Florescent Probe Research Articles

A colorimetric and ratiometric fluorescent probe for recognizing fluoride ion based on new chromophore reaction

Fluoride ion plays crucial roles in many biological, chemical, medical and environmental processes. Constructing a highly sensitive florescent probe for naked-eye detection F− is of particular importance but remains challenging. In this work, we developed a colorimetric and ratiometric fluorescent probe of pyrrolopyrrole aza-BODIPY (PPAB)-based polymer (P1) for recognizing F−. In presence of F−, P1 showed obvious color change from green to yellow with absorption maximum blueshift from 670 nm to 340 nm. The weak emission of 697 nm changed to strong orange fluorescence with appearance of new broad emission with maximum bands at 520 and 642 nm. P1 was capable of sensitively and selectively detecting F− with a low detection limit of 0.07 μM. The sensing mechanism revealed that B–N bond cleavage and following hydrolysis of P1 induced by F− was responsible for the distinct colorimetric and ratiometric fluorescent signals. The results indicated that PPAB core was an efficient recognition unit for F− detection for the first time. Finally, P1-loaded silicone or test paper could detect F− by naked-eye signals. The probe can be successfully applied in real water samples to detect F− concentration.

Pyridine-2,6-Dicarboxylic Acid As a Facile and Highly Selective "Turn-Off" Fluorimetric Chemosensor for Detection of Cu (II) Ions in Aqueous Media.

Copper metal is third most abundant trace element in human body. Determination of Cu (II) ions is a burning topic in field of environment protection and food safety because of its significant impact on ecosystem. In this study, 2,6-pyridine dicarboxylic acid (PDA) has been explored as "turn-off" florescent probe for florescent detection of Cu (II) ions. This sensor showed highly selective complexing ability towards Cu (II) ions. Addition of aqueous solution of Cu (II) ions remarkably quenched the fluorescence intensity of PDA while, on contrary, there was no any prominent fluorescence quenching interference on addition of various metal ions. The binding mode of PDA and Cu (II) ions was determined as stoichiometry of 1:1 and it was further confirmed by single crystal XRD analysis. Mechanisms of static and dynamic quenching were confirmed by stern-volmer plot. Limit of detection (LOD) and limit of quantification (LOQ) for Cu (II) ions was calculated as 3.6 µM and 1.23 µM respectively, which is far below the acceptable value (31.5µM) according to the World Health Organization. The use of the sensor for detection of Cu (II) ions in real samples in aqueous media was also performed.

Completing a 4,486 km Multi-stage Ultramarathon Increases Arterial Stiffness and Alters Circulating Factors That Cause Endothelial Cell Dysfunction

Background: Guideline-based levels of aerobic exercise can improve vascular function, in part by decreasing arterial stiffness and oxidative stress, and increasing nitric oxide bioavailability. However, results from single-stage ultramarathons and ultra-endurance feats in modalities such as biking or triathlons suggest that excessive levels of aerobic exercise may impair vascular function. Some athletes will complete multi-day ultra-endurance events. One such example is the TransEurope FootRace (TEFR), a transcontinental ultramarathon in which participants cover 4,486 km in 64 days. However, the impact of this multi-stage ultramarathon on vascular function is unknown. Purpose: Here, we tested the hypotheses that completing the TEFR would increase arterial stiffness measured in vivo and alter circulating factors that increase reactive oxygen species (ROS) production and reduce the activation of endothelial nitric oxide synthase (eNOS) ex vivo. Methods: Data were obtained from 29 men and 1 woman (48±11 years of age) before and within 10 days of completing the TEFR. Arterial stiffness was assessed as carotid-femoral pulse wave velocity measured via MRI. Human aortic endothelial cells (HAECs) in culture were exposed to 10% subject plasma, then stained with florescent probes to detect basal ROS production (CellROX). Protein concentrations of phosphorylated(p)‐eNOS(S1177), a primary activation site of eNOS, were determined in the cultured HAECs via WES. Protein expression was normalized to total protein in the sample. P-eNOS relative to total protein was compared with total eNOS relative to total protein to determine activated eNOS. Results: Completing the TEFR caused a clinically significant 31% increase in carotid-femoral pulse wave velocity (pre-race: 610±37 cm/s, post-race: 800±99 cm/s; p=0.0374). ROS production increased by 40% in HAECs exposed to post-race plasma compared with pre-race plasma (pre-race: 1308±86 AU, post-race: 1836±131 AU; p<0.0001). P-eNOS(S1177) decreased by 71% in HAECs after compared with before the race (pre-race: 0.080±0.038 AU; post-race: 0.023±0.005 AU; p=0.0047), whereas total eNOS was unchanged (pre-race: 1.646±0.328 AU, post-race 1.634±0.6533 AU, p=0.9137), suggesting a marked decrease in eNOS activation after the race. Conclusions: These findings indicate that completing a 64-day, 4,486 km ultramarathon increases arterial stiffness and changes factors in the circulation that increase ROS production and decrease eNOS activation, denoting reduced endothelial cell functioning. Performing this level of prolonged, strenuous physical exercise impairs vascular function in healthy highly trained adults. K01HL153326; SCHU 2514/1-1; SCHU 2514/1-2. 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.

