Spectroscopic Characterization of i-motif Forming c-myc Derived Sequences Double-Labeled with Pyrene

In current studies we use the oligonucleotides based on c-myc sequence: CCC CAC CCT CCC CAC CCT CCC C (cmyc22) and CCC CAC CCT CCC CAC CCT CCC CA (cmyc22A) functionalized by pyrene moieties at both termini. Results of the circular dichroism (CD), UV absorption melting experiments, and steady-state fluorescence measurements of pyrene-modified i-motifs as well as their unlabeled precursors are presented and discussed here. The pyrene labels have a remarkable influence on i-motif stability which was deduced from CD spectra and confirmed by UV melting experiments. Both probes emit fluorescence band of pyrene monomer with intensity decreasing upon pH lowering. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10895-013-1184-z) contains supplementary material, which is available to authorized users

Steady-State Fluorescence and Lifetime Emission Study of pH-Sensitive Probes Based on i-motif Forming Oligonucleotides Single and Double Labeled with Pyrene

Cytosine-rich nucleic acids undergo pH-stimulated structural transitions leading to formation of an i-motif architecture at an acidic pH. Thus, i-motifs are good foundation for designing simple pH-sensitive fluorescent probes. We report here steady-state and time-resolved fluorescence studies of pyrene-labeled probes based on RET sequence: C4GC4GC4GC4TA (RET21), AC4GC4GC4GC4TA (RET21A) and C4GC4GC4GC4T (RET20). Comparative studies with single- and double-labeled i-motif probes were carried out. For each probe, we have measured fluorescence spectra and decays for emission wavelength of 390 nm over a wide range of pH (from 4.0 to 8.0). Effect of the oligonucleotide sequence and the number of pyrene labels on the spectral characteristics of probes were discussed

Monitoring of pH Using an i-Motif-Forming Sequence Containing a Fluorescent Cytosine Analogue, tC

The i-motif is a four-stranded DNA structure formed from the cytosine (C)-rich ssDNA sequence, which is stabilized in slightly acidic pH. Additionally, labeling of a cytosine-rich sequence with a fluorescent molecule may constitute a way to construct a pH-sensitive biosensor. In this paper, we report tC-modified fluorescent probes that contain RET-related sequence C4GC4GC4GC4A. Results of the UV absorption melting experiments, circular dichroism (CD) spectra, and steady-state fluorescence measurements of tC-modified i-motifs are presented and discussed here. Efficient fluorescence quenching of tC fluorophore occurred upon lowering the pH from 8.0 to 5.5. Furthermore, we present and discuss fluorescence spectra of systems containing tC-modified i-motifs and complementary G-rich sequences in the ratios 1:1, 1:2, and 1:3 in response to pH changes. The fluorescence anisotropy was proposed for the study of conformational switching of the i-motif structure for tC-probes in the presence and absence of a complementary sequence. The possibility of using of the sensor for monitoring pH changes was demonstrated

Spectroscopic Studies upon Silver Nanoclusters Formed on Oligonucleotides Containing a Tricyclic Cytosine Analogue, tC

Silver nanoclusters (AgNCs) generated on DNA templates belong to a new class of fluorescent tags showing excellent brightness, photostability and biocompatibility. Thus, AgNCs-DNA has been applied in various applications, from the detection of DNA/RNA and environmental monitoring to bioimaging and cancer therapy. In this work, we report fluorescent AgNCs synthesized using two 1,3-diaza-2-oxophenothiazine (tC)-modified oligonucleotides that contain RET-related sequence CCCCGCCCCGCCCCGCCCCA. The communication compares the absorption and emission properties of the obtained systems with silver nanoclusters synthesized on the unmodified oligonucleotide. First, we showed the optimal conditions for AgNCs-DNA synthesis on three DNA templates: (1) RET20 with the sequence 5′-CCC CGC CCC GCC CCG CCC CA-3′; (2) RET19tC with the sequence 5′-CCC CGC CCC GCC CCG CCC tCA-3′; and (3) RET14tC with the sequence 5′-CCC CGC CCC GCC CtCG CCC CA-3′. Next, the silver nanoclusters were characterized by UV/Vis absorption, fluorescence and circular dichroism spectroscopy. Silver nanoclusters RET19tC-AgNCs and RET14tC-AgNCs indicated several times higher fluorescence intensities in the long-wave emission spectra as compared to RET20-AgNCs. Moreover, silver nanoclusters on tC-modified oligonucleotides showed higher stability over time. The possibility of using the silver nanoclusters RET19tC-AgNCs for monitoring pH changes will be also tested

