Ambient light induced antibacterial action of curcumin/graphene nanomesh hybrids

Curcumin and its derivates are well-known for their different biological activities including antibacterial. On the other hand there are controversial reports concerning the antibacterial potential of graphene and, in particular, graphene oxide. In this study we have reported for the first time the antibacterial activity of curcumin/graphene nanomesh hybrids under ambient light conditions. The graphene nanomesh was synthesized by electrochemical exfoliation of highly oriented pyrolytic graphite in 1 M solution of ammonium persulfate and further functionalized by curcumin. Identical values of minimum inhibitory concentration (1 mg mL(-1)) were determined for pure curcumin and curcumin/graphene nanomesh hybrids toward Staphylococcus aureus. All tested samples had more pronounced antibacterial activity against Gram positive bacteria, Staphylococcus aureus compared to Escherichia coli as a representative of Gram negative strains. The poor antibacterial potential of exfoliated graphene improves significantly by the functionalization with curcumin, which allows for its usage as a antibacterial coating

ASSESSMENT OF WATER QUALITY OF THE PEK RIVER BASED ON PHYSICOCHEMICAL ANALYSIS

Levels of physicochemical parameters (pH, electrical conductivity, sulphates, chlorides, temperature,turbidity, total hardness, iron, manganese, copper, dissolved oxygen, oxygen saturation, total suspendedsolid, ammonium nitrogen, total nitrogen and orthophosphates ) were determined in the water samplescollected from Pek River at 4 sample sites during 6 months. Monitoring was done at the source of river,on the border between the municipalities Majdanpek and Kučevo, on the border between themunicipalities Kučevo and Veliko Gradište and at the confluence of Pek into Danube River. Some ofthe physicochemical parameter values fall within national standard and WHO limits, some are not

Novel method for graphene functionalization

In this paper we present a novel method to obtain a stable dispersion of graphene in water using carbon quantum dots as surface active agents. In this way it is possible to achieve graphene concentrations in dispersion up to 2.7 mg ml(-1). Fourier transform infrared spectroscopy and UV-Vis measurements confirmed the presence of oxygen-containing functional groups in the graphene-carbon quantum dot (gCQD) structure, responsible for its good solubility in water. The stability of the gCQD dispersion is due to pi-pi interactions formed between graphene and graphene-like sites of carbon quantum dots. According to Raman spectroscopy, as well as transmission electron microscopy and atomic force microscopy analysis, graphene sheets consist of several layers.4th International School and Conference on Photonics, Aug 26-30, 2013, Belgrade, Serbi

Gamma ray-assisted irradiation of few-layer graphene films: a Raman spectroscopy study

This paper represents results of a Raman spectroscopy study of gamma-irradiated few-layer graphene thin films at three different doses: 25, 50 and 110 kGy. Graphene thin films were deposited by the vacuum filtration method and then transferred onto glass substrate. Raman spectroscopy and atomic force microscopy analysis have shown that the average in-plane crystallite size La of graphene thin films varies slightly when an irradiation dose is applied. Raman spectroscopy revealed that gamma irradiation of graphene thin films resulted in slight p-doping of the graphene thin film surface. It was found that during gamma irradiation at a dose of 110 kGy, the graphene sheets merged. As a result, the number of incorporated defects in the graphene structure was reduced (the ID/IG ratio decreased with the increase in the applied dose).4th International School and Conference on Photonics, Aug 26-30, 2013, Belgrade, Serbi

Graphene quantum dots and fullerenol as new carbon sources for single-layer and bi-layer graphene synthesis by rapid thermal annealing method