Multifunctional P(Py/NMPy) copolymer doped by DBSA for electronic, photoelectric and biomedical applications

Poly(N-methylpyrrole) (PNMPy) and Poly(Pyrrole/N-methylpyrrole) P(Py/NMPy) copolymer were prepared in an aqueous solution by interfacial polymerization in the presence of surfactive dopant dodecylbenzene sulphonic acid (DBSA). Structural, thermal, morphological and dielectric characterization studies were performed by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fluorescence (FL), Thermogravimetric (TG), Scanning electron microscopy (SEM-EDS), Atomic Force Microscope (AFM), Brunauer-Emmett-Teller (BET) surface area and LCR meter analyses. The antimicrobial activity of the samples was investigated by the Agar diffusion method. Characterization studies showed that both PNMPy and P(Py/NMPy) were semi-crystalline in nature, depending on the arrangement of methyl groups in the polymer chains and/or the DBSA doping. Also, due to the interaction between DBSA and polymer chains, the samples showed a significant FL emission intensity. In the surface analyses, phases of polymer matrix and DBSA were clearly observed. Dielectric analyses showed that the charge transport mechanisms of both samples are highly compatible with the correlated barrier hopping (CBH) model. The activation energies required for the hopping of the charge carriers in the PNMPy and P(Py/NMPy) chains were calculated as 0.23 and 0.17 eV, respectively. In antibacterial tests against the various bacteria species, PNMPy formed an inhibition zone between 26 and 29 mm, while the copolymer formed an inhibition zone between 29 and 32 mm. The results showed that P(Py/NMPy) copolymer is a multifunctional material that is very suitable for electronic and photoelectric applications, as well as biomedical ones relating to antibacterial agents, infection-resistant medical devices and florescent antibiotic probe.

