Studies on photoyellowing of silk fibroin and alteration of its tyrosine content

Abstract

The photoyellowing progress of silk fibroin and its influence factors under ultraviolet irradiation have been studied, which was conducted by combining different ultraviolet wavelengths, different ultraviolet irradiancies, and different irradiation times. The blue-ray whiteness after ultraviolet irradiation was tested to characterize the course of photoyellowing of silk fibroin. The result shows that the photoyellowing degree of silk fibroin varies significantly under ultraviolet irradiation of different wavelengths and with the increasing in ultraviolet irradiancy at 313-nm wavelength, the photoyellowing degree aggravates correspondingly, while the ultraviolet irradiancy at 340-nm wavelength has little obvious impact. Additionally, the photoyellowing degree of silk fibroin is positively correlated to ultraviolet irradiancy and irradiation time. To quantitatively analyze the alteration of tyrosine content during the photoyellowing of the silk fibroin, L-tyrosine standard curve Y = 8.14666X − 0.88951 was established using HPLC with linear coefficient r = 0.99991 and precision degree coefficient of tyrosine analyses RSD 1 = 0.21%. Meanwhile, the tyrosine content of silk fibroin after acid hydrolysis was quantitatively analyzed by HPLC with precision degree coefficient RSD 2 = 1.12%. It can be seen that the change rate of the blue-ray whiteness of silk fibroin is positively proportional to the photodegradation rate of tyrosine, but the photodegradation rate of tyrosine ingredient is lower than the change rate of the blue-ray whiteness of silk fibroin.

Preparation and Statistical Characterization of Tunable Porous Sponge Scaffolds using UV Cross-linking of Methacrylate-Modified Silk Fibroin

“…For this reason, the direct effect of the UV radiation on the protein can be excluded. The impact of the UV radiation on amino acids, as previously reported, is a function of time, energy adsorbed, and wavelength. In particular, photo-yellowing is mainly due to free radical photooxidation of the tryptophan and tyrosine residues, leading to the formation of yellow products.…”

Aging behavior of nano-CaCO3-modified polypropylene nonwoven fabric composites

“…Eight UV-B tubes (HK TL40 W/L1200*d38, Nanjing Huanke Equipment Co., Ltd, China) were used as light source, and their luminescence spectra were described in our previous research paper. 10 Before exposure to UV irradiation, both the PP nonwoven fabric and the CaCO 3 -modified PP nonwoven fabric were cut into 300 × 75 mm 2 samples. During the UV aging, irradiation was carried out without any pause.…”

Preparation, Structure, and Properties of Silk Fabric Grafted with 2-Hydroxypropyl Methacrylate Using the HRP Biocatalyzed ATRP Method

“…It is widely used in the textile field because of its outstanding mechanical strength, wear comfortability, and elegant luster, which has been praised as the queen of fibers [ 1 , 2 , 3 ]. However, silk has some shortcomings, such as bad crease recovery property and photo-yellowing stability [ 4 , 5 , 6 ]. Silk is very easy to wrinkle during wearing, especially after sweating or washing.…”