title: HSA-based phosphorescent probe for two-photon in vitro visualization.
abstract: Two-photon microscopy reveals several advantages over conventional one since it provides higher spatial resolution as well as deeper penetration into the sample under study. The development of suitable two-photon probes is one of the most challenging tasks in this area. Here we present phosphorescent non-covalent adduct of human serum albumin and Au-Ag alkynyl-diphosphine complex, [Au14Ag4(C2Ph)12(PPh2C6H4PPh2)6][PF6]4, which exhibits high cross section of two-photon-induced luminescence (δTPE) within large near-infrared excitation wavelength region (700-800 nm) with maximum δTPE about 38 GM at 740 nm. This feature makes it a promising probe for multiphoton bioimaging as demonstrated by successful visualization of glioma C6 cells and various tissues by two-photon confocal microscopy both in planar and z-stacking modes. Additionally, the broad excitation region enables optimization of the signal-to-background auto-fluorescence ratio via variation of excitation wavelength.
authors: Institute of Chemistry, Saint Petersburg State University, Universitetskii Pr. 26, Saint Petersburg 198504, Russia; Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Pr. V.O., 31, Saint Petersburg 199004, Russia. Electronic address: chelushkin@gmail.com.
authors: Pavel S
authors: PS
authors: Chelushkin
authors: Serbsky State Scientific Center for Social and Forensic Psychiatry, Kropotkinsky Per, 25, Moscow 119991, Russia; Pirogov Russian National Research Medical University, Ostrovitianov St. 1, Moscow 117997, Russia.
authors: Natalia V
authors: NV
authors: Nukolova
authors: Department of Physics, Saint Petersburg State University, Ulianovskaya St. 3, Saint Petersburg 198504, Russia; Research Institute of Nanobiotechnologies, Saint Petersburg State Polytechnical University, 29, Polytechnicheskaya St., Saint Petersburg 195251, Russia.
authors: Alexei S
authors: AS
authors: Melnikov
authors: Department of Physics, Saint Petersburg State University, Ulianovskaya St. 3, Saint Petersburg 198504, Russia; Research Institute of Nanobiotechnologies, Saint Petersburg State Polytechnical University, 29, Polytechnicheskaya St., Saint Petersburg 195251, Russia.
authors: Pavel Yu
authors: PY
authors: Serdobintsev
authors: Pirogov Russian National Research Medical University, Ostrovitianov St. 1, Moscow 117997, Russia.
authors: Pavel A
authors: PA
authors: Melnikov
authors: Institute of Chemistry, Saint Petersburg State University, Universitetskii Pr. 26, Saint Petersburg 198504, Russia.
authors: Dmitry V
authors: DV
authors: Krupenya
authors: Department of Chemistry, University of Eastern Finland, Joensuu 80101, Finland.
authors: Igor O
authors: IO
authors: Koshevoy
authors: Institute of Chemistry, Saint Petersburg State University, Universitetskii Pr. 26, Saint Petersburg 198504, Russia; Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoi Pr. V.O., 31, Saint Petersburg 199004, Russia.
authors: Sergey V
authors: SV
authors: Burov
authors: Institute of Chemistry, Saint Petersburg State University, Universitetskii Pr. 26, Saint Petersburg 198504, Russia. Electronic address: stunik@inbox.ru.
authors: Sergey P
authors: SP
authors: Tunik
mesh_terms: D000418:Albumins / Q000737:chemistry*; D045744:Cell Line, Tumor; D006046:Gold / Q000737:chemistry; D006801:Humans; D049408:Luminescent Agents / Q000138:chemical synthesis* / Q000737:chemistry; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D050607:Organogold Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D012834:Silver / Q000737:chemistry
chemical_list: D000418:Albumins; D049408:Luminescent Agents; D050607:Organogold Compounds; D012834:Silver; D006046:Gold
keywords: Human serum albumin; Imaging agents; Luminescence; Non-covalent interactions; Non-linear optics