title: Excited state proton transfer in the lysosome of live lung cells: normal and cancer cells.
abstract: Dynamics of excited state proton transfer (ESPT) in the lysosome region of live lung cells (normal and cancer) is studied by picosecond time-resolved confocal microscopy. For this, we used a fluorescent probe, pyranine (8-hydroxy-pyrene-1,3,6-trisulfonate, HPTS). From the colocalization of HPTS with a lysotracker dye (lysotracker yellow), we confirmed that HPTS resides in the lysosome for both of the cells. The diffusion coefficient (Dt) in the lysosome region was obtained from fluorescence correlation spectroscopy (FCS). From Dt, the viscosity of lysosome is estimated to be ∼40 and ∼30 cP in the cancer and normal cells, respectively. The rate constants of the elementary steps of ESPT in a normal lung cell (WI38) are compared with those in a lung cancer cell (A549). It is observed that the time constant of the initial proton transfer process in a normal cell (τ(PT) = 40 ps) is similar to that in a cancer cell. The recombination of the geminate ion pair is slightly faster (τ(rec) = 25 ps) in the normal cell than that (τ(rec) = 30 ps) in a cancer cell. The time constant of the dissociation (τ(diss)) of the geminate ion pair for the cancer cell (τ(diss) = 80 ps) is 1.5 times faster compared to that (τ(diss) = 120 ps) in a normal cell.
authors.affiliation: Department of Physical Chemistry, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700032, India.
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Chowdhury
authors.forename: Abhijit
authors.initials: A
authors.lastname: Saha
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Mandal
authors.forename: Batakrishna
authors.initials: B
authors.lastname: Jana
authors.forename: Surajit
authors.initials: S
authors.lastname: Ghosh
authors.forename: Kankan
authors.initials: K
authors.lastname: Bhattacharyya
mesh_terms: D001190:Arylsulfonates / Q000737:chemistry; D045744:Cell Line, Tumor; D002470:Cell Survival; D004058:Diffusion; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000473:pathology*; D008175:Lung Neoplasms / Q000473:pathology*; D008247:Lysosomes / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D011522:Protons
chemical_list: D001190:Arylsulfonates; D005456:Fluorescent Dyes; D011522:Protons; C005047:pyranine