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[en] Interaction of toluidine blue (TB), a biologically potent cationic phenothiazinium dye, with anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) have been thoroughly studied employing absorption and emission spectroscopy. A completely distinct spectral behavior of TB has been observed corresponding to pre-micellar and post-micellar region of AOT. Steady-state fluorescence anisotropy measurement has been carefully undertaken to rationalize the spectroscopic results. Effect of γ-cyclodextrin (γ-CD) on the spectral properties of TB has also been encountered for understanding of binding interaction between them. Molecular docking study has been accomplished to enlighten the probable orientation of TB inside the γ-CD core. Here particular interest has been focused on a mixed system, composed of AOT pre-micelles and γ-CD. A remarkable diminution of both absorption and emission intensities of TB has been observed in AOT pre-micelle with a simultaneous colorimetric change of TB solution from dark blue to lavender, and subsequent addition of γ-CD results in enhancement of intensities with dramatic reversal of the lavender colored solution to the original dark blue color. The emission characteristics of TB in the presence of AOT and γ-CD may prove as promising for an ‘IMPLICATION’ logic gate which may perform a significant role in the field of molecular electronics.
[en] Objective: To use toluidine blue intra-operatively to identify tumour involved margins after the removal of oral cavity squamous cell carcinoma, and to compare the findings with those of final histopathology. Methods: The study was conducted at the Aga Khan University Hospital from December 1, 2009, to March 14, 2010, and comprised 56 consecutive patients with biopsy-proven squamous cell carcinoma of oral cavity regardless of grade and stage of tumour. Intra-operatively toluidine blue was used on the resected tumour margins and the staining patterns were assessed. Results were then compared with the final histopathology report. Results: A total of 11(19.64%) margins were positive with toluidine blue staining out of which 8 (14.28%) were false positive. Sensitivity and specificity was found to be 100% and 84.9% respectively with a positive predictive value of 27.2%; a negative predictive value of 100%; and diagnostic accuracy of 85.71%. Conclusion: Toluidine blue costs only Rs25 (USD 0.30) and takes only 5 minutes for application and interpretation. It can be used with significant confidence in smaller lesions (T-I and T-II) as an alternative to frozen sections in developing countries where facilities are unavailable. Its use in larger lesions (T-III and TIV) remains the topic of controversy and awaits a multi centre trial with a larger cohort. (author)
[en] Highlights: • DNA binding of toluidine blue O, azure A and azure B was driven by negative enthalpy and positive entropy changes. • The DNA binding affinity of the dyes varied as toluidine blue O > azure A > azure B. • The small heat capacity changes indicated hydrophobic contribution in the binding process. • The salt dependent study suggested involvement of weak electrostatic interactions. • DNA thermal stabilization varied as toluidine blue O > azure A > azure B. -- Abstract: The DNA binding of toluidine blue O (TBO), azure A and azure B was characterised by isothermal titration calorimetry, differential scanning calorimetry and thermal melting studies. The DNA binding affinity of TBO was the highest followed by azure A and azure B. The binding in each case was exothermic with a positive entropy change. The affinity of the binding decreased as the [Na+] concentration increased. The non electrostatic contribution to the standard Gibbs energy remained the same over the range of (10 to 100) mM [Na+]. The negative change in heat capacity of the binding revealed a substantial hydrophobic contribution in the DNA binding of these dyes. An enthalpy–entropy compensation was observed in each system. The binding of these dyes stabilised the DNA against thermal strand separation. The energetics of the DNA binding of these dyes correlate well with the structural data that suggest their utility as potential DNA targeting agents
[en] Before performing spine non-fusion surgery that retains the facet joints, choosing an accurate radiographic method to evaluate the degree of facet joint degeneration is extremely important. Therefore, the objective of this study was to determine the accuracy and reliability of different radiographic classifications by analyzing the correlation between radiographic and pathologic grading of lumbar facet joint degeneration. Taking the pathologic examination as standard, the consistency of computed tomography (CT) and magnetic resonance imaging (MRI) assessment of lumbar facet joint degeneration was compared. A total of 74 facet joints obtained from 42 patients who underwent posterior lumbar surgery were evaluated. All patients underwent CT and MRI before surgery. The pathologic grade was evaluated with a method based on hematoxylin-eosin and toluidine blue staining. The radiographic grade was evaluated using the methods proposed by different authors. There was a moderate consistency between pathologic and radiographic grading for facet joint degeneration. The weighted kappa coefficients comparing pathologic with radiographic grading were 0.506 for CT, 0.561 for MRI, and 0.592 for CT combined with MRI, respectively. Taking the pathologic examination as standard, the consistency of CT and MRI examination was also moderate, and the weighted kappa coefficient was 0.459. The radiographic examination has moderate accuracy and reliability for evaluating degeneration of facet joints. Therefore, a more accurate method for evaluating the degeneration of facet joints is necessary before performing spine non-fusion surgery that retains the facet joints. The online version of this article (doi:10.1186/s12880-016-0129-9) contains supplementary material, which is available to authorized users
[en] In this work, thin films of Toluidine Blue (TB) have been prepared by thermal evaporation technique. The obtained films have been characterized using differential scanning calorimetry (DSC), atomic force microscope (AFM), UV–Vis.-NIR spectroscopy and electrochemical impedance spectroscopy (EIS). The thermal analysis has showed the morphological stability TB thin films over wide range of temperatures reaches up to 478 K. Further, the AFM images have revealed that the roughness of TB films have increased upon annealing process. Optical constants of TB films were calculated from the transmittance and reflectance measurements, in the spectral range from 200 to 2500 nm. The results have indicated that the type of electronic transition is direct forbidden and the values of energy bandgaps are temperature independent. AC-conductivity has been analyzed in the frequency range 0.2–3500 kHz and in the temperature range 303–453 K. In this context, the charge carriers transport has been interpreted in terms of the correlated barrier hopping mechanism.
