| Interactions and encapsulation of vitamins C, B3, and B6 with dendrimers in water. | |
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MedLine Citation:
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PMID: 20397156 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Titrations of commercial diaminobutane (DAB) and polyamidoamine (PAMAM) dendrimers by vitamins C (ascorbic acid, AA), B(3) (nicotinic acid), and B(6) (pyridoxine) were monitored by (1)H NMR spectroscopy using the chemical shifts of both dendrimer and vitamin protons and analyzed by comparison with the titration of propylamine. Quaternarizations of the terminal primary amino groups and intradendritic tertiary amino groups, which are nearly quantitative with vitamin C, were characterized by more or less sharp variations (Deltadelta) of the (1)H chemical shift (delta) at the equivalence points. The peripheral primary amino groups of the DAB dendrimers were quaternarized first, but not selectively, whereas a sharp chemical-shift variation was recorded for the inner methylene protons near the tertiary amines, thereby indicating encapsulation, when all the dendritic amines were quaternarized. With DAB-G5-64-NH(2), some excess acid is required to protonate the inner amino groups, presumably because of basicity decrease due to excess charge repulsion. On the other hand, this selectivity was not observed with PAMAM dendrimers. The special case of the titration of the dendrimers by vitamin B(6) indicates only dominant supramolecular hydrogen-bonding interactions and no quaternarization, with core amino groups being privileged, which indicates the strong tendency to encapsulate vitamins. With vitamin B(3), a carboxylic acid, titration of DAB-G3-16-NH(2) shows that only six peripheral amino groups are protonated on average, even with excess vitamin B(3), because protonation is all the more difficult due to increased charge repulsion, as positive charges accumulate around the dendrimer. Inner amino groups interact with this vitamin, however, thus indicating encapsulation presumably with supramolecular hydrogen bonding without much charge transfer. |
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Authors:
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Elodie Boisselier; Liyuan Liang; Maria Dalko-Csiba; Jaime Ruiz; Didier Astruc |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chemistry (Weinheim an der Bergstrasse, Germany) Volume: 16 ISSN: 1521-3765 ISO Abbreviation: Chemistry Publication Date: 2010 May |
Date Detail:
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Created Date: 2010-05-20 Completed Date: 2010-07-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9513783 Medline TA: Chemistry Country: Germany |
Other Details:
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Languages: eng Pagination: 6056-68 Citation Subset: IM |
Affiliation:
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Institut des Sciences Moléculaires, UMR CNRS no. 5255, Université Bordeaux 1, 351 Cours de la Libération, 33405 Talence Cedex, France. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Amines
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chemistry* Ascorbic Acid / chemistry* Dendrimers / chemistry* Hydrogen Bonding Hydrogen-Ion Concentration Magnetic Resonance Spectroscopy Models, Molecular Molecular Structure Niacinamide / chemistry* Titrimetry Vitamin B 6 / chemistry* Water / chemistry* |
| Chemical | |
Reg. No./Substance:
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0/Amines; 0/Dendrimers; 50-81-7/Ascorbic Acid; 7732-18-5/Water; 8059-24-3/Vitamin B 6; 98-92-0/Niacinamide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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