TSC study of the dielectric relaxations of human-bone collagen

✍ Scribed by M. Fois; A. Lamure; M. J. Fauran; C. Lacabanne

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 147 KB
• Volume: 38
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(20000401)38:7<987::aid-polb9>3.0.co;2-v

✦ Synopsis

Differential scanning calorimetry (DSC) and thermally stimulated current (TSC) were used to characterize human-bone collagen. DSC glass-transition and denaturation temperatures of the collagen in a dehydrated state were 90 and 215 °C, respectively. By TSC, the main relaxation mode, labeled ␣ and located around 90 °C, could be attributed to the dielectric manifestation of the glass transition. The corresponding molecular movements are cooperative with a compensation temperature close to the denaturation temperature. At low temperatures and in a hydrated state, a second mode labeled ␤ 2 was observed at Ϫ110 °C. Dehydration shifted this mode to higher temperatures, revealing a weak mode labeled ␥ at Ϫ150 °C. This ␥ mode was attributed to motions of aliphatic side chains. An analysis of low-temperature elementary spectra allowed us to assign the ␤ 2 mode to structural water movements and revealed an additional compensation phenomenon in the temperature range (Ϫ80 to Ϫ50 °C). Because the compensation temperature of this mode was close to the collagen glasstransition temperature, the corresponding mode ␤ 1 was attributed to polar side-chain motions, precursors of a collagen glass transition. Finally, around ambient temperature, three sharp peaks were attributed to hydrogen bonds breaking.