Combination Gd and USPIO MRI Contrast Agent

Dr. Thomas Tourdias and colleagues recently published a study where they investigated if a combination of gadolinium-enhanced MRI (dotarem) followed by the injection of ultrasmall superparamagnetic iron oxide particles (USPIO) (sinerem) had advantages for the assessment of disease activity in multiple sclerosis phenotypes. Very interesting and well done study, in which they found that the combination of gadolinium and USPIO in patients with MS can help identify additional active lesions compared with the current standard, the gadolinium-only approach, even in progressive forms of MS. Lesions that enhance with both agents may exhibit a more aggressive evolution than those that enhance with only one contrast agent.

To look at the details, please click here.

Base sequences set shapes of gold-DNA nanoparticles

DNA molecule control the shape and surface properties of gold-DNA nanoparticles. The findings could be used to create nanoparticles with shapes optimized for sensing, imaging, catalysis, and other applications.
Researchers often use DNA strands to help control morphology in nanoparticle synthesis, but the process has been by trial and error. Chemical biologist Yi Lu
of the University of Illinois, Urbana-Champaign, and coworkers, including Jinghong Li’s group at Tsinghua University, in Beijing, have discovered the method to this madness in preparing gold-DNA nanoparticles. By systematically varying DNA sequences added to solutions used to make gold-DNA nanoparticles, they found that like a genetic code, specific sequences lead
to distinct particle shapes and surface characteristics ( Angew. Chem. Int. Ed., DOI: 10.1002/anie.201203716 ).

Fluorescent Dye Maps Magnetic Field

How to Prepare Hybrid Nanoparticles

To create complex colloidal hybrid nanoparticles—materials with various types of nanoparticles fused together—nanoscience researchers at Pennsylvania State University are taking a cue from their colleagues in organic synthesis. Guided by mechanistic considerations, Raymond E. Schaak, Matthew R. Buck, and James F. Bondi use chemical transformations to tack together simpler pieces of the structure in a predictable manner (Nat. Chem., DOI: 10.1038/nchem.1195). “We are trying to bring the elegance of organic total synthesis to the world of inorganic nanostructures,” Schaak tells C&EN. “We approach the synthesis in a stepwise manner; identify plausible reaction mechanisms; and develop, define, and exploit unique solid-state analogs of concepts that underpin organic synthesis but that are not typically in the nanomaterials chemist’s toolbox, such as chemoselective and regioselective reactions, coupling chemistry, and substituent effects.” For example, the researchers create gold-platinum-iron oxide hybrid nanoparticles from the reduction of gold ions in the presence of Pt-Fe₃O₄. One might expect the resulting gold nanoparticle to fuse to the Pt, the Fe₃O₄, or both regions of the particle, but the Penn State team found that the gold particle fused exclusively to Pt, demonstrating regioselectivity in their synthetic scheme.

A Shotgun For Blood Clots

To dissolve blood clots, biomedical engineer Donald Ingber of Harvard University and colleagues modelled nanoparticles after platelets—cells that circulate in the blood and help stop bleeding by forming clots. The nanoparticles are less than 100 nm wide and made of synthetic polymers stuck together like a ball of wet sand. Like platelets, clumps of the particles flow freely in the blood and gravitate toward blocked vessels by sensing a change in blood flow. Once there, they break apart into individual particles that stick to the clot, releasing a drug called tissue plasminogen activator (tPA) that dissolves it.

Check out the paper and the interesting movie. The particles are not magnetic, but magnetic ones might also be useful.

New Magnetic Particle Catalyst Reduces Oxygen Very Efficiently

A three-component metal alloy mediates electrocatalytic reduction of oxygen to water more effectively than pure platinum and platinum-based bimetallic catalysts.
Oxygen reduction is a critical reaction
in fuel cells and metal-air batteries.
Nanoparticulate platinum supported
on carbon is considered the best catalyst
for that reaction, but kinetic factors
prevent platinum from reaching its
theoretical catalytic effectiveness. In
addition, the metal is costly and relatively
scarce. Recent investigations have focused on platinum-based bimetallic substitutes, but three-component systems have not been explored systematically. Vojislav R. Stamenkovic and coworkers prepared bimetallic and trimetallic thin films of platinum alloyed with iron, cobalt, and nickel and compared their measured electrocatalytic activities with their predicted oxygen binding energies. The group’s tests show that a catalyst consisting of 6-nm-diameter particles of PtCoNi (atomic ratio roughly 3:0.5:0.5) is more active for oxygen reduction than platinum-based bimetallic catalysts and four times as active as pure platinum. Check the paper out here.

Cargo-Towing Fuel-Free Magnetic Nanoswimmers for Targeted Drug Delivery

Catalytic nanowire motors are of interest for biomedical applications including drug delivery and gene therapy due to their ability to pick up, tow, and release particles. For example, Joseph Wang and co-workers, University of California, San Diego, USA, recently demonstrated the guided transport of drug-loaded liposomes, pancreatic cancer cells, and nucleic acids by fuel-driven nanomotors. Despite the advances in cargo-towing by catalytic nanomotors, future ex-vivo and in-vivo biomedical transport applications require the use of biocompatible, fuel-free nanomotors.

Wang and co-workers now report magnetically driven (fuel-free) nanomotors. These two- or three-segment, flexible nanowire motors consist of a rotating magnetic nickel head (≈ 1.5 μm long), along with a flexible silver segment (≈ 4 μm long). They are able to pick-up and transport various drug carriers from a loading zone to a predetermined destination through a predefined route. The transport occurs at a rate order of magnitude faster than that expected from Brownian motion and they are among the fastest fuel-free synthetic nanomotors reported to date. Check details out here.

Magnetophoresis at the Nanoscale: Tracking of Magnetic Targeting Efficiency

Amanda Silva et al. in Claire Wilhelm's lab wrote an interesting article about investigating magnetic targeting efficiency at the nanoscale. For their magnetophoretic mobility measurements, they developed a simple chamber including a microtip as a magnetic attractor for use under bright field or fluorescence microscopy. Different sets of magnetic nanocontainers were produced and their magnetophoretic mobility was investigated. The combination of the analysis of Brownian motion together with the magnetophoretic mobility inferred both the size, the magnetophoretic velocity and the magnetic content of the nanocontainers.

Additionally, nanomagnetophoresis experiments under fluorescence microscopy provided information on the constitutive core/shell integrity of the nanocontainers and the co-internalization of a fluorescent cargo. To see for yourself, check out their paper here.