No Fluorescent Labels: Australian Team Tracks Live-Cell Nanostructures in 3D for Days
No Fluorescent Labels: Australian Team Tracks Live-Cell Nanostructures in 3D for Days
Observing live cells under a microscope usually requires staining first. Fluorescent labels make structures "light up," but the dyes are phototoxic and can disturb or even damage cells, making long, continuous observation difficult. How to see the nanostructures of live cells clearly "without disturbing them" has long been a challenge in microscopy.
Recently, the team of Dr. Steve Lee at the John Curtin School of Medical Research, Australian National University (ANU), published research in Nature Communications proposing a label-free nanoscopy technique, RO-iSCAT, achieving continuous three-dimensional, real-time observation of live cells for several days.
1. How RO-iSCAT Works
RO-iSCAT stands for "rotational integration of oblique interferometric scattering." Its cleverness lies in two things: first, it rotates the illumination around the sample and delivers it at different angles; second, it integrates images from different heights. Off-axis illumination causes out-of-focus signals to shift laterally by a larger amount, so stray out-of-focus signals can be "pushed away," yielding speckle-free widefield interferometric scattering images with about a 10-fold improvement in signal-to-noise ratio and without any need for additional background subtraction.
2. What They Saw
Using this method, the team clearly recorded, for the first time, the slender thread-like nanostructures extended by cells. In imaging over several days, these structures were not static but kept extending, contracting and reconnecting, forming a complex network that transmits biochemical information to neighboring cells. Junyu Liu, the paper's first author and a doctoral student, recalls that when he first showed the images to his supervisor, the supervisor immediately realized "this is something new."
3. What It Can Be Used For
The team then applied the method to a variety of cells. In pancreatic cancer cells and human vascular cells, they observed that these cells form multiple "tight" connecting bridges with surrounding connective-tissue cells; such structures are thought to help tumors shape their local environment, grow and resist treatment. The research also suggests that some viruses may spread between cells precisely through these cell bridges.
Dr. Lee says the achievement came from curiosity-driven basic research, and the team members' backgrounds span mathematics, optics, biochemistry, physics and cell biology. For the microscopy industry, RO-iSCAT offers a new option that "sees for a long time without harming the sample," enabling researchers to re-examine intercellular communication, disease onset and drug-resistance mechanisms at the nanoscale.