TY - JOUR
T1 - A naphthalocyanine-based EPR probe for localized measurements of tissue oxygenation
AU - Ilangovan, Govindasamy
AU - Manivannan, Ayyakkannu
AU - Li, Haiquan
AU - Yanagi, Hisao
AU - Zweier, Jay L.
AU - Kuppusamy, Periannan
PY - 2002/1/15
Y1 - 2002/1/15
N2 - A new electron paramagnetic resonance (EPR) oximetry probe, based on a naphthalocyanine macrocycle, is reported to exhibit high oxygen sensitivity and favorable EPR characteristics for biological applications. The free radical probe, lithium naphthalocyanine (LiNc), is synthesized as fine microcrystalline powder with particle size less than 1 μm and high spin density. It exhibits a single sharp EPR peak, whose width varies linearly with oxygen partial pressure (pO2). The EPR spectrum is nonsaturable at typical microwave power levels (<25 mW at X-band). These unique characteristics make this probe ideal for measuring oxygen concentration in biological tissues, in vivo. The peak-to-peak width under anoxic conditions is 0.51 G (at X-band), and it increases linearly with increase in oxygen partial pressure and reaches 26.0 G for 100% oxygen (760 mmHg), showing an oxygen sensitivity of 34 mG/mmHg. The probe responds to changes in pO2 quickly and reproducibly, thus enabling dynamic measurements of regional oxygenation in real time. The application of this probe for oximetry is demonstrated in an in vivo biological system. The changes in pO2 were monitored in the leg muscle tissue of a living mouse breathing room air and carbogen (95% oxygen + 5% CO2), alternatively. The mean pO2 measured with this probe in muscle tissues was consistent with values reported previously using other methods. Overall, the probe shows very desirable characteristics for localized measurements of tissue oxygenation.
AB - A new electron paramagnetic resonance (EPR) oximetry probe, based on a naphthalocyanine macrocycle, is reported to exhibit high oxygen sensitivity and favorable EPR characteristics for biological applications. The free radical probe, lithium naphthalocyanine (LiNc), is synthesized as fine microcrystalline powder with particle size less than 1 μm and high spin density. It exhibits a single sharp EPR peak, whose width varies linearly with oxygen partial pressure (pO2). The EPR spectrum is nonsaturable at typical microwave power levels (<25 mW at X-band). These unique characteristics make this probe ideal for measuring oxygen concentration in biological tissues, in vivo. The peak-to-peak width under anoxic conditions is 0.51 G (at X-band), and it increases linearly with increase in oxygen partial pressure and reaches 26.0 G for 100% oxygen (760 mmHg), showing an oxygen sensitivity of 34 mG/mmHg. The probe responds to changes in pO2 quickly and reproducibly, thus enabling dynamic measurements of regional oxygenation in real time. The application of this probe for oximetry is demonstrated in an in vivo biological system. The changes in pO2 were monitored in the leg muscle tissue of a living mouse breathing room air and carbogen (95% oxygen + 5% CO2), alternatively. The mean pO2 measured with this probe in muscle tissues was consistent with values reported previously using other methods. Overall, the probe shows very desirable characteristics for localized measurements of tissue oxygenation.
KW - EPR oximetry
KW - Free radicals
KW - Lithium naphthalocyanine
KW - Oxygenation
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U2 - 10.1016/S0891-5849(01)00784-5
DO - 10.1016/S0891-5849(01)00784-5
M3 - Article
C2 - 11796202
AN - SCOPUS:0037081511
SN - 0891-5849
VL - 32
SP - 139
EP - 147
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
IS - 2
ER -