Graphene oxide reinforced poly (vinyl alcohol) nanocomposite: fabrication and characterization for thermal and mechanical properties investigations

We reported the fabrication of poly (vinyl alcohol) incorporated with two different sizes of graphene oxide particles. Scanning electron microscopy (SEM) revealed two sizes of graphene oxide, the first size is as prepared GO_300 nm and the second size is 100nm after hard sonication. The alteration in thermal and mechanical properties of PVA/ GO (5, 10, 15, 20%) nanocomposite compering with PVA are mainly due to the uniform dispersion of GO particles in the polymer matrix and huge interfacial interaction between PVA and GO sheets. Differential scanning calorimetry shows obvious changes in thermal characteristics of PVA after mixing with GO particles. The composite samples exhibit a significant finding at different concentrations and size distribution of GO. First published online 17 April 202

Analysis, characterization and some properties of polyacrylamide-Ni(II) complexes

The complexation of polyarylamide (PAam) with Ni(II) metal ions at different concentrations was investigated. The metal complexes were characterized by fourier transform infrared spectroscopy (FTIR), UV-visible, differential scanning calorimeter (DSC) and atomic force microscope (AFM). FTIR spectroscopy was used to study the characteristic shifts of the absorbance bands of C=O and N-H2. UV-visible spectroscopy was used to follow the complex formation of PAam-Ni(II) and showed the appearance of a new band that was absent both in PAam and Ni(II) salt solutions. Thermal parameters, such as the glass transition temperature (Tg) and the melting point (Tm) of the polymer-metal complex have been measured by DSC. The variation of Tg and Tm with different Ni(II) concentrations was attributed to the complexation of the native polymer during the increasing of Ni(II) concentration. AFM was used to study the surface morphology of PAam films and its complexation with Ni(II) at different concentrations. The root mean square roughness increased as the Ni(II) concentration increases

Study on the morphology of polyacrylamide – silica fumed nanocomposite thin films

Silica fumed nanoparticles were dispersed in polyacrylamide thin films by direct mixing. Atomic Force Microscopy study was carried out in order to analyze the surface roughness. Height distribution of surface roughness changes from Gaussian like for polyacrylamide to skew asymmetric when increasing the silica concentration. The length of the distribution tail increases, indicating the formation of multi-scale features that increase in number and size, as the silica increase.The authors acknowledge the financial support of the German research foundation (DFG), French academy of sciences and French Ministry of Foreign Affairs, Prof. Philippe Meyer and the Meyer Foundation

Spectroscopic investigations of pentobarbital interaction with human serum albumin

The interaction between pentobarbital and human serum albumin has been investigated. The basic binding interaction was studied by UV-absorption and fluorescence spectroscopy. From spectral analysis pentobarbital showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant (k) is estimated at 1.812 104 M 1 at 293 K. FT-IR spectroscopy with Fourier self-deconvolution technique was used to determine the protein secondary structure and drug binding mechanisms. The observed spectral changes of HSA–pentobarbital complex indicate a larger intensity decrease in the absorption band of a-helix relative to that of b-sheets. This variation in intensity is related indirectly to the formation of H-bonding in the complex molecules, which accounts for the different intrinsic propensities of a-helix and b-sheets.This work is supported by the German Research Foundation DFG Grant No. DR228/24-2

