title: Surfactant chain-length-dependent modulation of the prototropic transformation of a biological photosensitizer: norharmane in anionic micelles.
abstract: A photophysical study of norharmane (NHM), an efficient cancer cell photosensitizer, has been undertaken in well-characterized biomimetic micellar nanocavities formed by anionic surfactants of varying chain length, namely, sodium decyl sulfate (S10S), sodium dodecyl sulfate (S12S), and sodium tetradecyl sulfate (S14S), using steady-state and time-resolved fluorescence spectroscopy. The effect of the hydrophobic chain length on the structural dynamism of the fluorophore has been reported. Experimental results demonstrate that the equilibrium of this dynamism is sensitive to the environment. Variation in the surfactant chain length plays an important role in promoting a specific prototropic form of the probe molecule. A striking feature of the present study is that an increase in the surfactant chain length (hydrophobicity) favors the cationic species of NHM. This has been rationalized on the basis of changes in the local pH and the aggregation number of the micelles. A fluorescence quenching study of the micelle-bound probe using ionic quencher Cu2+ corroborates this.
authors: Department of Chemistry, Jadavpur University, Calcutta 700 032, India.
authors: Alok
authors: A
authors: Chakrabarty
authors: Arabinda
authors: A
authors: Mallick
authors: Basudeb
authors: B
authors: Haldar
authors: Pradipta
authors: P
authors: Purkayastha
authors: Paramita
authors: P
authors: Das
authors: Nitin
authors: N
authors: Chattopadhyay
mesh_terms: D000838:Anions / Q000737:chemistry; D002243:Carbolines; D006247:Harmine / Q000031:analogs & derivatives* / Q000737:chemistry; D008823:Micelles; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000838:Anions; D002243:Carbolines; D008823:Micelles; D017319:Photosensitizing Agents; D013501:Surface-Active Agents; D006247:Harmine; C010262:norharman