Increase In Fluorescence Intensity Research Articles

Effect of different substituent on the ESIPT process and fluorescence features of 2-(2-hydroxyphenyl)benzoxazole derivatives: A DFT/TD-DFT study

In this contribution, four derivatives of 5′-(para-R-Phenylene) vinyl-2-(2′-hydroxyphenyl) benzoxazole (PVHBO) were ingeniously designed by introducing two electron-withdrawing substituents and two electron-donating substituents, aiming to investigate the influence of different substituents on the photophysical properties of PVHBO and the excited state intramolecular proton transfer (ESIPT) process via the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. By utilizing the geometric parameters and the simulated infrared (IR) spectra, we compared the intramolecular hydrogen bonds (IHBs) strengths in the S0 and S1 states of the molecules. Via conducting the hole-electron analysis, the reduction in fluorescence intensity for the enol and keto forms of PVHBO, PVHBO-MeO, and PVHBO-NH2 were also well explicated. Besides, the potential energy curves (PECs) and corresponding transition state (TS) structures for both S0 and S1 states were also constructed to accurately obtain energy barriers of forward and reversed proton transfer processes. The calculated absorption and fluorescence spectra also show that PVHBO-NH2 has the largest Stokes shifts of 158 nm and 219 nm in both the enol and keto states, with a significant increase in fluorescence intensity observed upon the induction of electron-withdrawing groups. Through this work, it can provide the theoretical basis for the design of novel luminescent materials.

Impact of carbon concentration on optical and zeta potential properties of carbon quantum dots

Carbon quantum dots (CQDs) are fluorescent nanoparticles with diverse applications in multiple fields. The optical and physical properties of CQDs are influenced by several factors, such as the synthesis method, surface passivation and particle size. This study explores how carbon concentration affects the properties of CQDs. The CQDs were synthesized through a carbonization process with carbon concentrations varying from 0.03 to 0.15 g/ml. The samples of CQDs were characterized by using high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectroscopy, zeta potential, dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). The results indicate that carbon concentration significantly impacts the optical properties and zeta potential of CQDs. Specifically, higher carbon concentrations result in increased fluorescence intensity and larger particle size. HRTEM images reveal that the average size of the CQDs is below 10 nm, consistent with DLS measurements. These findings suggest that carbon concentration can serve as a straightforward and effective parameter for tuning CQDs properties, with potential applications in bioimaging, sensing and optoelectronics.

Spectral-fluorescent study of substituted trimethine cyanine dyes in solutions and in complexes with DNA. Effects of aggregation, moderate heating, and decreasing pH

Trimethine cyanine dyes are widely used as probes for the detection, study and quantification of biomolecules. In particular, cationic trimethine cyanines noncovalently interact with DNA with growing fluorescence. However, their use is often limited by the tendency to self-association – to the formation of aggregates. Disubstituted trimethine cyanines with hydrophobic substituents are especially prone to aggregation. In this work, we studied the interaction of a number of substituted trimethine cyanines with DNA (in aqueous buffer solutions) and showed that their aggregation strongly interfered with their use as fluorescent probes for DNA. To eliminate this drawback, preliminary heating of dye solutions with DNA to 60–70 °C was used, followed by cooling to room temperature. Compared to the experiments without heating, an increase in the dye fluorescence intensity was observed due to the partial thermal decomposition of the aggregates and the interaction of the resulting monomers with DNA. To decompose aggregates, another method was also used – protonation of the dyes with amino substituents in buffer solutions with pH 5.0, which also led to growing the dye fluorescence intensity in the presence of DNA. Complexes of the dyes with DNA were modeled using molecular docking. Effective binding constants of the dyes to DNA and detection limits when using the dyes as probes for DNA (LOD and LOQ) were determined. It is shown that dye 3 with heating in neutral buffer and dye 1 in acidic buffer may be recommended as sensitive probes for DNA. It is concluded that the method of preliminary heating may be applied to dyes prone to aggregation, for improving their properties as biomolecular probes. Another possible means to reduce the interfering effects of dye aggregates is to use easily protonated dyes (with amino substituents) in slightly acidic media.

Effects of Maternal Smoke Exposure on Endoplasmic Reticulum Stress and Autophagy in the Lungs of Offspring Mice.

