Surface study of collagen/poloxamine hydrogels by a ‘deep freezing’ ToF-SIMS approach

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• 作者：Alejandro Sosnik ; Rana N.S. Sodhi ; Peter M. Brodersen and Michael V. Sefton
• 关键词：Surface analysis ; ‘ ; Deep freezing’ ; ToF-SIMS ; Hydrogels ; Collagen ; Poloxamine
• 刊名：Biomaterials
• 出版年：2006
• 出版时间：April 2006
• 年：2006
• 卷：27
• 期：11
• 页码：2340-2348
• 全文大小：650 K

文摘

In order to determine the presence of collagen molecules at the surface of a collagen-modified poloxamine hydrogel (a semi-interpenetrating network), the surface composition was studied using Time-of-Flight Secondary Ion Mass Spectra (ToF-SIMS). Collagen was added to the poloxamine hydrogel (poloxamine is a commercially available four-arm poly(ethylene oxide)/poly(propylene oxide) block copolymer, PEO/PPO) to promote the attachment of endothelial or liver cells. X-ray photoelectron spectroscopy (XPS) of dry samples showed a sharp increase in the N content from 0.6 % in a pure poloxamine hydrogel to 8.8 % in the collagen-containing material. Afterwards, the surface was studied by a ‘deep freezing’ ToF-SIMS approach under progressive heating from −120 to −60 °C. The positive spectrum of collagen/poloxamine at −65 °C displayed distinct signals corresponding to different amino acid fragments such as CH₄N⁺ (30 m/z, Gly), C₃HN₂⁺ (43 m/z, Arg), C₂H₆N⁺ (44 m/z, Ala) and C₄H₅N₂⁺ (81 m/z, His) and others corresponding to the PEO and PPO blocks of poloxamine. In addition, the negative spectrum showed peaks at 26 m/z (CN⁻), 32 m/z (S⁻) and 42 m/z (CNO⁻) characteristic of fragments of the collagen molecule. Imaging experiments indicated the homogeneous distribution of the collagen on the surface. These results supported the use of ToF-SIMS for the surface characterization of hydrated hydrogels and confirmed the collagen presence as the means whereby cells attach to the modified poloxamine matrix.