D. Kleut

A novel method for the functionalization of γ-irradiated single wall carbon nanotubes with DNA

In this work we describe a novel method for highly efficient functionalization of single wall carbon nanotubes (SWCNTs) by DNA wrapping. Exposure of SWCNTs to gamma-irradiation (50 kGy) has lowered by one order of magnitude the amount of single stranded deoxyribonucleic acid (ssDNA) required for SWCNT modification. The resulting hybrids of gamma-irradiated SWCNTs and ssDNA were characterized by optical absorbance spectroscopy, Raman spectroscopy and Fourier transform infrared spectroscopy. Atomic force microscopy was used to investigate the morphology of hybrids. While gamma-irradiation in three different media has significantly improved the process of SWCNT dispersion, irradiation in ammonia was the most efficient. The gamma-irradiated SWCNTs functionalized with ssDNA were stabilized by electrostatic forces. This preliminary study suggests that gamma-irradiation can significantly improve the functionalization of SWCNTs with DNA.

Oxidative stress-mediated hemolytic activity of solvent exchange-prepared fullerene (C60) nanoparticles

The present study investigated the hemolytic properties of fullerene (C(60)) nanoparticles prepared by solvent exchange using tetrahydrofuran (nC(60)THF), or by mechanochemically assisted complexation with macrocyclic oligosaccharide gamma-cyclodextrin (nC(60)CDX) or the copolymer ethylene vinyl acetate-ethylene vinyl versatate (nC(60)EVA-EVV). The spectrophotometrical analysis of hemoglobin release revealed that only nC(60)THF, but not nC(60)CDX or nC(60)EVA-EVV, was able to cause lysis of human erythrocytes in a dose- and time-dependent manner. Atomic force microscopy revealed that nC(60)THF-mediated hemolysis was preceded by erythrocyte shrinkage and increase in cell surface roughness. A flow cytometric analysis confirmed a decrease in erythrocyte size and demonstrated a significant increase in reactive oxygen species production in red blood cells exposed to nC(60)THF. The nC(60)THF-triggered hemolytic activity was efficiently reduced by the antioxidants N-acetylcysteine and butylated hydroxyanisole, as well as by serum albumin, the most abundant protein in human blood plasma. These data indicate that nC(60)THF can cause serum albumin-preventable hemolysis through oxidative stress-mediated damage of the erythrocyte membrane.

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).

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 π–π 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.

Raman spectroscopy study of carbon-doped resorcinol-formaldehyde thin films

In this work, we investigated the properties of carbon resorcinol-formaldehyde (RF) cryogel thin films. RF cryogels were doped by single-wall carbon nanotubes, graphene and graphene quantum dots. The structure of the deposited films was investigated by Raman spectroscopy, and optical, transmission electron and atomic force microscopy. Raman spectroscopy was performed using three excitation laser energies in the visible range. The effect of glass substrate on the Raman features of investigated carbon cryogel thin films was determined as well. The particle size of the carbon-doped RF cryogel thin films was determined by atomic force microscopy.

Surface modification of single-wall carbon nanotube thin films irradiated by microwaves: a Raman spectroscopy study

In this work, we present the results of a Raman spectroscopy study of single-wall carbon nanotube (SWCNT) thin films treated with microwave irradiation. SWCNT thin films were deposited by the vacuum filtration method and transferred onto alumina substrate. These thin films were exposed to microwave irradiation of 25 and 250 W at 2.45 GHz. All samples were characterized by Raman spectroscopy and atomic force microscopy. Raman spectroscopy analysis showed that there was neither selective destruction of metallic nor semiconducting nanotubes. It was noticed that samples were heated only during microwave irradiation at 250 W. The major effect of microwave irradiation on SWCNTs was their debundling.