Stability of Oxygen Nanobubbles under Freshwater Conditions

The use of nanobubbles (NBs) has gained significant attention in various applications (e.g., aeration in biological water treatment, water disinfection, membrane defouling, and ground water and sediment remediation) in recent decades because of their superior characteristics such as the improved mass transfer at the gas-liquid interfaces, their lifetime up to a couple of weeks, the formation of reactive oxygen species (ROS) with high oxidative potential. However, there is a lack of information about the effect of various factors on the stability of NBs for a long storage period under freshwater conditions. In this study, a comprehensive investigation was conducted to systematically examine the stability of oxygen NBs in water under various conditions which are closely related to a typical freshwater or the drinking water treatment. The oxygen NB stability in water was evaluated by monitoring the change in the bubble concentrations, size distribution, average diameter, and zeta potential for 60 days of storage time under different pH, hardness, ionic strength, natural organic matter (NOM), chlorine, and temperature conditions. In addition, the formation of hydroxyl radical (•OH) was investigated using disodium terephthalate which form fluorescent adducts with •OH in the presence of oxygen NBs. Among the parameters investigated, the impacts of cations, low pH, and high SUVA254 NOM on the stability of oxygen NBs were more significant than other conditions. The half-lives of oxygen NBs under various conditions follow the order Ca2+ < Na+ < pH 3 < high SUVA254 NOM < pH 5 < 30 °C. Oxygen NBs were more stable in softwater than hardwater. Oxygen NBs were relatively stable for 3 days regardless of pH. For a longer storage period, oxygen NBs disappeared faster at pH 3 than at high pH. High SUVA254 NOM destabilized NBs more than low SUVA254 NOM, indicating the impact of hydrophobicity on the NB stability. The temperature effect on the NB stability was negligible for a short storage time, while higher temperature destabilized oxygen NBs for a longer storage time. One of the main disappearance pathway of oxygen NBs in water was found to be coalescing, rising, and leaving the container, which would be promoted greatly by cations, low pH and NOM with high aromaticity. The formation of hydroxyl radical in NB solutions was detected at pH 3 by a florescent probe molecule. When oxygen NBs are released in water bodies, high calcium, high SUVA254 NOM, and low pH would significantly reduce the availability of NBs and their residence time in freshwater.

Pt deposited on magnetic CoFe2O4 nanoparticles: Double enzyme-like activity, catalytic mechanism and fast colorimetric sensing of dopamine

Pt deposited on magnetic CoFe2O4 nanoparticles (Pt/CoFe2O4) were prepared successfully via a two-step method. Pt/CoFe2O4 possessed the superior intrinsic peroxidase-like performance together with a weak oxidase-like activity and fast catalyzed to oxidize the colorless 3, 3, 5, 5-tetramethylbenzidine (TMB) into a blue oxTMB, accompanied with a fast color reaction only in 15 s. Dopamine (DA) molecules attached with phenol hydroxyl groups, have some reducibility, resulting in consuming H2O2 and causing the blue fade of the TMB solution. The peroxidase-like performance of Pt/CoFe2O4 was consistent with the Michaelis-Menten kinetics. The catalytic mechanism of Pt/CoFe2O4 from the generated active species (O2− and OH) in the catalytic system was comprehensively investigated by florescent probe and ESR. Valuably, due to the strong magnetism, Pt/CoFe2O4 is easy to be separated from liquid mixtures avoiding of the secondary pollution in practical application. The method realizes simple, rapid (15 s), sensitive and visual detection of H2O2 and dopamine, which has potential application in real-time monitoring of small biomolecules.

Bactericidal Activity of the Bacterial ATP Synthase Inhibitor Tomatidine and the Combination of Tomatidine and Aminoglycoside Against Persistent and Virulent Forms of Staphylococcus aureus.

Tomatidine (TO), a steroid alkaloid, exerts a strong bactericidal activity on the infection-persistent phenotype of Staphylococcus aureus, the small-colony variant (SCV), with a minimal inhibitory concentration (MIC) of 0.06 μg/ml. Also, the combination of TO to an aminoglycoside (AMG) shows a strong synergistic effect against prototypical (WT) S. aureus (MIC 0.06 μg/ml), which is otherwise unaffected by TO alone (MIC > 128 μg/ml). We have recently established that the ATP synthase (subunit AtpE) was the molecular target of TO and that TO reduces the production of ATP in S. aureus. The purpose of this study was to understand how TO and the TO-AMG combination exert bactericidal activities against S. aureus SCV and WT strains, respectively. The impact of TO and of the TO-gentamicin (GEN) combination on the membrane potential and generation of reactive oxygen species (ROS) were determined using florescent probes. GEN uptake in WT was assessed in the presence of TO. Virulence of SCV and WT strains as well as of in vitro-selected mutants showing resistance to TO or the TO-GEN combination was evaluated in a murine thigh infection model. TO causes a reduction in membrane potential in both WT and SCV, but significant amounts of ROS are only produced in SCVs. Besides, the presence of TO improves the uptake of GEN by the WT strain and the combination TO-GEN generated 2.5-folds more ROS in WT, compared to that induced by GEN alone. Under anaerobic conditions, WT adopts a fermentative slow-growth phenotype and becomes susceptible to TO even if used alone. In vivo, TO- or TO-GEN-resistant strains were significantly altered in their ability to colonize tissues. These results shed light on the mechanism of action of TO and its synergy with AMGs against S. aureus WT. TO bactericidal activity against SCVs is attributable to both a critical drop in the membrane potential accompanied by a substantial ROS production. In the WT, TO helps GEN uptake and ROS is also important for the synergy. Acquiring resistance to TO significantly impairs virulence. The residual ATP synthase activity of SCVs might represent the Achilles’ heel of persistent S. aureus.