Graphene as a new material is in the spotlight due to its extraordinary properties and wide range of potential applications. Chemical vapour deposition, as a method for graphene synthesis from gaseous hydrocarbon sources has great promises for large-scale graphene synthesis. However, for such grow high temperatures of 800-1000 degrees C are typically required. Here we demonstrate synthesis of single-layer and bi-layer graphene thin films of approximately 10,m in size by rapid thermal annealing process at low annealing temperature such as 600 degrees C. Synthesis was performed on copper foil from graphene quantum dots and fullerenol as solid carbon sources at different concentrations. Raman spectroscopy study has shown that the number of grown graphene layers depends on the carbon source concentration. The quality of formed graphene layers withal depends on the carbon source and its concentration, whereby graphene from graphene quantum dots had better quality. (C) 2016 Elsevier Ltd. All rights reserved

Preparation of PEDOT:PSS thin films doped with graphene and graphene quantum dots

Enhanced conductivity, transparency and stability are the most important factors to consider in order to prepare electrodes for optoelectronic devices. In this paper, we investigated the properties of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films doped with graphene and graphene quantum dots. Samples were deposited by spin-coating onto glass substrates. Thin films were characterized by UV-vis and Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and four-point probe measurements. It was found that both graphene and graphene quantum dots improve the conductivity of PEDOT:PSS films with only small decrease in transparency. AFM and SEM analysis showed homogenous distribution of spherical nanoparticles of graphene quantum dots and irregular shaped nanoparticles of graphene in PEDOT:PSS

OPO laser light absorption and evolutionary behaviour of SWCNT thin films

In this paper we report a systematic study on the properties of irradiated SWCNT films by high power, pulsed visible irradiation of OPO laser in the range from 430 nm to 800 nm. Raman analysis showed that metallic and semiconducting SWCNTs were simultaneously affected by irradiation. It was found that laser irradiation had the most prominent effects on SWCNT films at 430 nm wavelength. To our surprise, semiconducting SWCNTs were more affected by irradiation than metallic and as a result several SWCNTs were isolated partially

Raman study of single wall carbon nanotube thin films treated by laser irradiation and dynamic and isothermal oxidation

The effect of visible and infrared irradiation on the structure of single wall carbon nanotubes (SWCNTs) is still an insufficiently resolved subject. In this paper, we report a detailed study of two types of SWCNT thin films treated by pulsed laser irradiation and dynamic and isothermal oxidation, respectively. Raman features of treated films were investigated by 532, 633 and 780?nm excitation lines, respectively. It was established that the 532?nm excitation laser line probes the surface of SWCNT films, while the two others probe the bulk of SWCNT films. It was found that during Raman measurements, one type of SWCNTs warms up significantly while the other type does not change temperature. Raman analysis of SWCNTs probed with 532?nm showed that effects of high power laser irradiation on two types of SWCNTs are completely different. Major effects are decomposition, debundlation and photooxidation. It was found that debundlation and removal of defective carbon are much more pronounced in one type of SWCNTs treated with dynamic oxidation. Dynamic oxidation affects mostly thinner SWCNTs that easily burn in air. The only significant effects of isothermal oxidation are the increase of defective amorphous carbon in the first type of SWCNTs and the decrease of D band and debundlation in the second type. Copyright (c) 2012 John Wiley and Sons, Ltd

Rapid thermal annealing of nickel-carbon nanowires for graphene nanoribbons formation

In this paper, we present a novel method for graphene nanoribbons formation using nickel nanowires as templates. Modification of electrochemical procedure for nickel nanowires synthesis was introduced by implementing graphene quantum dots as a carbon source. Thus, nickel nanowires with graphene quantum dots were prepared. These wires were exposed to rapid thermal annealing at high temperatures (500 degrees C, 700 degrees C and 800 degrees C). During this process carbon atoms dissolve in metal and precipitate to the nickel surface forming nickel-carbon nanowires. Atomic force microscopy, scanning electron microscopy and Raman spectroscopy were characterization methods used for analysis of changes in nickel-carbon nanowires properties depending on the different annealing temperatures. After etching nickel with nitric acid, graphene nanoribbons with average diameters of 32 nm and average lengths of 4 mu m were obtained. (C) 2016 Elsevier B.V. All rights reserved