NR probe showed little fluorescence at 650 nm. With the addition of Cys to the assay solution, the chlorine unit of the probe was substituted by the thiol group of Cys. Further, the amino and sulfhydryl groups in cysteine underwent an intramolecular rearrangement, which led to the Cys-NR probe water solution turning from colorless to pink with an enhancement in fluorescence. The red fluorescence at 650 nm increased about 20 times. Based on the turn-on signal, a selective Cys detection method is developed. The probe signal is not affected by various potential interferences or other competing biothiols and the limit of detection (LOD) is determined to be 0.44 μM. In addition, the probe is further employed for imaging of Cys in live cells, revealing good biological imaging ability that could provide a new way of intracellular Cys detection. [ABSTRACT FROM AUTHOR]

Microplastic (MP) contamination is a globally recognised issue in aquatic environments, and recently, there has been an increase in investigations focusing on lake contamination, revealing significant amounts of dispersed MPs. However, our understanding of the ingestion and effects of MPs on organisms living in lake ecosystems remains limited. This study aims to develop an effective protocol for assessing the ingestion of MPs by the talitrid amphipod Cryptorchestia garbinii, with the goal of verifying and evaluating the biological effects following ingestion. Individuals sampled from the shores of Lake Albano were exposed to four different polymers, namely low-density polyethylene (PE), polyethylene terephthalate (PET), polyester (PES), and polypropylene (PP), under laboratory conditions. To deliver MPs through the diet, we decided to employ DECOTABs (DEcomposition and COnsumption TABlets) which have been successfully used as a food source in aquatic toxicity tests. At the end of the experiments, we employed the solvatochromic and fluorescent dye Nile red to detect and quantify the MPs present in the digestive tube contents of the animals. The results clearly demonstrate the ingestion of the supplied polymers through the tabs, validating this method of exposure as effective. Furthermore, the measurement of glucose, glycogen, and lipid levels reveals that within 24 h of ingestion, MPs had an impact on the macromolecules involved in the energy metabolism of C. garbinii. This research underscores the suitability of this species as a model organism for studying MP uptake and its effects. [ABSTRACT FROM AUTHOR]

Reconstituted high-density lipoprotein nanoparticles (rHDL NPs) have been utilized as delivery vehicles to a variety of targets, including cancer cells. However, the modification of rHDL NPs for the targeting of the pro-tumoral tumor-associated macrophages (TAMs) remains largely unexplored. The presence of mannose on nanoparticles can facilitate the targeting of TAMs which highly express the mannose receptor at their surface. Here, we optimized and characterized mannose-coated rHDL NPs loaded with 5,6-dimethylxanthenone-4-acetic acid (DMXAA), an immunomodulatory drug. Lipids, recombinant apolipoprotein A-I, DMXAA, and different amounts of DSPE-PEG-mannose (DPM) were combined to assemble rHDL-DPM-DMXAA NPs. The introduction of DPM in the nanoparticle assembly altered the particle size, zeta potential, elution pattern, and DMXAA entrapment efficiency of the rHDL NPs. Collectively, the changes in physicochemical characteristics of rHDL NPs upon the addition of the mannose moiety DPM indicated that the rHDL-DPM-DMXAA NPs were successfully assembled. The rHDL-DPM-DMXAA NPs induced an immunostimulatory phenotype in macrophages pre-exposed to cancer cell-conditioned media. Furthermore, rHDL-DPM NPs delivered their payload more readily to macrophages than cancer cells. Considering the effects of the rHDL-DPM-DMXAA NPs on macrophages, the rHDL-DPM NPs have the potential to serve as a drug delivery platform for the selective targeting of TAMs. [ABSTRACT FROM AUTHOR]

