Two simple, selective and sensitive spectrophotometric methods are described for the determination of 6-aminopenicillanic acid (6-APA). The methods are based on the reaction of 6-APA with either bromophenol blue (BPB) or bromothymol blue (BTB), to give orange-red and green species, respectively. The coloured products are quantified spectrophotometrically at 625 and 616nm for BPB and BTB, respec...

The severe acute respiratory syndrome caused by COVID-19 is now a global catastrophic event. Currently thereis no approved drug or vaccine for the disease. Methylene blue (MB, oxidized form, blue color) has been used inmany different areas of clinical medicine, ranging from malaria to orthopedics. Leucomethylene Blue (reduced formof MB, colorless) may be applied for the treatm...

This paper describes the primary structures of two opsins of short-wavelength-absorbing visual pigments deduced from the mRNA sequences in the retina of the Japanese yellow swallowtail butterfly Papilio xuthus. A phylogenetic analysis of the amino acid sequences indicates that one of these visual pigments is of the ultraviolet-absorbing type and that the other is of the blue-absorbing type. We ...

The dyeing of woolen yarn with eggplant peel, a natural colorant, has been studied. The main coloring component in this natural colorant is anthocyanin, which is an interesting class of dyes in the blue and red area. Eight mordants including alum, copper sulfate, ferrous sulfate, potash alum, nickel chloride, zinc sulfate, tin chloride, and potassium dichromate were used for mordanting the ...

Two distinct D-amino acid dehydrogenases, each showing absolute speci&ity for methylene blue or 2,6-dichloroindophenol, respectively, were isolated from Pseudomonas @orescens (ATCC 11299B). The methylene blue-specific ~-amino acid dehydrogenase was detectable only in extracts from D-tryptophan-grown cells and was purified about 40-fold. The 2,6-dichloroindophenol-specif?c ~-amino acid dehydroge...

The optical sensor for "tea catechins" was built by immobilizing 2,2'-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline (PBHQ) on TiO₂ nanoparticles (NPs). The sensor worked by "indophenol blue" dye formation on PBHQ-immobilized TiO₂ NPs as a result of p-aminophenol (PAP) autoxidation with dissolved O₂ at pH 10. Among quercetin, rutin, naringenin, naringin, gallic acid, caffeic acid, ferulic acid...

Perovskite quantum dots (PQDs) have fascinating optoelectronic properties, such as high photoluminescence yield (PLQY) for a broad range of materials, and the possibility to obtain different bandgaps with same material or halide combinations. Nevertheless, blue-emissive materials generally present limited PLQY color instability. Here, two molecular organogels, based on derivative an amino acid ...

Indole-3-acetic acid (plant auxin) has low toxicity but dramatically enhances the killing of mammalian cells on illuminating phenothiazinium dyes with red light. Suitable dyes include toluidine blue, used in cancer diagnosis because of localization in tumors, and methylene blue, used in experimental photodynamic therapy of cancer. The photosensitized oxidation of indole acetic acid forms a free...

Spectral tuning by visual pigments involves the modulation of the physical properties of the chromophore (11-cis-retinal) by amino acid side chains that compose the chromophore-binding pocket. We identified 12 amino acid residues in the human blue cone pigment that might induce the required green-to-blue opsin shift. The simultaneous substitution of nine of these sites in rhodopsin (M86L, G90S,...

The phosphomolybdic acid (PMA) has been used as an adsorbent for the removal of dyes (Methylene blue and Congo red dye) from synthetic aqueous solution. Different factors of the adsorbent, like, contact time, pH of the sorption medium, concentration of the dye solution, were investigated by the batch sorption experiment. The adsorption equilibrium data was best fitted by the Langmuir isotherm m...