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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Physicochemical characterization of nanoparticles formed between DNA and phosphorylcholine substituted chitosans

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Author(s):
Case, Ana Helena [1] ; Dalla Picola, Isadora Pfeifer [1] ; Darbello Zaniquelli, Maria Elisabete [2] ; Fernandes, Julio Cesar [3] ; Taboga, Sebastiao Roberto [4] ; Winnik, Francoise M. [5, 6] ; Tiera, Marcio Jose [7]
Total Authors: 7
Affiliation:
[1] Sao Paulo State Univ, UNESP, IBILCE, Inst Biosci Humanities & Exact Sci, Dept Phys, BR-15054000 Sao Paulo - Brazil
[2] Univ Sao Paulo, Sch Philosophy Sci & Humanities, Dept Chem, FCL, Sao Paulo - Brazil
[3] Hop Sacre Coeur, Orthoped Res Lab, Montreal, PQ H4J 1C5 - Canada
[4] Sao Paulo State Univ, UNESP, IBILCE, Inst Biosci Humanities & Exact Sci, Dept Biol, BR-15054000 Sao Paulo - Brazil
[5] Univ Montreal, Dept Chem, Montreal, PQ H3C 3J7 - Canada
[6] Univ Montreal, Fac Pharm, Montreal, PQ H3C 3J7 - Canada
[7] Sao Paulo State Univ, UNESP, IBILCE, Inst Biosci Humanities & Exact Sci, Dept Chem & En, BR-15054000 Sao Paulo - Brazil
Total Affiliations: 7
Document type: Journal article
Source: Journal of Colloid and Interface Science; v. 336, n. 1, p. 125-133, AUG 1 2009.
Web of Science Citations: 18
Abstract

The interactions between phosphorylcholine-substituted chitosans (PC-CH) and calf-thymus DNA (ct-DNA) were investigated focusing on the effects of the charge ratio, the pH, and phosphorylcholine content on the size and stability of the complexes using the ethidium bromide fluorescence assay, gel electrophoresis, dynamic light scattering. and fluorescence microscopy. The size and colloidal stability of deacetylated chitosan (CH/DNA) and PC-CH/DNA complexes were strongly dependent on phosphorylcholine content, charge ratios, and pH. The interaction strengths were evaluated from ethidium bromide fluorescence, and at N/P ratios higher than 5.0, no DNA release was observed in any synthesized PC-CH/DNA polyplexes by gel electrophoresis. The PC-CH/DNA polyplexes exhibited a higher resistance to aggregation compared to deacetylated chitosan (CH) at neutral pH. At low pH values highly charged chitosan and its phosphorylcholine derivatives had strong binding affinity with DNA, whereas at higher pH Values CH formed large aggregates and only C-CH derivatives were able to form small nanoparticles with hydrodynamic radii varying from 100 to 150 nm. Nanoparticles synthesized at low ionic strength with PC-CH derivatives containing moderate degrees of substitution (DS = 20% and 40%) remained stable for weeks. Photomicroscopies also confirmed that rhodamine-labeled PC(40)CH derivative nanoparticles presented higher colloidal stability than those synthesized using deacetylated chitosan. Accordingly, due to their improved physicochemical properties these phosphorylcholine-modified chitosans provide new perspectives for controlling the properties of polyplexes. (C) 2009 Elsevier Inc. All rights reserved. (AU)