Methanolysis of sodium borohydride (NaBH 4 ) is a way of recovering the hydrogen stored in the hydride. Though the reaction is spontaneous, it can be accelerated by virtue of Co-TiO 2 or Ru-TiO 2 catalysts. Under our experimental conditions, Co-TiO 2 shows high catalytic performances, higher than those of Ru-TiO 2 . Hydrogen generation rates of 144 to 644 L(H 2 ) min À1 g À1 (Co) were measured as the Co content was decreased. The kinetic parameters of the catalyzed reaction were determined. The Co-TiO 2 -catalyzed methanolysis follows a power law, i.e. r 20 ¼ k$[NaBH 4 ] 1.3 $[CH 3 OH] 0.9 with k ¼ 1.8 Â 10 À2 s À1 . The Langmuir-Hinshelwood bimolecular mechanism accounts for the kinetics. The apparent activation energy was found to be 20.4 kJ mol À1 whereas that of the catalyzed hydrolysis was 49.4 kJ mol À1 . Indeed, the catalyzed methanolysis was compared to the catalyzed hydrolysis as well as the catalyzed ethanolysis. For instance, it was remarked that water in methanol has a detrimental effect on the H 2 release kinetics. In parallel, the gravimetric hydrogen density of the system NaBH 4 -CH 3 OH has been optimized. Under our experimental conditions, it was found that the highest capacity that can be achieved is 3.4 wt%.
The success of nanoparticle-based therapies will depend in part on accurate delivery to target receptors and organs. There is, therefore, considerable potential in nanoparticles which achieve delivery of the right drug(s) using the right route of administration to the right location at the right time, monitoring the process by non-invasive molecular imaging. A challenge is harnessing immunotherapy via activation of Toll-like receptors (TLRs) for the development of vaccines against major infectious diseases and cancer. In immunotherapy, delivery of the vaccine components to lymph nodes (LNs) is essential for effective stimulation of the immune response. Although some promising advances have been made, delivering therapeutics to LNs remains challenging. It is here shown that iron-oxide nanoparticles can be engineered to combine in a single and small (<50 nm) nanocarrier complementary multimodal imaging features with the immunostimulatory activity of polyinosinic-polycytidylic acid (poly (I:C)). Whilst the fluorescence properties of the nanocarrier show effective delivery to endosomes and TLR3 in antigen presenting cells, MRI/SPECT imaging reveals effective delivery to LNs. Importantly, in vitro and in vivo studies show that, using this nanocarrier, the immunostimulatory activity of poly (I:C) is greatly enhanced. These nanocarriers have considerable potential for cancer diagnosis and the development of new targeted and programmable immunotherapies.
A new nanoparticle system with multimodal imaging features functionalized with immunostimulatory dsRNA (poly (I:C)) is reported by J. C. Mareque‐Rivas and co‐workers. As described on page 5054, the nanocarrier is capable of reaching endosomal TLR3 in cells of the immune system, significantly enhancing the capacity of poly (I:C) to trigger the induction of cytokines essential for activating the immune system. MRI and SPECT are combined to elucidate its delivery to lymph nodes – the command centres of the immune system.
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