Architecture and shape control of nanoobjects based on amphiphilic dendrimers

In the field of nanotechnology and nanoscience, dendrimers are key compounds having well-defined chemical structure. We nave already reported synthesis of globular carbohydrate macro molecule "sugar ball" which is applicable to gene and drug carriers [1-4]. Amphiphilic surface-sugar- substituted surface-block dendrimers have been also designed, synthesized and characterized [4]. Supramolecular architeucture based on amphiphilic dendrimers is important to create shape controlled smart nanoobjects[5]. The present report deals with synthesis and assembly of amphiphilic sugar-substituted poly(ethylene glycol) dendrimers. The dendrimers were synthesized by the reaction of N-acetyl-D-glucosamine, galactose, and lactose derivatives with poly(ethylene glycol) dendrimer having a hydroxy group and alkyl groups at the core and the surface, respectively, wnich were prepared by convergent method. The sugar moieties and the poly(ethylene glycol) dendrimer branches are regarded as hydrophilic parts, whereas the alkyl groups act as hydrophobic groups. Although hydrophobicity of the amphiphilic dendrimers is high, nanoparticles based on the amphiphilic dendrimers can be prepared by irradiation of ultrasonic wave. Fortunately the particle size, which is measured using DLS, could be controlled around ca. 200 nm. Monolayer of the amphiphilic dendrimers was successfully formed at the air/water interface. Intermolecular distance, i.e., intersugar distance, of the monolayer was found to be controlled around 2 nm by changing generation and hydrophobic groups of the dendrimers.