Scientists have developed a groundbreaking imaging technique that merges the strengths of two powerful microscopy methods, enabling researchers to simultaneously visualize the intricate architecture of cells and the precise locations of proteins — all in vivid color and at nanometer resolution. This innovation, known as multicolor electron microscopy, is poised to transform how biologists study living systems at the molecular level.
The breakthrough was presented at the 70th Biophysical Society Annual Meeting in San Francisco, held from February 21–25, 2026, drawing widespread attention from the global scientific community.
The Longstanding Challenge in Biological Imaging
For decades, scientists working in bioimaging have faced a frustrating trade-off: they could either see fine structural details within a cell or track specific molecules — but rarely both at the same time.
Traditional fluorescence microscopy works by attaching glowing tags to proteins of interest, then illuminating the sample with visible light to reveal those tags. While effective for locating specific molecules, this approach comes with significant limitations.
“The resolution is limited to about 250 to 300 nanometers, so you can’t see individual proteins clearly,” explained Roy, the lead researcher behind the technique. “But the bigger issue is that you don’t see the structure of the cell. You see whatever is labeled, but you don’t see everything else around it.”
Electron microscopy, by contrast, can reveal cellular structures in extraordinary detail — down to just a few nanometers — but has traditionally been unable to identify or color-code specific molecules. Scientists previously attempted to combine both methods by capturing separate images and overlaying them. However, precisely aligning images, especially in complex samples like brain tissue, proved extremely difficult and error-prone.
How the New Technique Works
The Harvard team’s solution is both elegant and efficient. Rather than conducting two separate imaging sessions, they use a single electron beam to accomplish both tasks simultaneously — capturing structural detail and molecular identity in one pass.
“We’re not sending in light — we’re sending an electron beam,” Roy said. “We have probes that you can attach to a protein that emit visible light when excited by electrons. This process is called cathodoluminescence. So from the same electron beam, you get two sets of information: the colored signal from the probes, and also the detailed structural image from the electrons.”
This dual-output approach eliminates the alignment problem entirely, since both sets of data are acquired from the same imaging session. The result is a single, unified image that captures molecular specificity and cellular structure together — something that was previously impossible.
A Surprising Discovery: Standard Dyes Work Too
One of the most unexpected breakthroughs came when the research team placed common fluorescent dyes into the electron microscope.
“The most surprising thing we observed was that standard dyes used in fluorescence microscopy also emit visible light when you excite them with electrons,” Roy said. “That had never been seen before.”
This discovery is significant because it means researchers can use existing fluorescent dyes that are already widely available, well-characterized, and compatible with established protein-labeling methods — without needing to develop any new tools. The team had previously developed lanthanide nanoparticles as specialized probes, but the finding that conventional dyes also work dramatically lowers the barrier to adoption across laboratories worldwide.
Demonstrated Success in Real Biological Samples
The multicolor electron microscopy technique has already been validated in mammalian cells and complex biological tissues, including fungus-infected flies. These demonstrations confirm that the method is not limited to simple lab preparations — it holds real-world applicability for studying disease, cellular signaling, and the spatial organization of molecular clusters within living tissue.
The approach opens exciting possibilities for studying how proteins interact, how molecular clusters organize within cells, and where critical biological processes unfold within the cell’s architecture — all with unprecedented precision.
The Road Ahead: Moving Into 3D
Currently, the technique produces flat, two-dimensional images. The next major frontier for the research team is extending multicolor electron microscopy into three dimensions.
“We want to extend this multicolor electron microscopy approach to 3D,” Roy said. “To get there, we aim to implement this technique in ultrathin sections of cell-embedded matrices and/or in cryo-electron microscopy — that’s the next step.”
Cryo-electron microscopy involves flash-freezing biological samples to preserve cells in their natural state, then imaging them from multiple angles to construct detailed 3D reconstructions. Combining this approach with multicolor capabilities would represent a monumental leap forward in biological imaging — offering scientists a complete, three-dimensional map of cellular structures and molecular locations simultaneously.
As this technology matures, it is expected to accelerate discoveries in fields ranging from neuroscience and cancer biology to infectious disease research and drug development.