Cigarette smoke (CS) induces autophagy and endoplasmic reticulum (ER) stress in the lungs. Research suggests that maternal exposure to CS during pregnancy leads to decreased lung function in offspring. However, the effects of maternal CS exposure on lung autophagy and ER stress in offspring during pregnancy remain unclear. C57BL/6J female mice were divided into the AA (air treatment during both pre-pregnancy and pregnancy), AS (air treatment during pre-pregnancy and CS treatment during pregnancy), SA (CS treatment during pre-pregnancy and air treatment during pregnancy), and SS (CS treatment during both pre-pregnancy and pregnancy) groups. The male offspring mice were selected to the study and euthanized 49 days after birth for the study. Hematoxylin and eosin (HE) staining was employed to observe pathological alterations, while transmission electron microscopy (TEM) was utilized to examine ultrastructure and autophagic vesicles. Additionally, the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method was applied to identify apoptosis in lung tissues. Immunofluorescence, Real-Time PCR, and Western Blot analyses were conducted to assess the expression of ER stress and autophagy-related markers in lung tissues. The findings revealed that exposure to CS heightened the extent of pathological damage and the abundance of autophagosomes in the lungs of offspring mice. TUNEL results indicated an increased fluorescence intensity in the AS, SA and SS groups, with the most significant in AS and SS groups. Furthermore, CS exposure augmented the fluorescence intensity and expression of ER stress and autophagy-related proteins. The expression of C/EBP-homologous protein (CHOP) exhibited no discernible difference between the SA and SS groups but showed a significant increase in the AS group. Conversely, the expression levels of glucose-regulated protein 78 (GRP78), Caspase-12, Beclin-1, and microtubule-associated protein 1 light chain 3 (LC3) exhibited no significant difference between the AS and SA groups, whereas they were significantly upregulated in the SS group. Preconceptional and gestational exposure to CS heightened ER stress and autophagy in the lungs of mouse offspring. However, in mothers who smoked, withdrawal from CS during pregnancy led to a reduction in ER stress and autophagy in the lungs of their offspring.

An activatable azophenyl fluorescent probe for hypoxic fluorescence imaging in living cells.

Cellular hypoxia is a common pathological process in various diseases. Detecting cellular hypoxia is of great scientific significance for early diagnosis of tumors. The hypoxia fluorescence probe analysis method can efficiently and conveniently evaluate the hypoxia status in tumor cells. These probes are covalently linked by hypoxic recognition groups and organic fluorescent molecules. Currently, the fluorescent molecules used in these probes often exhibit the aggregation-caused quenching effect, which is not conducive to fluorescence imaging in water. Herein, an activatable hypoxia fluorescence probe was constructed by covalently linking aggregation-induced emission luminogens to the hypoxic recognition group azobenzene. It does not emit fluorescence in solution and in solid state under light excitation due to the presence of photosensitive azo bonds. It can be cleaved by intracellular azoreductase into fluorescent amino derivatives with aggregation-induced emission characteristic. As the concentration of oxygen in cells decreases, its fluorescence intensity increases, making it suitable for fluorescence imaging to detect hypoxic environment in live cancer cells. This work broadens the molecular design approach for activatable hypoxia fluorescent probes.

Optimizing enzyme properties to enhance dihydroxyacetone production via methylglyoxal biosensor development