[en] Treating Nicotiana africana Merxm. pollen with three levels UV radiation prior to pollinating four cultivars of flue-cured tobacco (Coker 176, NC95, McN944 and PD4), Nicotiana tabacum produced 1,953 viable seedlings from an estimated total of 170,248 seeds, of which 1,667 were haploid and 286 were hybrids. Drenching N. tabacum flowers with toluidine blue 18 hours after pollination with normal N. africana pollen, yielded 511 viable seedlings from 70,613 seeds, of which 346 were haploid and 165 hybrids. Untreated pollen gave 548 viable seedlings from 56,291 seeds, comprising 341 haploids and 208 hybrids. Contrary to results from a previous histological study, in vivo pollen tube growth rate appears to be similar irrespective of pollen source or treatment, and fertilization seems to occur at about the same time as in the selfed control. From an estimated total of 803,854 seeds sown, 3,014 viable seedlings were obtained. Coker 176 gave significantly higher yields of haploids than the other three cultivars. Field grown plants produced more haploids than greenhouse grown plants. Further evidence was obtained to support selective chromosomal elimination as the mechanism governing the development of maternal haploids from this interspecific cross
[en] Highlights: • Non-spherical gold nanoparticles were electrodeposited. • The nanoparticles were employed to fabricate a Leishmania infantum DNA sensor. • The DNA sensor was applied to detect clinical samples. - Abstract: Detecting and monitoring the pathogens with high selectivity and sensitivity is critical for public health. In the present study, we demonstrated a specific analytical strategy for sensitive detection of Leishmania infantum genome. The developed sensor utilized toluidine blue as a hybridization indicator and a Leishmania infantum-specific capture DNA sequence immobilized on a high-surface area gold nanostructure as an electrochemical transducer. The produced analytical response was based on the hybridization of the single-stranded DNA from the target with the immobilized DNA sequence at the electrode surface. The developed DNA sensor in this study was successfully employed to detect a synthetic Leishmania infantum target sequence in a wide concentration range from 1 × 10-18 to 1 × 10-10 mol L-1 with a detection limit of 0.2 amol L-1 with the ability to discriminate the target sequence from mismatched sequences. Moreover, the designed DNA sensor showed a good reproducibility and stability during repeated regeneration and hybridization cycles. The DNA sensor could detect Leishmania infantum genome in a wide concentration range from 15 to 50 ng µL-1 with a detection limit of 29 ng µL-1. Furthermore, clinical trials confirmed the applicability of the developed DNA sensor for practical applications.
[en] In this work, we report the hydrothermal synthesis of quaternary Cu2FeSnS4 (CFTS) semiconducting nanostructures at two different reaction durations. Synthesis durations were found to have a great impact on the properties of the CFTS nanostructures. The photocatalytic activity of CFTS nanostructures was investigated against methyl red (MR) degradation under sodium light irradiation. CFTS nanoflakes show significant degradation of the dye within 3 h of light illumination. CFTS nanoparticles with rough surfaces show the maximum photocatalytic activity, degrading almost 74% of the dye. Reusing CFTS nanoparticles in four consecutive degradation cycles led only to a marginal fall in the degradation efficiency, demonstrating their photocatalytic stability. (paper)
[en] Toluidine blue O (TBO) was adsorbed on the octakis(hydridodimethylsiloxy)octasilsesquioxane (Q8M8H) surface. The characterization of the precursor (Q8M8H) and resulting materials obtained by the reaction of Q8M8H and toluidine blue (CTBO) were defined using Fourier transform infrared spectra, nuclear magnetic resonance solid-state 13C and Si29 magic angle spinning. The electrochemical polymerization in a glassy carbon electrode was verified by means of a film silsesquioxane formation (FCTBO) using cyclic voltammetry in a potential range of -0.5 to 1.3 V (vs. saturated calomel electrode (SCE)) in a Britton Robinson (B-R) buffer solution (pH 2.0). The cyclic voltammogram of the film exhibits two redox couples with a formal potential of -0.15 and -0.02 V (B-R buffer pH 5). The formal potential shifts linearly in the cathodic direction by increasing the pH solution with a slope of 71 and 57 mV per unit for the first and second couple, respectively. The film was electrochemically very stable