This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Imaging oxygen in 3D with sub-micron spatial resolution can be made possible by combining phosphorescence quenching technique with multiphoton laser scanning microscopy. However, Pt and Pd porphyrin-based phosphorescent dyes, traditionally used as phosphors in biological oxygen sensing, exhibit extremely low two-photon absorption (2PA) cross-sections. Using chromophors with large known two photon cross sections linked to porphyrins, we are investigating the possibility of generating high phosphorescence yields after photoexcitation and subsequent energy transfer between chormophor and porphyrin. Such complexes would be highly desirable for single molecule (SM) studies employing phosphorescence instead of fluorescence. Up to this point, the use of phosphorescence is quite limited in SM techniques due to the low level of signal. Oxygen dependent quenching of phosphorescence is a sensitive method for measuring molecular oxygen. Our proposed complexes could play a key role in measuring molecular oxygen in tissue employing an imaging technique in vivo.
Specific aims of our project include: (1) Synthesize 2P absorbing phosphorescent probes, in which 2P antenna dyes are separated from the triplet emitter by a dendritic """"""""insulator,"""""""" to prevent intamolecular quenching of the phosphorescence via electron transfer. (2) Modify the existing confocal microscope system by coupling it with a femtosecond Ti:Sapphire laser and a time domain phosphorometer to perform 2P excitation of antenna chromophores, scanning the object in axial planes under the surface and measuring phosphorescence lifetimes. (3) Align and test the entire setup using an appropriate model with microscopic oxygen gradients. Validate the technique by performing in vivo oxygen imaging in the dorsal window tumor model in rats.

National Institute of Health (NIH)
National Center for Research Resources (NCRR)
Biotechnology Resource Grants (P41)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BCMB-N (40))
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pennsylvania
Schools of Arts and Sciences
United States
Zip Code
Sheth, Rahul A; Arellano, Ronald S; Uppot, Raul N et al. (2015) Prospective trial with optical molecular imaging for percutaneous interventions in focal hepatic lesions. Radiology 274:917-26
Roussakis, Emmanuel; Spencer, Joel A; Lin, Charles P et al. (2014) Two-photon antenna-core oxygen probe with enhanced performance. Anal Chem 86:5937-45
Courter, Joel R; Abdo, Mohannad; Brown, Stephen P et al. (2014) The design and synthesis of alanine-rich ?-helical peptides constrained by an S,S-tetrazine photochemical trigger: a fragment union approach. J Org Chem 79:759-68
Singh, Prabhat K; Kuroda, Daniel G; Hochstrasser, Robin M (2013) An ion's perspective on the molecular motions of nanoconfined water: a two-dimensional infrared spectroscopy study. J Phys Chem B 117:9775-84
Chuntonov, Lev; Ma, Jianqiang (2013) Quantum process tomography quantifies coherence transfer dynamics in vibrational exciton. J Phys Chem B 117:13631-8
Kuroda, Daniel G; Bauman, Joseph D; Challa, J Reddy et al. (2013) Snapshot of the equilibrium dynamics of a drug bound to HIV-1 reverse transcriptase. Nat Chem 5:174-81
Culik, Robert M; Annavarapu, Srinivas; Nanda, Vikas et al. (2013) Using D-Amino Acids to Delineate the Mechanism of Protein Folding: Application to Trp-cage. Chem Phys 422:
Lam, A R; Moran, S D; Preketes, N K et al. (2013) Study of the ?D-crystallin protein using two-dimensional infrared (2DIR) spectroscopy: experiment and simulation. J Phys Chem B 117:15436-43
Kuroda, Daniel G; Singh, Prabhat K; Hochstrasser, Robin M (2013) Differential hydration of tricyanomethanide observed by time resolved vibrational spectroscopy. J Phys Chem B 117:4354-64
Goldberg, Jacob M; Speight, Lee C; Fegley, Mark W et al. (2012) Minimalist probes for studying protein dynamics: thioamide quenching of selectively excitable fluorescent amino acids. J Am Chem Soc 134:6088-91

Showing the most recent 10 out of 128 publications