Fluorescent Chitosan Modified with Heterocyclic Aromatic Dyes.
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ABSTRACT:
SUBMITTER: Kaczmarek H
PROVIDER: S-EPMC8585458 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole (assigned as IBm, BTh, and BOx) has been studied. The thermal properties of these CS derivatives have been determined using the Thermogravimetric Analysis coupled with the Fourier Transform Infrared spectroscopy of volatile degradation products. The influence of UV radiation on the thermal resistance of modified, fluorescent chitosan samples was also investigated. Based on the temperature onset as well as the decomposition temperatures at a maximal rate, IBm was found to be more thermally stable than BOx and BTh. However, this dye gave off the most volatile products (mainly water, ammonia, carbon oxides, and carbonyl/ether compounds). The substitution of dyes for chitosan changes its thermal stability slightly. Characteristic decomposition temperatures in modified CS vary by a few degrees (<10 °C) from the virgin sample. Considering the temperatures of the main decomposition stage, CS-BOx turned out to be the most stable. The UV irradiation of chitosan derivatives leads to minor changes in the thermal parameters and a decrease in the number of volatile degradation products. It was concluded that the obtained CS derivatives are characterized by good resistance to heat and UV irradiation, which extends the possibilities of using these innovative materials.
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Project description:Two new 2D Cd(II)-based coordination polymers (CPs), viz. [Cd₂(H₂L)₂(2,2'-bipy)₂] (1) and [Cd(L)0.5(phen)·0.5H₂O] (2), have been constructed using ethylene glycol ether bridging tetracarboxylate ligand 5,5'(4,4'-phenylenebis(methyleneoxy)) diisophthalic acid (H₄L). Both CPs behaved as profound fluorescent sensor for Fe3+ ion and nitro-aromatics (NACs), specifically 2,4,6-trinitrophenol (TNP). The stability at elevated temperature and photocatalytic behaviors of both 1 and 2 for photo-decomposition of aromatic dyes have also been explored. An attempt has been made to explore the plausible mechanism related with the decrease in fluorescence intensity of 1 and 2 in presence of NACs using theoretical calculations. Additionally, the probable mechanism of photo catalysis by 1 and 2 to photo-degrade aromatic dyes has been explained using density of states (DOS) calculations.
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Project description:The simultaneous measurement of gene expression for thousands of genes in a single analysis by the microarray technology allows researchers to describe transcriptomes in various samples of interest. Problems with variation in data quality derived from microarray experiments are well known and might result from poor RNA quality, background problems, or sub optimal signal strength. To assess variation due to the fluorescent dye chosen, three different dye pairs were tested for labelling of cDNA in gene expression analysis experiments on a porcine immune focused oligonucleotide microarray (POM3). This in-house oligonucleotide microarray allowed a direct comparison of background fluorescence, Median signal intensities, numbers of spots detected, and resistance to photobleaching between different dye pairs. We tested Alexa Flour 546/647, Cy3/Cy5 as well as Oyster 550/650 all from Genisphere Inc., Hatfield, PA, USA. Keywords: Comparison of fluorescent dyes
2009-01-16 | GSE4855 | GEO
Project description:The simultaneous measurement of gene expression for thousands of genes in a single analysis by the microarray technology allows researchers to describe transcriptomes in various samples of interest. Problems with variation in data quality derived from microarray experiments are well known and might result from poor RNA quality, background problems, or sub optimal signal strength. To assess variation due to the fluorescent dye chosen, three different dye pairs were tested for labelling of cDNA in gene expression analysis experiments on a porcine immune focused oligonucleotide microarray (POM3). This in-house oligonucleotide microarray allowed a direct comparison of background fluorescence, Median signal intensities, numbers of spots detected, and resistance to photobleaching between different dye pairs. We tested Alexa Flour 546/647, Cy3/Cy5 as well as Oyster 550/650 all from Genisphere Inc., Hatfield, PA, USA. Keywords: Comparison of fluorescent dyes Each dye pairs were hybridized on two slides. The same two samples were compared on all the slides used in the present study. The liver sample from a healthy animal was labeled with the high wavelength dyes (Oyster 650/Alexa 647/Cy5) and the liver sample from the sick animal was labeled with the low wavelength dyes (Oyster 550/Alexa 546/Cy3). Each slide was scanned 3 times, immediately after hybridization (first round), after 1 month of storage in darkness and after 24 hours on the bench (12 hours of daylight and 12 hours of artificial light). Total RNA from the infected and control liver samples were extracted using RNeasy midi kit (Qiagen, Denmark) and DNase treated using RNase-Free DNase Set (Qiagen). 