Neutral Red (neutral + red)

Distribution by Scientific Domains


Selected Abstracts


Development of Novel Glucose and Pyruvate Biosensors at Poly(Neutral Red) Modified Carbon Film Electrodes.

ELECTROANALYSIS, Issue 8 2006
Application to Natural Samples
Abstract Amperometric biosensors based on the corresponding oxidase enzyme with poly(neutral red) redox mediator have been developed for the determination of glucose and pyruvate. The enzymes have been immobilized on top of poly(neutral red) modified carbon film electrodes with glutaraldehyde as the cross-linking agent. The biosensors were characterized by cyclic voltammetry and by electrochemical impedance spectroscopy. The glucose biosensor exhibited a linear response in the range 90,,M to 1.8,mM with a detection limit of 22,,M and the pyruvate biosensor in the range 90 to 600,,M with a detection limit of 34,,M. The relative standard deviations were found to be 2.1% (n=3) and 2.8% (n=4) respectively. The interference effects of various compounds were also studied. The glucose content of several types of wine and the amount of pyruvate in onion and garlic were determined and the results were compared with those obtained by standard spectrophotometric methods. [source]


Reactive oxygen species formation is not enhanced by exposure to UMTS 1950 MHz radiation and co-exposure to ferrous ions in Jurkat cells

BIOELECTROMAGNETICS, Issue 7 2009
Francesca Brescia
Abstract This study was designed to assess if radiofrequency (RF) radiation induces oxidative stress in cultured mammalian cells when given alone or in combination with ferrous ions (FeSO4). For this purpose the production of reactive oxygen species (ROS) was measured by flow cytometry in human lymphoblastoid cells exposed to 1950 MHz signal used by the third generation wireless technology of the Universal Mobile Telecommunication System (UMTS) at Specific Absorption Rate of 0.5 and 2.0 W/kg. Short (5,60 min) or long (24 h) duration exposures were carried out in a waveguide system under strictly controlled conditions of both dosimetry and environment. Cell viability was also measured after 24 h RF exposure using the Resazurin and Neutral Red assays. Several co-exposure protocols were applied to test if RF radiation is able to alter ROS formation induced by FeSO4 (RF given before or concurrently to FeSO4). The results obtained indicate that non-thermal RF exposures do not increase spontaneous ROS formation in any of the experimental conditions investigated. Consistent with the lack of ROS production, no change in cell viability was observed in Jurkat cells exposed to RF radiation for 24 h. Similar results were obtained when co-exposures were considered: combined exposures to RF radiation and FeSO4 did not increase ROS formation induced by the chemical treatment alone. In contrast, in cultures treated with FeSO4 as positive control, a dose-dependent increase in ROS formation was recorded, validating the sensitivity of the method employed. Bioelectromagnetics 30:525,535, 2009. 2009 Wiley-Liss, Inc. [source]


Lable-Free Electrochemical DNA Sensor Based on Gold Nanoparticles/Poly(neutral red) Modified Electrode

ELECTROANALYSIS, Issue 6 2010
Keying Zhang
Abstract We present a new strategy for the label-free electrochemical detection of DNA hybridization based on gold nanoparticles (AuNPs)/poly(neutral red) (PNR) modified electrode. Probe oligonucledotides with thiol groups at the 5-end were covalently linked onto the surface of AuNPs/PNR modified electrode via S-Au binding. The hybridization event was monitored by using differential pulse voltammetry (DPV) upon hybridization generates electrochemical changes at the PNR-solution interface. A significant decrease in the peak current was observed upon hybridization of probe with complementary target ssDNA, whereas no obvious change was observed with noncomplementary target ssDNA. And the DNA sensor also showed a high selectivity for detecting one-mismatched and three-mismatched target ssDNA and a high sensitivity for detecting complementary target ssDNA, the detection limit is 4.210,12,M for complementary target ssDNA. In addition, the DNA biosensor showed an excellent reproducibility and stability under the DNA-hybridization conditions. [source]


Poly(neutral red): Electrosynthesis, Characterization, and Application as a Redox Mediator

ELECTROANALYSIS, Issue 12 2008
Rasa Pauliukaite
Abstract The synthesis by electropolymerization, the characterization, and applications of poly(neutral red) (PNR), including as a redox mediator, are reviewed. PNR's high electrical conductivity and its redox characteristics have led to special applications of the polymer, and it has been used for the development of electrochemical and optical sensors. Moreover, the attractive properties of PNR allow it to be applied in the development of electrochemical biosensors. Future perspectives are indicated. [source]


Development of Novel Glucose and Pyruvate Biosensors at Poly(Neutral Red) Modified Carbon Film Electrodes.