Effects of Hydrogenized Water on Intracellular Biomarkers for Antioxidants, Glucose Uptake, Insulin Signaling and SIRT 1 and Telomerase Activity

Hydrogen has been shown in several clinical trials to be completely safe without adverse events and there are no warnings in the literature of its toxicity or adverse effects during long-term exposure. Molecular hydrogen has proven useful and convenient as a novel antioxidant and modifier of gene expression in many conditions where oxidative stress and changes in gene expression result in cellular damage. Our intracellular biomarker studies have shown that a hydrogenized water drink formula containing 2.6 ppm dissolved hydrogen was able to penetrate cellular membranes and function as an antioxidant in human liver cells (HePG2) utilizing the Cellular Antioxidant Assay (CAA). This assay uses the protection of a florescent probe as a marker for cellular damage by reactive oxygen species (ROS), such as peroxyl radical, and compares this to the known antioxidant standard, Quercetin. Using this system oxidative damage was reduced in a dose-dependent manner. One ml of hydrogenized water was found to possess antioxidant capacity equivalent to 0.05 µmole of quercetin. When examined in a human colon cell line (Caco-2 cells), hydrogenized water demonstrated a dose- and time-dependent permeability inhibition of an intracellular fluorescent glucose derivative (2-NBDG), indicating decreased glucose uptake. In another study, the impact of hydrogenized water on Akt phosphorylation (Ser473), a biomarker for insulin signaling, was monitored in human skeletal muscle cells. The hydrogenized water treatment markedly elevated the level of phosphorylation of Akt (Ser473) in a dose-dependent manner. The anti-aging effects of hydrogenized water were examined utilizing SIRT1 expression as a biomarker of aging in human umbilical cells (HUVECs). Hydrogenized water increased dose-dependent SIRT1 gene expression. Hydrogenized water also increased telomerase activity (an anti-aging biomarker in HUVEC cells) up to 148% when cells were treated with media containing 25% hydrogenized water formula. Increased telomerase activity caused by hydrogenized water may be able to protect telomeres from degradation, suggesting the possible use of hydrogenized water in therapeutic interventions of age-related diseases. These studies show that commercial hydrogenized water improved the levels or activities of a few intracellular biomarkers specific for antioxidant activity, glucose uptake, insulin signaling and SIRT 1 and telomerase activities. Industrial Relevance: The molecular hydrogen used in this study indicates that certain commercial sources of hydrogenized water can provide similar antioxidant and gene expression modifications seen in other sources of molecular hydrogen. The biomarkers evaluated here lend well to hydrogenized water’s biological activity relating to health conditions and aging.

