| Title | Chemical modification of chitosan by phosphorylation: An XPS, FT-IR and SEM study |
| Publication Type | Journal Article |
| 2005 |
| Authors | Amaral, IF, Granja, PL, Barbosa, MA |
| Journal | Journal of Biomaterials Science, Polymer EditionJ. Biomater. Sci. Polym. Ed. |
| Volume | 16 |
| Issue | 12 |
| Pagination | 1575 - 1593 |
| Date Published | 2005/// |
| 09205063 (ISSN) |
| Acetylation, amine, animal, Animals, Apatite, article, bone conduction, butanol, calcium ion, cation exchange, cephalopod, chelate, Chemical modification, chemistry, Chitin, chitosan, comparative study, controlled study, Decapodiformes, Fourier transform infrared spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Growth factor, immobilization, Implants (surgical), infrared spectroscopy, isolation and purification, Microscopy, Electron, Scanning, molecular weight, organophosphate, phosphate, Phosphate groups, Phosphates, Phosphorylation, Phosphorylation method, Plastics applications, priority journal, reflectometry, room temperature, Scanning electron microscopy, SEM-EDS, signal transduction, spectrometry, Spectrometry, X-Ray Emission, Spectroscopy, Fourier Transform Infrared, Surface chemical reaction, Surface Properties, surface property, temperature, time, Time Factors, viscosity, X ray photoelectron spectroscopy, X-rayphotoelectron spectroscopy (XPS) |
| In the present work, the surface of chitosan membranes was modified using a phosphorylation method carried out at room temperature. Phosphorylation may be of particular interest in materials for orthopaedic applications, due to the cation-exchange properties of phosphate functionalities. Phosphate groups chelate calcium ions, thus inducing the deposition of an apatite-like layer known to improve the osteoconduction of polymer-based implants. Additionally, the negatively charged phosphate functionalities, together with the positively charged amine groups from chitosan, are expected to provide chitosan with an amphoteric character, which may be useful as a combinatorial therapeutic strategy, by simultaneously allowing the immobilization of signalling molecules like growth factors. Phosphorylation was carried out at room temperature using the H 3 PO
4/Et
3 PO
4/P
2O
5/butanol method. Surface characterization was performed by XPS, ATR-FT-IR, and SEM. Cross-sections were analyzed by SEM fitted with EDS. The phosphate content increased with the reaction time, as shown by XPS and ATR-FT-IR, a P/N atomic ratio of 0.73 being obtained after 48 h of treatment. High-resolution XPS spectra regarding C
1s, O
1s, N
1s and P
2p are discussed. The introduction of a neutralization step led to a reduction of P content, which pointed out to the presence of phosphates ionically bound to protonated amines, in addition to phosphate esters. EDS analysis of cross-sections revealed a gradual P reduction up to 50% towards the inner part of the membrane. © VSP 2005.
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