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Development of antimicrobial biomaterials produced from chitin-nanofiber sheet/silver nanoparticle composites.

Nguyen VQ, Ishihara M, Kinoda J, Hattori H, Nakamura S, Ono T, Miyahira Y, Matsui T - J Nanobiotechnology (2014)

Bottom Line: CNFSs were immersed in suspensions of Ag NPs (5.17 ± 1.9 nm in diameter; mean ± SD) for 30 min at room temperature to produce CNFS/Ag NPs.Ultrathin sectioning of bacterial cells also was carried out to observe the bactericidal mechanism of Ag NPs.The TEM images indicated that the Ag NPs are dispersed and tightly adsorbed onto CNFSs.

View Article: PubMed Central - PubMed

Affiliation: Faculty of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan. imvinhs@yahoo.com.vn.

ABSTRACT

Background: Chitin nanofibers sheets (CNFSs) with nanoscale fiber-like surface structures are nontoxic and biodegradable biomaterials with large surface-to-mass ratio. CNFSs are widely applied as biomedical materials such as a functional wound dressing. This study aimed to develop antimicrobial biomaterials made up of CNFS-immobilized silver nanoparticles (CNFS/Ag NPs).

Materials and methods: CNFSs were immersed in suspensions of Ag NPs (5.17 ± 1.9 nm in diameter; mean ± SD) for 30 min at room temperature to produce CNFS/Ag NPs. CNFS/Ag NPs were characterized by transmission electron microscopy (TEM) and then tested for antimicrobial activities against Escherichia (E.) coli, Pseudomonas (P.) aeruginosa, and H1N1 influenza A virus, three pathogens that represent the most widespread infectious bacteria and viruses. Ultrathin sectioning of bacterial cells also was carried out to observe the bactericidal mechanism of Ag NPs.

Results: The TEM images indicated that the Ag NPs are dispersed and tightly adsorbed onto CNFSs. Although CNFSs alone have only weak antimicrobial activity, CNFS/Ag NPs showed much stronger antimicrobial properties against E. coli, P. aeruginosa, and influenza A virus, with the amount of immobilized Ag NPs onto CNFSs.

Conclusions: Our results suggest that CNFS/Ag NPs interacting with those microbes exhibit stronger antimicrobial activities, and that it is possible to apply CNFS/Ag NPs as anti-virus sheets as well as anti-infectious wound dressings.

No MeSH data available.


Related in: MedlinePlus

Representative TEM images of morphology and structure ofE. coliandP. aeruginosa. (A)E. coli treated with Ag NPs; (B) normal E. coli; (C)P. aeruginosa treated with Ag NPs; (D) normal P. aeruginosa. Exposure to Ag NPs resulted in damage to the structure of bacterial cell membranes, condensed DNA, and coagulated cytoplasmic components. Normal bacterial cells were smooth, exhibiting intact surfaces and undamaged structures of inner membranes. Scale bars are as indicated.
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Fig7: Representative TEM images of morphology and structure ofE. coliandP. aeruginosa. (A)E. coli treated with Ag NPs; (B) normal E. coli; (C)P. aeruginosa treated with Ag NPs; (D) normal P. aeruginosa. Exposure to Ag NPs resulted in damage to the structure of bacterial cell membranes, condensed DNA, and coagulated cytoplasmic components. Normal bacterial cells were smooth, exhibiting intact surfaces and undamaged structures of inner membranes. Scale bars are as indicated.

Mentions: The mechanism(s) of bactericidal activity of Ag NPs remain poorly understood. Ultrathin sectioning was carried out to obtain further understanding of the bactericidality and the interaction of the Ag NPs with bacterial cells. After 1 h treatment with a suspension of Ag NPs, the cytoplasmic components of E. coli and P. aeruginosa were coagulated, leading to vacant spaces within the cells. Gross inspection of the TEM images revealed non-homogeneity of the cytoplasm in the Ag NP-treated cells compared with the controls (Figure 7). The density of cytoplasmic components in treated cells was obviously decreased compared with the control. Plasma membranes of treated cells were detached from the cell wall, leaving open spaces between the membrane and cell wall. Furthermore, DNA was condensed (Figure 7).Figure 7


Development of antimicrobial biomaterials produced from chitin-nanofiber sheet/silver nanoparticle composites.

