Unveiling the Role of Oxidation Debris on the Surface Chemistry of Graphene through the Anchoring of Ag Nanoparticles

Faria, Andréia Fonseca de; Martinez, Diego Stéfani T.; Moraes, Ana Carolina Mazarin de; Costa, M.E.H. Maia da; Barros, Eduardo B.; Filho, A. G. Souza; Paula, Amauri J.; Alves, Oswaldo Luiz

doi:10.1021/cm301939s

Cited by 83 publications

(103 citation statements)

References 49 publications

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“…More recently, it was reported that the amount of OD formed is similar, around 1/3 of initial GO, regardless of the oxidation production method [35]. As the presence of debris affect GO properties [31,[35][36][37][38] , it is important to determine the OD structure and be able to assess a correct interpretation of the GO structure.…”

Section: Introductionmentioning

confidence: 99%

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Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Rodriguez-Pastor

Ramos-Fernández

Varela-Rizo

et al. 2015

Carbon

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Please cite this article as: Rodriguez-Pastor, I., Ramos-Fernandez, G., Varela-Rizo, H., Terrones, M., Martin-Gullon, I., Towards the understanding of the graphene oxide structure: How to control the formation of humic-and fulviclike oxidized debris, Carbon (2014), doi: http://dx.doi.org/10.1016/j.carbon. 2014.12.027 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract Former structural models of graphene oxide (GO) indicated that it consists of graphenelike sheets with oxygen groups, and no attention was paid to the resulting sheet size. We now provide evidence of the complex GO structure consisting of large and small GO sheets (or oxidized debris). Different oxidation reactions were studied. KMnO 4 derived GO consists of large sheets (20-30 wt. %), and oxidized debris deposits, which are formed by humic-and fulvic-like fragments. Large GO sheets contain oxygen groups, especially at the edges, such as carbonyl, lactone and carboxylic groups. Humic-like debris consists of an amorphous gel containing more oxygenated groups and trapped water molecules. The main desorbable fraction upon heating is the fulvic-like material, which contains oxygen groups and fragments with high edge/surface ratio. KClO 3 in HNO 3 or the Brodie method produces a highly oxidized material but at the flake level surface only; little oxidized debris and water contents are found. It is noteworthy that an efficient basal cutting of the graphitic planes in addition to an effective intercalation is caused by KMnO 4 , and the aid of NaNO 3 makes this process even more effective, thus yielding large monolayers of GO and a large amount of humic-and fulvic-like substances.

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Section: Introductionmentioning

confidence: 99%

“…Based on this property, humic and fulvic acids are generally separated by base and acid washing procedures. A similar approach is employed to remove debris from the GO surface [31,36].…”

Section: Introductionmentioning

confidence: 99%

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Rodriguez-Pastor

Ramos-Fernández

Varela-Rizo

et al. 2015

Carbon

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“…This phenomenon suggested that AgNPs catalyze the material combustion, leading to a decrease in its decomposition temperature. 35 Furthermore, as the graphitic domains were completely decomposed at 600°C, the residues above this temperature on the TGA curve could be related to the silver content on GO-Ag nanocomposite. The final residue was approximately 50 wt%, thus implying that the mass ratio proportion of Ag:GO was approximately 1:1.…”

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confidence: 99%

Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus

Moraes¹,

Lima²,

Faria³

et al. 2015

IJN

114

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Background Methicillin-resistant Staphylococcus aureus (MRSA) has been responsible for serious hospital infections worldwide. Nanomaterials are an alternative to conventional antibiotic compounds, because bacteria are unlikely to develop microbial resistance against nanomaterials. In the past decade, graphene oxide (GO) has emerged as a material that is often used to support and stabilize silver nanoparticles (AgNPs) for the preparation of novel antibacterial nanocomposites. In this work, we report the synthesis of the graphene-oxide silver nanocomposite (GO-Ag) and its antibacterial activity against relevant microorganisms in medicine. Materials and methods GO-Ag nanocomposite was synthesized through the reduction of silver ions (Ag + ) by sodium citrate in an aqueous GO dispersion, and was extensively characterized using ultraviolet-visible absorption spectroscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, and transmission electron microscopy. The antibacterial activity was evaluated by microdilution assays and time-kill experiments. The morphology of bacterial cells treated with GO-Ag was investigated via transmission electron microscopy. Results AgNPs were well distributed throughout GO sheets, with an average size of 9.4±2.8 nm. The GO-Ag nanocomposite exhibited an excellent antibacterial activity against methicillin-resistant S. aureus , Acinetobacter baumannii , Enterococcus faecalis , and Escherichia coli . All (100%) MRSA cells were inactivated after 4 hours of exposure to GO-Ag sheets. In addition, no toxicity was found for either pristine GO or bare AgNPs within the tested concentration range. Transmission electronic microscopy images offered insights into how GO-Ag nanosheets interacted with bacterial cells. Conclusion Our results indicate that the GO-Ag nanocomposite is a promising antibacterial agent against common nosocomial bacteria, particularly antibiotic-resistant MRSA. Morphological injuries on MRSA cells revealed a likely loss of viability as a result of the direct contact between bacteria and the GO-Ag sheets.

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“…These related-graphene nanomaterials show singular electronic, mechanical, and thermal properties. Their field of applications includes nanocomposites, supercapacitors, nanoelectronics, sensors, molecular vehicles, and nanomedicine platforms (Faria et al 2012).…”

Section: Nanomaterials: Antimicrobial Properties and Mechanisms Of Acmentioning

confidence: 99%

Toxicity of Nanomaterials to Microorganisms: Mechanisms, Methods, and New Perspectives

2013

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In the last few years, several nanomaterials with unique physicochemical properties have been developing. Specially, nano-sized materials such as silver and zinc nanoparticles, carbon nanotubes, and graphene oxide have been attracting great attention due to their potential as novel antimicrobial agents. Worldwide, the constant and indiscriminate use of conventional antibiotics has been responsible for the development of several resistant microbial species. In this context, there is a real and increasing demand for new antimicrobial agents. Nanomaterials offer several benefits due to their small size (high aspect volume/ area) that provides to nanoparticles great ability to get through physical barriers such as membranes and cellular walls. Henceforth, the aim of this present chapter is to discuss the toxicological aspects of nanomaterials to microorganisms, describing the methods to evaluate their antimicrobial activity and highlighting their implications on the microbial communities of soil and water environments. We also stress the main industrial applications of antimicrobial-engineered nanomaterials.

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Unveiling the Role of Oxidation Debris on the Surface Chemistry of Graphene through the Anchoring of Ag Nanoparticles

Cited by 83 publications

References 49 publications

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

Graphene oxide-silver nanocomposite as a promising biocidal agent against methicillin-resistant Staphylococcus aureus

Toxicity of Nanomaterials to Microorganisms: Mechanisms, Methods, and New Perspectives

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