Carboxymethylation of ulvan and chitosan and their use as polymeric components of bone cements

• Published in: Acta biomaterialia Vol. 9; no. 11; pp. 9086 - 9097
• Main Authors: Barros, A.A.A., Alves, A., Nunes, C., Coimbra, M.A., Pires, R.A., Reis, R.L.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2013
• Subjects: Acetylation - drug effects; Animals; Biocompatible Materials - chemistry; Biocompatible Materials - pharmacology; Bone cements; Bone Cements - chemistry; Bone Cements - pharmacology; calcium; Calcium - analysis; Carboxymethylation; Cell Death - drug effects; cement; Chitosan; Chitosan - analogs & derivatives; Chitosan - chemistry; Chitosan - pharmacology; Compressive Strength - drug effects; Elastic Modulus - drug effects; Fourier transform infrared spectroscopy; Glass Ionomer Cements - chemistry; Glass-ionomers; Loligo; Magnetic Resonance Spectroscopy; Materials Testing; Mice; Microscopy, Electron, Scanning; Molecular Weight; nuclear magnetic resonance spectroscopy; Phosphorus - analysis; Polymers - chemistry; Polymers - pharmacology; Polysaccharides - chemistry; Polysaccharides - pharmacology; Porosity; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; titration; Ulva lactuca; Ulvan; Water - chemistry; X-Ray Diffraction; Carboxymethylation; Chitosan; Bone cements; Ulvan; Glass-ionomers
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2013.06.036

Ulvan, extracted from the green algae Ulva lactuca, and chitosan, extracted from Loligo forbesis squid-pen, were carboxymethylated, yielding polysaccharides with an average degree of substitution of ∼98% (carboxymethyl ulvan, CMU) and ∼87% (carboxymethyl chitosan, N,O-CMC). The carboxymethylation was confirmed by Fourier transform infrared spectroscopy and quantified by conductimetric titration and 1H nuclear magnetic resonance. The average molecular weight increased with the carboxymethylation (chitosan, Mn 145→296kDa and Mw 227→416kDa; ulvan, Mn 139→261kDa and Mw 368→640kDa), indicating successful chemical modifications. Mixtures of the modified polysaccharides were tested in the formulation of polyacrylic acid-free glass-ionomer bone cements. Mechanical and in vitro bioactivity tests indicate that the inclusion of CMU in the cement formulation, i.e. 0.50:0.50N,O-CMC:CMU, enhances its mechanical performance (compressive strength 52.4±8.0MPa and modulus 2.3±0.3GPa), generates non-cytotoxic cements and induces the diffusion of Ca and/or P-based moieties from the surface to the bulk of the cements.