title: Spectroscopic studies on bilirubin aggregate at liquid/liquid interface.
abstract: Bilirubin (BR) aggregating at liquid/liquid interface was firstly detected by Fourier transform infrared (FTIR) imaging/spectroscopy combining with ultraviolet-visible (UV/Vis) absorption spectra. In the UV/Vis absorption spectra of BR aggregate, a new shoulder appeared at 474 nm, and BR absorption maximum underwent red shift from 450 nm to a longer wavelength at 497 nm, which indicates that BR aggregate was formed at the interface. Meanwhile, the BR molecule structure changed or conformation torsion, that is, the increase in orbit overlap or dihedral angle and the enhancement of exciton coupling. In the study of FTIR imaging/spectroscopy, the hydrogen bond-sensitive infrared bands of BR aggregate showed remarkable changes in band shift and intensity compared with those of BR powder, suggesting that the intramolecular hydrogen bonds broke out and internal structure changed. These new findings will be helpful for understanding of the BR molecular interaction, transportation, complex with serum albumin and metal ions, and the effect of BR aggregating on biomembrane and human tissues.
authors: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors: Zhi-Yan
authors: ZY
authors: Xiao
authors: Jian-Hua
authors: JH
authors: Yin
mesh_terms: D001663:Bilirubin / Q000737:chemistry*; D006801:Humans; D006860:Hydrogen Bonding; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D001663:Bilirubin