The role of microglial inflammasome activation in pyroptotic cell death following penetrating traumatic brain injury

BackgroundTraumatic brain injury remains a significant cause of death and disability in the USA. Currently, there are no effective therapies to mitigate disability except for surgical interventions necessitating a need for continued research into uncovering novel therapeutic targets. In a recent study, we used a rodent model of penetrating traumatic brain injury known as penetrating ballistic-like brain injury (PBBI) to examine the role of innate immunity in post-traumatic secondary injury mechanisms. We previously reported that the inflammasome, a multiprotein complex composed of apoptosis-associated speck-like protein containing card and caspase-1, plays a role in secondary cell death mechanisms after PBBI, including inflammatory cell death (pyroptosis).MethodsIn the current study, we used flow cytometry analysis to evaluate activated microglia and CD11b-positive leukocytes after PBBI and assessed inflammasome activation and pyroptosis of specific cellular populations. Sprague-Dawley male rats underwent PBBI or sham-operated procedures and ipsilateral cortical regions processed for flow cytometry and cellular analysis. Flow cytometry results were compared using one-way ANOVA followed by Tukey’s multiple comparisons.ResultsAt 48 h following PBBI, there was an increase in activated microglia and infiltrating leukocytes compared to sham controls that were associated with increased caspase-1 activity. Using a florescent probe to identify caspase-1 activity and a fluorescent assay to determine cell viability, evidence for pyroptosis in CD11b+ cells was also determined. Finally, while post-traumatic treatment with an anti-ASC antibody had no effect on the number of activated microglia and infiltrating leukocytes, antibody treatment decreased caspase-1 activity in both resident microglia and infiltrating leukocytes and reduced pyroptotic CD11b+ cell death.ConclusionsThese results provide evidence for inflammasome activation in microglia and infiltrating leukocytes after penetrating traumatic brain injury and a role for pyroptotic cell death in the pathophysiology. In addition to inhibiting neuronal cell death, therapeutic treatments targeting inflammasome activation may also provide beneficial effects by reducing the potentially detrimental consequences of activated microglia and infiltrating CD11b+ leukocytes following penetrating traumatic brain injury.

Design and Synthesis of a Fluorescent Probe with a Large Stokes Shift for Detecting Thiophenols and Its Application in Water Samples and Living Cells.

A turn-on florescent probe (probe-KCP) was developed for highly selective detection of thiophenols based on a donor-excited photo-induced electron transfer mechanism. Herein, the synthesis of the probe, a chalcone derivative, through a simple straightforward combination of a carbazole-chalcone fluorophore with a 2,4-dinitrophenyl functional group. In a kinetic study of the probe-KCP for thiophenols, the probe displayed a short response time (~30 min) and significant fluorescence enhancement. In selection and competition experiments, the probe-KCP exhibited excellent selectivity for thiophenols over glutathione (GSH), cysteine (Cys), sodium hydrosulfide (NaSH), and ethanethiol (C2H5SH) in addition to common anions and metal ions. Using the designed probe, we successfully monitored and quantified thiophenols, which are highly toxic. This turn-on fluorescence probe features a remarkably large Stokes shift (130 nm) and a short response time (30 min), and it is highly selective and sensitive (~160-fold) in the detection of thiophenols, with marked fluorescence in the presence of thiophenols. probe-KCP responds to thiophenols with a good range of linearity (0–15 μM) and a detection limit of 28 nM (R2 = 0.9946) over other tested species mentioned including aliphatic thiols, thiophenol analogues, common anions, and metal ions. The potential applications of this carbazole-chalcone fluorescent probe was successfully used to determine of thiophenols in real water samples and living cells with good performance and low cytotoxicity. Therefore, this probe has great potential application in environment and biological samples.

Differentiating RNA from DNA by a molecular fluorescent probe based on the “door-bolt” mechanism biomaterials

Although excellent florescent probes have been developed for DNA, good probes for RNA remain lacking. The shortage of reported and commercial RNA probes is attributable to their severe interference from DNA. As DNA and RNA have similar structures but different functions, it has been an imperative challenge to develop RNA probes that differentiate from DNA. In this study, an NIR fluorescent probe, NBE, is described, which contains a bulky julolidine group that can fit in a spacious RNA pocket and emit intense fluorescence. However, NBE has no response to DNA, as it cannot intercalate into the double strands or even in the DNA minor groove. The sensing mechanism is similar to the effect of a door-bolt. NBE shows excellent performance in RNA sensing (outstanding photostability, high selectivity and fast response), whether in aqueous buffers, fixed cells or living cells. These findings might provide not only a potential imaging tool but also a new design strategy for the recognition of RNA while avoiding interference from DNA.