Swept Source Optical Coherence Tomography Analysis of a Selected Eye’s Anterior Segment Parameters in Patients with Pseudoexfoliation Syndrome

Background: Pseudoexfoliation syndrome (PEX) is a systemic, age-related disorder characterized by the production and accumulation of pseudoexfoliation material. To date, detailed characteristics have not been published regarding the iridocorneal angle and cornea in patients with pseudoexfoliation syndrome determined through swept source optical coherence tomography (SS-OCT). Methods: A total of 150 eyes of patients with pseudoexfoliation syndrome (ages 69–86 years) and 166 eyes in a control group (ages 54–79 years) were analyzed. Results: The central corneal thickness in the PEX group was 549.56 μm and was slightly (insignificantly) higher than that of the control group (540.56 µm). The anterior chamber of the eye was visibly shallower in patients with PEX syndrome than in those of the control group (2.49 mm vs. 3.07 mm; p < 0.001). The Fourier analysis parameters of the cornea showed multiple differences between the PEX and control groups. With respect to iris area, the parameters showed statistically significant differences between the PEX and control groups in all four quadrants of the eye. No statistical significance was found in the PEX group for the iridocorneal angle parameters, or corneal and lens parameters depending on gender and age. Conclusions: PEX syndrome is characterized by a significant impact on the anterior eye segment, including higher anterior and posterior keratometric values, lower anterior chamber depth, higher iris thickness, and narrower angle parameters. The characteristic anterior eye segment features of PEX syndrome can be detected using SS-OCT, which could potentially assist clinicians in properly managing the disease

Content of heavy metals in tattoo ink - health risk

Wprowadzenie. Tatuaż stanowi jedną z najstarszych form ozdabiania ciała. Dawniej oznaczał przynależność plemienną, często był oznaką inicjacji religijnej, odwagi, siły lub też dorosłości. Obecnie tatuaż stał się częścią mody i kultury. Jego wykonanie polega na wprowadzaniu pod skórę niewielkiej ilości pigmentu, za pomocą jej nakłuwania. Do tatuowania stosuje się różne pigmenty, które w swoim składzie mogą zawierać m.in. metale ciężkie: antymon, arsen, chrom, kobalt, beryl, ołów, nikiel oraz nanocząsteczki, ftalany i węglowodory, które mogą oddziaływać szkodliwie na gospodarkę hormonalną, a niektóre z nich mają działanie kancerogenne. Cel pracy. Celem pracy była analiza zawartości metali ciężkich w tuszach do tatuażu oraz narażenia osób tatuowanych na metale ciężkie, w zależności od zastosowanego koloru rysunku i pochodzenia tuszu. Materiał i metody. Materiał badawczy stanowiło 10 próbek tuszów do tatuażu (5 czarnych i 5 kolorowych). Każdą z próbek zbadano pod kątem zawartości takich metali ciężkich jak: kadm, ołów, cynk, arsen, chrom oraz rtęć. Wyniki. Wyniki badań wykazały duże zróżnicowanie stężeń metali ciężkich (Cd, Pb, Zn, Hg, As, Cr) w badanych próbkach tuszów do tatuażu. W tuszach koloru czarnego odnotowano najwyższe stężenie rtęci i chromu, w tuszu białym: kadmu, ołowiu i cynku, natomiast w zielonym – arsenu. Wnioski. Przeprowadzone badania wskazują na znaczącą zawartość metali ciężkich w tuszach do tatuażu, która uzależniona jest od koloru i producenta tuszu. Tusze kolorowe zawierają kadm, ołów i arsen w większych stężeniach niż częściej stosowane tusze czarne. Wykorzystywanie tuszów kolorowych w większych ilościach (gęsty wzór i większa powierzchnia ciała nim pokryta) może stanowić ryzyko dla zdrowia.Objectives. Introduction of Tattoo is one of the oldest forms of body decoration. It meant tribal affiliation, was often a sign of religious initiation, courage, strength, or adulthood. Currently, the tattoo has become part of fashion and culture, and its implementation is the establishment of a small amount into the skin pigment, using the puncture. For tattooing are used different types of pigments, which can contain heavy metals: antimony, arsenic, chromium, cobalt, beryllium, lead, nickel and nanoparticles, phthalates and hydrocarbons. Those substances may have a detrimental effect on the hormonal economy and some of them have carcinogenic effects. The aim of the study was to analyze the content of heavy metals in tattoo ink and exposure to heavy metals tattooed people depending on the color of the drawing used and the origin of the ink. Material and methods. The material consisted of 10 samples for tattoo inks (5 black and 5 colored). Each sample was examined for the content of heavy metals such as cadmium, lead, zinc, arsenic, chromium and mercury. Results. The results showed large differences in the concentrations of heavy metals (Cd, Pb, Zn, Hg, As, Cr) in the test samples of the tattoo inks. The black color inks recorded the highest concentration of mercury and chromium, the white ink: cadmium, lead and zinc, while the green arsenic. Conclusions. The study indicates a significant content of heavy metals in tattoo inks, which depends on the color and the ink manufacturer. The color inks contain cadmium, lead and arsenic in higher concentrations than black inks, more commonly used. The use of colored inks in large amounts (more dense pattern and the larger body surface area covered) may constitute a health risk