Plastic pollution in the environment has become a much-discussed issue worldwide. In recent decades, the contamination of all environments has become increasingly evident, in particular, that of water is highly concerning. Ingestion by different animal species under natural conditions has also been demonstrated. Among these is the Talitrid Amphipod Cryptorchestia garbinii, which lives on the banks of the internal waterways and lakes' shorelines. As detritivores species, it is very exposed to microplastics that can be ingested, probably mistaking them for food. Aiming to highlight the microplastic ingestion and the role of this species as an entry point for the food web, we analyzed 80 specimens from 4 sites along the shores of Garda Lake, one of the first lakes in Italy to be studied for this type of contamination. The microplastics ingested were observed and quantified through the Nile Red staining method. We were able to verify the presence of ingested microplastics in all the samples analyzed and, therefore, in the food web. This species could serve as valuable natural models of plastic exposure. Microplastic sentinel species can be used as a proxy for environmental exposure and ecosystem monitoring tools to quantify and assess the impacts of microplastic contamination. [ABSTRACT FROM AUTHOR]

A spectrophotometric study of the system heptanol—Nile red (NR)—water was carried out, where, for the first time for such studies, a non-colloidal surfactant that does not form micelles was taken as a surfactant. The dependence of the solubility of NR on the concentration of heptanol in an aqueous solution was studied. The experiments were carried out at a given chemical potential of NR, which was provided by an excess of the solid phase of NR. The existence of a solubilization effect has been theoretically and experimentally established: An increase in the solubility of NR with an increase in the concentration of heptanol in solution. It was found that heptanol protomicelles with a solubilization core as an NR molecule are formed in such a system, so that in the absence of micelles, the protomicelles take on the entire solubilization load. From the experimental data, the concentration of protomicelle formation was calculated, which can also be taken as the concentration of NR monomerization in an aqueous solution, since the formation of protomicelles prevents the dye aggregation. Based on the results obtained, the following generalizations were made: (1) non-colloidal surfactants, although they do not give micelles, are capable of forming protomicelles; and (2) non-colloidal surfactants can serve as a practical means of dye monomerization. [ABSTRACT FROM AUTHOR]

Environmental plastic contamination is a global problem, which is driven by the growing demand for plastics. Over time, plastics undergo fragmentation processes and become so-called microplastics, which have been shown to be a threat to the various environments where their presence occurs. The most accepted hypothesis is that, like macroplastics, microplastics have fragmented into smaller and smaller particles, with sub-micrometer sizes. However, little is known about fragmentation rates and which are the most determining factors in this process. The main objective of the present study was to investigate the biofragmentation capacity of microplastics by Daphnia similis, a microcrustacean from inland waters. The organisms were exposed to polystyrene spheres (PS; 24 µm), under two concentrations: 135 and 1350 items/50 mL, for a period of 6 days. The rate of biofragmentation was obtained by analyzing the size of the particles over time (48, 96, and 144 h); ingestion and survival rates were also investigated. At the end of the exposure, the microspheres had their size reduced by 32.8%. From the first 48 h, the organisms ingested particles, and the rate of ingestion was dose dependent. Mortality was shown to increase in the treatment of higher concentration. The results demonstrate the ability of this microcrustacean to induce the reduction of the dimensions of microplastics, evidencing a fragmentation pathway previously neglected. [ABSTRACT FROM AUTHOR]

Fluorescent staining of microplastics as a detection method is consistently gaining importance in microplastics research, as it is fast, easy to use, and requires low technical effort. In this study, a complete procedure was developed, from sample collection to sample processing and detection, to measure microplastics with low cost and time requirements. The developed procedure was tested by measuring the microplastics in the effluent of a German wastewater treatment plant over a period of one year. The results show that the process is especially well suited to investigate temporal variations of microplastic contamination, which requires a large number of samples to be processed. Further, the precision and selectivity of the detection process could be improved by applying newly developed Nile red derivatives for fluorescent staining. A low budget modification of a microscope for fluorescent imaging is compared to a modification with precise optical bandpass filters. A script enabling automated microplastic detection and counting was developed, improving the accuracy and comparability of the process.