BackgroundDihydroxyacetone (DHA) stands as a crucial chemical material extensively utilized in the cosmetics industry. DHA production through the dephosphorylation of dihydroxyacetone phosphate, an intermediate product of the glycolysis pathway in Escherichia coli, presents a prospective alternative for industrial production. However, insights into the pivotal enzyme, dihydroxyacetone phosphate dephosphorylase (HdpA), remain limited for informed engineering. Consequently, the development of an efficient tool for high-throughput screening of HdpA hypermutants becomes imperative.ResultsThis study introduces a methylglyoxal biosensor, based on the formaldehyde-responding regulator FrmR, for the selection of HdpA. Initial modifications involved the insertion of the FrmR binding site upstream of the −35 region and into the spacer region between the −10 and −35 regions of the constitutive promoter J23110. Although the hybrid promoter retained constitutive expression, expression of FrmR led to complete repression. The addition of 350 μM methylglyoxal promptly alleviated FrmR inhibition, enhancing promoter activity by more than 40-fold. The methylglyoxal biosensor system exhibited a gradual increase in fluorescence intensity with methylglyoxal concentrations ranging from 10 to 500 μM. Notably, the biosensor system responded to methylglyoxal spontaneously converted from added DHA, facilitating the separation of DHA producing and non-producing strains through flow cytometry sorting. Subsequently, the methylglyoxal biosensor was successfully applied to screen a library of HdpA mutants, identifying two strains harboring specific mutants 267G > T and D110G/G151C that showed improved DHA production by 68% and 114%, respectively. Expressing of these two HdpA mutants directly in a DHA-producing strain also increased DHA production from 1.45 to 1.92 and 2.29 g/L, respectively, demonstrating the enhanced enzyme properties of the HdpA mutants.ConclusionsThe methylglyoxal biosensor offers a novel strategy for constructing genetically encoded biosensors and serves as a robust platform for indirectly determining DHA levels by responding to methylglyoxal. This property enables efficiently screening of HdpA hypermutants to enhance DHA production.

Coxiella burnetii-containing vacuoles interact with host recycling endosomal proteins Rab11a and Rab35 for vacuolar expansion and bacterial growth.

Coxiella burnetii is a gram-negative obligate intracellular bacterium and a zoonotic pathogen that causes human Q fever. The lack of effective antibiotics and a licensed vaccine for Coxiella in the U.S. warrants further research into Coxiella pathogenesis. Within the host cells, Coxiella replicates in an acidic phagolysosome-like vacuole termed Coxiella-containing vacuole (CCV). Previously, we have shown that the CCV pH is critical for Coxiella survival and that the Coxiella Type 4B secretion system regulates CCV pH by inhibiting the host endosomal maturation pathway. However, the trafficking pattern of the 'immature' endosomes in Coxiella- infected cells remained unclear. We transfected HeLa cells with GFP-tagged Rab proteins and subsequently infected them with mCherry-Coxiella to visualize Rab protein localization. Infected cells were immunostained with anti-Rab antibodies to confirm the Rab localization to the CCV, to quantitate Rab11a and Rab35- positive CCVs, and to quantitate total recycling endosome content of infected cells. A dual-hit siRNA mediated knockdown combined with either immunofluorescent assay or an agarose-based colony-forming unit assay were used to measure the effects of Rab11a and Rab35 knockdown on CCV area and Coxiella intracellular growth. The CCV localization screen with host Rab proteins revealed that recycling endosome-associated proteins Rab11a and Rab35 localize to the CCV during infection, suggesting that CCV interacts with host recycling endosomes during maturation. Interestingly, only a subset of CCVs were Rab11a or Rab35-positive at any given time point. Quantitation of Rab11a/Rab35-positive CCVs revealed that while Rab11a interacts with the CCV more at 3 dpi, Rab35 is significantly more prevalent at CCVs at 6 dpi, suggesting that the CCV preferentially interacts with Rab11a and Rab35 depending on the stage of infection. Furthermore, we observed a significant increase in Rab11a and Rab35 fluorescent intensity in Coxiella-infected cells compared to mock, suggesting that Coxiella increases the recycling endosome content in infected cells. Finally, siRNA-mediated knockdown of Rab11a and Rab35 resulted in significantly smaller CCVs and reduced Coxiella intracellular growth, suggesting that recycling endosomal Rab proteins are essential for CCV expansion and bacterial multiplication. Our data, for the first time, show that the CCV dynamically interacts with host recycling endosomes for Coxiella intracellular survival and potentially uncovers novel host cell factors essential for Coxiella pathogenesis.

Multi-target aptamer assay for endocrine-disrupting phthalic acid ester panel screening in plastic leachates

