1: NMR Biomed. 2004 Aug;17(5):303-10. 

Development and evaluation of biocompatible inks for the local measurement of
oxygen using in vivo EPR.

Charlier N, Beghein N, Gallez B.

Laboratory of Medicinal Chemistry and Radiopharmacy, Biomedical Magnetic
Resonance Unit, Avenue Mounier 73.40, University Catholique de Louvain, B-1200
Brussels, Belgium.

In vivo EPR oximetry is a powerful minimally invasive method that allows the
measurement of oxygen in tissues through the use of a paramagnetic probe. In the
present study, we investigated new strategies for preparing biocompatible inks
containing carbon black particles (Printex U), which could be used as oxygen
sensors. The carbon black particles were dispersed in solutions of biocompatible
polymers of carboxy methyl cellulose (CMC), hydroxypropyl methyl cellulose
(HPMC) or polyvinyl pyrrolidone (PVP). A total of 12 polymers with different
molecular weights were tested. A physico-chemical characterization of the inks
was carried out to assess the sedimentation of the particles, the rheological
behavior of these inks, and the relative diffusion of the inks. The preparations
with CMC and PVP had the highest viscosity and stability. The presence of the
polymers did not modify the calibration curves (EPR linewidth as a function of
the pO2) of the carbon black. In vivo, the oxygen sensors were stable for at
least one month in muscles as the EPR linewidth remained fully sensitive to
induced ischemia or carbogen challenge. The calibration curve was not modified
after this period of implantation. A first study of biocompatibility was carried
out in vitro (hemolysis and cytotoxicity assay) and in vivo (histological
examination). No sign of toxicity was observed using these inks. These
preparations are good candidates for future in vivo studies including clinical
trials. Copyright 2004 John Wiley & Sons, Ltd.

PMID: 15366029 [PubMed - in process]