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Functionalization of chitosan membranes through phosphorylation: Atomic force microscopy, wettability, and cytotoxicity studies
Author(s) -
Amaral I. F.,
Granja P. L.,
Melo Luís V.,
Saramago B.,
Barbosa M. A.
Publication year - 2006
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.23737
Subject(s) - membrane , apatite , contact angle , wetting , surface modification , phosphoric acid , cytotoxicity , surface energy , chemical engineering , chitosan , chemistry , materials science , nuclear chemistry , biophysics , organic chemistry , biochemistry , mineralogy , in vitro , composite material , biology , engineering
Grafting negatively charged groups such as phosphates is a well‐known strategy for inducing the deposition of apatite‐like layers under simulated physiological conditions. In this investigation, chitosan was phosphorylated in an attempt to enhance its osteoconduction. Chitosan membranes were phosphorylated at 30°C with the H 3 PO 4 /Et 3 PO 4 /P 2 O 5 /butanol reaction system for periods up to 48 h. This method is an alternative to the phosphoric acid/urea/dimethylformamide phosphorylation method, which involves the use of much higher temperatures. In this study, the effects of the phosphorylation reaction time on the surface morphology and surface free energy of phosphorylated membranes were investigated with atomic force microscopy and static‐contact‐angle measurements, respectively. In addition, the modified membranes were evaluated with respect to their cytotoxicity toward bone cells through the incubation of human osteoblastic cells with extracts of the materials for two different periods: 24 and 120 h. The results revealed a reduction of the average surface roughness at the nanometer scale with increasing phosphorylation reaction time. Wettability studies showed an increase in the polar component of the surface free energy with increasing reaction time as a result of the increase in the phosphate surface concentration. Cytotoxicity studies revealed no cytotoxic effect of phosphorylated membranes on osteoblastic cells, regardless of the incubation period. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 276–284, 2006