Supramolecular Organization of Toluidine Blue Dye in Solid Amorphous Phases

Abstract

Toluidine blue (TB) dye molecules are intensively utilized for large-area photophysics applications such as carcinoma detection, photoinactivation of bacteria, biosensors, and photovoltaic cells. Understanding the nature of the TB aggregation state becomes an essential point of the research process in order to know the structure-function relationship and to foresee technological applications of this class of metachromatic-dye molecules. However, no structural information on toluidine blue is available in the literature, maybe because of the poor crystalline character of the aggregate. Here, we present the first structural determination of TB organic molecules using the energy dispersive X-ray diffraction technique. The investigation highlights dimeric arrangements of stacked molecules in antiparallel fashion, forming a superstructure of two dimers in a transverse arrangement. The behavior of the TB higher aggregates indicates that these dye molecules, in spite of repulsion due to similar charge (cationic dyes), undergo self-aggregation to form helical conformations.

Spectroscopic Studies on the Biomolecular Recognition of Toluidine Blue: Key Information Towards Development of a Non-Contact, Non-Invasive Device for Oral Cancer Detection

“…The distance between the donor and acceptor was calculated to be 36 Angstrom. Thus, the experimental finding indicates that EtBr and TB can be intercalated simultaneously maintaining a distance of about 10 base pairs (21). It has to be noted that, higher concentration in TB compromises structural integrity of the DNA and eventually the DNA-TB complex precipitates.…”

“…Although the cationic dye TB is being used as screening stain for the diagnosis of oral cancer for long time (30), a systematic study on the interaction of the dye with biological macromolecules is sparse in the literature. In a molecular simulation study followed by X-ray crystallographic investigation, it is shown that TB in solution may remain in six different aggregated forms (21,22). We have observed that the aggregation behavior of the dye TB depends on the biological macromolecules and their conformation.…”

“…In our work, we are interested in exploring the basic photochemistry behind the application mentioned above and simultaneously explore the possibility of quantitatively detecting oral cancer via spectroscopic methods exploiting the interaction of TB with DNA. In a recent study, it is shown that absorption spectrum of TB can fitted in to different bands of six different aggregation species simultaneously present in the sample under investigation (21,22). The overall TB spectrum may be mainly attributed to the H-type aggregation, although some of the species also show the J type bands with distinct spectrum band.…”

Morpho-Chemical Observations of Human Deciduous Teeth Enamel in Response to Biomimetic Toothpastes Treatment

“…The changing of the P and Ca amounts along the enamel crystal rods partially covered by the interprismatic matrix is clearly shown by the variation in amplitude and in width of the corresponding energy peaks (Figure 1g). For quantifying the P and Ca contents detected in each EDS frame map, each K α peak was processed by Gaussian fitting to estimate the corresponding peak area [17]. The estimated areas of each characteristic P and Ca peaks were normalized by the corresponding peak area belonging to the entire probed area of 30 × 40 µm 2 .…”

Organometallic Oligomer Resolved by Radial Distribution Function of X-ray Diffraction Analysis

“…To simplify the model description, the structural parameters are referred to the centers of mass of the single chain in Figure A, including the main structural parameters. ,, In the inset the complete single chain of all atoms is shown. The atomic Cartesian coordinates corresponding to the cis -Pt-DEBP and the trans -[Pt(PBu 3 ) 2 Cl] tail/head of the oligomer are available in the Supporting Information, Tables 2S and 3S.…”