[INLINE:1] The formation of axonal spheroid is a common feature following spinal cord injury. To further understand the source of Ca2+ that mediates axonal spheroid formation, we used our previously characterized ex vivo mouse spinal cord model that allows precise perturbation of extracellular Ca2+. We performed two-photon excitation imaging of spinal cords isolated from Thy1YFP+ transgenic mice and applied the lipophilic dye, Nile red, to record dynamic changes in dorsal column axons and their myelin sheaths respectively. We selectively released Ca2+ from internal stores using the Ca2+ ionophore ionomycin in the presence or absence of external Ca2+. We reported that ionomycin dose-dependently induces pathological changes in myelin and pronounced axonal spheroid formation in the presence of normal 2 mM Ca2+ artificial cerebrospinal fluid. In contrast, removal of external Ca2+ significantly decreased ionomycin-induced myelin and axonal spheroid formation at 2 hours but not at 1 hour after treatment. Using mice that express a neuron-specific Ca2+ indicator in spinal cord axons, we confirmed that ionomycin induced significant increases in intra-axonal Ca2+, but not in the absence of external Ca2+. Periaxonal swelling and the resultant disruption in the axo-myelinic interface often precedes and is negatively correlated with axonal spheroid formation. Pretreatment with YM58483 (500 nM), a well-established blocker of store-operated Ca2+ entry, significantly decreased myelin injury and axonal spheroid formation. Collectively, these data reveal that ionomycin-induced depletion of internal Ca2+ stores and subsequent external Ca2+ entry through store-operated Ca2+ entry contributes to pathological changes in myelin and axonal spheroid formation, providing new targets to protect central myelinated fibers.

Background. An increased production and widespread use of plastics have made microplastic (MP) pollution a serious environmental problem. Most of MP found in the marine environment comes from rivers, however, the freshwater pollution by MP is less studied. Filter-feeding organisms, like bivalve molluscs, are the primary target orga­nisms for MP. Nevertheless, the studies of MP accumulation in the bivalves mainly focus on the marine species and depend on expensive equipment. The goal of this study was to detect the presence of MP in the body of freshwater bivalve mollusc Unio tumidus from a typical field site in Western Ukraine and under laboratory sub-chronic exposure to microplastic at a typical concentration for freshwater. Materials and Methods. For the study, we exposed molluscs to waterborne MP (0.1–0.5 mm) in the concentration of 1.0 mg L-1 corresponding to ~850 items L-1 for 14 days and analysed the concentration of MP in the soft tissues and water every two days. The molluscs and water from the field site, confirmed as polluted one, were also analysed. To estimate the number of MP particles, we used a modified method based on the cleavage of biological materials with potassium hydroxide and hydrogen peroxide and microscopic analysis of MP after the staining with fluorescent Nile Red dye. Results. The MP concentration in the soft tissues of the specimens from the refe­rence site was 9.5 items per soft body and demonstrated a bell-shaped response curve throughout the 14-days exposure with maximum of 327.0 items per body on the 10th day and a negative correlation with the concentration of MP in the experimental tank that changed within the range of 590–790 items L-1. The level of MP in the field specimens from the polluted area was 76.5 items per body, and in the water, it was about 103 items L-1. The maximum MP abundance factor, calculated as CFi = Ci/C0 (utilising the value 9.5 as C0), was 83.18 and 8.05 for 10 days of exposure and field specimens, correspondingly. Conclusion. These data indicate the high accumulative ability of U. tumidus towards microplastics and draw attention to the utilizing of this species for the biomonitoring of microplastics pollution and depuration of surface waters from it.