Swept Source Optical Coherence Tomography Analysis of the Selected Eye’s Anterior Segment Parameters

Background: The present study determined the mean reference values of the anterior segment parameters of the selected eye using swept source optical coherence tomography (SS-OCT) in healthy Caucasian participants. Methods: A total of 166 volunteers (age 54–79 years), women (n = 92) and men (n = 74), were analyzed. One eye of each subject was randomly selected for anterior segment imaging. The anterior segment of the eye was scanned with CASIA2. The analyzed anterior segment parameters were divided into three groups, namely parameters of the cornea, lens, and angle. Results: The OCT (e.g., Ks, Kf, pKf, pKs, and central corneal thickness) and Fourier parameters of the cornea were significantly different between females and males. The iridocorneal angle was the smallest in the upper quadrant for all distance from the apex of the angle (250, 500, and 750 µm). Conclusions: Therefore, SS-OCT enables the analysis of parameters of the cornea, anterior chamber, lens, and iridocorneal angle, highlighting its clinical utility. Sex-specific differences in the analyzed parameters should be taken into account during the diagnosis of corneal diseases. The configuration of the filtration angle is an important marker during glaucoma diagnosis and drainage implant surgery. Measurements with CASIA 2is characterized by very good repeatability

Cholesterol-Bearing Fluorescent G-Quadruplex Potassium Probes for Anchoring at the Langmuir Monolayer and Cell Membrane

The purpose of the present work was to design, synthesize and spectrally characterize cholesterol-anchored fluorescent oligonucleotide probes (Ch(F-TBA-T), Ch(py-TBA-py)), based on G-quadruplexes, which were able to incorporate into a lipid structure (Langmuir monolayer, living cell membrane). The probes, based on the thrombin-binding aptamer (TBA) sequence, were labeled with fluorescent dyes which enabled simultaneous monitoring of the formation of G-quadruplex structures and visualization of probe incorporation into the cellular membrane. The combinations of fluorophores used included fluorescence resonance energy transfer (FRET) and excimer emission approaches. The structural changes of the probes upon binding with K+ or Na+ ions were monitored with fluorescence techniques. These systems showed a very high binding preference for K+ over Na+ ions. The use of confocal fluorescence microscopy indicated successful anchoring of the cholesterol-bearing fluorescent probes to the living cell membrane. These structurally simple cholesterol-based fluorescent probes have good potential for opening up new and exciting opportunities in the field of biosensors; e.g., in vivo detection of K+ ions

Swept Source Optical Coherence Tomography Analysis of the Selected Eye’s Anterior Segment Parameters

Background: The present study determined the mean reference values of the anterior segment parameters of the selected eye using swept source optical coherence tomography (SS-OCT) in healthy Caucasian participants. Methods: A total of 166 volunteers (age 54–79 years), women (n = 92) and men (n = 74), were analyzed. One eye of each subject was randomly selected for anterior segment imaging. The anterior segment of the eye was scanned with CASIA2. The analyzed anterior segment parameters were divided into three groups, namely parameters of the cornea, lens, and angle. Results: The OCT (e.g., Ks, Kf, pKf, pKs, and central corneal thickness) and Fourier parameters of the cornea were significantly different between females and males. The iridocorneal angle was the smallest in the upper quadrant for all distance from the apex of the angle (250, 500, and 750 µm). Conclusions: Therefore, SS-OCT enables the analysis of parameters of the cornea, anterior chamber, lens, and iridocorneal angle, highlighting its clinical utility. Sex-specific differences in the analyzed parameters should be taken into account during the diagnosis of corneal diseases. The configuration of the filtration angle is an important marker during glaucoma diagnosis and drainage implant surgery. Measurements with CASIA 2is characterized by very good repeatability