A multi-target aptamer assay was developed as a phthalic acid ester (PAE) panel to screen selected PAEs in plastic leachate samples. The panel comprises 13 PAEs (PAE-13), namely dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, di-n-hexyl phthalate, diisobutyl phthalate, diisononyl phthalate, diisodecyl phthalate, mono-2-ethylhexyl phthalate, di-2-ethylhexyl phthalate, diphenyl phthalate, butyl benzyl phthalate, dicyclohexyl phthalate, and phthalic acid. Herein, we proposed an aptamer assay using a newly truncated aptamer (20-mer) and the 7-aminoactinomycin D fluorophore, which selectively binds to guanine in single-stranded DNA, resulting in increased fluorescence intensity. The assay is highly selective for PAE-13 clusters. The selectivity of the assay was evaluated using 13 different PAEs and mixtures depending on the side chain structure. The quantitative detection of PAEs was demonstrated by adopting mixed PAE-13 simulants and achieved a limit of detection of ∼1.4 pg/mL. The repeatability and reproducibility of the assay were also evaluated by presenting acceptable coefficients of variation (%CV less than 10% and 15%, respectively). The performance of the assay was demonstrated by analyzing the plastic leachate samples, and the positive correlation (correlation coefficient, r = 0.985) was confirmed by comparing them with the total sum of individual PAE peak areas obtained by gas chromatography mass spectrometry analysis.

Coumarin-Modified Starch Fluorescent Nanoparticles as Sensor of Fe3+ and Zn2+ ions Utilizing Dynamic Quenching and Chelation Mechanisms.

Zinc and iron are two essential trace minerals that play a pivotal role in maintaining optimal health and well-being in the human body. Despite being required in relatively small quantities, their significance can be understated as they participate in a wide array of critical physiological processes such as oxygen transport, DNA synthesis, controlling nutrient availability, etc. Understanding the distribution and behavior of these ions in natural water bodies is essential for assessing water quality, studying ecological processes, and managing environmental impacts. In this study, we have developed a dual fluorescence probe using starch which was functionalized with coumarin derivatives, for efficient detection of Fe3+ and Zn2+ ions. This structure led a self-assembled starch/coumarin (SC) fluorescent nanoparticles with strong fluorescence intensity under ultraviolet light (365nm). The quenching effect of Fe3+ on the SC fluorescent probe enabled efficient specific detection of Fe3+. Furthermore, Zn2+ ions increased fluorescence intensity of coumarin compounds (λemission = 459). This phenomenon occurs when the coumarin compound forms a complex or interacts with the zinc ion, resulting in enhanced fluorescence emission. In summary, the developed fluorescent probe offered a promising approach for sensitive and specific detection of iron and zinc ions in aqueous solutions.

Targeted detection of Barrett’s neoplasia: A case report

Barrett’s esophagus (BE) is a precursor condition for esophageal adenocarcinoma (EAC). This case report describes the in vivo use of a fluorescently-labeled peptide heterodimer specific for epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor (HER2) to identify residual neoplasia in a 52-year-old female patient with BE. This targeted contrast agent was topically administered after an incomplete endoscopic mucosal resection of high-grade dysplasia with carcinoma in situ. A flexible fiber-coupled multi-modal scanning fiber endoscope was used to capture near-infrared fluorescence images. This instrument was passed through the working channel of a standard upper endoscope for use as an accessory. Increased fluorescence intensity was observed from nodular mucosa as a real-time “red flag” to identify the presence of neoplasia. Pathologic tests were conducted on the resected tissues, confirming the presence of stage T1a EAC. The expression EGFR and HER2 was confirmed by immunohistochemistry ex vivo. These findings support integrated imaging as a potential strategy to detect Barrett’s neoplasia.

The changing of α5-GABAA receptors expression and distribution participate in sevoflurane-induced learning and memory impairment in young mice.

Sevoflurane is a superior agent for maintaining anesthesia during surgical procedures. However, the neurotoxic mechanisms of clinical concentration remain poorly understood. Sevoflurane can interfere with the normal function of neurons and synapses and impair cognitive function by acting on α5-GABAAR. Using MWM test, we evaluated cognitive abilities in mice following 1 h of anesthesia with 2.7%-3% sevoflurane. Based on hippocampal transcriptome analysis, we analyzed the differential genes and IL-6 24 h post-anesthesia. Western blot and RT-PCR were performed to measure the levels of α5-GABAAR, Radixin, P-ERM, P-Radixin, Gephyrin, IL-6, and ROCK. The spatial distribution and expression of α5-GABAAR on neuronal somata were analyzed using histological and three-dimensional imaging techniques. MWM test indicated that partial long-term learning and memory impairment. Combining molecular biology and histological analysis, our studies have demonstrated that sevoflurane induces immunosuppression, characterized by reduced IL-6 expression levels, and that enhanced Radixin dephosphorylation undermines the microstructural stability of α5-GABAAR, leading to its dissociation from synaptic exterior and resulting in a disordered distribution in α5-GABAAR expression within neuronal cell bodies. On the synaptic cleft, the expression level of α5-GABAAR remained unchanged, the spatial distribution became more compact, with an increased fluorescence intensity per voxel. On the extra-synaptic space, the expression level of α5-GABAAR decreased within unchanged spatial distribution, accompanied by an increased fluorescence intensity per voxel. Dysregulated α5-GABAAR expression and distribution contributes to sevoflurane-induced partial long-term learning and memory impairment, which lays the foundation for elucidating the underlying mechanisms in future studies.