ELECTROANALYSIS, Issue 8 2006
Application to Natural Samples
Abstract Amperometric biosensors based on the corresponding oxidase enzyme with poly(neutral red) redox mediator have been developed for the determination of glucose and pyruvate. The enzymes have been immobilized on top of poly(neutral red) modified carbon film electrodes with glutaraldehyde as the cross-linking agent. The biosensors were characterized by cyclic voltammetry and by electrochemical impedance spectroscopy. The glucose biosensor exhibited a linear response in the range 90,,M to 1.8,mM with a detection limit of 22,,M and the pyruvate biosensor in the range 90 to 600,,M with a detection limit of 34,,M. The relative standard deviations were found to be 2.1% (n=3) and 2.8% (n=4) respectively. The interference effects of various compounds were also studied. The glucose content of several types of wine and the amount of pyruvate in onion and garlic were determined and the results were compared with those obtained by standard spectrophotometric methods. [source]


Characteristics of okadaic acid,induced cytotoxic effects in CHO K1 cells

ENVIRONMENTAL TOXICOLOGY, Issue 6 2003
C. Huynh-Delerme
Abstract This article reports the results of investigations into the process of cell death induced in the Chinese hamster ovary cell K1 subclone (CHO K1) by okadaic acid (OA), a hydrophobic polyether produced by marine dinoflagellates. The IC50 was about 13 nM OA after 24 h of treatment, as determined using neutral red. With the MTT assay, the IC50 was 25 nM, although in this case 25% of the initial staining was still observed at 100 nM. Hoechst staining showed that mitotic figures accumulated at 12 nM OA after a 24- or 48-h treatment. In experiments limited to a 3-day treatment without changing the medium, CHO K1 cells were engaged in the death process at 50 nM OA after about 20 h and at 10 nM OA after 48 h. In many cells nuclear fragmentation that resulted in the apparent appearance of vesicles correlated with increasing cellular volume. But additional cell fragmentation was not observed with any treatment, and the chromatin material seemed to progressively disappear inside the cells. DNA fragmentation was analyzed by electrophoresis and with the TUNEL technique. With both techniques, the DNA was fragmented by 48 h in both 25 and 50 nM OA. Electrophoresis showed that both adherent and nonadherent cells were affected. Annexin-positive/ propidium iodide (PI),negative cells were rarely observed after OA treatment. Some were seen under the scanning cytometer after 20 h at 50 nM OA or after 48 h at 10 nM OA, but they were never detected by flow cytometry. Most of the time scanning cytometry showed either unstained cells or PI-positive (annexin-positive or -negative) cells (48 h, 50 nM, or 72 h, 10 nM). Flow cytometry cytograms showed two cell subpopulations: one composed of a majority of smaller cells, the other of larger cells. The larger cells markedly decreased with time and OA treatment (50 and 100 nM). Stained-cell counting showed that all cells that stained were both annexin- and PI positive and that most PI-positive cells were smaller. Ki67 antigen labeling showed the proliferative activity of CHO K1 cultures but also demonstrated the loss of this activity in smaller cells treated with 50 nM OA for 48 h. We concluded that in our culture conditions the main OA target within CHO K1 cultures was dividing cells. Our results suggest that cells with disturbed metaphase,anaphase enter apoptosis, leading to necrotic daughter cells. 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 383,394, 2003 [source]


Anthracene photoinduced toxicity to plhc-1 cell line (Poeciliopsis lucida) and the role of lipid peroxidation in toxicity

