Polyethylene Glycol-Polyamidoamine Dendritic Micelle as Solubility Enhancer and the Effect of the Length of Polyethylene Glycol Arms on the Solubility of Pyrene in Water


Unimolecular dendritic micelles designed as solubility enhancers were obtained by coupling polyethylene glycol (PEG) to StarburstTM polyamidoamine (PAMAM) dendrimers. Micelles-750, -2000, and -5000 have a generation 3.0 dendrimer core (32 primary amine end groups) and PEG arms with molecular weights of 750, 2000, and 5000, respectively. The conjugate of dendrimer core and PEG was characterized by MALDI-TOF MS and 1H NMR. 1H NMR was also used to estimate the average number of PEG arms on each dendrimer molecule. A typical hydrophobic compound, pyrene, was sonicated in an excess amount together with micelles at 50°C for 6 h to produce its saturated water solution. The change of the solubility of pyrene was monitored at 334 nm, its maximum adsorption wavelength, by UV-VIS spectra. Concentrated micelles tended to dissolve more pyrene. However, there is no obvious linear relationship between micelle type and the amount of pyrene entrapped within micelles. Micelle-2000 could solubilize more pyrene than micelle-750. It is hypothesized that micelle-5000 did not solubilize more pyrene than micelle-2000 because of the PEG shell disruption by adjacent interpenetration of individual micelles when PEG arm length increased.


Chemical and Biochemical Engineering


The authors gratefully acknowledge the funding from an NSF CAREER award (BES-9984840), a University of Akron Faculty Research Grant (FRG-1484), and a Sigma Xi Grant-in-Aid of Research.

Keywords and Phrases

Polyethylene glycol; Pyrene; Solubility; StarburstTM polyamidoamine dendrimer; Unimolecular dendritic micelle

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Article - Journal

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© 2004 Elsevier Inc., All rights reserved.

Publication Date

01 May 2004

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