Improved Catalytic Performance of Au/α-Fe2O3-Like-Worm Catalyst for Low Temperature CO Oxidation

The gold catalysts supported on various morphologies of α-Fe₂O₃ in carbon monoxide (CO) oxidation reaction have been studied for many researchers. However, how to improve the catalytic activity and thermal stability for CO oxidation is still important. In this work, an unusual morphology of α-Fe₂O₃ was prepared by hydrothermal method and gold nanoparticles were supported using a deposition-precipitation method. Au/α-Fe₂O₃ catalyst exhibited great activity for CO oxidation. The crystal structure and microstructure images of α-Fe₂O₃ were carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and the size of gold nanoparticles was determined by transmission electron microscopy (TEM). X-ray photoelectron spectra (XPS) and Fourier transform infrared spectra (FTIR) results confirmed that the state of gold was metallic. The 1.86% Au/α-Fe₂O₃ catalyst calcined at 300 °C had the best catalytic performance for CO oxidation reaction and the mechanism for CO oxidation reaction was also discussed. It is highly likely that the small size of gold nanoparticle, oxygen vacancies and active sites played the decisive roles in CO oxidation reaction.

Worm-Like Biomimetic Nanoerythrocyte Carrying siRNA for Melanoma Gene Therapy

A major challenge in siRNA vectors is developing approaches that ensure that when administered in vivo, the vectors can target their requisite site of action. This study reports a third type of nanoworm, biomimetic nanoerythrocytes for siRNA delivery, except for filomicelle and nanoworm iron-oxide particle, which is the first approach that allows for targeted siRNA delivery by a process involving red blood cell (RBC) membrane cloaking of charge-reversible polyplexes of siRNA and polycation. RBC membrane cloaking protects siRNA from RNase A degradation. Moreover, the RBC membrane-cloaked charge-reversible siRNA vector (RBC-reversible polyplex (RP)) not only stays longer in the blood circulation than that of negatively charged bovine serum albumin (BSA) spheres and positively charged BSA, but is also able to escape from late endosomes/lysosomes, to achieve effective transfection for gene knockdown. The knockdown result in vivo is remarkably consistent with that of intracellular trafficking and transfection in vitro. Due to the outstanding biocompatibility and active targeting (cRGD), the 7 mg kg^-1 dose siSurvivin in RGD-RBC-RP exhibits obviously superior anticancer effects at the animal level after two weeks. Therefore, the biomimetic worm-like nanoerythrocyte charge-reversible gene vector is a new and general method for highly efficient siRNA therapy in vivo.

Shape-controlled paclitaxel nanoparticles with multiple morphologies: rod-shaped, worm-like, spherical, and fingerprint-like

Although many nanocarriers have been developed to encapsulate paclitaxel (PTX), the drug loading and circulation time in vivo always are not ideal because of its rigid “brickdust” molecular structure. People usually concentrate their attention on the spherical nanocarriers, here paclitaxel nanoparticles with different geometries were established through the chemical modification of PTX, nanoprecipitation, and core-matched cargos. Previously we have developed rod-shape paclitaxel nanocrystals using block copolymer, pluronic F127. Unfortunately, the pharmacokinetic (PK) profile of PTX nanocrystals is very poor. However, when PTX was replaced by its prodrug, the geometry of the nanoparticles changed from rod-shaped to worm-like. The worm-like nanoparticles can be further changed to spherical nanoparticles using the nanoprecipitation method, and changed to fingerprint-like nanoparticles upon the addition of the core-matched PTX. The nanoparticles with nonspherical morphologies, including worm-like nanoparticles and fingerprint-like nanoparticles, offer significant advantages in regards to key PK parameters in vivo. More important, in this report the application of the core-matching technology in creating a core-matched environment capable of controlling the in vivo PK of paclitaxel was demonstrated, and it revealed a novel technique platform to construct nanoparticles and improve the poor PK profiles of the drugs.

IR spectroscopic analyses of amyloid fibril formation of β2-microglobulin using a simplified procedure for its in vitro generation at neutral pH

β2-microglobulin (β2m) is known to be the major component of fibrillar deposits in the joints of patients suffering from dialysis-related amyloidosis. We have developed a simplified procedure to convert monomeric recombinant β2m into amyloid fibrils at physiological pH by a combination of stirring and heating, enabling us to follow conformational changes associated with the assembly by infrared spectroscopy and electron microscopy. Our studies reveal that fibrillogenesis begins with the formation of relatively large aggregates, with secondary structure not significantly altered by the stirring-induced association. In contrast, the conversion of the amorphous aggregates into amyloid fibrils is associated with a profound re-organization at the level of the secondary and tertiary structures, leading to non-native like parallel arrangements of the β-strands in the fully formed amyloid structure of β2m. This study highlights the power of an approach to investigate the formation of β2m fibrils by a combination of biophysical techniques including IR spectroscopy.