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Macromolecules, 2014, 47 (3), pp 916–921.
Shiqun Shao, † Jingxing Si, †, ‡ Jianbin Tang, † Meihua Sui, *, † and Youqing Shen*, †
† Key Laboratory of Biomass Chemical Engineering of Ministry of Education, Center for Bionanoengineering & the State Key Laboratory of Chemical Engineering, Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China 310027 and
‡ Department of Respiratory Medicine, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China 310009
* Corresponding author at Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou, China, 310027. Tel./fax: +86 571 87951493; E-mail address: [email protected] (M. Sui); [email protected] (Y. Shen).
Author Contributions: S.S. and J.S. contributed equally.
Abstract
Novel classes of jellyfish-shaped amphiphilic dendrimers composed of 7 hydrophilic poly(ethylene glycol) (PEG) arms and 14 hydrophobic polyester dendrons with β-cyclodextrin (βCD) as the core molecule were synthesized by a facile method. Seven PEG chains were first conjugated to the C-6 positions of native βCD. Subsequently, dendritic polyester architectures were constructed from the remaining 14 secondary hydroxyl groups at C-2 and C-3 positions of the βCD moiety, resulting in jellyfish-shaped amphiphilic dendrimers of different generations (7PEG-βCD-Gx) with well-defined molecular structures. The amphiphilic dendrimers self-assembled into different morphologies dependent upon the hydrophilic fraction of the dendrimers, and very surprisingly, the fourth-generation dendrimers consisting of only several percent of PEG could form aggregates with extremely narrow size distributions.
Copyright © 2014 American Chemical Society.
Significance Statement:
Amphiphilic dendrimers are characterized by structural perfection and multivalence, and exhibit unique self-assembly properties, such as low critical aggregation concentrations, and high thermodynamic stability, when compared with their linear counterparts. Through sequential click reactions of asymmetrical monomers, we synthesized a series of amphiphilic jellyfish-shaped dendrimers, which were comprised of seven Poly(ethylene glycol) (PEG) arms and fourteen polyester dendrons with β-CD as the core. These dendrimers had narrow molecular weight distribution and well-defined structures. In aqueous solutions, these amphiphilic dendrimers, even with quite low fractions of hydrophilic segments, could self-assemble into stable nanostructures with extremely uniform size distributions. For instance, the fourth-generation dendrimers 7PEG-βCD-G4 formed stable aggregates in water with low PDI ranging from 0.002 to 0.063. Moreover, the critical aggregate concentrations of 7PEG550-βCD-G4, 7PEG750-βCD-G4, and 7PEG1000-βCD-G4 were determined as low as 4.89, 2.6 and 4.87 μg/mL, respectively. Furthermore, we demonstrated that dendrimers with varied PEG chain length and/or generation could self-assemble into different morphologies. For example, 7PEG550-βCD-G4 dendrimers could form spherical vesicle with “cave” in the core, whereas 7PEG750-βCD-G4 dendrimers formed unilamellar vesicles. These amphiphilic jellyfish-shaped dendrimers hold potential as an effective delivery carrier and deserve further investigation.
Figure legends:
(A) Schematic representation of jellyfish-shaped amphiphilic dendrimers.
(B) GPC traces of 7PEG1000-βCD-Gx dendrimers.
(C) TEM and DLS images of aggregates self-assembled from 7PEG750-βCD-G4 in water.
