Bioethanol Production from Unpretreated Cellulose under Neutral Selfsustainable Hydrolysis/Hydrogenolysis Conditions Promoted by the Heterogeneous Pd/Fe3O4 Catalyst.

The direct conversion of untreated microcrystalline cellulose into C2-C3 alcohols, through a one-pot process promoted by the heterogeneous bimetallic Pd/Fe3O4 catalyst, is presented. The process is selfsustainable without the addition of external molecular hydrogen or acid/basic promoters and is mainly selective toward ethanol. At 240 °C, a complete cellulose conversion was reached after 12 h with an ethanol molar selectivity of 51% among liquid products. The synergistic effect played by water (which aids in the chemical pretreatment means of cellulose through the hydrolysis process) and the Pd/Fe3O4 catalyst (which catalyzes the hydrogenolysis reaction driving the pattern of obtained products) is elucidated.

Removal of heavy metal ions from wastewaters using dendrimer-functionalized multi-walled carbon nanotubes.

Dendrimer-functionalized multi-walled carbon nanotubes (MWCNT) for heavy metal ion removal from wastewaters were developed. Triazole dendrimers (TD) were built directly onto the carbon nanotube surface by successive click chemistry reactions affording the zero- and first-generation dendrimer-functionalized MWCNT (MWCNT-TD1 and MWCNT-TD2). The Moedritzer-Irani reaction carried out on the amino groups present on the MWCNT-TD2 sample gave the corresponding α-aminophosphonate nanosystem MWCNT-TD2P. Both MWCNT-TD2 and MWCNT-TD2P nanosystems have been characterized by physical, chemical, and morphological analyses. Their chelating abilities towards the toxic metal ions Pb2+, Hg2+, and Ni2+ and the harmless Ca2+ ion have been experimentally evaluated in the two different sets of experiments and at the salt concentrations of 1 mg/mL or 1 µg/mL by inductively coupled plasma mass spectrometry (ICP-MS). The results of these studies pointed out the interesting chelating behavior for the phosphonated nanosystem towards the Hg2+ ion. The complexation mode of the best chelating system MWCNT-TD2P with mercury was investigated through density functional theory (DFT) calculations, suggesting a chelation mechanism involving the two oxygen atoms of the phosphate group. The synthesized dendrimers, supported on the multi-walled carbon nanotubes, have shown the potential to be used for the selective toxic metal ion removal and recovery.

Graphene quantum dots for cancer targeted drug delivery.

A biocompatible and cell traceable drug delivery system Graphene Quantum Dots (GQD) based, for the targeted delivery of the DNA intercalating drug doxorubicin (DOX) to cancer cells, is here reported. Highly dispersible and water soluble GQD, synthesized by acidic oxidation and exfoliation of multi-walled carbon nanotubes (MWCNT), were covalently linked to the tumor targeting module biotin (BTN), able to efficiently recognize biotin receptors over-expressed on cancer cells and loaded with DOX. Biological test performed on A549 cells reported a very low toxicity of the synthesized carrier (GQD and GQD-BTN). In GQD-BTN-DOX treated cancer cells, the cytotoxicity was strongly dependent from cell uptake which was greater and delayed after treatment with GQD-BTN-DOX system with respect to what observed for cells treated with the same system lacking of the targeting module BTN (GQD-DOX) or with the free drug alone. A delayed nuclear internalization of the drug is reported, due to the drug detachment from the nanosystem, triggered by the acidic environment of cancer cells.

Tunable doxorubicin release from polymer-gated multiwalled carbon nanotubes.

Two pH and temperature controlled drug delivery systems for cancer therapy are here reported by using vapour phase and liquid phase functionalized multiwalled carbon nanotubes (MWCNT). Both oxidized MWCNT were functionalized at the carboxyl groups with a short hydrophilic polyethylene glycol (PEG) chain. The nanosystems were loaded with doxorubicin and covered with the biocompatible polymer polylactide, able to form hydrogen bonding with PEG and to entrape the drug inside the two polymeric chains. The different oxidative reaction conditions of MWCNT have demonstrated to deeply affect their agglomeration ability and the available reactive surface area for drug loading which in turn, affected the drug release abilities of the synthesized polymer-gated drug delivery systems. The in vitro release abilities as well as their antiproliferative effect on three different human cancer cell lines were evaluated and compared, highlighting the possibility to tune the amount of drug released by controlling the functionalization degree of the carbon nanotube based material. Biological tests highlighted the high biocompatibility of both systems and their ability to deliver doxorubicin to cancer cells.

ß-Cyclodextrin-grafted on multiwalled carbon nanotubes as versatile nanoplatform for entrapment of guanine-based drugs.

The design of ß-cyclodextrin/multiwalled carbon nanotubes hybrid (ß-CD-MWCNT) as nanoplatform for the entrapment and delivery of guanine based drugs is described here. The functionalized carbon nanomaterials have been characterized by XPS spectroscopy, electron microscopy (FEG-SEM and TEM), AFM, TGA, and FT-IR to achieve insights on structure, morphology and chemical composition. The drug binding abilities of nanocarrier towards the guanine (G) and Acyclovir (Acy) were proved by UV-vis and DSC experiments. Host-guest equilibrium association constants and drug loading have been evaluated for G/ß-CD-MWCNT and Acy/ß-CD-MWCNT complexes. The release studies showed a sustained delivery of Acy without initial burst effect confirming a strong interaction of drug with the nanoplatform sites. The preliminary antiviral data indicated that the Acyclovir loaded into the ß-CD-MWCNT platform interferes with HSV-1 replication and the antireplicative effect was higher than the free drug.