Peptide-Based Turn-On Fluorescent Probes for Highly Specific Detection of Survivin Protein in the Cancer Cells.

Survivin is highly expressed in most human cancers, making it a promising target for cancer diagnosis and treatment. In this study, we developed peptide probes consisting of Bor65-75, a high-affinity survivin-binding peptide, and a survivin protein segment using peptide linkers as survivin-sensitive fluorescent probes (SSFPs). All conjugates were attached to 5(6)-carboxyfluorescein (FAM) at the C-terminal as a fluorophore and to 4((4(dimethylamino)phenyl)azo)benzoic acid (DABCYL) at the N-terminal as a quencher. Fluorescence (or Förster) resonance energy transfer (FRET) quenching via intramolecular binding of Bor65-75 with survivin protein segment could be diminished by the approach of survivin to SSFPs, which dissociate Bor65-75 from SSPF and increased the distance between FAM and DABCYL. A binding assay using recombinant human survivin protein (rSurvivin) demonstrated moderate to high affinity of SSFPs for survivin (dissociation constants (K d) = 121-1740 nM). Although the SSFPs (0.5 μM) had almost no fluorescence under baseline conditions, a dose-dependent increase in fluorescence intensity was observed in the presence of rSurvivin (0.1-2.0 μM). In particular, the proline-rich SSFP (SSFP5) showed the highest (2.7-fold) fluorescence induction at 2.0 μM survivin compared to the signals in the absence of survivin. Confocal fluorescence imaging demonstrated that SSFP5 exhibited clear fluorescence signals in survivin-positive MDA-MB-231 cells, whereas no marked fluorescence signals were observed in survivin-negative MCF-10A cells. Collectively, these results suggest that SSFPs can be used as survivin-specific FRET imaging probes.

THE IMPACT OF WINTER SWIMMING ON FUNCTIONAL MICROVASCULAR CHANGES

Objective: Microcirculation plays an important role in the development of cardiovascular control. Therefore, the aim of our study was to investigate the impact of winter swimming on functional changes in cutaneous microcirculation Flow-mediated skin fluorescence (FMSF) is a novel and non-invasive technique assessing microvascular function based on the measurements of nicotinamide adenine dinucleotide hydrogen (NADH) fluorescence intensity in the epidermis and post occlusive reactive hyperemia test. NADH intensity changes in response to blockage and release of blood flow in the brachial artery, which corresponds to microvascular function. Design and method: FMSF examinations were performed before and after the winter swimming period lasting from November 2022 to April 2023 in 37 subjects (mean age 46±4,0 years, 65% women). The mean frequency of winter swimming activity was 1,3 times per week. We analysed the following variables: the ischemic response (IRmax and IRindex) – the ratio of relative to baseline maximal increase in fluorescence intensity during cuff occlusion and the hyperaemic response after cuff release (HRmax and HRindex). Flowmotion, measured at baseline (FM) and at reperfusion (FM(R)), reflects flow oscillations. Normoxia oscillatory index (NOI) represents the proportion of endothelial and neurogenic blood flow oscillations in relation to all oscillations detected in low frequency range. The hypoxia sensitivity (HS), measured during reperfusion, reflects the intensity of flowmotion related to myogenic oscillations. Results: The statistical analysis revealed following results according to the winter swimming: Conclusions: Increase in microvascular oscillations denoted by NOI and HS suggests a beneficial impact of winter swimming on cutaneous microcirculation. Improvement in microcirculation performance may partly explain lowering of cardiovascular risk in regular winter swimmers.

