Free Salt Dyeing by Treatment of Cotton Fabric Using Carboxyethyl Chitosan and Synthesized Direct Dyes to Enhance Dyeing Properties and Antibacterial Activity

AIM

The purpose of this paper is to synthesize and characterize two new direct dyes based on chromenes derivatives.

BACKGROUND

The synthesis of carboxyethyl chitosan (CECS) by the reaction of chitosan and acrylic acid via Michael's addition reaction was conducted. Cotton fabrics were treated with CECS to enhance the exhaustion of dye, fastness properties, and antimicrobial activity of dyed fabric.

METHODS

Chitosan (CS) and acrylic acid were combined in Michael's addition process to successfully produce N-carboxyethylchitosan (CECS). Then, the cotton was treated with different concentrations of carboxyethyl chitosan (0.5-5 wt.%) and then dyed by synthesized mono azo and diazo direct dyes based on chromene derivatives.

RESULTS AND DISCUSSION

The results regarding dyeing and antibacterial activity indicated highquality dyeing properties, However, direct dyes showed higher exhaustion and fixation values, fastness properties, and the colorimetric CIE L*a*b* C*h° data of the dyed cotton fabric.

CONCLUSION

Cotton fabrics treated with carboxyethyl chitosan and dyed with direct dyes were found to have higher antibacterial activity upon a concentration of 2.5 wt.%. In addition, the antibacterial activity towards Gram-positive bacteria was reported to be more than Gram-negative bacteria.

Synthesis and properties of tetrazole-containing polyelectrolytes based on chitosan, starch, and arabinogalactan

The synthesis of tetrazole-containing derivatives of chitosan, starch, and arabinogalactan was carried out by a sequence of reactions including cyanoethylation of polysaccharides and subsequent azidation of cyanoethyl derivatives. The reaction of cyanoethylation of polysaccharides with acrylonitrile proceeds in the temperature range 40–60°C in the presence of NaOH. The transformation of nitrile groups into tetrazole rings (azidation) of cyanoethylated polysaccharide derivatives was carried out with a mixture of sodium azide with ammonium chloride in DMF at 105°C. The reaction with the participation of derivatives of starch and arabinogalactan is characterized by the degree of conversion of nitrile groups into tetrazole rings, which is close to the maximum. The introduction of unsubstituted tetrazole rings into the structure of polysaccharides of acidic N–H substantially changes some of their properties. Like other carbo- and hetero-chain polymers containing N–H unsubstituted tetrazole rings in the structure, tetrazolated polysaccharides exhibit the properties of acidic polyelectrolytes. Tetrazole-containing derivatives of chitosan exhibit the properties of polyampholytes. The presence of tetrazole rings in the structure of modified polysaccharides allows the reaction with epoxy compounds to yield network polymers capable of limited swelling in aqueous media with the formation of polyelectrolyte hydrogels.

Potential use of N-carboxyethylchitosan in biomedical applications: Preparation, characterization, biological properties

N-carboxyethylchitosan (CECS) was successfully prepared via Michael addition reaction of chitosan (CS) with acrylic acid in water. The structure of CECS was characterized by Fourier transform Infra-Red spectrometry (FT-IR), ¹HNMR, elemental analysis, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC). Antibacterial activity of CECS was evaluated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by using minimum inhibition concentration (MIC). The results showed that the prepared CECS soluble in water at wide range of pH values. In addition, it has amorphous character improve its chemical reactivity than CS itself, in addition it has been showed stronger antibacterial activity than chitosan itself due to the presence of both -COOH and -NH₂ groups and the CECS shows higher antibacterial activity towards S. aureus than E. coli. Finally, the cytotoxicity of CECS has been evaluated through Cell viability assay, which confirm that CECS is non-toxic and tissue compatible like CS.