3DNATM Array 900 expression array detection kits (Genisphere Inc.) were used for the labeling and cDNA synthesis reaction of the RNA in the present study. Three different pairs of fluorescent dyes Oyster 550/650 (Genisphere Inc.), Alexa 546/647 (Genisphere Inc.), and Cy3/Cy5 (Genisphere Inc.) were used in separate labeling reactions. Labeling was done according to the manufacturers protocol for large-scale cDNA synthesis. For the cDNA synthesis 9.2µg total RNA from each liver sample was used and mixed with 20U AmpliQ RTenzyme and 10x first strand buffer (Bie og Berntsen, Rødovre, Denmark). Hybridization and washing were performed according to the manufacturers instructions (Genisphere) using Corning hybridization chambers. For one cDNA hybridization reaction; 6.5µl cDNA from each synthesis, 0.5µl Salmon sperm (10µg/µl) and 13.5µl 2 x Formamide-Based Hybridization Buffer (3DNA Array 900, Genisphere) was used. A total hybridization mix of 29µl was applied under a 22I x 25 mm LifterSlip (Erie Scientific, Portsmouth, NH, USA) carefully avoiding air bubbles. Slides were incubated at 44oC in a water bath over night. Wash buffer 1 (3DNA Array 900, Genisphere) was preheated to 44oC for the post cDNA hybridization wash. For two 3DNA hybridization reaction mixes; 2.5µl of each Capture reagent and 26µl SDS-Based hybridization buffer was mixed to a final volume of 52µl. 26µl 3DNA hybridization mix was applied to each slide, and incubated in darkness in a water bath at 50oC for 4 hours. Wash buffer 1 was preheated to 60oC for the post 3DNA hybridization wash. Slides were scanned on a CCD ArrayWoRxe auto (Applied Precision, Issaquah, WA, USA) using different exposure times (0.3 for 595 nm and 1.2 for 685 nm).
2010-05-06 | E-GEOD-4855 | biostudies-arrayexpress
Project description:Herein, we present a new synthetic route to cyanine-based heterobifunctional dyes and their application as fluorescent linkers between polymers and biomolecules. The synthesized compounds, designed in the visible spectral range, are equipped with two different reactive groups for highly selective conjugation under physiological conditions. By applying indolenine precursors with functionalized benzenes, we achieved water-soluble asymmetric cyanine dyes bearing maleimido and N-hydroxysuccinimidyl functionalities in a three-step synthesis. Spectroscopic characterization revealed good molar absorption coefficients and moderate fluorescence quantum yields. Further reaction with polyethylene glycol yielded dye-polymer conjugates that were subsequently coupled to the antibody cetuximab, often applied in cancer therapy. Successful coupling was confirmed by mass shifts detected by gel electrophoresis. Receptor-binding studies and live-cell imaging revealed that labeling did not alter the biological function. In sum, we provided a successful synthetic pathway to rigid heterobifunctional cyanine dyes that are applicable as fluorescent linkers, for example, for connecting antibodies with macromolecules. Our approach contributes to the field of bioconjugation chemistry, such as antibody-drug conjugates by combining diagnostic and therapeutic approaches.
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Project description:2-Amino-9H-pyrido[2,3-b]indole (A?C) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are carcinogenic heterocyclic aromatic amines (HAA) that arise during the burning of tobacco and cooking of meats. UDP-glucuronosyltransferases (UGT) detoxicate many procarcinogens and their metabolites. The genotoxic N-hydroxylated metabolite of A?C, 2-hydroxyamino-9H-pyrido[2,3-b]indole (HONH-A?C), undergoes glucuronidation to form the isomeric glucuronide (Gluc) conjugates N(2)-(?-d-glucosidurony1)-2-hydroxyamino-9H-pyrido[2,3-b]indole (A?C-HON(2)-Gluc) and O-(?-d-glucosidurony1)-2-hydroxyamino-9H-pyrido[2,3-b]indole (A?C-HN(2)-O-Gluc). A?C-HON(2)-Gluc is a stable metabolite but A?C-HN(2)-O-Gluc is a biologically reactive intermediate, which covalently adducts to DNA at levels that are 20-fold higher than HONH-A?C. We measured the rates of formation of A?C-HON(2)-Gluc and A?C-HN(2)-O-Gluc in human organs: highest activity occurred with liver and kidney microsomes, and lesser activity was found with colon and rectum microsomes. A?C-HN(2)-O-Gluc formation was largely diminished in liver and kidney microsomes, by niflumic acid, a selective inhibitor UGT1A9. In contrast, A?C-HON(2)-Gluc formation was less affected and other UGT contribute to N(2)-glucuronidation of HONH-A?C. UGT were reported to catalyze the formation of isomeric Gluc conjugates at the N(2) and N3 atoms of 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine (HONH-PhIP), the genotoxic metabolite of PhIP. However, we found that the N3-Gluc of HONH-PhIP also covalently bound to DNA at higher levels than HONH-PhIP. The product ion spectra of this Gluc conjugate acquired by ion trap mass spectrometry revealed that the Gluc moiety was linked to the oxygen atom of HONH-PhIP and not the N3 imidazole atom of the oxime tautomer of HONH-PhIP as was originally proposed. UGT1A9, an abundant UGT isoform expressed in human liver and kidney, preferentially forms the O-linked Gluc conjugates of HONH-A?C and HONH-PhIP as opposed to their detoxicated N(2)-Gluc isomers. The regioselective O-glucuronidation of HONH-A?C and HONH-PhIP, by UGT1A9, is a mechanism of bioactivation of these ubiquitous HAAs.