The role of CCN1 in kidney-brain crosstalk

Cognitive impairment and dementia are major global health problems of the aging human population. It is estimated that about 55 million people were living with dementia in 2019 and this number is expected to triple by 2050. Dementia can result from abnormal structure and function of brain blood vessels that may develop in a variety of conditions including chronic kidney disease (CKD). Recent studies from our laboratory suggest that in addition to controlling blood volume and blood pressure (renin), and blood cell count (erythropoietin), the kidney produces novel systemic angiogenic hormones to maintain blood vessels, such as the matricellular protein Cellular Communication Network factor 1 (CCN1). These hormones are then released to the blood and may act as new molecular mechanisms of kidney-brain crosstalk. We hypothesized that kidney-derived CCN1 helps to preserve the normal structure and function of blood vessels throughout the body, including a healthy blood-brain barrier (BBB). We further hypothesized that reduced plasma CCN1 caused by diminished renal production of CCN1 due to kidney disease plays a major role in the development of brain vascular dysfunction, and therefore in the pathogenesis and progression of dementia and cognitive impairment. Intravital multiphoton (MPM) imaging of the intact mouse brain in control or after 5/6 nephrectomy (5/6 Nx), a well-established mouse model of chronic kidney disease (CKD) was used to measure changes in BBB permeability with or without chronic CCN1 treatment. Kidney and BBB structure/function phenotyping was performed using CCN1 ELISA assay, the Medibeacon transdermal GFR measurement system, tissue harvest, and immunohistochemistry. Compared to control, 5/6 Nx mice had reduced plasma CCN1 levels, reduced GFR, but no difference in systolic blood pressure. MPM imaging showed increased fluorescence intensity of mid-size plasma proteins (A680 conjugated Albumin 70 kDa) compared to high molecular weight markers (A488 conjugated Dextran 500 kDa) in brain interstitium in 5/6 Nx compared to control. In addition, the density of cell-to-cell junctions in brain endothelial cells were 20% reduced in CKD compared to control healthy mice. In brain endothelial cells cultured in vitro, CCN1 treatment had protective effects on cell proliferation, motility and angiogenesis as confirmed by scratch and tube formation assays. In summary, this study identified new mechanisms of kidney-brain crosstalk, and helped to improve our mechanistic understanding of cerebrovascular pathology in CKD. DK123564, DK064324, DK135290. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Mild Alkaline-Enhanced depolymerization of Long-Flame coal for the synthesis of Coal-Derived fluorescent carbon dots with application as probes

The intricate composition and structural of low-rank coal have hindered its broad utilization in the field of material science. The study utilized an alkaline hydrothermal method to enhance the depolymerization of long-flame coal and achieve the purification of fluorescent carbon dots for the first time, which were then being employed for the trace detection of Cu2+ or Fe3+ ions. The carbon extraction efficiency reached 58 %, with the carbon dots averaging size of 1.36 ± 0.42 nm, the sp2 hybridized structure of the carbon dots indicated successfully purification under alkaline conditions. After reduction with sodium borohydride, defects in the core region of the carbon dots were repaired, and the C = O functional groups were transformed into O–H groups, leading to an increase in fluorescence intensity. At a concentration of 0.25 g/L of carbon dots, demonstrated high emission intensity at both long and low emission wavelengths, which can be used as LED luminescent material. Furthermore, the application of these carbon dots in detecting heavy metal ions (Cu2+, Fe3+) in aqueous solutions was explored, showing as low as detection limit of ∼ 0.04 μM. This study achieved higher depolymerization of coal and purification of fluorescent carbon dots for use in probe-based detection, providing fresh perspectives on the high-value utilization of low-rank coal.

SBFI-26 enhances apoptosis in docetaxel-treated triple-negative breast cancer cells by increasing ROS levels

