Cholic acid hydrazide-dextran conjugates (CAH-DEX's) with stable acryl hydrazone linkages were synthesized from cholic acid hydrazide and poly(aldehyde dextran) and were characterized by Fourier transform infrared (FTIR) spectroscopy, H-1-NMR, and surface tension measurements. The conjugates developed a lower critical aggregation concentration, which was determined by 1,6-diphenyl-1,3,5-hexatriene dye solubilization methods, 1.41 and 2.10 X 10(-2) mg/mL for CAH-DEX 9.0 and CAH-DEX 6.5, respectively. A hydrophobic drug, indomethacin (IN), was physically entrapped inside the self-aggregates, and the IN-loaded self-aggregates were analyzed with a dynamic light-scattering system, transmission electron microscopy, and atomic force microscopy. The maximum loading of IN reached 29.9% of the CAH-DEX self-aggregates, which suggested a high loading efficiency of 51.2%. The size of the self-aggregates increased when the drug was entrapped. IN was released from CAH-DEX self-aggregates at pH 4 much slower than at pH 7.4, and in pH 4 media, the release profile was pseudo-zero-order in kinetic terms for up to 14 days. There was almost no change in the FTIR spectra of the CAH-DEX's, which were incubated in buffers of pH 7.4 and pH 4 for 24 h, which indicated that acryl hydrazone was considerably resistant to hydrolysis. (C) 2004 Wiley Periodicals, Inc.