title: Phosphorescent oxygen sensor with dendritic protection and two-photon absorbing antenna.
abstract: Imaging oxygen in 3D with submicron spatial resolution can be made possible by combining phosphorescence quenching technique with multiphoton laser scanning microscopy. Because Pt and Pd porphyrin-based phosphorescent dyes, traditionally used as phosphors in biological oxygen measurements, exhibit extremely low two-photon absorption (2PA) cross-sections, we designed a nanosensor for oxygen, in which a 2P absorbing antenna is coupled to a metalloporphyrin core via intramolecular energy transfer (ET) with the purpose of amplifying the 2PA induced phosphorescence of the metalloporphyrin. The central component of the device is a polyfunctionalized Pt porphyrin, whose triplet state emission at ambient temperatures is strong, occurs in the near infrared and is sensitive to O2. The 2PA chromophores are chosen in such a way that their absorption is maximal in the near infrared (NIR) window of tissue (e.g., 700-900 nm), while their fluorescence is overlapped with the absorption band(s) of the core metalloporphyrin, ensuring an efficient antenna-core resonance ET. The metalloporphyrin-antenna construct is embedded inside the protecting dendritic jacket, which isolates the core from interactions with biological macromolecules, controls diffusion of oxygen and makes the entire sensor water-soluble. Several Pt porphyrin-coumarin based sensors were synthesized and their photophyics studied to evaluate the proposed design.
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Raymond P
authors.initials: RP
authors.lastname: Briñas
authors.forename: Thomas
authors.initials: T
authors.lastname: Troxler
authors.forename: Robin M
authors.initials: RM
authors.lastname: Hochstrasser
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Vinogradov
mesh_terms: D000042:Absorption; D015374:Biosensing Techniques; D007834:Lasers; D008163:Luminescent Measurements; D008665:Metalloporphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D036641:Microscopy, Fluorescence, Multiphoton; D036103:Nanotechnology / Q000379:methods; D010100:Oxygen / Q000032:analysis*; D017785:Photons; D010984:Platinum / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D008665:Metalloporphyrins; D010984:Platinum; D010100:Oxygen