title: Solvation dynamics of DCM in a polypeptide-surfactant aggregate: gelatin-sodium dodecyl sulfate.
abstract: Solvation dynamics of 4-(dicyanomethylidene)-2-[p-(dimethylamino)styryl]-6-methyl-4H-pyran (DCM) is studied in a polypeptide-surfactant aggregate consisting of gelatin and sodium dodecyl sulfate (SDS) in potassium dihydrogen phosphate (KP) buffer. The average solvation time (tauS) in gelatin-SDS aggregate at 45 degrees C is found to be 1780 ps, which is about 13 times slower than that in 15 mM SDS in KP buffer at the same temperature. The fluorescence anisotropy decay in gelatin-SDS aggregate is also different from that in SDS micelles in KP buffer. DCM displays negligible emission in the presence of gelatin in aqueous solution. Thus the solvation dynamics in the presence of gelatin and SDS is exclusively due to the probe (DCM) molecules at the gelatin-micelle interface. The slow solvation dynamics is ascribed to the restrictions imposed on the water molecules trapped between the polypeptide chain and micellar aggregates. The critical association concentration (cac) of SDS for gelatin is determined to be 0.5 +/- 0.1 mM.
authors.affiliation: Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
authors.forename: Arnab
authors.initials: A
authors.lastname: Halder
authors.forename: Pratik
authors.initials: P
authors.lastname: Sen
authors.forename: Anupam Das
authors.initials: AD
authors.lastname: Burman
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D002021:Buffers; D004123:Dimethylamines / Q000737:chemistry; D005454:Fluorescence Polarization; D005780:Gelatin / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008823:Micelles; D009842:Oligopeptides / Q000737:chemistry*; D011714:Pyrans / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013343:Styrenes / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D002021:Buffers; D004123:Dimethylamines; D008823:Micelles; D009842:Oligopeptides; D011714:Pyrans; D012997:Solvents; D013343:Styrenes; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D005780:Gelatin; C082825:4-(dicyanomethylene)-2-methyl-6-(4-(dimethylamino)styryl)-4H-pyran