title: Investigation of beta-carotene-gelatin composite particles with a multiwavelength UV/vis detector for the analytical ultracentrifuge.
abstract: A multiwavelength UV/vis detector for the analytical ultracentrifuge (MWL-AUC) has been developed recently. In this work, beta-carotene-gelatin composite particles are investigated with MWL-AUC. Band centrifugation with a Vinograd cell is used to ensure maximum sample separation. Spectral changes of the system are observed in dependence of the sedimentation coefficient and are attributed to a previously unknown inhomogeneity of the beta-carotene chemical composition with both H- and J-aggregates coexisting in a mixture. In addition, our data suggest that pure H- and J-aggregates exist in a particle while their relative concentrations in a mixture determine the color characteristics of the sample. The unique abilities and properties of MWL-AUC include sedimentation coefficient distributions for all possible wavelengths, full UV/vis spectra of each different species in the mixture and 3D movies of the sedimentation process. These properties significantly extend the scope of the analytical ultracentrifuge technique and show that complex biopolymer multicomponent mixtures can be resolved into their individual species.
authors.affiliation: Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors.forename: Engin
authors.initials: E
authors.lastname: Karabudak
authors.forename: Wendel
authors.initials: W
authors.lastname: Wohlleben
authors.forename: Helmut
authors.initials: H
authors.lastname: Cölfen
mesh_terms: D000042:Absorption; D003116:Color; D005780:Gelatin / Q000737:chemistry*; D008956:Models, Chemical; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods; D014461:Ultracentrifugation / Q000295:instrumentation / Q000379:methods; D014466:Ultraviolet Rays; D014741:Video Recording; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D019207:beta Carotene; D005780:Gelatin