title: Water gelation of an amino acid-based amphiphile.
abstract: The water immobilization by a simple amino acid-containing cationic surfactant was investigated. A variety of techniques, such as (1)H NMR spectroscopy, circular dichroism (CD), steady-state fluorescence spectroscopy, and field-emission scanning electron microscopy (FESEM) were applied to determine the formation and architecture of the hydrogel. The new gelator with a minimum gelation concentration (MGC) of 0.3 % w/v shows prolonged stability and a low melting temperature (39 degrees C). (1)H NMR experiments revealed that intermolecular hydrogen bonding between the amide groups and pi-pi stacking of the indole rings are the two regulating parameters for gelation. Furthermore, fluorescence studies with 8-anilino-1-naphthalenesulfonic acid (ANS) as the probe indicate the participation of hydrophobicity during gelation. The luminescence study using both ANS and pyrene, along with FESEM results, indicate a critical concentration, well below the MGC, at which fibres begin to form. These cross-link further to give thicker fibers, leading to the formation of a hydrogel (0.3 % w/v). This new hydrogelator expresses high supramolecular chirality, as evidenced by the CD spectra. In addition, the gelator molecule was found to be nontoxic up to a concentration of 4 mM (0.2 % w/v). The high supramolecular chirality, prolonged stability, low melting point, and biocompatibility of the molecule make it a focus of chemical and biological interest.
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Debapratim
authors.initials: D
authors.lastname: Das
authors.forename: Antara
authors.initials: A
authors.lastname: Dasgupta
authors.forename: Sangita
authors.initials: S
authors.lastname: Roy
authors.forename: Rajendra Narayan
authors.initials: RN
authors.lastname: Mitra
authors.forename: Sisir
authors.initials: S
authors.lastname: Debnath
authors.forename: Prasanta Kumar
authors.initials: PK
authors.lastname: Das
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000817:Anilino Naphthalenesulfonates; D002470:Cell Survival / Q000187:drug effects; D002942:Circular Dichroism; D003432:Cross-Linking Reagents; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D020100:Hydrogels / Q000138:chemical synthesis* / Q000494:pharmacology; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D017348:Microscopy, Electron, Scanning Transmission; D008968:Molecular Conformation; D013050:Spectrometry, Fluorescence; D013778:Tetrazolium Salts; D013844:Thiazoles; D014867:Water / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D000817:Anilino Naphthalenesulfonates; D003432:Cross-Linking Reagents; D020100:Hydrogels; D013778:Tetrazolium Salts; D013844:Thiazoles; D014867:Water; C027132:1-anilino-8-naphthalenesulfonate; C022616:thiazolyl blue