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Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing 5 mol % of 1-3, competitive fluorophore displacement experiments were performed, where rhodamine 6G (Rh6G) was used as a fluorescent guest. The addition of Rh6G to the DMPC vesicles containing 3 resulted in a decrease in the fluorescence intensity of Rh6G with an increase of its fluorescence anisotropy, indicating that Rh6G binds to the DMPC-3 vesicles. In the case of DMPC-1 and DMPC-2 vesicles, significant changes in the fluorescence spectra of Rh6G were not observed. When ACh was added to the DMPC-3 vesicles in the presence of Rh6G ([3]/[Rh6G]=100), the fluorescence intensity of Rh6G increased with a decrease in its fluorescence anisotropy. From the analysis of fluorescence titration data, the association constants were determined to be 7.1×105 M-1 for Rh6G-3 complex and 1.1×102 M-1 for ACh-3 complex at the DMPC-3 vesicles. To get a direct evidence for the binding of Rh6G and its displacement by ACh at the DMPC-3 vesicles, diffusion times of the Rh6G were measured by using FCS. Binding selectivity of the DMPC-3 vesicles for ACh, choline, GABA, l-aspartic acid,l-glutamic acid, l-arginine, l-lysine, l-histamine and ammonium chloride was also evaluated using FCS.

Purpose To compare the potential retinal toxicity of two commercially Brilliant blue G dyes (Brilliant Peel and Ocublue Plus) and Indocyanine green (ICG) at usual clinical concentration. Methods Brilliant Peel 0.025% (n ¼ 9), Ocublue Plus 0.025% (n ¼ 9), and ICG 0.05% (n ¼ 9) were injected intravitreally into Sprague-Dawley rat left eyes with balanced salt solution injected in the contralateral eyes as control. Evaluation of the effect of the dyes on retinal architecture was done by histological analysis of neurosensory retinal thickness and retinal ganglion cell (RGC) counts 7 days after intravitreal injection. Paired t-test was done to detect the presence of biologically significant thinning in neurosensory retina and five retinal layers for each dye (paired t-tests). One-way ANOVA and Tukey's Honestly Significant Difference test were used to assess whether different dyes caused significant thinning in mean neurosensory retinal thickness and reduction of mean RGC density. Results Eyes treated with ICG had significantly thinner mean total neurosensory retinal thickness compared with the control eyes (P-value ¼ 0.01), followed by those treated with Ocublue Plus (P-value ¼ 0.03). Brilliant Peel did not cause significant thinning in any of the five retinal layers (all P-values40.05). No significant difference in mean thinning of the total retinal thickness was detected between dyes (P-value ¼ 0.11). The mean thickness of the photoreceptor outer segment and outer plexiform layers were significantly reduced in ICG-injected eyes when compared with the control eyes (P-value ¼ 0.02). No significant difference in mean thinning between the three dyes was detected at all five retinal layers using one-way ANOVA (all P-values40.35). RGC density was significantly reduced for ICG (P-value ¼ 0.01) but only marginally for Ocublue Plus (P-value ¼ 0.05). No significant reduction in RGC density was observed for Brilliant Peel (P-value ¼ 0.2). Conclusion Intravitreal Brilliant Peel is safe to rats retina. The retinal thinning and reduction in RGC density induced by Ocublue Plus requires further studies to determine the safety profile of this product. Potential retinal toxicity is seen with ICG 0.05%.

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