Bright-field image of a magnetotactic bacterium (top) and scanning electron microscope image of the same bacterium (bottom). (Photo courtesy of DARPA)
In science, many of the most interesting events occur at a scale far smaller than the unaided human eye can see.
Medical researchers might realize a range of breakthroughs if they could look deep inside living biological cells, but existing methods for imaging either lack the desired sensitivity and resolution or require conditions that lead to cell death, such as cryogenic temperatures.
Recently, however, a team of Harvard University-led researchers working on DARPA’s Quantum-Assisted Sensing and Readout (QuASAR) program demonstrated imaging of magnetic structures inside of living cells.
Using equipment operated at room temperature and pressure, the team was able to display detail down to 400 nanometers, which is roughly the size of two measles viruses.
For a sense of scale, click here.
The QuASAR program shrinks equipment and removes temperature constraints for high-resolution sensing and imaging at nano-scale .
The Harvard QuASAR team’s technique is described in a Nature paper titled “Optical magnetic imaging of living cells.”
Essentially, the researchers used imperfections in diamond known as nitrogen-vacancy (NV) color centers to function as high-precision probes of the magnetic fields produced by living magnetotactic bacteria — organisms that contain magnetic nanoparticles.
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