Publications in January and February 2014
At the beginning of 2014, a variety of highly interesting chitosan-related articles were released by scientists from all over the world. All in all, 281 novel articles have been published, which promise new insights into the diversity of the biopolymer. The most successful nations in the field of chitosan research are again China publishing 88 articles, USA 33 reports and India contributed 23 articles.
|Chitosan in General
|Evaluation Studies as Topic
Table: Ranking of the top terms of chitosan-related publications in January and February 2014.
Chitosan and its derivatives are intensively studied for their antimicrobial properties. The growth of various organisms like bacteria, fungi, yeast and algae can be inhibited by the biopolymer. Numerous publications analysed distinct compositions of chitosan with regard to their antibacterial activity. The following three publications provide new approaches of increasing the antibacterial efficiency of chitosan and to extend its scope of application.
Sonochemical coating of textiles with hybrid ZnO/chitosan antimicrobial nanoparticles.
Petkova P., Francesko A., Fernandes M.M. et al., ACS Appl Mater Interfaces. Vol. 22; 6 (2): 1164-72. January 2014
In the present study, a novel concept of antimicrobial textiles was developed, to minimize infectious diseases caused by bacterial strains like Staphylococcus aureus and Escherichia coli. The authors used a sonochemical deposition method and coat cotton fabrics with zinc-oxide (ZnO) nanoparticles. The highest antibacterial activity was measured for fabrics treated with 2 mM ZnO suspension for 30 min. To further improve antibacterial activity, ZnO nanoparticles were simultaneously deposited with chitosan, creating hybrids of ZnO-chitosan.
|ZnO-chitosan coated fabrics:
|Improvement over ZnO-coated fabrics
|against E. coil
|against S. aureus
|Antibacterial activity (AA)
Durability of AA
tested by multiple washing cycles
|Biocompatibility: fibroblast viability increased by
Conclusion: The antibacterial effect of ZnO-impregnated textiles was significantly improved by chitosan. In addition, a treatment with ZnO-chitosan preserved the antibacterial potency of washed fabrics. Coating fabrics with ZnO-chitosan can reduce bacterial growth and might be particularly useful for sensitive areas like intensive care units of hospitals.
Synthesis, characterization, and antimicrobial activity of kojic acid grafted chitosan oligosaccharide.
Liu X., Xia W., Jiang Q. et al., J Agric Food Chem. Vol. 62 (1): 297-303. January 2014
The objective of this study was to improve the antibacterial properties of water-soluble chitosan derivatives (COS) by conjugating them with kojic acid (KA). This acid is synthesized by several species of fungi and possesses antibacterial and anti-inflammatory properties. The COS/KA hybrid was generated by an alkylation reaction at C-3 and C-6 position of COS.
Results for COS/KA derivatives:
- Highly soluble in organic solvents and in aqueous solutions
- Increased antibacterial and antifungal activity compared to COS:
- Staphylococcus aureus , Escherichia coli
- Aspergillus niger, Saccharomyces cerevisiae
- Antibacterial activity increased proportionally with the degree of substitution of COS/KA
Conclusion: The solubility chitosan and also its antibacterial and antifungal activity are significantly improved by conjugating kojic acid to the biopolymer. Various application options are thinkable, as new antibacterial agents could be useful for medical, pharmaceutical and food industries.
Nitric oxide-releasing chitosan oligosaccharides as antibacterial agents.
Lu Y., Slomberg D.L., Schoenfisch M.H. Biomaterials., Vol. 35 (5): 1716-24.February 2014
In this study a nitric oxide (NO)-releasing chitosan scaffold was designed to enhance the antimicrobial activity of the biopolymer. Chitosan was modified to a secondary amine-functionalized polymer by two synthesis steps. 2-methyl aziridine was initially grafted to chitosan and the scaffold was then fumigated with NO. NO is part of the mammalian immune response and fights pathogenic bacteria. The bactericidal function of NO is mediated by nitrosative and oxidative stress, which can disrupt bacterial membranes.
- Increased NO payload compared to other macromolecular NO-donors
- Water-soluble chitosan easily penetrate bacterial biofilms
- Biofilm eradication depends on molecular weight and ionic charge of the polymer, Low molecular weight and cationic charge are favourable
- No significant cytotoxicity to fibroblast
Conclusion: The NO-releasing chitosan polymer possesses excellent antibacterial activity against gram positive and gram negative bacteria. Since the polymer is also biodegradable, it is superior to other NO-releasing materials invented so far. Thus, chitosan-NO-based antibacterial agents might be useful for clinical applications.