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Synthesis and Characterization of Phosphorylcholine-Substituted Chitosans Soluble in Physiological pH Conditions

Marcio J. Tiera,^† Xing-Ping Qiu,^‡ Sofiane Bechaouch,^§ Qin Shi, Júlio C. Fernandes, and Françoise M. Winnik*^‡

Departamento de Qumica e Cincias Ambientais, UNESP-Universidade Estadual Paulista, So Jos do Rio Preto, Brazil, Faculty of Pharmacy and Department of Chemistry, Universit de Montral, CP 6128 Succursale Centre Ville, Montral, Qubec, Canada H3C 3J7, Laboratoire des Polymres-Biopolymres-Matriaux Organiques, Facult des Sciences de Monastir, Monastir, Tunisia, and Orthopedic Research Laboratory, Hpital du Sacr-Cur de Montral, Universit de Montral, Montral, Qubec, Canada H4J 1C5

Biomacromolecules, 2006, 7 (11), pp 3151–3156

DOI: 10.1021/bm060381u

Publication Date (Web): October 3, 2006

†

UNESP-Universidade Estadual Paulista.

‡

Faculty of Pharmacy and Department of Chemistry, Université de Montréal.

Faculté des Sciences de Monastir.

Hôpital du Sacré-Cœur de Montréal, Université de Montréal.

To whom correspondence should be addressed. E-mail: francoise.winnik@umontreal.ca.

Abstract

A polymer analogous synthesis involving the reductive amination of phosphorylcholine (PC)−glyceraldehyde with primary amines of deacetylated chitosan (M_w ≈ 57000 g mol^-1) was used to prepare phosphorylcholine-substituted chitosans (PC−CH) with a degree of substitution (DS) ranging from 11 to 53 mol % PC-substituted glucosamine residues. The PC−CH derivatives were characterized by ¹H NMR spectroscopy, FTIR spectroscopy, and multiangle laser light scattering gel permeation chromatography (MALLS-GPC). The pK_a of the PC-substituted amine groups (pK_a ≈ 7.20) was determined by ¹H NMR titration. The PC−CH samples (1.0 g L^-1) were shown to be nontoxic using an MTT assay performed with human KB cells. Aqueous solutions of PC−CH samples (4.0 g L^-1) of DS ≥ 22 mol % PC-substituted glucosamine residues remained clear, independently of pH (4.0 < pH < 11.0). The remarkable water solubility and nontoxicity displayed by the new PC−CH samples open up new opportunities in the design of chitosan-based biomaterials and nanoparticles.