MAGNETIC MICROCAPSULES AS NOVEL BIOMONITORS OF CROSS-LINKING AGENTS AND DIET-DEPENDENT REACTIVE OXYGEN SPECIES IN THE HUMAN GASTROINTESTINAL-TRACT

Six healthy, scientifically informed human volunteers were given C-14-labeled polyethyleneimine (PEI) microcapsules by mouth. Fecal C-14 recovery was inversely related to mean gut transit time (r = -0.66), and the extent of cross-linking between the membrane and core PEI was inversely related to total fecal output (r = -0.81). Cross-linking of PEI microcapsules may be a biomonitor of endogenous cross-linking agents within the human gastrointestinal tract. Extensive loss of [C-14]CH3 label occurred from the microcapsules during human transit and in in vitro fermentations with human fecal flora. A mechanism whereby reactive oxygen species could arise in the iron-rich core of these microcapsules, leading to loss of [C-14]CH3 label, is proposed.