Jellyfish-Shaped Amphiphilic Dendrimers: Synthesis and Formation of Extremely Uniform Aggregates.

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.

 

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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.

 

Jellyfish Shaped Amphiphilic Dendrimers  Synthesis and Formation of

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