Nguyen VQ, Ishihara M, Kinoda J, Hattori H, Nakamura S, Ono T, Miyahira Y, Matsui T - J Nanobiotechnology (2014)

Representative TEM images of morphology and structure ofE. coliandP. aeruginosa. (A)E. coli treated with Ag NPs; (B) normal E. coli; (C)P. aeruginosa treated with Ag NPs; (D) normal P. aeruginosa. Exposure to Ag NPs resulted in damage to the structure of bacterial cell membranes, condensed DNA, and coagulated cytoplasmic components. Normal bacterial cells were smooth, exhibiting intact surfaces and undamaged structures of inner membranes. Scale bars are as indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4263038&req=5

Fig7: Representative TEM images of morphology and structure ofE. coliandP. aeruginosa. (A)E. coli treated with Ag NPs; (B) normal E. coli; (C)P. aeruginosa treated with Ag NPs; (D) normal P. aeruginosa. Exposure to Ag NPs resulted in damage to the structure of bacterial cell membranes, condensed DNA, and coagulated cytoplasmic components. Normal bacterial cells were smooth, exhibiting intact surfaces and undamaged structures of inner membranes. Scale bars are as indicated.
Mentions: The mechanism(s) of bactericidal activity of Ag NPs remain poorly understood. Ultrathin sectioning was carried out to obtain further understanding of the bactericidality and the interaction of the Ag NPs with bacterial cells. After 1 h treatment with a suspension of Ag NPs, the cytoplasmic components of E. coli and P. aeruginosa were coagulated, leading to vacant spaces within the cells. Gross inspection of the TEM images revealed non-homogeneity of the cytoplasm in the Ag NP-treated cells compared with the controls (Figure 7). The density of cytoplasmic components in treated cells was obviously decreased compared with the control. Plasma membranes of treated cells were detached from the cell wall, leaving open spaces between the membrane and cell wall. Furthermore, DNA was condensed (Figure 7).Figure 7

Bottom Line: CNFSs were immersed in suspensions of Ag NPs (5.17 ± 1.9 nm in diameter; mean ± SD) for 30 min at room temperature to produce CNFS/Ag NPs.Ultrathin sectioning of bacterial cells also was carried out to observe the bactericidal mechanism of Ag NPs.The TEM images indicated that the Ag NPs are dispersed and tightly adsorbed onto CNFSs.

View Article: PubMed Central - PubMed

Affiliation: Faculty of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo, 191-0065, Japan. imvinhs@yahoo.com.vn.

ABSTRACT

Background: Chitin nanofibers sheets (CNFSs) with nanoscale fiber-like surface structures are nontoxic and biodegradable biomaterials with large surface-to-mass ratio. CNFSs are widely applied as biomedical materials such as a functional wound dressing. This study aimed to develop antimicrobial biomaterials made up of CNFS-immobilized silver nanoparticles (CNFS/Ag NPs).

Materials and methods: CNFSs were immersed in suspensions of Ag NPs (5.17 ± 1.9 nm in diameter; mean ± SD) for 30 min at room temperature to produce CNFS/Ag NPs. CNFS/Ag NPs were characterized by transmission electron microscopy (TEM) and then tested for antimicrobial activities against Escherichia (E.) coli, Pseudomonas (P.) aeruginosa, and H1N1 influenza A virus, three pathogens that represent the most widespread infectious bacteria and viruses. Ultrathin sectioning of bacterial cells also was carried out to observe the bactericidal mechanism of Ag NPs.

Results: The TEM images indicated that the Ag NPs are dispersed and tightly adsorbed onto CNFSs. Although CNFSs alone have only weak antimicrobial activity, CNFS/Ag NPs showed much stronger antimicrobial properties against E. coli, P. aeruginosa, and influenza A virus, with the amount of immobilized Ag NPs onto CNFSs.

Conclusions: Our results suggest that CNFS/Ag NPs interacting with those microbes exhibit stronger antimicrobial activities, and that it is possible to apply CNFS/Ag NPs as anti-virus sheets as well as anti-infectious wound dressings.

No MeSH data available.


Related in: MedlinePlus