Institute of Chemical Technologies and Analytics, TU Wien, Getreidemarkt 9, A-1060 Vienna, Austria.
Institute of Science and Technology in Art, Academy of Fine Arts Vienna, Schillerplatz 3, A-1010 Vienna, Austria.
Molecules. 2023 Jun 6;28(12):4584. doi: 10.3390/molecules28124584.
From the moment of production, artworks are constantly exposed to changing environmental factors potentially inducing degradation. Therefore, detailed knowledge of natural degradation phenomena is essential for proper damage assessment and preservation. With special focus on written cultural heritage, we present a study on the degradation of sheep parchment employing accelerated aging with light (295-3000 nm) for one month, 30/50/80% relative humidity (RH) and 50 ppm sulfur dioxide with 30/50/80%RH for one week. UV/VIS spectroscopy detected changes in the sample surface appearance, showing browning after light-aging and increased brightness after SO-aging. Band deconvolution of ATR/FTIR and Raman spectra and factor analysis of mixed data (FAMD) revealed characteristic changes of the main parchment components. Spectral features for degradation-induced structural changes of collagen and lipids turned out to be different for the employed aging parameters. All aging conditions induced denaturation (of different degrees) indicated by changes in the secondary structure of collagen. Light treatment resulted in the most pronounced changes for collagen fibrils in addition to backbone cleavage and side chain oxidations. Additional increased disorder for lipids was observed. Despite shorter exposure times, SO-aging led to a weakening of protein structures induced by transitions of stabilizing disulfide bonds and side chain oxidations.
从生产的那一刻起，艺术品就不断地暴露在潜在的环境因素中，这些因素可能会导致艺术品退化。因此，详细了解自然降解现象对于正确的损伤评估和保护至关重要。本文特别关注书面文化遗产，研究了羊皮纸在光（295-3000nm）下加速老化一个月、相对湿度（RH）为 30/50/80%和 50ppm 二氧化硫以及相对湿度为 30/50/80%下加速老化一周的降解情况。紫外可见光谱检测到样品表面外观的变化，在光老化后出现棕褐色，在 SO 老化后亮度增加。ATR/FTIR 和拉曼光谱的带解卷积以及混合数据的因子分析（FAMD）揭示了主要羊皮纸成分的特征变化。用于降解诱导的胶原蛋白和脂质结构变化的光谱特征对于所采用的老化参数来说是不同的。所有老化条件都导致了胶原蛋白的变性（不同程度），这是由胶原蛋白二级结构的变化引起的。光处理除了骨干断裂和侧链氧化外，还导致胶原蛋白原纤维发生最明显的变化。还观察到脂质的额外无序增加。尽管暴露时间较短，但 SO 老化也会导致稳定的二硫键和侧链氧化等转化引起的蛋白质结构减弱。
