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Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior.

Shameli K, Ahmad MB, Zargar M, Yunus WM, Rustaiyan A, Ibrahim NA - Int J Nanomedicine (2011)

Bottom Line: AgNO(3) and NaBH(4) were used as a silver precursor and reducing agent, respectively.The smaller Ag NPs were found to have significantly higher antibacterial activity.These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. kamyarshameli@gmail.com

ABSTRACT
Silver nanoparticles (Ag NPs) were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT) as a solid support at room temperature. AgNO(3) and NaBH(4) were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO(3). The interlamellar space limits changed little (d-spacing = 1.24-1.47 nm); therefore, Ag NPs formed on the MMT suspension with d-average = 4.19-8.53 nm diameter. The Ag/MMT nanocomposites (NCs), formed from AgNO(3)/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA). The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.

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Schematic illustration of the synthesized Ag NPs in the interlayer space of MMT suspension by chemical reduction method.
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f1-ijn-6-581: Schematic illustration of the synthesized Ag NPs in the interlayer space of MMT suspension by chemical reduction method.

Mentions: The surfaces of MMT suspension assist the Ag NPs nucleation during the reduction process. The schematic illustration of the synthesis of Ag/MMT NCs from AgNO3/MMT suspension produced by using sodium borohydride is shown in Figure 1. Meanwhile, as shown in Figure 2, the AgNO3/MMT (S0) was colorless, but after the addition of the reducing agent to the suspensions, they turned light brown (S2), brown (S4), and dark brown (S5), indicating the formation of Ag NPs in the MMT suspensions. The formation of Ag NPs was also followed by measuring the surface plasmon resonance (SPR) bands of the AgNO3/MMT and Ag/MMT NCs suspensions at a wavelength of 300–700 nm (Figure 2). Comparing the PXRD patterns of MMT and Ag/MMT NCs (S1, S2 and S5), in the small-angle range of 2θ (2° < 2θ < 12°), indicated that the intercalated Ag NPs formed between adjacent MMT lamellar layers were smaller, but that most of the Ag NPs were formed at the MMT suspension interface (Figure 3). In addition, the PXRD patterns in the wide-angle range of 2θ (30° < 2θ < 80°) were also employed to determine the crystalline structures of the synthesized Ag NPs (Figure 4). The TEM images and their size distributions of Ag NPs showed that the mean diameter of the nanoparticles ranged from about 4.19 to 8.53 nm (Figure 5). As shown in Figure 6, the SEM images indicated that there were no structure changes between the initial MMT and Ag/MMT NCs (S2, S4, and S5). Additionally, the EDXRF spectra for the MMT and Ag/MMT NCs confirmed the presence of elemental compounds in MMT and Ag NPs with no other impurity peaks (Figures 6B and F). The chemical structures of MMT and Ag/MMT NCs were analyzed by using FT-IR spectroscopy (Figure 7). The approximate efficiency gradually increased from S1 to S5, respectively (Table 1). The antibacterial studies showed comparatively similar effects for all samples as indicated by the inhibition zone test between MMT, AgNO3/MMT, and Ag/MMT NCs against different bacteria (Figure 8, Table 2).


Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior.

Shameli K, Ahmad MB, Zargar M, Yunus WM, Rustaiyan A, Ibrahim NA - Int J Nanomedicine (2011)

Schematic illustration of the synthesized Ag NPs in the interlayer space of MMT suspension by chemical reduction method.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3107717&req=5

f1-ijn-6-581: Schematic illustration of the synthesized Ag NPs in the interlayer space of MMT suspension by chemical reduction method.
Mentions: The surfaces of MMT suspension assist the Ag NPs nucleation during the reduction process. The schematic illustration of the synthesis of Ag/MMT NCs from AgNO3/MMT suspension produced by using sodium borohydride is shown in Figure 1. Meanwhile, as shown in Figure 2, the AgNO3/MMT (S0) was colorless, but after the addition of the reducing agent to the suspensions, they turned light brown (S2), brown (S4), and dark brown (S5), indicating the formation of Ag NPs in the MMT suspensions. The formation of Ag NPs was also followed by measuring the surface plasmon resonance (SPR) bands of the AgNO3/MMT and Ag/MMT NCs suspensions at a wavelength of 300–700 nm (Figure 2). Comparing the PXRD patterns of MMT and Ag/MMT NCs (S1, S2 and S5), in the small-angle range of 2θ (2° < 2θ < 12°), indicated that the intercalated Ag NPs formed between adjacent MMT lamellar layers were smaller, but that most of the Ag NPs were formed at the MMT suspension interface (Figure 3). In addition, the PXRD patterns in the wide-angle range of 2θ (30° < 2θ < 80°) were also employed to determine the crystalline structures of the synthesized Ag NPs (Figure 4). The TEM images and their size distributions of Ag NPs showed that the mean diameter of the nanoparticles ranged from about 4.19 to 8.53 nm (Figure 5). As shown in Figure 6, the SEM images indicated that there were no structure changes between the initial MMT and Ag/MMT NCs (S2, S4, and S5). Additionally, the EDXRF spectra for the MMT and Ag/MMT NCs confirmed the presence of elemental compounds in MMT and Ag NPs with no other impurity peaks (Figures 6B and F). The chemical structures of MMT and Ag/MMT NCs were analyzed by using FT-IR spectroscopy (Figure 7). The approximate efficiency gradually increased from S1 to S5, respectively (Table 1). The antibacterial studies showed comparatively similar effects for all samples as indicated by the inhibition zone test between MMT, AgNO3/MMT, and Ag/MMT NCs against different bacteria (Figure 8, Table 2).

Bottom Line: AgNO(3) and NaBH(4) were used as a silver precursor and reducing agent, respectively.The smaller Ag NPs were found to have significantly higher antibacterial activity.These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. kamyarshameli@gmail.com

ABSTRACT
Silver nanoparticles (Ag NPs) were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT) as a solid support at room temperature. AgNO(3) and NaBH(4) were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO(3). The interlamellar space limits changed little (d-spacing = 1.24-1.47 nm); therefore, Ag NPs formed on the MMT suspension with d-average = 4.19-8.53 nm diameter. The Ag/MMT nanocomposites (NCs), formed from AgNO(3)/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA). The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications.

Show MeSH
Related in: MedlinePlus