A. Paul Alivisatos and Alex Zettl of the University of California, Berkeley; Jungwon Park and David A. Weitz of Harvard University; and coworkers produced 3D images of angstrom-sized metal particles in solution at near-atomic resolution (Science 2015, DOI: 10.1126/science.aab1343).
The imaging technique used by the researchers, based on transmission electron microscopy (TEM), may enable scientists to monitor dynamics of individual particles within a colloid in their native state. Structural details gleaned from the imaging method may also lead to new uses for nanoparticles in catalysis, biological imaging, and other areas.
Drawing on a liquid-sampling technique the researchers reported in 2012 , they packaged a few droplets of colloidal platinum nanoparticles in a nanosized graphene bubble. Then they used a microscope equipped with a highly sensitive detector to zoom in on individual particles and record many short-exposure images.
Because the particles were constantly moving, the images were inherently low quality. But by applying a computational technique the researchers developed for this purpose, they were able to produce high-resolution 3-D reconstructions of randomly moving nonidentical particles.
This work is likely to make an impact in biological imaging, catalysis, and other fields, says Joerg R. Jinschek, a TEM specialist for microscope maker FEI who is based in the Netherlands. Jinschek explains that attaching a colloidal particle to a rigid surface—as has been done for imaging purposes in the past—can alter its structure. Because structure and other properties often depend on a particle’s state or environment, researchers want detailed information about nanoparticles in their natural states, Jinschek says. He adds that being able to image freely moving nanoparticles in liquids, as was done in the new study, will help scientists determine relationships between a nanoparticle’s structure and its function.
Jennifer Andrew, Jeffrey Anker and Thompson Mefford organized now already for the 4th time the Frontiers in Biomagnetic Nanoparticles meeting. It took place in Telluride, Montana, U.S.A. from June 23-25, 2015, a wonderful location high in the Rockies (2590 m above sea level!). With 80 participants, this meeting is smaller than its "twin meeting", the International Conference on the Scientific and Clinical Applications of Magnetic Carriers, but it features just as high-standing talks in the (odd) years between the larger conference.
This time, we had an especially interesting time during discussions about how magnetic hyperthermia works, why it seems to work even without (measurable) heat production, and if we actually should rename the effect to thermophoresis. Especially Tim St. Pierre, his student Michael McPhail and Julian Carrey brought up many interesting points, and we are sure that the discussions will go on during next year's Magnetic Carrier meeting.
Another interesting area that quite a few talks were discussing was the use of magnetic nanoparticles as T2 (and T1) contrast agents in Magnetic Resonance Imaging. Especially the group from NIST Boulder gave some interesting talks, while the shape anisotropy was also mentioned as very important. Jin Xie very nicely reviewed the area and their recent developments and showed how Fe5C2 nanoparticles might replace some of the Gd-based agents in the future.
The next Frontiers of Biomagnetic Particles meeting will take place in 2017 again. Make sure you write it into your calendar!
The Magnetic Fluids & Applications meetings are organized in Timisoara since 1980 by the Politehnica University of Timisoara and the Timisoara Branch of the Romanian Academy. The workshop Multifunctional nanoparticles, magnetically controllable fluids,