Simple Summary: In order to reliably record pollution from microplastics within animals, indicators for a monitoring program must be found. For this purpose, we collected invertebrates, fish, and sediment cores at 10 sites along the Wadden Sea coast of Lower Saxony, Germany; determined the amount of microplastics; and made recommendations for potential bioindicator species, based on the sampling conditions and results. The species studied included lugworm (Arenicola marina), common periwinkle (Littorina littorea), blue mussel (Mytilus edulis), and European flounder (Platichthys flesus). In total, microplastics were detected in 88% of the specimens and in each sediment core sample. Regarding the polymer composition, eight different types of microplastic were identified. Based on the results, the species blue mussel and European flounder are recommended for microplastic monitoring in biota. Monitoring strategies are becoming increasingly important as microplastic contamination increases. To find potentially suitable organisms and sites for biota monitoring in the German Wadden Sea, we collected invertebrates (n = 1585), fish (n = 310), and sediment cores (n = 12) at 10 sites along the coast of Lower Saxony between 2018 and 2020. For sample processing of biota, the soft tissue was digested and the sediment samples additionally underwent a subsequent density separation step. Microplastic particles were identified using Nile red and fluorescence microscopy, followed by polymer composition analysis of a subset of particles via µRaman spectroscopy. All investigated species, sediment cores, and sites contained microplastics, predominantly in the morphology class of fragments. Microplastics were found in 92% of Arenicola marina, 94% of Littorina littorea, 85% of Mytilus edulis, and 79% of Platichthys flesus, ranging from 0 to 248.1 items/g. Sediment core samples contained MPs ranging from 0 to 8128 part/kg dry weight of sediment. In total, eight polymers were identified, predominantly consisting of polyethylene, polyvinylchloride, and polyethylene terephthalate. Considering the sampling, processing, and results, the species Mytilus edulis and Platichthys flesus are suitable species for future microplastic monitoring in biota. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have recently been acknowledged as a new major and ubiquitous environmental pollutant with still unclear, yet potentially high, risks for different ecosystems and human health. Nevertheless, quantitative identification protocols rely on long and subjective visual counting necessarily performed on microscopes by well-trained operators. In this study, an automatic, fast, portable, and inexpensive method for the quantitative detection of MPs in water is proposed. The system is based on the typical optical setup of a fluorescence confocal microscope specifically adapted to automatically count dye-stained MPs in flowing liquids using a low-power laser beam. The fluorescence pulses emitted by flowing MPs are revealed and processed by a specific software using a pattern recognition algorithm to discriminate and count real fluorescence pulses out of noise fluctuations. The system was calibrated with commercial orange fluorescent 10 µm and 1 µm polystyrene microspheres, and remarkable agreement with theoretical predictions was obtained regarding different parameters. Tests were also performed with laboratory-prepared MPs dispersed in different types of real water samples. In this case, the agreement with theory was slightly worse and differences found in the quantitative results require further investigation. However, the present study demonstrated the proof of concept of a method for quick automated MP counting in water. [ABSTRACT FROM AUTHOR]

To explore the cytotoxicity of chitosan-modified ploy lactic-co-glycolic acid (CS-PLGA) drug-loaded nanoparticle (NP) and its role in the treatment of inner ear disease, the CS-PLGA NP loaded with Nile red (CS-PLGA-NR NP) was constructed, and the safety of its transport in the inner ear was explored. First, PLGA NPs with different particle sizes were prepared and modified with CS to obtain CS-PLGA-NR NPs. After the CS-PLGA-NR NP suspension was incubated with HEI-OC1 cells, cytotoxicity and cellular uptake were detected. Subsequently, the CS-PLGA-NR NP suspension was injected into SD rat binaural tympanum, and healthy rats were taken as control. Morphological differences in the hair cells morphology and tissue morphology in rat vestibular sensory area and cochlea sensory area were measured via immunohistochemical staining and HE staining. It was found that the shape of the prepared PLGA NP was relatively round and evenly distributed, and there was no adhesion. In addition, different NPs had similar infrared spectrum characteristics. Verified by X-ray photoelectron spectroscopy (XPS), CS-PLGA-NR NPs were successfully prepared. In vitro test results showed that the viability of HEI-OC1 cells after being incubated with 1–10 mg/mL CS-PLGA-NR NP was higher than 90%, and the cell uptake also increased with the increase of concentration of CS-PLGA-NR NP (within the range of 0–150 μg/mL). In vivo results showed that after CS-PLGA-NR NP treatment, the rat hair cells in vestibule and cochlea sensory areas were arranged regularly, without deficient. In addition, the morphology and size of rat vestibule and cochlea tissue cells were normal, and no inflammatory cells such as granulocytes appeared. In summary, the prepared CS-PLGA-NR NP had low cytotoxicity and favorable inner ear tissue biocompatibility. [ABSTRACT FROM AUTHOR]

