Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.
Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.
Sakadzić
Sava
S
Photon Migration Imaging Laboratory, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA.
Roussakis
Emmanuel
E
Yaseen
Mohammad A
MA
Mandeville
Emiri T
ET
Srinivasan
Vivek J
VJ
Arai
Ken
K
Ruvinskaya
Svetlana
S
Devor
Anna
A
Lo
Eng H
EH
Vinogradov
Sergei A
SA
Boas
David A
DA
D000818:Animals; D002540:Cerebral Cortex / Q000098:blood supply*; D002560:Cerebrovascular Circulation; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D010100:Oxygen / Q000032:analysis* / Q000097:blood*; D010313:Partial Pressure; D011522:Protons; D051381:Rats
D011522:Protons; D010100:Oxygen