Application of Ionic Liquids in the Downstream Processing of Lignocellulosic Biomass.

Chemical transformations of lignocellulosic substrates to valuable platform chemicals are challenging as lignin and cellulose have high thermal and chemical stabilities. However, certain ionic liquids are able to dissolve and deconstruct biomass and, in the presence of catalysts, convert the dissolved/deconstructed species into useful platform chemicals. Herein, we provide a concise overview of the role of ionic liquids in biomass processing. Using 5-hydroxymethylfurfural as an example of a renewable building block, available from cellulose, we show how ionic liquids can facilitate its production.

Gold nanoparticles grown on ionic liquid-functionalized single-walled carbon nanotubes: new materials for photothermal therapy.

Gold nanoparticles were grown on single-walled carbon nanotubes (SWNTs) coated with a thiol-functionalized ionic liquid resulting in the formation of core-shell structures referred to as SWNT-IL-Au nanohybrid materials. The nanohybrid materials were characterized by high-resolution transmission electron microscopy (HR-TEM), Raman-, and UV/Vis absorption spectroscopy. The nanohybrid materials were found to enter lysosomes in HeLa cells and show negligible cytotoxicity. Interestingly, they have an enhanced NIR absorption that is effectively transferred into heat to cause localized hyperthermia, resulting in rapid cell death; overall, the material appears to have excellent properties for photothermal therapeutic applications.

Multi-layered tumor-targeting photothermal-doxorubicin releasing nanotubes eradicate tumors in vivo with negligible systemic toxicity.

Multi-layered single-walled carbon nanotubes, termed SWNT@BSA@Au-S-PEG-FA@DOX, which integrate photothermal therapy with small molecule drug delivery, were prepared using a facile layer-by-layer assembly process. Oxidized and cut single-walled carbon nanotubes (SWNTs) were coated with bovine serum albumin (BSA) to provide abundant active sites for the nucleation of Au seeds, which are subsequently converted into gold nanoparticles (Au NPs) by in situ reduction. The resulting SWNT@BSA@Au material exhibits ideal photothermal properties. Further modification of the nanomaterial with folic acid terminated-polyglycol (FA-PEG-SH) and subsequent loading with doxorubicin (DOX) afford the SWNT@BSA@Au-S-PEG-FA@DOX. The FA terminated PEG endows the material with high water-dispersibility, biocompatibility and cancer cell selectivity. A high drug loading ratio for DOX of up to 590% was achieved, with the drug release being pH and temperature dependent, adding to the selectivity of the system. High efficacy of the SWNT@BSA@Au-S-PEG-FA@DOX material, when combined with photothermal therapy (irradiation of the tumor with an 808 nm laser, 1 W cm-2 for 5 min, 24 h after systemic injection of the nanomedicine), was demonstrated in vivo, resulting in complete tumor eradication. Remarkably, the side effects are negligible with only minor damage to normal tissues including the liver and kidneys being observed.

Direct Conversion of Mono- and Polysaccharides into 5-Hydroxymethylfurfural Using Ionic-Liquid Mixtures.

Platform chemicals are usually derived from petrochemical feedstocks. A sustainable alternative commences with lignocellulosic biomass, a renewable feedstock, but one that is highly challenging to process. Ionic liquids (ILs) are able to solubilize biomass and, in the presence of catalysts, convert the biomass into useful platform chemicals. Herein, we demonstrate that mixtures of ILs are powerful systems for the selective catalytic transformation of cellulose into 5-hydroxymethylfurfural (HMF). Combining ILs with continuous HMF extraction into methyl-isobutyl ketone or 1,2-dimethoxyethane, which form a biphase with the IL mixture, allows the online separation of HMF in high yield. This one-step process is operated under relatively mild conditions and represents a significant step forward towards sustainable HMF production.

Targeted delivery and controlled release of doxorubicin to cancer cells using modified single wall carbon nanotubes.

A targeted drug delivery system that is triggered by changes in pH based on single wall carbon nanotubes (SWCNTs), derivatized with carboxylate groups and coated with a polysaccharide material, can be loaded with the anticancer drug doxorubicin (DOX). The drug binds at physiological pH (pH 7.4) and is only released at a lower pH, for example, lysosomal pH and the pH characteristic of certain tumor environments. By manipulating the surface potentials of the modified nanotubes through modification of the polysaccharide coating, both the loading efficiency and release rate of the associated DOX can be controlled. Folic acid (FA), a targeting agent for many tumors, can be additionally tethered to the SWCNTs to selectively deliver DOX into the lysosomes of HeLa cells with much higher efficiency than free DOX. The DOX released from the modified nanotubes has been shown to damage nuclear DNA and inhibit the cell proliferation.

A nearly planar water sheet sandwiched between strontium-imidazolium carboxylate coordination polymers.

The crystal structure of a strontium-imidazolium polymeric material obtained from the reaction of zwitterionic 1,3-bis(carboxymethyl)imidazolium with SrCO(3) (2:1) in water is reported. The compound crystallized in the orthorhombic space group Pcc2 with a = 14.545(3) A, b = 8.514(5) A, c = 8.5619(14) A, V = 1060.2(6) A(3), and Z = 2. The macromolecular structure is constructed from 8-coordinate strontium, which binds to six different imidazolium carboxylate molecules. The two-dimensional polymer is separated by water sheets in which the water molecules form near-planar hexagons.