Microplastic pollution (plastic debris < 5 mm) has become a global environmental problem due to the accumulation of plastic debris in water bodies over the decades. The present study was conducted to determine the abundance, shape, color, size, and composition of microplastics in the sand collected at recreational beaches in Vung Tau city of Vietnam. Ten sand samples were collected, five from Front Beach and five from Back Beach. These samples were extracted and analyzed for microplastics with a dissecting microscope, Nile red staining and the Fourier Transform Infrared (FTIR) technique. Results showed that microplastics were present in all study areas, with concentrations ranging from 5 to 27 MPs/100 g of dry sand. Colored and fibers dominated in both beaches (70-80%), of which fibers shorter than 0.5 mm were commonly found. Many detected microplastics were black and blue with a similar percentage, 32.55 % and 34.66 %. The predominant microplastics were polyethylene (PE) and polypropylene (PP). The study proved the efficacy of Nile Red with FTIR in quantifying microplastics in the sand samples. The results alert the wide spreading of plastic debris along the beaches, which poses many risks to human entertainment activities and local ecosystems. [ABSTRACT FROM AUTHOR]

Microplastic (MP) is yet another form of chronic anthropogenic contribution to the environment. MPs are plastic particles (<5 mm) that have been widely found in the most diverse natural environments, but their real impacts on ecosystems are still under investigation. Here, we studied the toxicity of naturally aged secondary polypropylene (PP) MPs after constant exposure to ultraviolet radiation (26 µm) to the third instar larvae of Chironomus sancticaroli, a dipteran species. The concentrations tested were 13.5; 67.5; and 135 items g−1 of dry sediment. C. sancticaroli organisms were investigated for fragment ingestion, mortality and changes in enzymatic biomarkers after 144 h of exposure. The organisms were able to ingest MPs from the first 48 h, and the amount of items internalized was dose-dependent and time-dependent. Overall, the results show that mortality was low, being significant at the lowest and highest concentrations (13.5 and 135 items g−1). Regarding changes in biochemical markers, after 144 h MDA and CAT activities were both significantly altered (increased and reduced, respectively), while SOD and GST levels were unchanged. In the present study, naturally aged polypropylene MPs induced biochemical toxicity in C. sancticaroli larvae, with toxicity being higher according to exposure time and particle concentration. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) have been identified as important point sources of micropollutants and microplastics into the environment. Existing fourth cleaning steps are designed to remove dissolved micropollutants, however do not target dispersed solids such as microplastics. Therefore, the ability of an Advanced Oxidation Process (AOP) and Granular Activated Carbon (GAC) in parallel and serial connection to remove microplastics was investigated and determined. The pilot plants were operated at the municipal WWTP Landau, Germany, a three-step biological waste treatment plant with a capacity of 80,000 population equivalents. A Nile red-based detection method was applied to quantify microplastics. Neither method showed a significant removal of microplastics. To achieve a simultaneous removal of microplastics and dissolved micropollutants, a pilot plant using organosilanes for microplastics' removal was connected in series with the GAC. When added to the water, the organosilanes attach to the microplastics and collect them in agglomerates by chemically binding them in a water-induced sol–gel process. The pilot plant for microplastics' removal was operated with a flow rate of 12 m3/h and a retention time of 10 min; the GAC with 2 m3/h and a retention time of 1 h. An average reduction in micropollutants by 86.2 ± 2.0% and a reduction in microplastics by 60.9 ± 27.5% was reached. Thus, there is an effective reduction in micropollutants and a significant reduction in microplastics. Further optimizations of the pilot plant are expected to result in a more stable and higher removal performance. [ABSTRACT FROM AUTHOR]

Continuous progress has been made in the development of new molecules for therapeutic purposes. This is driven by the need to address several challenges such as molecular instability and biocompatibility, difficulties in crossing the plasma membrane, and the development of host resistance. In this context, cell-penetrating peptides (CPPs) constitute a promising tool for the development of new therapies due to their intrinsic ability to deliver therapeutic molecules to cells and tissues. These short peptides have gained increasing attention for applications in drug delivery as well as for their antimicrobial and anticancer activity but the general rules regulating the events involved in cellular uptake and in the following processes are still unclear. Here, we use fluorescence microscopy methods to analyze the interactions between the multifunctional peptide Transportan 10 (TP10) and the giant plasma membrane vesicles (GPMVs) derived from cancer cells. This aims to highlight the molecular mechanisms underlying functional interactions which bring its translocation across the membrane or cytotoxic mechanisms leading to membrane collapse and disruption. The Fluorescence Lifetime Imaging Microscopy (FLIM) method coupled with the phasor approach analysis proved to be the winning choice for following highly dynamic spatially heterogeneous events in real-time and highlighting aspects of such complex phenomena. Thanks to the presented approach, we were able to identify and monitor TP10 translocation into the lumen, internalization, and membrane-induced modifications depending on the peptide concentration regime. [ABSTRACT FROM AUTHOR]

