PREPARATION AND EVALUATION OF GLUTARALDEHYDE CROSS-LINKED CHITOSAN MICROSPHERES AS A GADOLINIUM RESERVOIR FOR NEUTRON-CAPTURE THERAPY

Chitosan microspheres (CMSs) containing water-soluble gadolinium dieth ylenctriaminepentaacetic acid (Gd-DTPA) were prepared by an emulsion m ethod using Span 80 as a surfactant and glutaraldehyde (GA) as a cross -linker for the gadolinium neutron-capture therapy of cancer, When Gd- DTPA was applied at more than a 1 : 1 number ratio of its carboxylic g roups to the amino groups of chitosan, the content of Gd in CMS was sa turated at about 13% and the mass median diameter of CMS was increased beyond that of placebo CMS, The increase in the amount of Span 80 and GA applied led to a decrease in the CMS size and the Gd content, The electrostatic interaction between chitosan and Gd-DTPA and the prefere ntial surface-hardening by GA contributed to the formation of fine, sp herical, Gd-enriched and prolonged-releasing CMSs with a mass median d iameter of 1.9 mu m, a Gd content of 6.1% and a 50% dissolution time o f 2.3 h.