title: Excited state proton transfer dynamics of Topotecan inside biomimicking nanocavity.
abstract: The excited state proton transfer (ESPT) dynamics of a potentially important anticancer drug, Topotecan (TPT), has been explored in aqueous reverse micelle (RM) using steady-state and time-resolved fluorescence measurements. Both the time-resolved emission spectrum and time-resolved area normalized emission spectrum infer the generation of excited state zwitterionic form of TPT from the excited state cationic form of TPT, as a result of ESPT process from the -OH group of TPT to the nearby water molecule. The ESPT dynamics were found to be severely retarded inside the nanocavities of RMs, yielding time constants of 250 ps to 1.0 ns, which is significantly slower than the dynamics obtained in bulk water (32 ps). The observed slow ESPT dynamics in RM compared to bulk water is mainly attributed to the sluggish hydrogen-bonded network dynamics of water molecules inside the nanocavity of RM and the screening of the sodium ions present at the interface.
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research (IISER) , Pune 411008, Maharashtra, India.
authors.forename: Raj Kumar
authors.initials: RK
authors.lastname: Koninti
authors.forename: Krishna
authors.initials: K
authors.lastname: Gavvala
authors.forename: Abhigyan
authors.initials: A
authors.lastname: Sengupta
authors.forename: Partha
authors.initials: P
authors.lastname: Hazra
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D032701:Biomimetics; D005454:Fluorescence Polarization; D008823:Micelles; D036103:Nanotechnology; D011522:Protons; D019772:Topotecan / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D008823:Micelles; D011522:Protons; D019772:Topotecan