Introduction: Fatty acid binding protein 5 (FABP5) exhibits heightened expression levels in triple-negative breast cancer. The inhibitor of FABP5, Stony Brook fatty acid‐binding protein inhibitor 26 (SBFI-26), has demonstrated the capacity to suppress cell proliferation, migration, and invasion. This study delves into the functional mechanism and impact of combining SBFI-26 with docetaxel in treating MDA-MB-231 cells of triple-negative breast cancer. Methods: Various concentrations of docetaxel and SBFI-26 were chosen for individual or combined treatments. The effects of SBFI-26, docetaxel, or their combination on cell cycle arrest and apoptosis were assessed using flow cytometry. Western blotting was utilised to detect the expression of apoptosis-related proteins, namely cysteinyl aspartate-specific proteases 3 (Caspase3), B cell leukemia/lymphoma 2 (Bcl-2), and Bcl-2 associated X (Bax), while intracellular reactive oxygen species (ROS) levels were determined using a fluorescence spectrophotometer. Results: The IC50 values for SBFI-26 and docetaxel in inhibiting MDA-MB-231 cells were determined to be 106.1 μM and 86.14 nM, respectively. Significantly, the combination treatment augmented the proportion of G1 phase (apoptotic) cells by 3.67-fold compared to the control group (P < 0.0001). Furthermore, the apoptosis rate in the combination group was 2.59-fold higher than that in the docetaxel group (P < 0.0001) and demonstrated a significant increase of 1.82-fold compared with the SBFI-26 group (P < 0.001). Analyses revealed a decrease in the protein expression of Bcl-2, while Bax and Caspase3 exhibited an increase in the combination group for MDA-MB-231 cells. Moreover, the combined treatment group demonstrated a 2.97-fold increase (P < 0.0001) in ROS fluorescence intensity compared to the control group, a noteworthy 1.39-fold increase (P < 0.01) compared to the SBFI-26 treatment group, and a substantial 1.70-fold increase (P < 0.0001) compared to the docetaxel treatment group. Conclusion: These findings suggest that the co-administration of SBFI-26 with docetaxel effectively enhances apoptosis in triple-negative breast cancer MDA-MB-231 cells by elevating intracellular ROS levels.

Cyanidin-3-O-glucoside protects Zearalenone-induced in vitro maturation disorders of porcine oocytes by alleviating NOX4-dependent oxidative stress and endoplasmic reticulum stress in cumulus cells

Zearalenone (ZEN) is widely found in foodstuffs and has serious harmful effects on female fertility, especially in pigs. Cyanidin-3-O-glucoside (C3G), a type of anthocyanin, exists in most dark fruits and vegetables; it has many positive dietary effects including as an antioxidant, anti-inflammatory, or anti-apoptotic agent. However, the beneficial effects of C3G alongside ZEN-induced damage in porcine oocytes and the underlying molecular mechanism have not been investigated. In this work, porcine cumulus-oocyte complexes (COCs) were divided into Control (Ctrl), ZEN, ZEN + C3G (Z + C), and C3G, and treated for 44–46 h in vitro. The results showed that C3G could alleviate ZEN-induced disorders of first polar body (PBI) extrusion, abnormalities of spindle assembly, cortical granule distribution, and mitochondrial distribution; these results were produced via restoring transzonal projections (TZPs), and inhibiting nicotinamide adenine dinucleotide phosphate oxidase (NOX4)-dependent oxidative stress and ‘glucose regulatory protein 78/protein kinase-like endoplasmic reticulum kinase/α subunit of eukaryotic initiation factor 2α/activating transcription factor 4/C/EBP-homologous protein’ (GRP78/PERK/eIF2α/ATF4/CHOP)-mediated endoplasmic reticulum stress (ERS) during oocyte maturation. Moreover, the over-expression of NOX4 in cumulus cells could result in a significant increase in ROS levels and ER fluorescence intensity in oocytes. In conclusion, C3G promoted in vitro maturation of porcine oocytes exposed to ZEN via mitigating NOX4-dependent oxidative stress and ERS in cumulus cells. These results contribute to our comprehension of the molecular mechanisms underlying the protective effects of C3G against ZEN toxicity in porcine oocytes, and they provide a novel theoretical foundation and strategy for future applications of C3G in the improvement of female reproduction.

Novel Anthracene and Carbazole Based Aggregation Induced Enhanced Emission Active Schiff Base as a Selective Sensor for Cu2+ ions.

