Influence of Amino Acids, Buffers, and pH on the γ‑Irradiation-Induced Degradation of Alginates

• Published in: Biomacromolecules 2014-12, Vol.15 (12), p.4590-4597
• Main Authors: Ulset, Ann-Sissel T, Mori, Hideki, Dalheim, Marianne Ø, Hara, Masayuki, Christensen, Bjørn E
• Format: Article
• Language: English
• Subjects: Alginates - chemistry; Alginates - radiation effects; Amino Acids - chemistry; Applied sciences; Biocompatible Materials; Biological and medical sciences; Buffers; Crosslinking and degradation; Exact sciences and technology; Gamma Rays; Glucuronic Acid - chemistry; Glucuronic Acid - radiation effects; Hexuronic Acids - chemistry; Hexuronic Acids - radiation effects; Hydrogen-Ion Concentration; Medical sciences; Molecular Weight; Physicochemistry of polymers; Polymers and radiations; Sterilization; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Technology. Biomaterials. Equipments
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm501386n

Alginate-based biomaterials and medical devices are commonly subjected to γ-irradiation as a means of sterilization, either in the dry state or the gel (hydrated) state. In this process the alginate chains degrade randomly in a dose-dependent manner, altering alginates’ material properties. The addition of free radical scavenging amino acids such as histidine and phenylalanine protects the alginate significantly against degradation, as shown by monitoring changes in the molecular weight distributions using SEC-MALLS and determining the pseudo first order rate constants of degradation. Tris buffer (0.5 M), but not acetate, citrate, or phosphate buffers had a similar effect on the degradation rate. Changes in pH itself had only marginal effects on the rate of alginate degradation and on the protective effect of amino acids. Contrary to previous reports, the chemical composition (M/G profile) of the alginates, including homopolymeric mannuronan, was unaltered following irradiation up to 10 kGy.