Small particles of fusinite and carbohydrate chars coated with aqueous soluble polymers: preparation and applications for in vivo EPR oximetry.
Gallez B, Debuyst R, Dejehet F, Liu KJ, Walczak T, Goda F, Demeure R, Taper H, Swartz HM
Laboratory of Medicinal Chemistry and Radiopharmacy, University of Louvain, Brussels, Belgium.
The development of oxygen-sensitive paramagnetic materials is being
pursued actively because of their potential applications in in vivo EPR
oximetry. Among these materials, several charcoals and carbohydrate chars
are of special interest because of their desirable EPR properties: high
sensitivity of the EPR linewidth to the partial pressure of oxygen, simple
EPR spectra, and high spin density. Their potential use in humans, however,
is limited by the need to demonstrate that they will not lead to deleterious
effects. A strategy was used to optimize the biocompatibility of the oxygen-sensitive
materials by decreasing the size of the particles and coating them with
suspending or surfactive agents such as arabic gum, poloxamer (Pluriol
6800), and polyvinylpyrrolidone. The coated particles of a carbohydrate
char and fusinite were characterized in vitro for their size, stability,
and pO2 sensitivity. The feasibility of performing pO2 measurement was
examined in vivo by inducing ischemia in the gastrocnemius muscle of mice.
The use of arabic gum for coating the fusinite particles preserved the
pO2 sensitivity in vivo, whereas the other surfactive agents led to a loss
of the pO2 sensitivity in vivo. Small particles of fusinite coated by arabic
gum and intravenously administered to mice accumulated in the liver, whereas
the uncoated fusinite was toxic when injected intravenously due to the
large size and aggregation of the particles. Histological studies performed
up to 6 months after the injection in muscles of mice did not indicate
any toxicity from the materials used in the present study.
PMID: 9660565, UI: 98322002