New 3-D video shows how virus-sized particle enters cell

A team of researchers has achieved an unprecedented look at a virus-like particle as it tries to break into and infect a cell.

The technique researchers at Princeton University developed could help scientists learn more about how to deliver drugs via nanoparticles- which are about the same size as viruses- as well as how to prevent viral infection from occurring.

The video reveals a virus-like particle zipping around in a rapid, erratic manner until it encounters a cell, bounces and skids along the surface, and either lifts offagain or, in much less time than it takes to blink an eye, slips into the cell's interior.

"The challenge in imaging these events is that viruses and nanoparticles are small and fast, while cells are relatively large and immobile. That has made it very hard to capture these interactions," Kevin Welsher, a postdoctoral researcher in Princeton's Department of Chemistry and first author on the study, said.

The researchers solved the problem by using two cameras, one that locked onto the virus-like nanoparticle and followed it faithfully, and another that filmed the cell and surrounding environment.

Putting the two images together yielded a level of detail about the movement of nano-sized particles that has never before been achieved, Yang said.

Prior to this work, he said, the only way to see small objects at a similar resolution was to use a technique called electron microscopy, which requires killing the cell.

In addition to simply viewing the particle's antics, the researchers can use the technique to map the contours of the cell surface, which is bumpy with proteins that push up from beneath the surface.

By following the particle's movement along the surface of the cell, the researchers were able to map the protrusions, just as a blind person might use his or her fingers to construct an image of a person's face.

The study was published in Nature Nanotechnology.