| Parenteral iron therapy with complexes of polynuclear iron with carbohydrate compounds such as dextran, sucrose or gluconate is considered a safe and necessary measure to compensate anemia and iron losses in a number of diseases. However, relatively little is known about the biochemistry underlying its therapeutic efficiency.; In the present work, the shapes of three iron-carbohydrate complexes have been investigated by Tapping Mode™ atomic force microscopy. The sizes of the iron cores and the thicknesses of the ligand shells have been determined by comparison of transmission electron microscopy and atomic force microscopy measurements. The spin-state of iron has been revealed and extinction coefficients for all three complexes calculated. None of the complexes catalyze the formation of hydroxyl radicals which would have led to a degradation of a high-molecular-weight glycosaminoglycan hyaluronan. X-ray diffraction analysis and FT-IR spectroscopy were coupled with elemental analysis and the microscopic techniques to determine a structure for the iron core, the location of the carbohydrate component within the particle, and the carbohydrates' binding mode for each complex type.; The core particles of all three formulations were found to be composed of iron oxyhydroxide akaganeite.; For the iron-sucrose complex the average overall particle size is 6 nm in diameter and composed of an iron core of 3.2 nm, surrounded by a 1.3 nm shell of sucrose.; For the iron-gluconate formulation the average overall particle size is about 5 nm and is composed of an iron core of 2 nm diameter, surrounded by a 0.4 nm thick shell of strongly bound gluconate molecules and a 1 nm thick shell of weakly associated sucrose molecules.; For the iron-dextran complex the average overall particle size is about 30 nm. It is composed of an ellipsoidal core of 20–35 nm in length, and about 6 nm in width, surrounded by a shell of oxidized dextran, resulting in an overall spherical shape. |
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