Gluconic acid from biomass fast pyrolysis oils: specialty chemicals from the thermochemical conversion of biomass

Fast pyrolysis of biomass to produce a bio-oil followed by catalytic upgrading is a widely studied approach for the potential production of fuels from biomass. Because of the complexity of the bio-oil, most upgrading strategies focus on removing oxygen from the entire mixture to produce fuels. Here we report a novel method for the production of the specialty chemical, gluconic acid, from the pyrolysis of biomass. Through a combination of sequential condensation of pyrolysis vapors and water extraction, a solution rich in levoglucosan is obtained that accounts for over 30% of the carbon in the bio-oil produced from red oak. A simple filtration step yields a stream of high-purity levoglucosan. This stream of levoglucosan is then hydrolyzed and partially oxidized to yield gluconic acid with high purity and selectivity. This combination of cost-effective pyrolysis coupled with simple separation and upgrading could enable a variety of new product markets for chemicals from biomass.

Targeting single-walled carbon nanotubes for the treatment of breast cancer using photothermal therapy

This paper focuses on the targeting of single-walled carbon nanotubes (SWNTs) for the treatment of breast cancer with minimal side effects using photothermal therapy. The human protein annexin V (AV) binds specifically to anionic phospholipids expressed externally on the surface of tumour cells and endothelial cells that line the tumour vasculature. A 2 h incubation of the SWNT-AV conjugate with proliferating endothelial cells followed by washing and near-infrared (NIR) irradiation at a wavelength of 980 nm was enough to induce significant cell death; there was no significant cell death with irradiation or the conjugate alone. Administration of the same conjugate i.v. in BALB/c female mice with implanted 4T1 murine mammary at a dose of 0.8 mg SWNT kg(-1) and followed one day later by NIR irradiation of the tumour at a wavelength of 980 nm led to complete disappearance of implanted 4T1 mouse mammary tumours for the majority of the animals by 11 days since the irradiation. The combination of the photothermal therapy with the immunoadjuvant cyclophosphamide resulted in increased survival. The in vivo results suggest the SWNT-AV/NIR treatment is a promising approach to treat breast cancer.

Confirmation of K-momentum dark exciton vibronic sidebands using 13C-labeled, highly enriched (6,5) single-walled carbon nanotubes

A detailed knowledge of the manifold of both bright and dark excitons in single-walled carbon nanotubes (SWCNTs) is critical to understanding radiative and nonradiative recombination processes. Exciton-phonon coupling opens up additional absorption and emission channels, some of which may "brighten" the sidebands of optically forbidden (dark) excitonic transitions in optical spectra. In this report, we compare (12)C and (13)C-labeled SWCNTs that are highly enriched in the (6,5) species to identify both absorptive and emissive vibronic transitions. We find two vibronic sidebands near the bright (1)E(11) singlet exciton, one absorptive sideband ~200 meV above, and one emissive sideband ~140 meV below, the bright singlet exciton. Both sidebands demonstrate a ~50 cm(-1) isotope-induced shift, which is commensurate with exciton-phonon coupling involving phonons of A[Formula: see text] symmetry (D band, ω ~ 1330 cm(-1)). Independent analysis of each sideband indicates that both sidebands arise from the same dark exciton level, which lies at an energy approximately 25 meV above the bright singlet exciton. Our observations support the recent prediction of, and mounting experimental evidence for, the dark K-momentum singlet exciton lying ~25 meV (for the (6,5) SWCNT) above the bright Γ-momentum singlet. This study represents the first use of (13)C-labeled SWCNTs highly enriched in a single nanotube species to unequivocally confirm these sidebands as vibronic sidebands of the dark K-momentum singlet exciton.

Antitumor immunologically modified carbon nanotubes for photothermal therapy

An immunologically modified nanotube system was developed using an immunoadjuvant, glycated chitosan (GC), as surfactant of single-walled carbon nanotube (SWNTs). This SWNT-GC system not only retained both optical properties of SWNTs and immunological functions of GC, but also could enter cells due to the carrier properties of SWNTs. Cellular SWNTs induced thermal destruction of tumor cells when irradiated by a near-infrared laser and, at the same time, cellular GC could serve both as damage associated molecular pattern molecules (DAMPs) and pathogen associated molecular pattern molecules (PAMPs) to enhance the tumor immunogenicity and enhance the uptake and presentation of tumor antigens, leading to special antitumor response. Using this system and a 980 nm laser, we treated tumors, both in vitro and in vivo, and investigated the induced thermal and immunological effects. Laser + SWNT-GC afford a remarkable efficacy in suppressing tumor growth in animal cancer models, in many cases resulting in complete tumor regression and long-term survival. Mice successfully treated by Laser + SWNT-GC could establish resistance to tumor rechallenge. This system forms a multifunctional temporal-spatial continuum, which can synergize photothermal and immunological effects. The Laser + SWNT-GC could represent a promising treatment modality to induce systemic antitumor response through a local intervention, while minimizing the adverse side effects.

Vascular targeted single-walled carbon nanotubes for near-infrared light therapy of cancer

A new approach for targeting carbon nanotubes to the tumor vasculature was tested using human endothelial cells and MCF-7 breast cancer cells in vitro. Single-walled carbon nanotubes were functionalized with the F3 peptide using a polyethylene glycol linker to target nucleolin, a protein found on the surface of endothelial cells in the vasculature of solid tumors. Confocal microscopy and Raman analysis confirmed that the conjugate was internalized by actively dividing endothelial cells. Dividing endothelial cells were used to mimic these cells in the tumor vasculature. Incubation with the conjugate for 8 h or more caused significant cell death in both actively dividing endothelial cells and MCF-7 breast cancer cells, an effect that is hypothesized to be due to the massive uptake of the conjugate. This targeted cell killing was further enhanced when coupled with near-infrared laser treatment. For confluent (non-dividing) endothelial cells, no cytotoxic effect was seen for incubation alone or incubation coupled with laser treatment. These results are promising and warrant further studies using this conjugate for cancer treatment in vivo.

Nanostructured carbon-metal oxide hybrids as amphiphilic emulsion catalysts

Nanohybrids composed of "onion-like" carbon, single-walled (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) fused to silica or alumina particles have been compared as stabilizers of water/oil emulsions and interfacial catalysts. The amphiphilic character of these nanohybrids makes them effective in stabilizing emulsions (up to 85 % of total volume) comprising of small droplets (less than 40 μm). Furthermore, these nanohybrids have been used as supports for transition metal particles (palladium and copper) to catalyze reactions at the water/oil interface. Three different reaction systems have been conducted in the emulsions to demonstrate the principle: 1) hydrogenation of phenanthrene; 2) hydrogenation of glutaraldehyde and benzaldehyde; 3) oxidation of tetralin. Comparison of the maximum conversions achieved in emulsions as opposed to the single phase, together with much better control of selectivity in the two-phase system shows the benefits of using these nanohybrid catalysts.