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000
Jonghoon Choi
Abstract Many polycyclic aromatic hydrocarbons (PAHs) are acutely toxic to fish and other aquatic organisms in the presence of solar ultraviolet radiation (SUVR) of environmentally realistic intensities. In the present study, the photoinduced toxicity of a PAH (anthracene; ANT) to topminnow hepatoma cell line (PLHC-1) was assessed. After the toxicity was characterized, the role of lipid peroxidation in PAH photoinduced toxicity was examined by measuring lipid peroxidation products and by assessing the effect of lipid peroxidation antagonist (Trolox) treatment. In cytotoxicity tests using two assays (MTT, neutral red), the SUVR/ANT treatment elicited toxicity to PLHC-1 cells in a concentration- and SUVR (exposure duration and intensity)-dependent pattern. As found in previous organism-level studies, no significant cytotoxicity was observed in the cells exposed either to fluorescent light/ANT or to SUVR only. The SUVR/ANT treatment elicited the lipid peroxidation process and Trolox pretreatment significantly reduced SUVR/ANT-induced cell mortality. Microscopic observation showed that Trolox pretreatment relieved the SUVR/ANT-inflicted damage, such as cell shrinkage and membrane disruption. Together with a recent finding in our lab that increased production of superoxide anion and a lipid peroxidation product (malondialdehyde) was found in SUVR/ANT-treated fish microsomes, the present study suggests that reactive oxygen radical-induced lipid peroxidation is an important factor in PAH photoinduced toxicity to fish. [source]


Food plaquette digestion in the ciliated protozoan Hyalophysa chattoni

INVERTEBRATE BIOLOGY, Issue 2 2001
Stephen C. Landers
Abstract. The digestion of food plaquettes in the ciliated protozoan Hyalophysa chattoni was analyzed by light and electron microscopy. Through the use of nigrosin as a tracer for light microscopy and polystyrene microparticles for electron microscopy, we have demonstrated that food plaquettes transform to late-stage digestive vesicles. Eventually, in the phoront, some of the late-stage vesicles merge to form larger fusion vesicles, which are retained in the peripheral cytoplasm of the ensuing feeding stage. After the feeding stage settles and encysts, these vesicles are either retained by the daughter cells or are left in the divisional cyst as residual bodies. Food plaquettes, digestive vesicles, and fusion vesicles stain positively with neutral red and acridine orange, indicating an acidic pH. These results portray a unique digestive pathway in which stored, undigested material is reorganized into larger fusion vesicles as the cell prepares for additional feeding. [source]


Kojic acid reduces the cytotoxic effects of sulfur mustard on cultures containing human melanoma cells in vitro

JOURNAL OF APPLIED TOXICOLOGY, Issue 6 2001
C. N. Smith
Abstract In vivo experiments have shown that melanocytes are more sensitive than keratinocytes to the cytotoxic effects of sulfur mustard when it is applied topically to pig skin.1 It has been hypothesized that this is caused by the uncoupling of the melanogenic pathway by depletion of cellular glutathione, resulting in the uncontrolled production of cytotoxic quinone free-radical species by tyrosinase.2. In the present study, the feasibility of blocking the melanogenic pathway as a means of reducing the cytotoxicity of sulfur mustard was evaluated using kojic acid. Kojic acid is a topically applied depigmenting agent that exerts its effect by acting as a slow-binding, competitive inhibitor of tyrosinase.3 Preincubation of G361 pigmented melanoma cells and mixed cultures of G361 cells and SVK keratinocytes with 2.5 mM kojic acid resulted in significant increases in the viability of these cultures as determined by neutral red (NR) and gentian violet (GV) dye binding assays for up to 48 h following exposure to 50 M sulfur mustard. The highest levels of protection were seen in the G361 cultures, with a 26.8% increase in culture viability (NR assay) compared with the sulfur-mustard-only controls at 24 h. Preincubation of SVK cells alone with kojic acid resulted in lower increases in viability (2.5% at 24 h by the NR assay). Inhibition of the melanogenic pathway reduces the sensitivity of cultures containing pigment cells to sulfur mustard. Crown copyright 2001. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source]


Comparative effectiveness of hand and ultrasonic instrumentations in root surface planing in vitro