Intracellular Delivery of β-Galactosidase Enzyme Using Arginase-Responsive Dextran Sulfate/Poly-l-arginine Capsule for Lysosomal Storage Disorder.

β-Galactosidase (β-gal) is one of the important lysosomal enzymes that is involved in the breakdown of glycosphingolipids (e.g., GM1 ganglioside), and its deficiency leads to GM1 Gangliosidosis, a lysosomal storage disorder (LSD). Intracellular delivery of β-gal is one of the preferable methods to treat this kind of LSDs. However, it cannot permeate the cell membrane due to its intricate macromolecular nature, low stability, and degradation by endogenous proteases. To this end, we report efficient intracellular delivery of β-gal via arginase-responsive dextran sulfate/poly-l-arginine polymer capsules (DS/PA capsules). The therapeutic activity of β-gal enzyme has been assessed in two gene-deficient diseased cell lines, SV (β-galactosidase gene-deficient mouse fibroblast) and R201C (deficient human β-galactosidase gene-introduced mouse fibroblast), and in wild-type mouse fibroblast immortalized cell lines. The activity of β-gal enzyme has been estimated within cells by using fluorescein isothiocyanate-cholera toxin B as a florescent probe that illustrates the level of GM1 ganglioside, the β-gal substrate. We found 1.8-, 3.4-, and 2.8-fold reduction in the substrate level in R201C, SV, and wild-type mouse fibroblast, respectively, which confirms the release and therapeutic activity of β-gal enzyme inside the cells. Moreover, enzyme delivery in gene-deficient diseased cell lines (SV and R201C) via DS/PA capsules reduced the level of enzyme substrate to a normal endogenous level, which is present in untreated wild-type mouse fibroblast cells. We note that loading of β-gal enzyme within DS/PA capsules was estimated to be 3 mU per hundred capsules and more than 77% of β-gal is released within 12 h. Overall, these results highlight the potential of DS/PA capsules as an efficient delivery carrier for therapeutic enzyme.

Reaction-based fluorescent turn-on probe for selective detection of thiophenols in aqueous solution and living cells

A novel turn-on florescent probe based on a nucleophilic substitution reaction was developed for the detection of thiophenols in aqueous solution and in living cells. In this probe, 10-hydroxyl derivative of coumarin 6H was selected as fluorophore, 2, 4-dinitrophenlate moiety acted simultaneously as recognition unit and fluorophore quencher. This probe features a remarkable large Stokes shift (128 nm) and shows a highly selective detection process for thiophenols with significant fluorescence turn-on response. Notably, biothiols, aliphatic thiols, amino acids and reducing anions do not interfere with the sensing of thiophenols. The probe shows good linearity ranges with low detection limit of 36 nM for thiophenols. More importantly, it was successfully applied for practical detection of thiophenols in real water samples with a good recovery and imaging of thiophenols in living cells, demonstrating its practical application in environmental samples and biological systems.

Development of a convenient and supersensitive high-throughput screening system for genetically encoded fluorescent probes of small molecules using a confocal microscope

Monitoring the dynamic patterns of intracellular signaling molecules, such as inositol 1,4,5-trisphosphate (IP3) and Ca2+, that control many diverse cellular processes, provides us significant information to understand the regulatory mechanism of cellular functions. For searching more sensitive and higher dynamic range probes for signaling molecules, convenient and supersensitive high throughput screening systems are required. Here we show the optimal “in Escherichia coli (E. coli) colony” screening method based on the twin-arginine translocase (Tat) pathway and introduce a novel application of a confocal microscope as a supersensitive detection system to measure changes in the fluorescence intensity of fluorescent probes in E. coli grown on an agar plate. To verify the performance of the novel detection system, we compared the changes detected in the fluorescent intensity of genetically encoded Ca2+ indicator after Ca2+ exposure to two kinds of conventional fluorescence detection systems (luminescent image analyzer and fluorescence stereomicroscope). The rate of fluorescence change between Ca2+ binding and unbinding detected by novel supersensitive detection system was almost double than those measured by conventional detection systems. We also confirmed that the Tat pathway-based screening method is applicable to the development of genetically encoded probes for IP3. Our convenient and supersensitive screening system improves the speed of developing florescent probes for small molecules.

