Synthesis of amine functionalized graphite nanosheets and their water-soluble derivative for drug loading and controlled release

A facile route to synthesize amine (–NH2) functionalized graphite nanosheets (AFGNS) by 2-step controlled chemical modification of microcrystalline graphite is described. The method begins with nitration by mixed acid (HNO3 : H2SO4 in 1 : 1 v/v ratio), followed by reduction with Na2S to form AFGNS. The AFGNS was reacted with carboxylic acid-terminated polyethylene glycol (PEG) chains (MeO–mPEG–COOH, MW = 5000 Da) in the presence of a carbodiimide coupling agent to obtain a water-soluble PEGylated AFGNS (P-AFGNS) composite. Anticancer drug doxorubicin (DOX) was loaded on this composite with a loading capacity of 0.296 mg mg−1 for an initial concentration of 0.232 mg mL−1 DOX and 0.136 mg mL−1 of P-AFGNS and the release of DOX from this water-soluble DOX loaded P-AFGNS composite at two different temperatures was found to be strongly pH dependent

Carbon nanodot–ORMOSIL fluorescent paint and films

Controlled carbonisation of P123 block-co-polymer in ethanol yielded micelle-protected carbon nanodots (CNDs) at room temperature. A purified and concentrated CND solution (quantum yield 10%) was incorporated into the organically-modified SiO2 (ORMOSIL) sol for the fabrication of transparent fluorescent coatings of thickness [similar]3 μm on glass. These films are scratch resistant with a surface hardness value of 8H. The sol can also be useful as a fluorescent ink/paint. The films retained the pristine photophysical properties of CNDs

A scoping review and thematic analysis of social and behavioural research among HIV-serodiscordant couples in high-income settings.

CAPRISA, 2015.Abstract available in pdf

Selective Cu4Pd alloy nanoparticles anchoring on amine functionalized graphite nanosheets and their use as reusable catalysts for a C-C coupling reaction with the sacrificial role of Cu for Pd-regeneration

A facile method for the synthesis of phase selective alloy nanoparticles (NPs), Cu4Pd and their in situ anchoring on the surface of amine functionalized graphite nanosheets (AFGNS) by solvothermal process has been demonstrated. It has been seen that upon adding CuCl2 center dot H2O and PdCl2 into the reaction medium containing AFGNS, the -NH2 group initially helps to immobilize Cu2+ ions from CuCl2 center dot H2O. During the solvothermal reaction in presence of N,N-dimethylformamide (DMF; solvent cum reducing agent) Pd2+ gets reduced first due to its higher reduction potential. These Pd NPs in turn help in the reduction of Cu2+ to Cu in an epitaxial manner. Finally at high temperature and long reaction time Cu and Pd combine to form the Cu4Pd alloy NPs along with a small fraction of Cu NPs. The conditions to obtain Cu4Pd NPs have been optimized through controlled reactions. The as prepared Cu4Pd@AFGNS composite has been successfully used for Suzuki-Miyuara C-C coupling reaction with sufficiently high yield and reusability of up to five cycles. The progress of the reaction was monitored using a fluorimeter. Interestingly, it has been observed that the small fraction of the Cu NPs present in the system played a sacrificial role in regenerating metallic Pd NPs in the first and second reaction cycles, followed by Cu from the Cu4Pd alloy itself from the third cycle onwards which played the sacrificial role to regenerate Pd(0). A probable reaction mechanism of the catalytic reaction with Cu4Pd@AFGNS has been suggested

Enrichment of Metallic Single-Walled Carbon Nanotubes with Simultaneous Purification by Nitric Acid Treatment

Controlled treatment of pristine single-walled carbon nanotubes (SWCNT) with HNO3 (11 M) for 20 hours at 50 degrees C with subsequent repeated cycles of washing, centrifugation and ultrasonication in aqueous media have shown enrichment of the product with pure and debundled nanotubes of metallic variety. On the other hand, no such enrichment was observed when the tubes were treated with a mixture of concentrated nitric acid and sulfuric acid. The electrical varieties of the tubes were ascertained from the analysis of Raman and UV-Vis spectra and dc-resistivities. The purity of the product was gauged from transmission electron microscope images, energy dispersive spectra, thermogravimetric analysis and Raman spectra. A mechanism involving preferential attack of NO3- on the semiconducting tubes under the condition of the adopted protocol has been proposed from the comparison of the results after the treatment of the same pristine SWCNT with mixed acid (conc. HNO3 and H2SO4)

gamma-Alumina Nanorod/Reduced Graphene Oxide as Support for Poly(ethylenimine) to Capture Carbon Dioxide from Flue Gas