Fluorescent staining of microplastics as a detection method is consistently gaining importance in microplastics research, as it is fast, easy to use, and requires low technical effort. In this study, a complete procedure was developed, from sample collection to sample processing and detection, to measure microplastics with low cost and time requirements. The developed procedure was tested by measuring the microplastics in the effluent of a German wastewater treatment plant over a period of one year. The results show that the process is especially well suited to investigate temporal variations of microplastic contamination, which requires a large number of samples to be processed. Further, the precision and selectivity of the detection process could be improved by applying newly developed Nile red derivatives for fluorescent staining. A low budget modification of a microscope for fluorescent imaging is compared to a modification with precise optical bandpass filters. A script enabling automated microplastic detection and counting was developed, improving the accuracy and comparability of the process. [ABSTRACT FROM AUTHOR]

Traditional stereomicroscopy (SM) is limited for the identification of microplastics of less than 500 µm in wastewater treatment plants (WWTPs). Accordingly, novel methods for the accurate quantification of these microplastics are needed. In this study, we investigated the polymer type, morphology, size distribution, and abundance of microplastics in each unit of three selected WWTPs by SM and a fluorescence-based protocol (FR) combined with FTIR. Using the FR method, most microplastics detected in the three WWTPs were 50–200 µm in size. Polyethylene, polypropylene, and polyamide were the main polymer types, and the distributions of fibers, films, and debris were determined. Despite highly similar microplastic removal rates (78.6‒95.2% (SM) and 77.4‒94.2% (FR)) in the WWTPs by the two methods, the microplastic abundances obtained by FR (405‒6987 items/L) were approximately 2 orders of magnitude higher than the corresponding results by SM (1‒21 items/L). In addition, a considerable number of small-sized microplastics (< 500 µm) were detected in the effluents (405‒947 items/L) using FR. These results clearly reveal that microplastics in WWTPs have been seriously underestimated in most previous studies based on SM. Further research should focus on the environmental risks of small-sized microplastics from WWTPs. [ABSTRACT FROM AUTHOR]

This study investigated spectral laser-induced fluorescence signals of dyes in fuels for automotive and aerospace applications under low temperatures and cryogenic conditions down to 183 K. For this purpose, a fluorescence chamber was developed based on cooling with liquid nitrogen. The design enabled a minimal inner chamber temperature of 153 K. Furthermore, the applicability of two-color LIF for liquid thermometry was evaluated under these conditions. The temperature determination was based on the temperature-sensitive fluorescence intensity ratio of the special dyes doped into the fuels determined in suitable spectral regions, which represented common bandpass filters. For this purpose, the fluorescence signals of the dye doped into the gasoline and jet fuel surrogate isooctane were tested as well as blends of isooctane and the ethanol biofuels E20 (comprising 80 vol.% isooctane and 20 vol.% ethanol), E40, and E100. Additionally, a realistic multi-component fuel Jet A-1 mixed with a suitable fluorescence dye was investigated. E100 was doped with Eosin-Y, and the remaining fuels were doped with Nile red. Temperature-dependent spectral LIF intensities were recorded in the range of 183 K–293 K, which simulate extreme environments for aerospace and automotive applications. Frozen fuel–dye mixtures cause significant extinction effects and prevent sufficient signal detection at low and cryogenic temperatures, defining the detection limit. A temperature decrease led to a spectral shift in the emission peaks of E100 doped with Eosin-Y toward shorter wavelengths, while the spectra of mixtures doped with Nile red were shifted toward longer wavelengths. The suggested bandpass filters produced the temperature-sensitive intensity ratio (the average over the temperature interval) of the dyes with the largest sensitivity for Jet A-1 (5.2%/K), followed by E100 (4.95%/K), E40 (4.07%/K), E20 (3.23%/K), and isooctane (3.07%/K), even at cryogenic temperatures.

