Correlating the Atomic Structure of Bimetallic Silver–Gold Nanoparticles to Their Antibacterial and Cytotoxic Activities

Padmos, J. Daniel; Langman, Maxine; MacDonald, Katelyn; Comeau, Patricia; Yang, Zhan; Filiaggi, Mark; Zhang, Peng

doi:10.1021/acs.jpcc.5b00145

Cited by 46 publications

(42 citation statements)

References 62 publications

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“…6). Based on a minimum cell viability of 70%, 30 Ag NPs is considered to be cytotoxic at $10 mg mL À1 , which is similar to the previous report that Ag NPs exhibited a signicant cytotoxicity at >5.0 mg mL À1 to HepG2. 39 However, at the same total metal ion concentration, Au@Ag NPs were more compatible than pure Ag NPs, even at a concentration up to 80 mg mL…”

Section: Cytotoxicity Of Gold@silver Core-shell Nanoparticlessupporting

confidence: 85%

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Shell thickness-dependent antibacterial activity and biocompatibility of gold@silver core–shell nanoparticles

et al. 2017

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Antimicrobial activity of silver is highly effective and broad-spectrum; however, poor long-term antibacterial efficiency and cytotoxicity toward mammalian cells have restricted their applications. Here, we fabricated Au@Ag NPs with tailored shell thickness, and investigated their antibacterial activities against both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) and the cytotoxicity toward SH-SY5Y human cells, for the first time. Our results demonstrate that Au@Ag NPs with a thickness of 5 nm or Au : Ag ratio 1 : 1 (Au@Ag-2 NPs) have the highest antibacterial activity and excellent biocompatibility. The minimum inhibitory concentration (MIC) values of Au@Ag-2 NPs in terms of effective silver concentration are 5 mg mL À1 for E. coli and 7.5 mg mL À1 for S. aureus, IntroductionTo cope with the overwhelming challenges of infectious diseases resulting from pathogenic bacteria, nano-sized materials, emerging as new types of safe and cost-effective bactericidal materials, have been widely investigated. Among those numerous nanomaterials, silver nanoparticles (Ag NPs) are the most promising antibacterial agents because of their inherent properties of high thermal stability, limited microbial resistance, and broad-spectrum antimicrobial activity against bacteria, viruses and other eukaryotic microorganisms. 1-4 Sondi and co-workers 5 demonstrated that Ag NPs can easily adsorb to the membrane surface of bacteria through electrostatic interaction, form permeable pits, and cause an osmotic collapse in the cells. The other possible mechanism is the release of silver ions (Ag + ) from the oxidized Ag NPs. 6-8 Ag NPs are easy to oxidize and produce a high concentration of Ag + , the released Ag + then destroys the respiratory chain and leads to the formation of reactive oxygen species (ROS), such as hydroxyl radicals, H 2 O 2 and hydroperoxyl radicals, which nally trigger cell damage of the cellular components and leads to the death of the bacteria. 9-11 In spite of this, the easy oxidation of pure Ag NPs and the toxicity in mammalian cells remain challenges in Ag NP applications. 12-14To address this problem, Ag NPs have been decorated with other nanomaterials by the formation of nanostructures. Song et al. 15synthesized the silver/polyrhodanine compositedecorated silica nanoparticles, which exhibited excellent antimicrobial activity toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) because of the antibacterial effects of both the silver nanoparticles and the polyrhodanine. Tan et al. 16synthesized antibacterial Ag@dsDNA@GO, which can wrap around the Xanthomonas perforans cell and results in rapid cell apoptosis, showing the synergistic antibacterial effect. While these nanostructures can effectively enhance the antibacterial activity of Ag NPs, they oen require complex and tedious preparation methods, and suffering from low yields, poor longterm antibacterial activity, and biocompatibility problems. 17,18Bimetallic core-shell nanoparticles are graduall...