The synthesis of a mesoporous gamma-Al2O3 nanorod/reduced graphene oxide (gamma-Al2O3NR/RGO) composite with a higher surface area and thermal conductivity than unmodified gamma-Al2O3 has been accomplished, and these materials were characterized in detail. The composite was used successfully as a support for poly(ethylenimine) (PEI) to capture CO2 at high temperature. The PEI-modified composite (gamma-Al2O3NR/ RGO/PEI) showed an excellent CO2 adsorption from simulated flue gas at 75 degrees C and complete desorption at 100 degrees C with recyclability. The maximum CO2 adsorption capacity of this material was 200.6 mgg(PEI)(-1) (1.14 mmol CO(2)g(adsorbent)(-1)) with an amine efficiency of 0.22, which is higher than that of bare gamma-Al2O3/PEI. As a result of its high thermal conductivity, the overheating of the adsorbent during exothermic CO2 adsorption by PEI was restricted and as a result the thermal degradation of PEI was prevented. Accordingly, the adsorption capacity of gamma-Al2O3NR/RGO/PEI does not deteriorate like that of bare gamma-Al2O3/PEI during repeated CO2 adsorption- desorption cycles

Cu2O Nanoparticles Anchored on Amine-Functionalized Graphite Nanosheet: A Potential Reusable Catalyst

Synthesis of Cu2O-amine-functionalized graphite nanosheet (AFGNS) composite has been accomplished at room temperature. In the first step, AFGNS is synthesized by wet chemical functionalization where the -NH2 groups formed on nanosheet surface help to anchor the Cu2+ ions homogeneously through coordinate bonds. Reduction of Cu2+ (3.4 x 10(-2) mmol) in the presence of NaBH4 (1.8 mmol) can be restricted to Cu1+ on AFGNS surface at room temperature. This leads to the formation of uniform Cu2O nanoparticles (NP) on AFGNS. The role played by the -NH2 groups in anchoring Cu2+ ions and followed by stabilizing the Cu2O NP on AFGNS was understood by controlled reactions in the absence of -NH2 groups and without any graphitic support, respectively. The prepared Cu2O-AFGNS composite shows excellent catalytic activity toward degradation of an azo dye, methyl orange, which is an environmental pollutant. The dye degradation proceeds with high rate constant value, and the composite shows high stability and excellent reuse capability

Carboxylic acid terminated, solution exfoliated graphite by organic acylation and its application in drug delivery

Graphite nanosheets are considered as a promising material for a range of applications from flexible electronics to functional nanodevices such as biosensors, intelligent coatings and drug delivery. Chemical functionalization of graphite nanosheets with organic/inorganic materials offers an alternative approach to control the electronic properties of graphene, which is a zero band gap semiconductor in pristine form. In this paper, we report the aromatic electrophilic substitution of solution exfoliated graphite nanosheets (SEGn). The highly conjugated pi-electronic system of graphite nanosheets enable it to have an amphiphilic characteristic in aromatic substitution reactions. The substitution was achieved through Friedel-Crafts (FC) acylation reaction under mild conditions using succinic anhydride as acylating agent and anhydrous aluminum chloride as Lewis acid. Such reaction renders towards the carboxylic acid terminated graphite nanosheets (SEGn-FC) that usually requires harsh reaction conditions. The product thus obtained was characterized using various spectroscopic and microscopic techniques. Highly stable water-dispersed sodium salt of carboxylic acid terminated graphite nanosheets (SEGn-FC-Na) was also prepared. A comparative sheet-resistance measurements of SEGn, SEGn-FC and SEGn-FC-Na were also done. Finally, the anticancer drug doxorubicin (DOX) was loaded on water dispersible SEGn-FC-Na with a loading capacity of 0.266 mg mg(-1) of SEGn-FC-Na and the release of DOX from this water-soluble DOX-loaded SEGn-FC-Na at two different temperatures was found to be strongly pH dependent