First ever pictures of single proteins thanks to graphene sheet

(Image credit: Jean-Nicolas Longchamp of the University of Zurich, Switzerland)

You’d think twice about snapping a selfie if the camera flash was bright enough to burn your skin off. Biologists face a similar problem when studying proteins under the microscope, as modern imaging techniques can destroy the molecules. Now graphene – the ultra-thin form of carbon – has come to the rescue, and delivered the very first pictures of a single protein.

Taking pictures of proteins lets us understand their structure and functions. This is important for treating diseases in which proteins go wrong, such as Alzheimer’s. But imaging methods such as X-ray crystallography or cryo-electron microscopy rely on averaging readings from millions of molecules, giving us a blurry view.

Averaging is needed because illuminating molecules with X-rays or high-energy electrons can damage the protein, meaning you may not get the full picture from a single image, and also because it’s tricky to keep a single molecule in one place long enough to take its picture. Now Jean-Nicolas Longchamp of the University of Zurich, Switzerland, and his colleagues have come up with a way to do just that.

They start by spraying a solution of the proteins on to a sheet of graphene, fixing the proteins in place. Then they place this under an electron holographic microscope, which uses interference patterns between electrons to produce an image.

Handy slide

This kind of instrument relies on low-energy electrons that don’t damage the protein. The snag is that they are also less able to penetrate through to the microscope’s detector. This is where graphene comes in handy. “In optical microscopy you have a glass slide. For our electron microscopy we had to find a substrate thin enough to have the electrons passing through,” says Longchamp.

The team tested their method on a range of protein molecules, all just a few nanometres in size, such as the haemoglobin found in red blood cells. The results agreed well with molecular models derived from X-ray crystallography (see image below), suggesting the images are accurate.

(Image credit: Jean-Nicolas Longchamp of the University of Zurich, Switzerland)

Now they plan to snap pictures of other molecules that can’t be imaged with existing techniques, and hope eventually to contribute to new medical treatments. “There are some diseases which are related to the wrong structure of certain proteins,” says Longchamp. “In the future, we could image the difference in the structure of a healthy person and a person who has a disease.”

Reference: arxiv.org/abs/1512.08958

ORIGINAL: New Scientist

8 January 2016

Modular Add-On Brings Polarized Light Microscopy, Malaria Diagnosis to Smartphones

Researchers at Texas A&M University have developed a novel point-of-care device for field-based diagnosis of malaria using a smartphone. The mobile-optical-polarization imaging device (MOPID) attaches to smartphones or tablets and co-opts the camera to detect birefringent hemozoin in histological samples, which is indicative of malarial infection.

Despite advances in diagnostic approaches and treatment, malaria remains one of the leading sources of disease and death in developing nations. The “gold standard” of detection, evaluation of Giemsa-stained blood smears via bright-field microscopy, often requires skilled technicians and laboratory environments that are few and far between in the regions that are most in need. Even when available for field-testing, white light microscopy tends to report many false positive diagnoses as well. Bench-top polarized light microscopy systems, while more definitive, are large, expensive pieces of equipment that are complex to operate, and to maintain as well.

The MOPID, though, appears to offer a highly-mobile and effective alternative, at a cost that should be palatable in underserved countries. The device in its current form has demonstrated imaging properties that compare favorably with a reference Leica DMLM polarized microscope – a resolution of 1.05 μm, system magnification in the range of 50x, and field of view measuring 0.78 mm x 0.79 mm.

Going forward towards release and dissemination of the technology, the group is currently concentrating on preparing units for in vivo field-testing in Rwanda. To do so, they will be taking efforts to lower the physical profile of the device, improve upon human factors engineering and user-interface components, and lower costs. The ultimate vision is for each MOPID diagnostic test to be priced under $1.00 per result, anywhere in the world.

The MOPID device marks another in a series of recent mobile device imaging innovations that are empowering clinicians and researchers without access to traditional acquisition tools (see our recent post on the smartphone-powered D-EYE Digital Ophthalmoscope or read about technology pioneer Jonathan Rothberg’s plan to bring ultrasound to mobile devices).

Study in Scientific Reports: Malaria Diagnosis Using a Mobile Phone Polarized Microscope…

ORIGINAL: Medgadget

ZACH KAUFMAN

SEPTEMBER 4TH, 2015