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Project description:Heterocyclic aromatic amines (HAAs) are mutagens and potential human carcinogens. Our group and others have demonstrated that HAAs may also produce selective dopaminergic neurotoxicity, potentially relevant to Parkinson's disease (PD). The goal of this study was to elucidate mechanisms of HAA-induced neurotoxicity through examining a translational biochemical weakness of common PD models. Neuromelanin is a pigmented byproduct of dopamine metabolism that has been debated as being both neurotoxic and neuroprotective in PD. Importantly, neuromelanin is known to bind and potentially release dopaminergic neurotoxicants, including HAAs (eg, β-carbolines such as harmane). Binding of other HAA subclasses (ie, aminoimidazoaazarenes) to neuromelanin has not been investigated, nor has a specific role for neuromelanin in mediating HAA-induced neurotoxicity been examined. Thus, we investigated the role of neuromelanin in modulating HAA-induced neurotoxicity. We characterized melanin from Sepia officinalis and synthetic dopamine melanin, proposed neuromelanin analogs with similar biophysical properties. Using a cell-free assay, we demonstrated strong binding of harmane and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) to neuromelanin analogs. To increase cellular neuromelanin, we transfected SH-SY5Y neuroblastoma cells with tyrosinase. Relative to controls, tyrosinase-expressing cells exhibited increased neuromelanin levels, cellular HAA uptake, cell toxicity, and oxidative damage. Given that typical cellular and rodent PD models form far lower neuromelanin levels than humans, there is a critical translational weakness in assessing HAA-neurotoxicity. The primary impacts of these results are identification of a potential mechanism by which HAAs accumulate in catecholaminergic neurons and support for the need to conduct neurotoxicity studies in systems forming neuromelanin.
| S-EPMC6944224 | biostudies-literature
Project description:Many aromatic amines and heterocyclic aromatic amines (HAAs) are known carcinogens for animals, and there is also strong evidence of some in human cancer. The activation of these compounds, including some arylamine drugs, involves N-hydroxylation, usually by cytochrome P450 enzymes (P450) in Family 1 (1A2, 1A1, and 1B1). We previously demonstrated that the bioactivation product of the anticancer agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203), an N-hydroxylamine, can be reduced by P450 2S1 to its amine precursor under anaerobic conditions and, to a lesser extent, under aerobic conditions [Wang, K., and Guengerich, F. P. (2012) Chem. Res. Toxicol. 25, 1740-1751]. In the study presented here, we tested the hypothesis that P450 2S1 is involved in the reductive biotransformation of known carcinogenic aromatic amines and HAAs. The N-hydroxylamines of 4-aminobiphenyl (4-ABP), 2-naphthylamine (2-NA), and 2-aminofluorene (2-AF) were synthesized and found to be reduced by P450 2S1 under both anaerobic and aerobic conditions. The formation of amines due to P450 2S1 reduction also occurred under aerobic conditions but was less apparent because the competitive disproportionation reactions (of the N-hydroxylamines) also yielded amines. Further, some nitroso and nitro derivatives of the arylamines could also be reduced by P450 2S1. None of the amines tested were oxidized by P450 2S1. These results suggest that P450 2S1 may be involved in the reductive detoxication of several of the activated products of carcinogenic aromatic amines and HAAs.
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Project description:Screening of bead-based peptide libraries against fluorescent dye-labeled target proteins was found to be significantly influenced by the dye characteristics. Commercially available red fluorescent dyes with net negative charges adversely showed strong interactions with library beads. The introduction of zwitterionic dyes significantly reduced the unwanted interactions, which sheds light upon using the right fluorescent probe for acquisition of reliable results in various fluorescence-assisted applications.
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