Graphene Oxide Nanohybrids as Platforms for Carboplatin Loading and Delivery

Nanographene oxide particles (NGO) were produced via oxidative exfoliation of graphite. Three different sizes of NGO (300 nm, 200 nm and 100 nm) have been separated by using probe sonication and sucrose density gradient centrifugation. There is great interest in functionalized NGO as a nanocarrier for in vitro and in vivo drug delivery, in order to improve dispersibility and stability of the nanocarrier platforms in physiological media. In this study, the NGO particles were covalently functionalized with zero generation polyamidoamide (PAMAM-G0) and with gelatin via noncovalent interaction. Spectroscopic techniques have been used to discriminate the chemical states of NGO prior and after functionalization. The X-ray photoelectron spectroscopy (XPS) revealed a clear change in the chemical state of NGO after functionalization, for both covalent and noncovalent approaches. Raman spectroscopy gave obvious insight after oxidation of graphite and functionalization of NGO particles depending on the variation of intensity ratios between D, G and 2D bands. The Fourier transform infrared spectroscopy (FTIR) exhibited the presence of oxygen containing functional groups distributed onto graphene sheets after oxidation of graphite. Furthermore, the FTIR is complementary with the XPS which performed a strong reduction in the oxygen contents after functionalization. UV visible spectroscopy was used to understand the binding capacity of gelatin coated NGO particles. The Microscopy tools, scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to estimate the dimensions of NGO particles (thickness and lateral width). The nanohybrid systems (NGO-PAMAM and Gelatin-NGO) loaded with carboplatin (CP) were sought for anticancer activity investigation in HeLa and neuroblastoma cancer cells respectively. Mesenchymal stem cells (hMSCs) were used as a model of normal cells. On HeLa cells, the pristine NGO particles with average widths of 200 nm and 300 nm showed a cytotoxic effect at low (50 g.ml−1) and high (100 g.ml−1) concentrations. While the pristine NGO sample with an average width of 100 nm revealed no significant cytotoxicity at 50 g.ml−1, and only recorded a 10% level at 100 g.ml−1. The mesenchymal stem cells showed less than 35% viability for all size distributions. After functionalization with PAMAM, the carrier was found to be able to deliver carboplatin to the cancer cells, by enhancing the drug anticancer efficiency. Moreover, the carboplatin loaded NGO carrier shows no significant effect on the viability of hMSCs even at high concentration (100 g.ml−1). On neuroblastoma cells, the cell viability assay validated gelatin-NGO nanohybrids as a useful nanocarrier for CP release and delivery, without obvious signs of toxicity. The nano-sized NGO (200 nm and 300 nm) did not enable CP to kill the cancer cells efficiently, whilst the CP loaded gelatin-NGO 100 nm resulted in a synergistic activity through increasing the local concentration of CP inside the cancer cells

Removal of toxic hexavalent chromium via graphene oxide nanoparticles: study of kinetics, isotherms, and thermodynamics

In this study, graphene oxide (GO) was prepared by the Hummers' method from graphite material. The adsorption potential of GO-200 nm for the removal of Cr(vi) ions was investigated. Fourier transform infrared (FTIR) spectroscopy was used to analyze Cr(vi) before and after adsorption. The adsorption isotherm was fitted by the Langmuir model and the maximum adsorption capacity of the GO was 41.27 mg g−1 at 25 °C. Thermodynamic parameters (ΔG°), (ΔH°), and (ΔS°) were calculated and exhibited as +2.63 kJ mol−1 K−1, +4.30 kJ mol−1 K−1, and +5.56 kJ mol−1 K−1 at 30 mg L−1 of Cr(vi) solution, respectively

Graphene oxide-based drug delivery vehicles: functionalization, characterization, and cytotoxicity evaluation

As a consequence of graphene oxides (GOs) high chemical versatility, there is great interest in functionalized as a nanocarrier for in vitro and in vivo drug delivery. Within this review, the structure and properties of GO that allow covalent and noncovalent functionalization are discussed. In short, toxicity investigations show functionalized GO is biocompatible. Various works demonstrate the potential of GO derivatives as exciting nanocarriers for the loading and delivery of therapeutic drugs.140381sciescopu

Size-dependent nanographene oxide as a platform for efficient carboplatin release

Nanographene oxides (NGO) with well-defined sizes were produced from graphite via chemical exfoliation and separated into three different size distributions (300 nm, 200 nm, and 100 nm) using intense sonication and sucrose density gradient centrifugation. Prior to carboplatin (CP) loading, the NGO was functionalized with zero generation polyamidoamide (PAMAM) which renders improved dispersibility and stability of the nanocarrier platform in physiological media. Cell viability tests were conducted on pristine NGO samples with average widths of 200 nm and 300 nm that showed a cytotoxic effect on HeLa cancer cells and mesenchymal stem cells at low (50 μg ml-1) and high (100 μg ml-1) concentrations, while the pristine NGO sample with an average width of 100 nm revealed no significant cytotoxicity at 50 μg ml-1, and only recorded a 10% level at 100 μg ml-1. After functionalization with PAMAM, the carrier was found to be able to deliver carboplatin to the cancer cells, by enhancing the drug anticancer efficiency. Moreover, the carboplatin loaded NGO carrier shows no significant effect on the viability of mesenchymal stem cells (hMSCs) even at high concentration (100 μg ml-1). © 2013 The Royal Society of Chemistry.112151sciescopu