In present work our group has synthesized two novel Schiff-bases, Di-Carbazole based Schiff-base (DB-1) and Di-Anthracene based Schiff-base (DB-2) using condensation reaction and characterized thorough different spectroscopic techniques such as mass spectrometry, IR spectroscopy, 1H and 13C NMR spectroscopy. Furthermore, the AIE(Aggregation induced emission) studies were done using water-THF mixture. As compared to pure THF, the DB-2 showed a 17.8-fold increase in fluorescence intensity with a bathochromic shift of 64nm in 80% water: THF mixture. For DB-1increase was seen at 70% water-THF combination. The analysis of the dynamic light scattering (DLS) further supported this excellent AIEE (Aggregation induced enhanced emission) characteristic. Furthermore, the spectrofluorometric techniques were used to examine the capacity of both Schiff bases to detect the heavy metals. It was discovered that only DB-1, with a detection limit of 2.4 × 10-8 M, was selective for the Cu2+ ion, whereas DB-2 had no sensing capability for metal ions. The Job's plot was used to determine the stoichiometry ratio of the DB-1 with Cu2+ to further examine the process. It was discovered that the ratio was 1:1 (DB-1:Cu2+). Additionally, the association constant of DB-1 for Cu2+ was 5.1 × 1011 M-1, demonstrating the excellent binding affinity of DB-1 for the Cu2+ ion.

Formation of Volatile Pyrazinones in Amadori Rearrangement Products and Maillard Reaction Systems and the Major Formation Pathways.

Amadori rearrangement products (ARPs) are gaining more attention for their potential usage in the food flavor industry. Peptide-ARPs have been studied, but pyrazinones that were theoretically found in the Maillard reaction (MR) have not been reported to be formed from small peptide-ARPs. This study found four pyrazinones: 1-methyl-, 1,5-dimethyl-, 1,6-dimethyl-, and 1,5,6-trimethyl-2(1H)-pyrazinones in both MR and ARP systems. It was the first time 1-methyl-2(1H)-pyrazinone was reported, along with 1,5-dimethyl- and 1,5,6-trimethyl-2(1H)-pyrazinones being purified and analyzed by nuclear magnetic resonance for the first time. The primary formation routes of the pyrazinones were also proven as the reaction between diglycine and α-dicarbonyls, including glyoxal, methylglyoxal, and diacetyl. The pyrazinones, especially 1,5-dimethyl-2(1H)-pyrazinone, have strong fluorescence intensity, which may be the reason for the increase of fluorescence intensity in MR besides α-dicarbonyls. Cytotoxicity analysis showed that both Gly-/Digly-/Trigly-ARP and the three pyrazinones [1-methyl-, 1,5-dimethyl-, and 1,5,6-trimethyl-2(1H)-pyrazinones] showed no prominent cytotoxicity in the HepG2 cell line below 100 μg/mL, further suggesting that ARPs or pyrazinones could be used as flavor additives in the future. Further research should be conducted to investigate pyrazinones in various systems, especially the peptide-ARPs, which are ubiquitous in real food systems.

Direct fluorescence and spectrophotometric-based detection of azithromycin using fluorescein isothiocyanate: Method development and comparative analysis

New methods for the analysis of azithromycin (AZM) have been devised, employing direct fluorescence and spectrophotometric techniques. This research focused on the development and validation of these methods, especially based on the formation of an ion-pair complex with fluorescein isothiocyanate (FITC). The resulting complex enhanced the fluorescence intensity at a wavelength of 520 nm and the absorbance at 480 nm. The impact of different solvent compositions was investigated, with methanol and a 1:1 mixture of methanol and Milli-Q proving to be the most sensitive. The optimal FITC concentration was determined as 50 µg/ml, and the molar ratio of the AZM-FITC ion-pair complex was determined to be 1:1. Notably, an instantaneous increase in fluorescence intensity was observed, eliminating the need for incubation. The developed methods were validated for sensitivity, accuracy, and precision, with the fluorescence-based method demonstrating superior sensitivity and precision compared to the spectrophotometric method. Under optimum conditions, the fluorescence-based method achieved a linear range of 0–31.25 µg/ml with a limit of detection (LOD) of 0.41 µg/ml and a limit of quantification (LOQ) of 1.23 µg/ml., In contrast, the spectrophotometric method had an LOD of 0.82 µg/ml and an LOQ of 2.49 µg/ml. Additionally, the fluorescence-based method exhibited a narrower recovery range in artificial urine samples, suggesting higher precision in complex matrices. Overall, these methods offer rapid and sensitive AZM analysis with potential applications in diverse matrices such as biological samples post-extraction.