Materials 2009, 2(3), 883-902; doi:10.3390/ma2030883
Article

Surface Hydrophobic Modification of Fifth-Generation Hydroxyl-Terminated Poly(amidoamine) Dendrimers and Its Effect on Biocompatibility and Rheology

1 Research Branch, Department of Veterans Affairs Medical Center JC 151, 915 N. Grand Blvd. St. Louis, MO 63106, USA 2 Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Box 8096, 660 S. Euclid, St. Louis, MO 63110, USA 3 Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, MO 63130, USA 4 Executive Branch, Department of Veterans Affairs Medical Center JC 151, 915 N. Grand Blvd. St. Louis, MO 63106, USA
* Author to whom correspondence should be addressed.
Received: 25 June 2009; in revised form: 24 July 2009 / Accepted: 31 July 2009 / Published: 4 August 2009
(This article belongs to the Special Issue Biocompatibility of Materials)
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Abstract: Water-soluble, commercially-available poly(amidoamine) (PAMAM) dendrimers are highly-branched, well-defined, monodisperse macromolecules having an ethylenediamine core and varying surface functional groups. Dendrimers are being employed in an increasing number of biomedical applications. In this study, commercially obtained generation 5 hydroxyl-terminated (G5OH) PAMAM dendrimers were studied as potential proteomimetics for ophthalmic uses. To this end, the surface of G5OH PAMAM dendrimers were hydrophobically modified with varying amounts of dodecyl moieties, (flexible long aliphatic chains), or cholesteryl moieties (rigid lipid found in abundance in biological systems). Dendrimers were characterized by 1H-NMR, DLS, DSC and HPLC. The hydrophobic modification caused aggregation and molecular interactions between dendrimers that is absent in unmodified dendrimers. In vitro tissue culture showed that increasing the amount of dodecyl modification gave a proportional increase in toxicity of the dendrimers, while with increasing cholesteryl modification there was no corresponding increase in toxicity. Storage and loss modulus were measured for selected formulations. The hydrophobic modification caused an increase in loss modulus, while the effect on storage modulus was more complex. Rheological properties of the dendrimer solutions were comparable to those of porcine lens crystallins.
Keywords: dendrimers; surface modification; amphiphilic molecules; biocompatibility; rheology; lens crystallins

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MDPI and ACS Style

Hamilton, P.D.; Jacobs, D.Z.; Rapp, B.; Ravi, N. Surface Hydrophobic Modification of Fifth-Generation Hydroxyl-Terminated Poly(amidoamine) Dendrimers and Its Effect on Biocompatibility and Rheology. Materials 2009, 2, 883-902.

AMA Style

Hamilton PD, Jacobs DZ, Rapp B, Ravi N. Surface Hydrophobic Modification of Fifth-Generation Hydroxyl-Terminated Poly(amidoamine) Dendrimers and Its Effect on Biocompatibility and Rheology. Materials. 2009; 2(3):883-902.

Chicago/Turabian Style

Hamilton, Paul D.; Jacobs, Donghui Z.; Rapp, Brian; Ravi, Nathan. 2009. "Surface Hydrophobic Modification of Fifth-Generation Hydroxyl-Terminated Poly(amidoamine) Dendrimers and Its Effect on Biocompatibility and Rheology." Materials 2, no. 3: 883-902.

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