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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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Fourier transform infrared FTIR spectra of chitosan and its hydrogels: (a) Chitosan; (b) oxalyl bis 4-(2,5-dioxo-2H-pyrrol-1(5H)-yl)benzamide; (c) H0.5; (d) H5.
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f1-ijms-13-11194: Fourier transform infrared FTIR spectra of chitosan and its hydrogels: (a) Chitosan; (b) oxalyl bis 4-(2,5-dioxo-2H-pyrrol-1(5H)-yl)benzamide; (c) H0.5; (d) H5.

Mentions: An additional proof for the synthesis of the hydrogels is given by their FTIR spectra as shown in Figure 1. The FTIR spectrum of chitosan (Figure 1a) showed four strong peaks at 1155, 1072, 1030, and 895 cm−1, which were characteristic peaks of the saccharide structure. The very strong broad peak around 3600 to 3000 cm−1 should be assigned to the stretching vibration of O–H, the extension vibration of the N–H, and the intermolecular hydrogen bonds of the polysaccharide. Primary amines have two peaks in this region at 3460 and 3190 cm−1. There were weak absorption peaks at 1653 and 1567 cm−1 corresponded to amide I and amide II, respectively, which indicated that chitosan had a high deacetylation degree. On comparing the FTIR spectra of chitosan (Figure 1a) and its hydrogels H0.5 and H5 (Figure 1c,d), it was found firstly that the broad band between 3600 and 3000 cm−1 due to the O–H and N–H group stretching vibration was observed. In addition, the characteristic doublet peak of the NH2 group at 3460 and 3190 cm−1 disappeared and a single peak around 3428 cm−1 for the NH group appeared. These results support that the NH2 group had reacted with the cross-linker. Further, the very strong characteristic peak of the C=O group of the imide ring of the cross-linker at 1711 cm−1 (Figure 1b) disappeared upon cross-linking with chitosan. This suggests that the cross-linking reaction occurs via imide ring opening. Secondly, a new peak around 1632 cm−1 appeared in the spectra of the hydrogels, which is the characteristic band for the C=O group of the amide linkage overlapped with both the C=C (aliphatic), C=C (aromatic) groups. Its intensity increased with increasing amount of the cross-linker incorporated into the hydrogels. This evidence confirms the structure of the prepared hydrogels.


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

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

Fourier transform infrared FTIR spectra of chitosan and its hydrogels: (a) Chitosan; (b) oxalyl bis 4-(2,5-dioxo-2H-pyrrol-1(5H)-yl)benzamide; (c) H0.5; (d) H5.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1-ijms-13-11194: Fourier transform infrared FTIR spectra of chitosan and its hydrogels: (a) Chitosan; (b) oxalyl bis 4-(2,5-dioxo-2H-pyrrol-1(5H)-yl)benzamide; (c) H0.5; (d) H5.
Mentions: An additional proof for the synthesis of the hydrogels is given by their FTIR spectra as shown in Figure 1. The FTIR spectrum of chitosan (Figure 1a) showed four strong peaks at 1155, 1072, 1030, and 895 cm−1, which were characteristic peaks of the saccharide structure. The very strong broad peak around 3600 to 3000 cm−1 should be assigned to the stretching vibration of O–H, the extension vibration of the N–H, and the intermolecular hydrogen bonds of the polysaccharide. Primary amines have two peaks in this region at 3460 and 3190 cm−1. There were weak absorption peaks at 1653 and 1567 cm−1 corresponded to amide I and amide II, respectively, which indicated that chitosan had a high deacetylation degree. On comparing the FTIR spectra of chitosan (Figure 1a) and its hydrogels H0.5 and H5 (Figure 1c,d), it was found firstly that the broad band between 3600 and 3000 cm−1 due to the O–H and N–H group stretching vibration was observed. In addition, the characteristic doublet peak of the NH2 group at 3460 and 3190 cm−1 disappeared and a single peak around 3428 cm−1 for the NH group appeared. These results support that the NH2 group had reacted with the cross-linker. Further, the very strong characteristic peak of the C=O group of the imide ring of the cross-linker at 1711 cm−1 (Figure 1b) disappeared upon cross-linking with chitosan. This suggests that the cross-linking reaction occurs via imide ring opening. Secondly, a new peak around 1632 cm−1 appeared in the spectra of the hydrogels, which is the characteristic band for the C=O group of the amide linkage overlapped with both the C=C (aliphatic), C=C (aromatic) groups. Its intensity increased with increasing amount of the cross-linker incorporated into the hydrogels. This evidence confirms the structure of the prepared 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