In vitro degradation and drug-release properties of water-soluble chitosan cross-linked oxidized sodium alginate core-shell microgels

Hydrogels based on sodium alginate (SA) have already been widely used in biomedical applications using Ca(2+) as a cross-linker; however, these hydrogels tend to disintegrate in electrolyte solutions. To solve this problem, we present a kind of oxidized sodium alginate (OSA) microgel using water-soluble chitosan (WSC) as a cross-linker. This microgel was successfully prepared via an emulsion cross-linking technique at room temperature. The microgel was cross-linked by the formation of both Schiff base bonds and inter-polyelectrolyte complexes, which can efficiently eliminate the disintegration of the microgel in electrolyte solutions. Morphological properties of the resulting microgels were determined by transmission electron microscopy (TEM), hydrodynamic diameters of the microgels were characterized by dynamic light scattering (DLS). The objective of this work was to achieve the colon-specific delivery of an anti-ulcerative colitis drug. 5-Aminosalicylic acid (5-ASA) was chosen as a model drug and the in vitro drug-release profile was established in buffer solutions with 0.1 M HCl/NaCl (pH 1.2) and 0.1 M phosphate-buffered saline (PBS, pH 7.4) at 37°C. The microgel was incubated in 0.1 M PBS (pH 7.4) at 37°C to determine its degradation behavior. Cell cytotoxicity (tested by MTT assay) showed that this microgel had no significant cytotoxicity. These results indicated that this microgel prepared by introducing WSC into OSA may have potential applications in oral controlled drug-delivery systems. Therefore, the OSA/WSC microgel may be a useful carrier for the colon-specific delivery of anti-inflammatory drugs including 5-ASA and the enhanced therapeutic effect of ulcerative colitis.

Preparation and characterization of chitin benzoic acid esters

Chitin benzoic acid esters were prepared using a phosphoryl mixed anhydride method. The products were characterized by 1H-NMR and FT-IR spectroscopy. FT-IR analysis revealed that the degree of O-acyl substitution of the products was in a range of 1.17-1.83. Morphological surface changes in the parent molecule due to the introduction of benzoic acid moieties were observed by scanning electron microscopy. The surface of the products was porous, in contrast to the sheet-shape of the parent molecules. The solubility of the products, which improved with increased degree of acid substitution, was tested in various organic solvents.

Spherical N-carboxyethylchitosan/hydroxyapatite nanoparticles prepared by ionic diffusion process in a controlled manner

The nanocomposites containing hydroxyapatite (HA) and biomacromolecules have attracted considerable research interest in implants, tissue scaffolds and drug controlled delivery. In this study, the N-carboxyethylchitosan/hydroxyapatite (NCECS/HA) nanoparticles were prepared by the ionic diffusion process in a controlled manner. The crystallization, particle size, size distribution and aggregation morphology of the NCECS/HA nanocomposites were dependent on the mole ratio of the glucosamine unit in NCECS to the Ca(2+). Fourier transform-infrared spectroscopic (FTIR) result indicated that there are chemical bonds formed between NCECS and HA. X-ray diffraction (XRD) analysis showed that the crystallization of HA in NCECS matrix was significantly retarded. Transmission electron microscopy (TEM) results revealed that NCECS/HA nanocomposites have the spherical morphology with the diameter ranging from 10 to 40 nm. The NCECS mineralization is driven by the self-assembly of NCECS and HA. These NCECS/HA nanocomposites have potential applications as the carrier for the controlled delivery of growth factors and drugs.

Hybrid nanofibrous yarns based on N-carboxyethylchitosan and silver nanoparticles with antibacterial activity prepared by self-bundling electrospinning

Hybrid nanofibrous materials with antibacterial activity consisting of yarns from N-carboxyethylchitosan (CECh) and poly(ethylene oxide) (PEO) that contain 5 wt% or 10 wt% silver nanoparticles (AgNPs) were prepared. This was achieved by electrospinning using formic acid as a solvent and as a reducing agent for silver ions. AgNO₃ was used as an Ag(+)-containing salt. Its concentration was selected to be 0.02 mol/L or 0.04 mol/L in order the content of the AgNPs in the electrospun nanofibers to be 5 wt% or 10 wt%, respectively. The self-bundling of the fibers into yarns with a mean diameter of ca. 35 μm was enabled only by using a grounded needle electrode. The reduction of the silver ions to an elemental silver was evidenced by UV-vis spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The transmission electron microscopy (TEM) analyses revealed that AgNPs formed at AgNO₃ concentration of 0.02 mol/L were with a mean diameter of 4±0.5 nm and were distributed uniformly within the fiber. The increase of AgNO₃ concentration to 0.04 mol/L led to the preparation of AgNPs with a higher mean diameter and a broader diameter distribution as well as to aggregate formation. The performed studies on the antibacterial activity of CECh/PEO/AgNPs fibrous materials against Staphylococcus aureus showed that at AgNPs content of 5 wt% the mats had bacteriostatic, and at AgNPs content of 10 wt%-bactericidal activity.