Hydroxyapatite-magnetite-MWCNT nanocomposite as a biocompatible multifunctional drug delivery system for bone tissue engineering.

New magnetic hydroxyapatite-based nanomaterials as bone-specific systems for controlled drug delivery have been synthesized. The synthesized hydroxyapatite, HA, decorated with magnetite nanoparticles by a deposition method (HA/Fe3O4) and the nanocomposite system obtained using magnetic multi-walled carbon nanotubes (HA/MWCNT/Fe3O4) as a filler for HA have been characterized by chemical and morphological analyses, and their biological behavior was investigated. The systems have also been doped with clodronate in order to combine the effect of bone biomineralization induced by hydroxyapatite-based composites with the decrease of osteoclast formation induced by the drug. An analysis of the preosteoclastic RAW264.7 cell proliferation by MTT assay confirmed the high biocompatibility of the three systems. TRAP staining of RAW 264.7 conditioned with sRAKL to induce osteoclastogenesis, cultured in the presence of the systems doped and undoped with clodronate, showed the inhibitory effect of clodronate after we counted the MNC TRAP(+)cells but only in the osteoclast formation; in particular, the system HA/Fe3O4-Clo exerted a high inhibitory effect compared to the drug alone. These results demonstrate that the synthesized nanocomposites are a biocompatible magnetic drug delivery system and can represent a useful multimodal platform for applications in bone tissue engineering.

Recent advances in carbon nanotubes as delivery systems for anticancer drugs.

Problems associated with the administration of anticancer drugs, such as limited solubility, poor biodistribution,lack of selectivity, and healthy tissue damage, can be overcome by the implementation of drug delivery systems. A wide range of materials, including liposomes, microspheres, polymers and recently, carbon nanotubes (CNTs), have been investigated for delivering anticancer drugs on the purpose of reducing the number of necessary administrations, providing more localized and better use of the active agents, and increasing patient compliance. Carbon nanotubes (CNTs) have attracted particular attention as carriers of biologically relevant molecules due to their unique physical, chemical and physiological properties. The exact relationship between the physical-chemical properties of carbon nanotubes, their cell to-cell interactions, reactivity, and biological/systemic consequences are relevant issues and it is important to know suchinter-relationships beforehand to employ the benefits of these nanomaterials without the hazardous consequences. The purpose of this review is to present highlight of recent developments in the application of carbon nanotubes as cargoes for anti cancer drugs and in the diagnosis of cancer diseases.

A facile and ecofriendly functionalization of multiwalled carbon nanotubes by an old mesoionic compound.

This work reports for the first time a straightforward solvent-free chemical procedure to gain access to Δ-1-pyrroline grafted onto multiwalled carbon nanotubes by the 1,3-dipolar cycloaddition of the mesoionic 4-methyl-2-phenyloxazol-5(4H)-one.

Functionalization of multi-walled carbon nanotubes with coumarin derivatives and their biological evaluation.

We report the synthesis and the characterization of different multi-walled carbon nanotubes (MWCNTs) linked to natural molecules, 5,7-coumarins and/or oleic acid, obtained from purified pristine MWCNTs by a cascade of chemical functionalization. The activities of these modified MWCNTs were investigated in vitro on human umbilical vein endothelial cells (HUVECs) by evaluating their ability to influence cell viability and to induce cell apoptosis. Our data showed that pristine MWCNTs are markedly cytotoxic; conversely, the carboxylated carbon nanotubes, much more readily dispersed in aqueous solutions and CNT-Link, the key intermediate designed by us for the drug anchorage, are biocompatible at the tested concentrations (1 and 10 µg ml(-1)).

Crystalline quality evaluation of carbon nanotubes by kinetic analysis in quasi-isothermal conditions.

We demonstrate that the crystalline quality of multi-walled carbon nanotubes (MWCNTs) is better estimated by the apparent activation energy of the oxidation reaction, obtained by kinetic analysis in quasi-isothermal conditions, than by the peak-temperature position in the derivative mass loss curves. This is proven by the existence of a good correlation, reported for the first time herein, between apparent activation energy and G'-band to D-band intensity ratio derived from micro-Raman spectroscopy, which is largely accepted as an indicator of the overall MWCNT crystalline quality. In contrast, no clear reliance is found between G'/D intensity ratio and the peak-temperature position in the derivative mass loss curves. These conclusions were drawn after investigation of a large number of commercially available and laboratory prepared MWCNTs.

A highly sensitive oxygen sensor operating at room temperature based on platinum-doped In2O3 nanocrystals.

Semiconducting In2O3 nanocrystals, synthesised via a nonaqueous sol-gel method and doped with 1 wt% of platinum, have shown to possess a unique high sensitivity to oxygen at room temperature (RT). Consequently, a Pt/In2O3-based oxygen sensor for room temperature operation has been developed showing higher performance compared to the state-of-the-art devices.