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Section: Cytotoxicity Of Gold@silver Core-shell Nanoparticlessupporting

confidence: 85%

“…30 Au NPs (10 AE 2 nm) were synthesized by sodium citrate-tannin reduction. First, 1 mL of HAuCl 4 (1% by weight) was added into 79 mL of Millipore-Q water under stirring; the mixture was prepared as solution A.…”

Section: Synthesis Of Gold Nanoparticlesmentioning

confidence: 99%

Shell thickness-dependent antibacterial activity and biocompatibility of gold@silver core–shell nanoparticles

et al. 2017

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“…The AgAu bimetallic nanoparticles were synthesized via galvanic replacement using a modification of published procedures . The average size of the Ag x Au y nanoparticles increased with the increasing Au content, as reported previously (Figure A, B; Figure S1 and Table S1 in the Supporting Information) . The composition of the nanoparticles was determined using inductively coupled plasma mass spectrometry (ICP‐MS).…”

Section: Resultsmentioning

confidence: 96%

New Architectures for Designed Catalysts: Selective Oxidation using AgAu Nanoparticles on Colloid‐Templated Silica

Shirman

Lattimer

Luneau

et al. 2017

Chemistry A European J

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A highly modular synthesis of designed catalysts with controlled bimetallic nanoparticle size and composition and a well-defined structural hierarchy is demonstrated. Exemplary catalysts-bimetallic dilute Ag-in-Au nanoparticles partially embedded in a porous SiO matrix (SiO -Ag Au )-were synthesized by the decoration of polymeric colloids with the bimetallic nanoparticles followed by assembly into a colloidal crystal backfilled with the matrix precursor and subsequent removal of the polymeric template. This work reports that these new catalyst architectures are significantly better than nanoporous dilute AgAu alloy catalysts (nanoporous Ag Au ) while retaining a clear predictive relationship between their surface reactivity with that of single-crystal Au surfaces. This paves the way for broadening the range of new catalyst architectures required for translating the designed principles developed under controlled conditions to designed catalysts under operating conditions for highly selective coupling of alcohols to form esters. Excellent catalytic performance of the porous SiO -Ag Au structure for selective oxidation of both methanol and ethanol to produce esters with high conversion efficiency, selectivity, and stability was demonstrated, illustrating the ability to translate design principles developed for support-free materials to the colloid-templated structures. The synthetic methodology reported is customizable for the design of a wide range of robust catalytic systems inspired by design principles derived from model studies. Fine control over the composition, morphology, size, distribution, and availability of the supported nanoparticles was demonstrated.

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“…14 ). The NCs all exhibited similar features to the Ag(0) reference and showed the typical reduction in the first peak of the XANES due to nanosize and alloying effects 24 25 , thereby confirming the metallic oxidation state of the Ag on each surface.…”

Section: Resultsmentioning

confidence: 53%

The surface structure of silver-coated gold nanocrystals and its influence on shape control

et al. 2015

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Understanding the surface structure of metal nanocrystals with specific facet indices is important due to its impact on controlling nanocrystal shape and functionality. However, this is particularly challenging for halide-adsorbed nanocrystals due to the difficulty in analysing interactions between metals and light halides (for example, chloride). Here we uncover the surface structures of chloride-adsorbed, silver-coated gold nanocrystals with {111}, {110}, {310} and {720} indexed facets by X-ray absorption spectroscopy and density functional theory modelling. The silver–chloride, silver–silver and silver–gold bonding structures are markedly different between the nanocrystal surfaces, and are sensitive to their formation mechanism and facet type. A unique approach of combining the density functional theory and experimental/simulated X-ray spectroscopy further verifies the surface structure models and identifies the previously indistinguishable valence state of silver atoms on the nanocrystal surfaces. Overall, this work elucidates the thus-far unknown chloride–metal nanocrystal surface structures and sheds light onto the halide-induced growth mechanism of anisotropic nanocrystals.

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Correlating the Atomic Structure of Bimetallic Silver–Gold Nanoparticles to Their Antibacterial and Cytotoxic Activities

Cited by 46 publications

References 62 publications

Shell thickness-dependent antibacterial activity and biocompatibility of gold@silver core–shell nanoparticles

Shell thickness-dependent antibacterial activity and biocompatibility of gold@silver core–shell nanoparticles

New Architectures for Designed Catalysts: Selective Oxidation using AgAu Nanoparticles on Colloid‐Templated Silica

The surface structure of silver-coated gold nanocrystals and its influence on shape control

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