Ratiometry of monomer/excimer emissions of dipyrenyl calix[4]arene in aqueous media

Variations in the ratio of monomer/excimer emissions from pyrenyl groups bound to a calix[4]arene through facing carboxamidomethyl substituents have been investigated in H₂O/CH₃CN mixtures. Above a level of 50% H₂O, monomer emission declines and the excimer emission concomitantly increases. DFT calculations support the argument that disruption of intramolecular NHO bonds by water results in a geometry, which favors contact of the pyrene units and thus a strong excimer emission. Addition of Fe(III) to a H₂O/CH₃CN (4:1, v/v) solution of 1 at pH 6.1 quenches both monomer and excimer emissions through electron transfer (eT) from excited pyrene to the metal ion.     

Rapid Clearance of IR783 and Methyl-β-cyclodextrin Complex for Improved Tumor Imaging

Near-infrared (NIR) fluorescence cancer imaging with targeted NIR fluorophores holds considerable promise for accurate detection and cancer diagnosis. Among the various NIR heptamethine cyanine dyes reported previously, IR783 as a single small molecule has been widely used for tumor-targeted imaging without the additional conjugation of targeting moieties. Despite the potential advantages of IR783, the major problems, such as its non-specific uptake in normal tissues/organs and slow clearance, remain to be solved. A key determinant of sensitivity and detectability in tumor imaging is the improvement of the tumor-to-background ratio (TBR). Herein, a simple and effective supramolecular complex self-assembled from IR783 and methyl-β-cyclodextrin is developed to improve tumor imaging accompanied by rapid clearance from the body. The IR783-cyclodextrin complex allowed for rapid whole body biodistribution, which remarkably reduced non-specific background uptake, and thus increased the TBR value within 24 h post-injection. Therefore, this strategy is applicable in combination with many different types of carbocyanine dyes for improved tumor imaging.     

Synthesis of a tetrapyrazinoporphyrazine-based fluorescent sensor for detection of Cu<Superscript>2+</Superscript> ion

In this study, a novel tetrapyrazinoporphyrazine-based fluorescent sensor for Cu²⁺ ion was synthesized and fully characterized by ¹H NMR, MALDI-TOF MS, and elemental analysis. A tetrapyrazinoporphyrazine substituent was used as the reporting group and a 2,2′-dipyridylamine moiety was employed as the recognition group. The effects of various metal ions on the absorption and emission spectra of the designed molecule were investigated, demonstrating that this compound shows selectivity and sensitivity toward the Cu²⁺ ion. Upon addition of Cu²⁺ ion, a fluorescent intensity of the tetrapyrazinoporphyrazine-based sensor decreased gradually at 655 nm. To confirm a selective binding ability of 2,2′-dipyridylamine moiety toward Cu²⁺ ion, a comparative study was performed using tetrapyrazinoporphyrazine derivative with bromine instead of 2,2′-dipyridylamine moiety. Furthermore, association constant and detection limit value of the synthesized compound toward Cu²⁺ ion were derived from a repetitive titration experiment. Also, a reversibility of the prepared sensor was confirmed through additional test using compound and ethylenediaminetetraacetic acid.     

Shape-controlled synthesis of silver sulfide nanocrystals by understanding the origin of mixed-shape evolution

The shape of silver sulfide nanomaterials was successfully controlled by understanding the origin of the mixed-shape problem.     

Photoreactive immobilization of 11-(2,4-dinitro-5-fluorobenzene)undecenamide on a hydrogenated silicon (100) surface for protein immobilizations

Several nucleophiles such as proteins or poly(ethyleneimine) could be easily conjugated with a 11-(2,4-dinitro-5-fluorobenzene)undecenamide (DFUA) monolayer photochemically prepared on a silicon (100) surface.     

Bee venom stimulates human melanocyte proliferation, melanogenesis, dendricity and migration

Pigmentation may result from melanocyte proliferation, melanogenesis, migration or increases in dendricity. Recently, it has been reported that secreted phospholipase A(2)(sPLA(2)) known as a component of bee venom (BV), stimulates melanocyte dendricity and pigmentation. BV has been used clinically to control rheumatoid arthritis and to ameliorate pain via its anti-inflammatory and antinociceptive properties. Moreover, after treatment with BV, pigmentation around the injection sites was occasionally observed and the pigmentation lasted a few months. However, no study has been done about the effect of BV on melanocytes. Thus, in the present study, we examined the effect of BV on the proliferation, melanogenesis, dendricity and migration in normal human melanocytes and its signal transduction. BV increased the number of melanocytes dose and time dependently through PKA, ERK, and PI3K/Akt activation. The level of cAMP was also increased by BV treatment. Moreover, BV induced melanogenesis through increased tyrosinase expression. Furthermore, BV induced melanocyte dendricity and migration through PLA(2) activation. Overall, in this study, we demonstrated that BV may have an effect on the melanocyte proliferation, melanogenesis, dendricity and migration through complex signaling pathways in vitro, responsible for the pigmentation. Thus, our study suggests a possibility that BV may be developed as a therapeutic drug for inducing repigmentation in vitiligo skin.     

A new sesquiterpene glycoside from the aerial parts of Saussurea triangulata

Column chromatographic separation of a MeOH extract of the aerial parts of Saussurea triangulata led to the isolation of a new sesquiterpene glycoside 6, together with three quinic acid derivatives, two phenolics, two sesquiterpene glycosides and two flavonoids. The new compound 6 was identified as amarantholidol A glycoside by spectroscopic and chemical methods.