Synergistic Antiviral Effects of Metal Oxides and Carbon Nanotubes.

In this research, the synergistic antiviral effects of carbon nanotubes (CNTs) and metal oxides (MO) in the form of novel hybrid structures (MO-CNTs) are presented. Raw CNTs, Ni(OH)2, Fe2O3 and MnO2, as well as Ni(OH)2-CNT, Fe2O3-CNT and MnO2-CNT were explored in this study against Escherichia. coli MS2 bacteriophage, which was used as a virus surrogate. The nano particles were synthesized and characterized using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), particle size analysis, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Kinetic parameters such as the LD50 (lethal dose to kill 50% of the population), T50 and T80 (time taken to kill 50% and 80% of the population), SGR (specific growth rate) and IRD (initial rate of deactivation of the population) were also studied to examine the antiviral efficacy of these nanomaterials. Among all the nanomaterials, Ni(OH)2-CNT was the most effective antiviral agent followed by Fe2O3-CNT, MnO2-CNT, raw CNTs, Ni(OH)2, Fe2O3 and MnO2. When comparing the metal oxide-CNTs to the raw CNTs, the average enhancement was 20.2%. The average antiviral activity enhancement of the MO-CNTs were between 50 and 54% higher than the MO itself. When compared to the raw CNTs, the average enhancement over all the MO-CNTs was 20.2%. The kinetic studies showed that the LD50 of Ni(OH)2-CNT was the lowest (16µg/mL), which implies that it was the most toxic of all the compounds studied. The LD50 of Ni(OH)2, Fe2O3 and MnO2 were 17.3×, 14.5× and 10.8× times greater than their corresponding hybrids with the CNTs. The synergistic mechanism involved the entrapment of phage viruses by the nano structured CNTs leading to structural damage along with toxicity to phage from the release of MO ions. The metal oxide-CNT nano hybrids developed in this project are promising candidates in applications such as antiviral coatings, nanocomposites, adsorbents and as components of personal protection gears.

Nano Carbon Doped Polyacrylamide Gel Electrolytes for High Performance Supercapacitors.

Novel polyacrylamide gel electrolytes (PGEs) doped with nano carbons with enhanced electrochemical, thermal, and mechanical properties are presented. Carboxylated carbon nanotubes (fCNTs), graphene oxide sheets (GO), and the hybrid of fCNT/GO were embedded in the PGEs to serve as supercapacitor (SC) electrolytes. Thermal stability of the unmodified PGE increased with the addition of the nano carbons which led to lower capacitance degradation and longer cycling life of the SCs. The fCNT/GO-PGE showed the best thermal stability, which was 50% higher than original PGE. Viscoelastic properties of PGEs were also improved with the incorporation of GO and fCNT/GO. Oxygen-containing functional groups in GO and fCNT/GO hydrogen bonded with the polymer chains and improved the elasticity of PGEs. The fCNT-PGE demonstrated a slightly lower viscous strain uninform distribution of CNTs in the polymer matrix and the defects formed within. Furthermore, ion diffusion between GO layers was enhanced in fCNT/GO-PGE because fCNT decreased the aggregation of GO sheets and improved the ion channels, increasing the gel ionic conductivity from 41 to 132 mS cm-1. Finally, MnO2-based supercapacitors using PGE, fCNT-PGE, GO-PGE, and fCNT/GO-PGE electrolytes were fabricated with the electrode-specific capacitance measured to be 39.5, 65.5, 77.6, and 83.3 F·g-1, respectively. This research demonstrates the effectiveness of nano carbons as dopants in polymer gel electrolytes for property enhancements.

Direct incorporation of nano graphene oxide (nGO) into hydrophobic drug crystals for enhanced aqueous dissolution.

This paper reports the development of a successful anti-solvent method that incorporates colloidal nano scale graphene oxide (nGO) directly into hydrophobic drug crystals. The nGO dispersed in solution acted as nucleating sites for crystallization and were embedded into the drug crystals without altering its structure or physical properties such as melting point. Several composites of drugs Sulfamethoxazole and Griseofulvin were synthesized with nGO concentration ranging between 0.2 and 1.0 %. The presence of nGO dramatically enhanced the dissolution rate. The time needed to reach a 50 % release (T50) reduced from 42-14 min with the integration of 0.8 % nGO in SMZ, while in GF the reduction was from 44-27 min with 0.5 % nGO. Increased release rates are attributed to the presence of the hydrophilic nGO which hydrogen bond more so with the aqueous mediums. Therefore, the incorporation of nGO into poorly soluble drugs is an effective approach towards drug delivery and bioavailability improvement and opens a new approach to high performance drug delivery.

Stepwise Reduction of Graphene Oxide (GO) and Its Effects on Chemical and Colloidal Properties.

Graphene Oxides (GO) typically contains different oxygen containing groups such as hydroxyl, carboxyl and epoxy, and reduced GO (r-GO) represents a family of material with diverse chemical properties. In an effort to understand how properties of r-GO change as GO is reduced, a stepwise reduction of the same GO to r-GO containing different levels of oxygen was carried out, and their corresponding chemical and colloidal properties are reported. Starting with GO containing 49 percent oxygen, r-GOs containing 31, 19 and 9 percent oxygen were synthesized. The aqueous behavior in terms of solubility gradually decreased from 7.4 µg/ml for GO to nearly zero for r-GO with 9% oxygen, while dispersibility under sonication decreased from 8 to 2.5 µg/ml for the same samples. Hydrophobicity index as measured as the octanol water partition coefficient decreased from -3.89 to 5.2% as oxygen content dropped from 49 to 9%. Colloidal behavior was also dramatically affected by reduction, and critical coagulation concentration (CCC) dropped from 28 to 15 in presence of 0.5 mmole/l NaCl and from 6 to 2 in presence of 0.5 mmole/l MgCl2 as the oxygen in the original GO was reduced to 9%.

Microwave-Assisted Biogenic Synthesis of Metal-Decorated Reduced Graphene Oxide and their Electrochemical Properties.

Herein we report a microwave assisted, fungal (Ganoderma lucidum) extract mediated synthesis of noble metal decorated reduced graphene oxide(r-GO). The carbon to oxygen ratio increased from 1.46 in GO to 2.72 in r-GO. The electron rate transfer capabilities of Pt, Pd, Ru, Pt-Pd and Pt- Ru decorated r- GO were tested in ferri-ferro coupling reaction. Excellent electrochemical behaviour were observed in their ability to oxidize hydrazine, reduce H2O2, as well as oxygen reduction in alkaline medium and hydrogen evolution in acidic medium. These reactions represent diverse applications in energy production, storage, electrochemical sensing and electro catalysis, thus the method presented here can be quite useful in diverse applications.