Chitosan Dye Research Articles

Synthesis, characterization, and properties of antibacterial dye based on chitosan

A new low-molecular-weight antibacterial dye was obtained by reaction of Reactive Blue 19 and chitosan previously hydrolyzed with H2O2. The compounds were characterized by Fourier-transform infrared spectroscopy, 13C solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction analysis, and antibacterial, solubility, and dyeing performance tests including color difference and fastness. The results show that chitosan dyes were generated with covalent bonds between carbon and nitrogen atoms via reaction of alkene group of dye and primary amine group of chitosan. According to solubility tests, the solubility of the chitosan dye was controlled by the molecular weight of chitosan. In addition, compared with Reactive Blue 19, the antibacterial property of the chitosan dye was increased against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Besides, chitosan dye demonstrated better lightfastness and waterfastness than the original dye. Therefore, chitosan dye provides a new perspective for improving decorative and antimicrobial properties of wood products.

Photostabilization of Beauveria bassiana conidia using anionic dyes

Microbial biocontrol agents, which are selective and non-polluting measures for controlling insect pests, are sensitive to environmental factors, notably solar UV radiation. To overcome the constraint of photoinstability and provide adequate field performance, the photostabilizing potential of organo-clay matrices was studied. The clay mineral surfaces were modified by adsorption of chitosan, a polycationic biopolymer. The positively charged clay–chitosan complexes served for adsorption of potent photoprotective anionic dyes. A variety of clay–chitosan–dye matrices were prepared and examined as to their potential to photostabilize UV-irradiated fungal conidia of the entomopathogen Beauveria bassiana. The matrices were composed of palygorskite, montmorillonite, bentonite and kaolinite and of 6 anionic dyes: Acid Yellow 25 (AY), Chrysophenine G (Chrys.), Direct Yellow 50 (DY), Mordant Blue (MB), Fast Green (FG) and Naphthol Yellow S (NYS). The adsorption isotherms of dyes and their level of adsorption to the organo-clays were established. Clay–chitosan complexes per se were able to bestow significant measures of photoprotection, apparently due to their UV light scattering property. High and relatively consistent levels of photostabilization were observed with clay–chitosan matrices containing Chrys., AY, NYS and DY following prolonged irradiation. Depending on the clay-based matrix, MB and FG provided less persistent photostabilization levels. In contrast to the other clay–chitosan complexes, the high photoprotection bestowed by kaolinite–chitosan per se obscured to a great extent any contribution of the anionic dyes. Apparently, the photostabilization of the clay-based matrices is a combination of UV light scattering capacity of clay minerals and the UV screening effect due to the adsorbed dyes.

Poly(2‐hydroxyethylmethacrylate)/chitosan dye and different metal‐ion‐immobilized interpenetrating network membranes: Preparation and application in metal affinity chromatography

AbstractComposite membranes were synthesized with 2‐hydroxyethylmethacrylate and chitosan (pHEMA/chitosan) via an ultraviolet‐initiated photopolymerization technique in the presence of an initiator (α,α′‐azobisisobutyronitrile). The interpenetrating network (IPN) membranes were improved by the immobilization of dye molecules via hydroxyl and amino groups on the membrane surfaces from the IPNs. A triazidine dye (Procion Green H‐4G) was covalently immobilized as a ligand onto the IPN membranes. The protein showed various affinities to different chelated metal ions on the membrane surfaces that best matched its own distribution of functional sites, resulting in a distribution of binding energies. In support of this interpretation, two different metal ions, Zn(II) and Fe(III), were chelated with the immobilized dye molecules. The adsorption and binding characteristics of the different metal‐ion‐chelated dye‐immobilized IPN membranes for the lysozyme were investigated with aqueous solutions in magnetically stirred cells. The experimental data were analyzed with two adsorption kinetic models, pseudo‐first‐order and pseudo‐second‐order, to determine the best fit equation for the adsorption of lysozyme onto IPN membranes. The second‐order equation for the lysozyme–dye–metal‐chelated IPN membrane systems was the most appropriate equation for predicting the adsorption capacity for all the tested adsorbents. The reversible lysozyme adsorption on the dye‐immobilized and metal‐ion‐chelated membranes obeyed the Temkin isotherm. The lysozyme adsorption capacity of the pHEMA/chitosan dye, pHEMA/chitosan dye–Zn(II), and pHEMA/chitosan dye–Fe(III) membranes were 2.54, 2.85, and 3.64 mg cm−2, respectively. The nonspecific adsorption of the lysozyme on the plain pHEMA/chitosan membrane was about 0.18 mg cm−2. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1843–1853, 2003