Degradation markers of fibroin in silk through infrared spectroscopy

Evaluating the impact of different exogenous factors on silk textiles deterioration with use of size exclusion chromatography

“…Light, temperature and humidity have a detrimental impact on the rate of the degradation, manifested by, for example, glass transition [13], recrystallisation [14,15], oxidative [16][17][18][19] and photooxidative [20,21] changes, and photoinduced -S-S-bond breakdown [22,23]. Additionally, the material during natural ageing emits volatile organic compounds (VOCs), which results in mass loss [24].…”

“…This eventually gives rise to the loss of silk brightness [19,24,30]. Oxidative changes in functional groups of fibroin chains lead to their spatial rearrangement within amorphous regions [14,18], which together with water vapour, VOCs, oxygen or other agents facilitate chain scission. Additionally, upon thermal treatment a decrease in basic amino acids content and increase of the amount of acidic amino acids is observed [31].…”

“…In the literature, the degradation was evaluated by the changes of silk mechanical properties [34], colour [30], crystalline structure by X-ray diffraction [14,18,35], viscosity [36,37], molecular weight of silk component by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) [38] and molecular weight distribution by SEC [19,30,36,[39][40][41]. As the macroscopic properties (like mechanical endurance) of silk textiles may be reflected by the distribution of fibroin chain length, condition of the historical silk textiles can be evaluated from measurements of the molecular weight distribution of the silk [ref].…”

“…To spot possible degradation pathways, a thermal ageing in 90°C in oxygen atmosphere was applied, coupled with different humidity levels and in presence of VOCs. These factors are known to affect art materials at a different rate [18,30,33,40,49,51,[53][54][55]. The deterioration of silk fibres causes brittleness of the textile, resulting in loss of mechanical endurance.…”

“…The deterioration of silk fibres causes brittleness of the textile, resulting in loss of mechanical endurance. It is known that elevated relative humidity favours hydrolytic [18,40] and microbial [56][57][58][59] and oxidative [18] degradation of silk textiles. On other hand, accelerated ageing experiments on silk textiles indicated that dry-air atmosphere causes effects similar to damages detected in historic samples [19,60].…”