Synthesis, characterization and antibacterial activity of quaternized N,O-(2-carboxyethyl) chitosan

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.

Insights into the underlying mechanisms for integrated inactivation of A. spiroides and depression of disinfection byproducts by plasma oxidation

Cyanobacteria blooms threaten water supply and are potential sources for disinfection byproducts (DBPs) formation. In this study, the underlying mechanisms for effective removal of A. spiroides and the following depression on the formation of DBPs were disclosed. Highly efficient inactivation (more than 99.99%) of A. spiroides was realized by the plasma treatment within 12 min, and 93.4% of Anatoxin-a was also removed within 12 min, with no signals of resurrection after 7 days' re-cultivation. Transcriptomic analysis demonstrated that the expressions of the genes related to cell walls and peripherals, thylakoid membranes, photosynthetic membranes, and detoxification of toxins were distinctly altered. The generated reactive oxidative species (ROS), including ·OH, O₂^·-, and ¹O₂, attacked A. spiroides and resulted in membrane damage and algae organic matter (AOM) release. EEM-PARAFAC analysis illustrated that the AOM compositions were subsequently decomposed by the ROS. As a result, the formation potentials of the C-DBPs and N-DBPs were significantly inhibited, due to the effectively removal of AOM and Anatoxin-a. This study disclosed the underneath mechanisms for the effective inactivation of A. spiroides and inhibition of the following formation of the DBPs, and supplied a prospective technique for integrated pollutant control of cyanobacterial containing drinking water.

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.

Worse than cell lysis: The resilience of Oscillatoria sp. during sludge storage in drinking water treatment

Benthic Oscillatoria sp. may form dense surface blooms especially under eutrophic and calm conditions, which poses a threat to drinking water safety because it can produce toxic and odorous metabolites. This is the first study to investigate the effect of the conventional coagulant polyaluminium ferric chloride (PAFC) on removal of Oscillatoria sp., and the behavior of Oscillatoria sp. cells in sludges formed from different dosages of PAFC (control, optimum, and overdose system) during storage was also studied. Oscillatoria sp. cells can be removed efficiently by coagulation of PAFC. The adverse environmental stresses of sludge, such as lack of light and anoxic environment, decrease cell viability and induce the increase of superoxide dismutase activity (SOD) and malondialdehyde content (MDA) in Oscillatoria sp. cells during the first 4 days. Because Oscillatoria sp. can adapt to the low-light and hypoxic circumstances in sludge gradually, the cells regrow with prolonged storage time. Compared to planktonic Microcystis aeruginosa and Cylindrospermopsis raciborskii, regrowth of Oscillatoria sp. during storage may present a bigger threat, even though Microcystis aeruginosa and Cylindrospermopsis raciborskii cells will be damaged and release toxic compounds. Growth rates of algae in coagulated systems were lower than that in control system because of the restriction of flocs. It is worth noting that the chlorophyll a level was increased by a factor of 3.5 in the optimal-dose system, and worse, the overdose system increased by a factor of 6 in chlorophyll a after 8 d storage due to the benefit of higher Fe levels. Concentrations of extracellular geosmin and cylindrospermopsin also increased during storage, especially after 4 d, and varied in the following sequence for a given storage duration: control system > overdose system > optimum system. Overall, due to decrease of SOD and MDA in Oscillatoria sp. cells after 4 d storage, algae cells regrew rapidly, especially in overdose system. Hence, sludge should be treated within 4 d and excess PAFC dosing should be avoided.

Effect of chitosan quaternary ammonium salt on the growth and microcystins release of Microcystis aeruginosa

This present study was the first time to research the application potential of HTCC inM. aeruginosacontrol. To balance the inhibition efficiency ofM. aeruginosaand the release of MCs, 1.2 mg L⁻¹was chosen as appropriate dose.

Experimental design for determining quantitative structure activity relationship for antibacterial chitosan derivatives

Experimental design was utilized for synthesis and optimization of antimicrobial chitosan derivatives and for the development of their structure–activity relationship.

Preparation, characterization, and biochemical activities of N-(2-Carboxyethyl)chitosan from squid pens

Chitosan was prepared by alkaline N-deacetylation of β-chitin from squid pens, and N-carboxyethylated derivatives (N-CECS) with different degrees of substitution (DS) were synthesized. The carboxyethylation of the polysaccharide was identified by Fourier transform infrared, (1)H and (13)C nuclear magnetic resonance (NMR), and X-ray diffraction analyses. The DS of the derivatives was calculated by (1)H NMR and elemental analysis. All three N-CECS samples showed good water solubility at pH > 6.5. The antioxidant properties and bile acid binding capacity of the derivatives were studied in vitro. The highest bile acid binding capacity of all N-CECS reached 36.9 mg/g, which was 2.6-fold higher than that of chitosan. N-CECS showed a stronger scavenging effect on 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical ability, and EC50 values were below 2 mg/mL. The scavenging ability of N-CECS against superoxide radicals correlated well with the DS and concentration of N-CECS. These results indicated that N-carboxyethylation is a possible approach to prepare chitosan derivatives with desirable in vitro biochemical properties.