Laccase-catalyzed cross-linking of BSA mediated by tyrosine

Tyrosine was explored as a cross-linking agent to form cross-linked bovine serum albumin (BSA) using laccase as a catalyst. Liquid chromatography-mass spectrometry (LC-MS) and fluorescence spectra indicated that tyrosine can be mainly oxidized to be dityrosine. Spectra analysis and molecular weight were used to characterize the BSA treated with tyrosine and laccase. Both SDS-PAGE and size exclusion chromatography confirmed the formation of cross-linked BSA, while most of the protein products existed as BSA–tyrosine conjugates. The MALDI-TOF analysis revealed that five tyrosine units were grafted on one BSA monomer, however one cross-linked BSA consists of two BSA monomers and 18 tyrosine. Furthermore, the content of the amino acid of BSA was identified using amino acid analysis, among those the percentage of lysine presented a visible decline from 12.36% to 11.43%, corresponding to 4-5 lysine residues. The pure and modified BSA were hydrolyzed by trypsin and the corresponding peptides were obtained. Different mass of five peptides from LC-MS spectra after hydrolysis indicated that tyrosine could react with Lys-136, Lys-204, Lys-224, Lys-322 and Lys-537 in BSA, promoting the formation of BSA–tyrosine conjugates and cross-linked BSA.This study was supported by Chinese Government Scholarship under China Scholar Council (NO. 201906790043) and “the Fundamental Research Funds for the Central Universities (NO. JUSRP52007A). This study was also supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte

Environmentally Friendly Surface Treatment of Wool Fiber with Plasma and Chitosan for Improved Coloration with Cochineal and Safflower Natural Dyes

In this study, the effect of surface modification of wool fiber with oxygen plasma and chitosan (PC) on the color strength of the samples dyed with cochineal and safflower natural dyes has been studied. According to colorimetric measurements, plasma and chitosan treatments resulted in notable improvements in dyeability of wool fibers. The plasma and chitosan-treated wool sample could be dyed in less time and at lower temperature compared with untreated one. The dyebath pH had a prominent effect on color strength, which showed that the electrostatic force has an important role in dye adsorption. The optimum pH for maximum dye absorption was 3.6. The fastness properties, tensile strength, and elongation at break of dyed wool were improved after PC treatment. Scanning electron microscopy (SEM) images and ATR-FTIR analysis proved the coating of wool scales with a uniform thin layer of chitosan, which caused the improved dyeability of wool fibers with safflower and cochineal

Optimization of dyeing wool fibers procedure with Isatis tinctoria by Response Surface Methodology

The response surface method (RMS) was used to optimize the color strength (K/S) of the wool fibers dyed with Isatis tinctoria. The eight independent variable terms, in which two of them are categorical and the other six numerical, were selected at two levels (low and high). The ANOVA test results of the linear model showed that the model terms, including reducing agent amount, dyeing temperature, dyeing time, and dyestuff percentage, have a significant effect on K/S. The actual values agreed with the predicted values and the suggested equation model was satisfactory and accurat

Biosynthesis of silver nanoparticles using Reseda Luteola L. and their antimicrobial activity

Among different methods to synthesize silver nanoparticles (SNPs), the biological method has been the most extensively investigated. This study presents a facile and rapid method for biosynthesis of silver nanoparticles from Weld (Reseda Luteola L.) as a natural dye. An aqueous extract of the dye was used as a reducing agent for silver ions. The: evaluation of these nanoparticles was made by various methods. The formation and growth of the nanoparticles were studied using UV-Vis absorption spectroscopy, while their shape, size and morphologies were monitored by transmission electron microscopy (TEM). Moreover, the influence of the dye amount to silver ratio and contact time were evaluated to find their effects on synthesis' efficacy. Size distribution of SNPs were evaluated by means of Dynamic light scattering (DLS) measurements. Antibacterial potential of biosynthesized SNPs was investigated