An AIE and ICT based NIR florescent probe for cysteine and homocysteine

A combination of aggregation-induced emission and intramolecular charge transfer was achieved by using a triphenylamine analogue and a dicyanovinyl moiety as the electron donating and accepting units, respectively. Hence, we designed and synthesized a probe with a D-π-A framework as a near-infrared fluorescence turn-on probe for biothiols (cysteine and homocysteine). Owing to the remarkable intramolecular charge transfer effect as well as intramolecular rotations associated with the donor moiety, the probe exhibits extremely weak fluorescence, which becomes a good starting point for developing fluorescence “turn-on” probes. Upon reaction with cysteine or homocysteine utilizing the dicyanovinyl moiety, the intramolecular charge transfer character was weakened, and the reacting products were observed to aggregate in aqueous solutions, resulting in the aggregation-induced emission effect with red fluorescence at 651 and 656 nm, respectively. Hence, the probe could be used as a fluorescence “turn-on” sensor for cysteine and homocysteine, with the sensing time of less than 4 min and the detection limits of 8.4 μM and 5.7 μM towards cysteine and homocysteine, respectively. The probe could distinguish cysteine and homocysteine from glutathione. The sensing mechanism was systematically investigated by employing high resolution mass spectrometry, 1H NMR and density functional theory calculations as well as checking the solvent viscosity dependent fluorescence, and thus the nucleophilic addition products, the intramolecular charge transfer character, and the aggregation-induced emission behaviour were clearly elucidated. It is noteworthy that the low cytotoxicity, the intrinsic aggregation-induced emission nature and near-infrared emissions enable the application of the probe in living cell imaging.

Anti-Proliferative Activity of λ-Carrageenan Through the Induction of Apoptosis in Human Breast Cancer Cells.

BackgroundSulfated Polysaccharides (SPs) possess spectrum of pharmacological and therapeutic properties that could attributed to their origins variation, chemical structures and biological activities. Various studies have shown the impact of SPs on proliferation in different cancer cell lines.ObjectivesIn this study, we have evaluated the biological effects of λ-carrageenan, a highly SP, extracted from the red seaweed Laurencia papillosa, on MDA-MB-231 cancer cell line.Materials and MethodsMDA-MB-231 cells have treated with λ-carrageenan, the viability and apoptosis have assessed by the appropriate florescent probes on flow cytometer. The expression levels of mRNA of apoptotic genes have detected by real-time PCR analysis.ResultsOur results have indicated that the signaling pathway of λ-carrageenan inhibited the proliferation of MDA-MB-231 cells by up-regulating the pro-apoptotic genes caspase-8, caspase-9, caspase-3 which have been resulting the increased levels of active caspase-3 protein. Furthermore, This SP had that capacity to disrupt the mitochondrial function by altering the bax/bcl-2 ratio of expression which has considered an important element in apoptosis induction. ConclusionsThe presented results have signposted that λ-carrageenan was a promising bioactive polymer which could be a potential candidate in preventing or treating breast cancer.

