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. 2015 Apr 7;20(4):6002-21.
doi: 10.3390/molecules20046002.

Organic-inorganic hybrid nanoparticles for bacterial inhibition: synthesis and characterization of doped and undoped ONPs with Ag/Au NPs

Carlos Alberto Huerta Aguilar  1 , Adriana Berenice Pérez Jiménez  2 , Antonio Romero Silva  3 , Navneet Kaur  4 , Pandiyan Thangarasu  5 , Jorge Manuel Vázquez Ramos  6 , Narinder Singh  7
Affiliations

Organic-inorganic hybrid nanoparticles for bacterial inhibition: synthesis and characterization of doped and undoped ONPs with Ag/Au NPs

Carlos Alberto Huerta Aguilar et al. Molecules. .

Abstract

Organic nanoparticles (ONPs) of lipoic acid and its doped derivatives ONPs/Ag and ONPs/Au were prepared and characterized by UV-Visible, EDS, and TEM analysis. The antibacterial properties of the ONPs ONPs/Ag and ONPs/Au were tested against bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Salmonella typhi). Minimal Inhibitory Concentration (MIC) and bacterial growth inhibition tests show that ONPs/Ag are more effective in limiting bacterial growth than other NPs, particularly, for Gram positive than for Gram-negative ones. The order of bacterial cell growth inhibition was ONPs/Ag > ONPs > ONPs/Au. The morphology of the cell membrane for the treated bacteria was analyzed by SEM. The nature of bond formation of LA with Ag or Au was analyzed by molecular orbital and density of state (DOS) using DFT.

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Conflict of interest statement

The authors declare no conflict of interest

Figures

Figure 1
Figure 1
(a) Formation of α-lipoic acid ONPs; (b) preparation of ONPs/Ag and ONPs/Au.
Figure 2
Figure 2
Transmission Electron Microscope micrographs: (a) ONPs; (b) ONPs/Ag (ratio 10:1); (c) ONPs/Au (ratio 10:1); (d) Ag NPs and (e) Au NPs.
Figure 3
Figure 3
Energy Dispersive Spectrometry analysis: (a) ONPs, (b) ONPs/Ag (ratio 10:1), (c) ONPs/Au (ratio 10:1).
Figure 4
Figure 4
Characterization of ONPs; (a) visible appearance: (i) ONPs; (ii) ONPs/Ag and (iii) ONPs/Au; (b) UV-Visible profile of lipoic acid-ONPs.
Figure 5
Figure 5
Antibacterial effects: Bacterial survival (%) after treatment with different NPs (0.2 mM).
Figure 6
Figure 6
Comparative bacterial growth inhibition (1) Salmonella typhi and (2) Staphylococcus aureus: after treatment (a) Control; (b) AgNPs (0.02 mM); (c) ONPs (0.2 mM); (d) ONPs/Ag (0.2 mM).
Figure 7
Figure 7
Minimal inhibitory concentration (MIC) of bacteria treated with different NPs.
Figure 8
Figure 8
Disk diffusion test: (a) Staphylococcus aureus; (b) Salmonella typhi.
Figure 9
Figure 9
SEM images of bacterial strains after treatment with NPs. (a) Bacillus cereus with ONPs; (b) Bacillus cereus with ONPs/Ag; (c) Bacillus cereus with Ag NPs; (d) Salmonella typhi with ONPs; (e) Salmonella typhi with ONPs/Ag and (f) Salmonella typhi with AgNPs.
Figure 10
Figure 10
Optimized structures of LA (a) and its forms decorated with Ag (b) or Au (c).
Figure 11
Figure 11
Density of states for LA, and its doping with metal atoms: (a) LA-ONPs; (b) Ag doped (1.0%) with LA-ONPs and (c) Au doped (1.0%) LA-ONPs calculated through B3LYP/6-311G(d,p) for LA and B3LYP/LANL2DZ for Ag/Au-LA.
Figure 12
Figure 12
Frontier molecular orbitals: (a) LA; (b) LA/Ag.
See this image and copyright information in PMC

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