1: Biosens Bioelectron. 2006 Jan 15;21(7):1015-22. Epub 2005 Apr 15.

Development and evaluation of biocompatible films of polytetrafluoroethylene
polymers holding lithium phthalocyanine crystals for their use in EPR oximetry.

Dinguizli M, Jeumont S, Beghein N, He J, Walczak T, Lesniewski PN, Hou H,
Grinberg OY, Sucheta A, Swartz HM, Gallez B.

Biomedical Magnetic Resonance Unit, Laboratory of Medicinal Chemistry and
Radiopharmacy, Universite Catholique de Louvain, Brussels, Belgium.

Electron paramagnetic resonance (EPR) oximetry is a powerful technology that
allows the monitoring of oxygenation in tissues. The measurement of tissue
oxygenation can be achieved using lithium phthalocyanine (LiPc) crystals as
oxygen reporters. In order to have biocompatibility for the sensing system and
to assure long-term stability in the responsiveness of the system, we developed
films of Teflon AF 2400 with embedded LiPc crystals. These systems can be used
as retrievable inserts or parts of an implantable resonator or catheter. Atomic
force microscopy studies revealed that the surface of the films was regular and
planar. The response to oxygen of the sensor (EPR linewidth as a function of
pO(2)) remained unchanged after implantation in mice, and was not affected by
sterilization or irradiation. The use of resonators, holding LiPc embedded in
Teflon AF 2400, implanted in the gastrocnemius muscle of rabbits allowed the
monitoring of oxygen during several weeks. Several assays also demonstrated the
biocompatibility of the system: (1) no hemolytic effect was noted; (2) no
toxicity was found using the systemic injection test of extracts; (3)
histological analysis in rabbit muscle in which the films were implanted for 1
week or 3 months was similar to standard polyethylene biocompatible devices.
These advanced oxygen sensors are promising tools for future pre-clinical and
clinical developments of EPR oximetry. These developments can be applied for
other applications of biosensors where there is a need for oxygen permeable
membranes.

PMID: 16368480 [PubMed - indexed for MEDLINE]

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