Mo1833 Human Alpha-Defensin 6 Regulated by the Cooperation of Beta-Catenin and ATOH1, Might Be the Pathogenesis of Crohn's Disease

Recommended therapy of bacterial infection is generally based on in vitro susceptibility of an organism to an infecting organism. Yet drug bioavailability based on solubility, protein binding and other factors along with host resistance and inflammatory-immune response importantly alter response to treatment. The objective of the study was to establish in vivo animal model to study antimicrobial therapy of C. difficile infection. C. difficile isolate with hyper-virulent factors (toxin A/B plus binary toxin and 18 base pair deletion in tcdC gene) was used in the study. The cultured C. difficile was stained with near infrared (NIR) dye. Stained C. difficilewere determined by using fluorescent microscope and confocal microscope. To monitor stained bacterial trafficking in the gut animals were imaged in real-time. The intestines from treated animals were dissected at the end of imaging study. The bacterial signal intensity and migration pattern were recorded and compared. C. difficile toxin secretion in the different segment of GI system was analyzed. Results showed the C. difficile can be stained by NIR dye. Stained bacteria can be imaged by NIR camera system to track the C. difficile traffic in the gut in real-time. Untreated control animal has different bacteria migration pattern than the animal with C. difficile infection treated with ciprofloxacin. TheNIR florescent probe can be used to visualize C. difficile trafficking in the gastrointentinal tract through culturing, staining and imaging. Fig. 1. Confocal images of C. difficile. Viable bacterial stained with NIR dye (A. Red) and dead bacterial determined with Sytox green (B. Green). Stain efficiency was determined by co-localized all cells (C. Green) and NIR (C. Red). Confocal microscope analyzed NIR dye binding at subcellular level (D). Red and green represent NIR and cell nuclei, respectively. Results demonstrate C. difficile can be stained by NIR dye. Most bacteria remain viable after the staining procedure.

Development of a loop-mediated isothermal amplification of DNA by using florescent probe in detection of salmonella

Development of a loop-mediated isothermal amplification of DNA by using florescent probe in detection of salmonella

Synthesis and Characterization of Tb3+-Doped HA Nanoparticles Used as Biological Florescent Probe

A biological florescent probe Tb3+-doped hydroxyapatite (HA) nanoparticles was synthesized by hydrothermal method. During this process, L-lysine was added as a template, and different amount of Tb3+was added to investigate the influence on the florescent property. The products were characterized by using XRD, TEM and PL. Results showed that with Tb3+adding, the size and crystallinity of nanoparticles were changed, while their maximum emission intensity was at 544 nm and the best content of Tb3+was 2 mol%.

Poly(ethyl cyanoacrylate) nanoparticles for brain delivery of andrographolide

The limitations imposed by the blood-brain barrier (BBB) and the non-selective distribution of drugs in the brain have hindered the effective treatment of brain diseases and may result in severe side effects on the normal brains. The aim of this work was to deliver natural molecules into nanoparticles capable to provide sustained and controlled drug release, improved biodistribution and therapeutic efficacy for Alzheimer's Disease (AD) prevention and therapy. Novel fluorescent polymeric nanoparticles to target brain tissues were designed and optimised to follow their in vivo distribution as new strategies to cross the BBB, namely ethylcyanoacrylate nanospheres (ECA-NSs) coated with polysorbate 80. They were prepared by emulsion polymerization method using fluorescein isothiocyanate linked to dextran as a florescent probe [1]. NSs were characterized in terms of dimension, polydispersity, zeta potential, morphology, encapsulation efficacy, loading capacity and stability of probe by DLS, TEM and HPLC-DAD-FLD, respectively. A study after intracerebral injection of nanoparticles in nucleus basalis magnocellularis of rats, colynergic neuronal location, evidenced that NSs did not induce inflammatory response. NSs were also administered intraperitoneally and intravenously to anaesthetized rats to evaluate their biodistribution by fluorescent microscope images. The biodistribution studies revealed that NSs were able to cross the BBB and reach brain tissue, as a consequence they were loaded with andrographolide, a major diterpenoid of Andrographis paniculata (Burm. f.) Nees, whose clinical utility for the treatment of inflammation-related neurodegenerative disorder has been demonstrated [2]. ECA-NSs were produced with good yields, suitable for the intraperitoneally administration (mean diameter ≤300nm; PDI 0.2), with a sphere-like shape and a good encapsulation efficacy. The developed nanocarriers represent a valuable targeting system for AD therapy.