Layered double hydroxides (LDHs) have been extensively studied as drug delivery systems due to their favorable characteristics, including biocompatibility, high loading efficiency, and pH-responsive release. However, the current research predominantly focuses on LDHs as carriers for various anionic drugs, while there are only limited reports on LDHs as carriers for hydrophobic drugs. In this study, we successfully achieved the loading of a hydrophobic drug mimic, Nile red (NR), into LDHs using sodium dodecyl sulfate (SDS) as an intermediate storage medium. Furthermore, we optimized the experimental methods and varied the SDS/NR molar ratio to optimize this intercalation system. With an increase in the SDS/NR molar ratio from 2/1 to 32/1, the loading efficiency of LDH-SDS-NR for NR initially increased from 1.32% for LDH-SDS-NR_2/1 to 4.46% for LDH-SDS-NR_8/1. Then, the loading efficiency slightly decreased to 3.64% for LDH-SDS-NR_16.8/1, but then increased again to 6.31% for LDH-SDS-NR_32/1. We believe that the established method and the obtained results in this study broaden the application scope of LDHs as delivery systems for hydrophobic drugs and contribute to the further expansion of the application scope of LDHs.

Abstract Lipids extracted from microalgae for biofuel production have drawn the attention of researchers. Various methods for quantification of neutral lipids, such as solvent extraction or gravimetric, require a large volume of sample and are time-consuming. In this work, Nile Red was employed to evaluate the lipid content in microalgae Scenedesmus sp. through 2D fluorescence spectroscopy using chemometric modeling with a selection of wavelength pairs reducing the variable numbers. Cultivation of microalgae for 10 days was performed. Samples were taken starting after the 5th day of cultivation. Microalgae samples were dried using an oven with tangential airflow and the conventional Bligh and Dyer method for lipid extraction was employed. Before the measurement of fluorescence, the samples were diluted in ethanol at 40°C for 10 minutes, and then Nile Red solution (10 µg/mL ethanol) was added. The results of lipid quantification using the proposed technique achieved mean absolute percentage error (MAPE) lower than 5% and correlation coefficients around 0.99 in the test phase. Linear models using four excitation-emission pairs of fluorescence were fitted and were selected based on Pure Spectral Chemometric Modelling (PSCM). The method for lipid quantification using predictive linear models and 2D fluorescence proved to be robust and fast (requiring less than 30 min) compared to the conventional gravimetric method (which takes at least 5 hours) to obtain comparable results.

Investigating the role of lipids in mammalian preimplantation development is an important task in modern embryology. The aim of this study was to evaluate the amount of intracellular lipids in preimplantation mouse embryos during in vivo and in vitro development using confocal laser scanning microscopy. The development of preimplantation embryos was accompanied by a decrease in total lipid content, which was observed in vivo at the blastocyst stage and at the morula stage in vitro. Besides, total lipid content was lower during in vitro embryo development as compared to in vivo development. Thus, lipid metabolism during the preimplantation period depends on the conditions in which development occurs (in vivo or in vitro); at the blastocyst stage, the amount of intracellular lipids in preimplantation mouse embryos decreases significantly. [ABSTRACT FROM AUTHOR]

Transmittance or absorbance spectra of liquid samples are usually obtained by illuminating a quartz cuvette container with non-polarized light. A direct inversion of the absorbance allows to obtain the optical thickness and the absorption coefficient, as well as the intrinsic absorptivity of the medium when the concentration of the light absorbing molecules is known. A numerical inversion of transmittance spectra, based on a spectral projected gradient method, is carried out to obtain other optical parameters: optical constants (refractive index and extinction coefficient) and electronic polarizability of the molecules. This inversion approach is applied to transmittance spectra by samples of transparent Dodecane oil and light absorbing Nile Red dye, with an automated determination of the HOMO-LUMO energy gap of saturated Nile Red dissolved in Dodecane oil. The spectral variation of the optical constants of these two materials is reported for the first time, for wavelengths between 300 and 800 nm. [ABSTRACT FROM AUTHOR]