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 3 2004
Mahmood Khosravi
Abstract Background/aims: A variety of techniques are employed for planing and scaling of the superficial root surfaces, of which hand and ultrasonic instrumentations have been preferentially used in routine periodontics clinics. This study was undertaken to compare the effectiveness of ultrasonic scalers and hand curettes in facilitating fibroblast attachment to the scaled root surfaces. Materials and Methods: Sixteen patients with periodontally involved teeth and nine subjects without periodontal diseases (control subjects) were selected. Two single-rooted teeth were extracted from each subject. Mesial and distal surfaces of teeth were selected in treated and untreated groups, respectively. The mesial surface of each tooth was randomly chosen to be treated either by hand curettes or ultrasonic instrumentation. The degree of cell attachment on the root surfaces of treated and untreated groups from control subjects and patients was then determined by the use of a gingival fibroblast line established and employed at early passages. The attachment and proliferation of gingival fibroblasts on the root surfaces were evaluated using neutral red assay and scanning electron microscopy (SEM). Results: Fibroblast survival and proliferation on the surfaces of untreated periodontally involved roots were found to be significantly lower compared with control untreated surfaces (p<0.0001) or treated surfaces from patients (p<0.0001). No significant difference, however, was observed between root surfaces treated either by hand curettes or ultrasonic scalers. Conclusion: These results indicate the beneficial effectiveness of both techniques in root treatment and planing. [source]


Ethanol Can Modify the Effects of Certain Free Radical-Generating Systems on Astrocytes

ALCOHOLISM, Issue 4 2004
B. Gonthier
Abstract: The central nervous system is vulnerable to oxidative stress, especially when a toxicant can modify the physiological balance between anti- and pro-oxidant mechanisms. Among brain cells, astrocytes seem less vulnerable than neurons, but their impairment can dramatically affect neurons because of their protective role toward neurons. Ethanol is able to stimulate the formation of reactive oxygen species and modify the activity of most of the antioxidant agents. However, ethanol can react with the OH radical to form the ,-hydroxyethyl radical, which is considered to be less toxic. Ethanol also can stimulate H2O2 degradation through catalase activation. This study, therefore, sought to determine whether ethanol affected the sensitivity of astrocytes exposed to various free radical-generating systems. The cellular impact of such exposure was assessed by assays exploring cytotoxicity (i.e., NR (neutral red) and MMT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetiazolium bromide) reduction assays) and genotoxicity (comet assay) induced by these treatments. DNA alterations were evaluated by single-cell gel electrophoresis (comet assay), considered a precocious biomarker of intracellular alterations. After concomitant exposure to H2O2 and ethanol, the viability of astrocytes decreased significantly whereas the mean percentage of DNA in the tail increased, reflecting DNA damage (H2O2 was either directly added to the culture medium or endogenously produced from menadione). Ethanol also reduced the loss of viability and DNA alterations after exposure to OH radicals produced by a Fenton system. The exposure to a xanthine/xanthine oxidase system had the same effect. [source]


Preparation and adsorption of novel cellulosic fibers modified by , -cyclodextrin

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 4 2008
Youyi Xia
Abstract Novel cellulosic fibers modified by , -cyclodextrin (CFEC) were prepared for adsorption for heavy metal ions like copper (II) and organic dye like neutral red from their aqueous solutions. The modified cellulosic fibers gave higher copper ion adsorption, and showed copper ion uptake values of 6.24,mg/g at 293C, as against no adsorption for unmodified cellulosic fibers. Adsorption isotherm model indicated the adsorption of the novel modified fibers for heavy metal ions best fitted for Langmiur model. The adsorption was an exothermic reaction, and the reaction caloric was 6.295,kJ/mol. Copper ions could form a 7:4 complex with , -cyclodextrin (, -CD). The novel modified cellulosic fibers could also form inclusion complexes with neutral red via , -CD molecules. In addition, it was found that the novel modified cellulosic fibers had nearly the same mechanical and thermal properties as the unmodified cellulosic fibers because the modification did not destroy the main chain of cellulose molecules. Copyright 2008 John Wiley & Sons, Ltd. [source]