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Synthesis and antimicrobial activity of some novel cross-linked chitosan hydrogels.

Mohamed NA, Fahmy MM - Int J Mol Sci (2012)

Bottom Line: Their structures were confirmed by fourier transform infrared X-ray (FTIR), scanning electron microscopy (SEM) and X-ray diffraction.The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan.Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt; E-Mail: m.fahmy17@yahoo.com.

ABSTRACT
Four novel hydrogels based on chitosan were synthesized via a cross-linking reaction of chitosan with different concentrations of oxalyl bis 4-(2,5-dioxo-2H-pyrrol- 1(5H)-yl)benzamide. Their structures were confirmed by fourier transform infrared X-ray (FTIR), scanning electron microscopy (SEM) and X-ray diffraction. The antimicrobial activities of the hydrogels against two crop-threatening pathogenic fungi namely: Aspergillus fumigatus (A. fumigatus, RCMBA 06002), and Aspergillus niger (A. niger, RCMBA 06106), and five bacterial species namely: Bacillis subtilis (B. subtilis, RCMBA 6005), Staphylococcus aureus (S. aureus, RCMBA 2004), Streptococcus pneumoniae (S. pneumonia, RCMB 000101) as Gram positive bacteria, and Salmonella typhimurium (S. typhimurium, RCMB 000104), and Escherichia coli (E. coli, RCMBA 5003) as Gram negative bacteria have been investigated. The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan. The hydrogels were more potent in case of Gram-positive bacteria than Gram-negative bacteria. Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

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Powder X-ray diffraction of chitosan and its hydrogels: (a) Chitosan; (b) H0.5; (c) H1; (d) H2.5; (e) H5.
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f3-ijms-13-11194: Powder X-ray diffraction of chitosan and its hydrogels: (a) Chitosan; (b) H0.5; (c) H1; (d) H2.5; (e) H5.

Mentions: X-ray diffraction was employed to study the effect of cross-linking on the hydrogel morphology, and the powder X-ray diffractograms of chitosan and its hydrogels are presented in Figure 3a–e. From Figure 3a it can be seen that the two peaks showing the maximum intensity were obtained at 2θ = 31.6° and 2θ = 45.4°, indicating that chitosan is highly crystalline in nature. The incorporation of the cross-linker into chitosan severely decreases the intensity of both the peaks; that is, almost no peaks are obtained, which is clearly visible in Figure 3b–e. The cross-linked chitosan hydrogels showed an almost amorphous nature since the functional groups of chitosan underwent significant change after cross-linking. This suggested that a large number of hydrogen bonds in the chitosan powder was destroyed after crosslinking via NH2 groups, which efficiently destroyed the regularity of the packing of the original chitosan chains and resulted in the formation of amorphous hydrogels.


Synthesis and antimicrobial activity of some novel cross-linked chitosan hydrogels.

Mohamed NA, Fahmy MM - Int J Mol Sci (2012)

Powder X-ray diffraction of chitosan and its hydrogels: (a) Chitosan; (b) H0.5; (c) H1; (d) H2.5; (e) H5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472739&req=5

f3-ijms-13-11194: Powder X-ray diffraction of chitosan and its hydrogels: (a) Chitosan; (b) H0.5; (c) H1; (d) H2.5; (e) H5.
Mentions: X-ray diffraction was employed to study the effect of cross-linking on the hydrogel morphology, and the powder X-ray diffractograms of chitosan and its hydrogels are presented in Figure 3a–e. From Figure 3a it can be seen that the two peaks showing the maximum intensity were obtained at 2θ = 31.6° and 2θ = 45.4°, indicating that chitosan is highly crystalline in nature. The incorporation of the cross-linker into chitosan severely decreases the intensity of both the peaks; that is, almost no peaks are obtained, which is clearly visible in Figure 3b–e. The cross-linked chitosan hydrogels showed an almost amorphous nature since the functional groups of chitosan underwent significant change after cross-linking. This suggested that a large number of hydrogen bonds in the chitosan powder was destroyed after crosslinking via NH2 groups, which efficiently destroyed the regularity of the packing of the original chitosan chains and resulted in the formation of amorphous hydrogels.

Bottom Line: Their structures were confirmed by fourier transform infrared X-ray (FTIR), scanning electron microscopy (SEM) and X-ray diffraction.The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan.Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt; E-Mail: m.fahmy17@yahoo.com.

ABSTRACT
Four novel hydrogels based on chitosan were synthesized via a cross-linking reaction of chitosan with different concentrations of oxalyl bis 4-(2,5-dioxo-2H-pyrrol- 1(5H)-yl)benzamide. Their structures were confirmed by fourier transform infrared X-ray (FTIR), scanning electron microscopy (SEM) and X-ray diffraction. The antimicrobial activities of the hydrogels against two crop-threatening pathogenic fungi namely: Aspergillus fumigatus (A. fumigatus, RCMBA 06002), and Aspergillus niger (A. niger, RCMBA 06106), and five bacterial species namely: Bacillis subtilis (B. subtilis, RCMBA 6005), Staphylococcus aureus (S. aureus, RCMBA 2004), Streptococcus pneumoniae (S. pneumonia, RCMB 000101) as Gram positive bacteria, and Salmonella typhimurium (S. typhimurium, RCMB 000104), and Escherichia coli (E. coli, RCMBA 5003) as Gram negative bacteria have been investigated. The prepared hydrogels showed much higher antimicrobial activities than that of the parent chitosan. The hydrogels were more potent in case of Gram-positive bacteria than Gram-negative bacteria. Increasing the degree of cross-linking in the hydrogels resulted in a weaker antimicrobial activity.

Show MeSH
Related in: MedlinePlus