Amphiphilic cholesteryl grafted sodium alginate derivative: Synthesis and self-assembly in aqueous solution

A novel water soluble amphiphilic sodium alginate derivative grafted with 3 cholesteryl groups per 100 hexuronic acid residues (CSAD-3) has been first synthesized with N,N'-dicyclohexylcarbodiimide as a coupling agent and 4-(N,N'-dimethylamino)pyridine as a catalyst at room temperature. The result of fluorescence analysis shows that CSAD-3 forms self-aggregates in 0.15 mol/L aqueous NaCl solution and its critical aggregation concentration (CAC) is 0.33 g/L. The value of CAC decreases with increase of the concentration of aqueous NaCl solution. The CSAD-3 self-aggregates are able to encapsulate hydrophobic compounds like pyrene. The hydrodynamic diameter of CSAD-3 self-aggregates in aqueous NaG solution is 136 nm determined by dynamic light scattering measurement. The oblate particles with the size about 100-200 nm are observed in the negatively dyed TEM image of CSAD-3 self-aggregates. (c) 2007 Elsevier Ltd. All rights reserved.