Ancient Egyptian pigment inspires new bright brain imaging tool

For medical imaging, innovative contrast agents are in high demand. Materials scientist Robert Nissler has therefore developed an ultra-bright near-infrared nano-pigment designed to provide high-resolution images of intricate brain structures. In ancient Egypt, the precursor to the copper-based Zurich Blue was already prized for its brilliant blue color.

Imaging techniques are used to detect diseases and to monitor medical treatments. To do this, innovative contrast agents must keep pace with advances in radiological capabilities. A team led by Robert Nissler and Inge Herrmann from the Nanomaterials in Health laboratory at Empa in St. Gallen, ETH Zurich, Balgrist University Hospital and the University of Zurich has therefore developed a nano-pigment that enables high-resolution images of brain structures.

Vibrant blue color

The team found a promising candidate in a historical copper-based material known as Egyptian Blue. The pigment is one of the first artificially produced dyes in human history and was used over 4,500 years ago, for example in wall paintings, on ancient ceramics, and on Egyptian statues.

In addition to its bright blue color, which is visible to the naked eye, Egyptian Blue reveals its secret to special cameras as soon as it is illuminated with near-infrared light in the dark: It fluoresces and emits light.

Scalable and gentle

The fluorescence property in long-wavelength light was of great interest to the researchers, although the challenge lay in processing the raw material so gently that two-dimensional nanostructures are created which retain their fascinating luminosity during the process. Nissler employed so-called flame synthesis for this purpose, which completely reverses the historical manufacturing process: Instead of grinding copper ore and processing it with heat until a fine pigment is produced, Nissler started with nanoparticles that first form metal oxide particles during flame synthesis; in a second step using laser irradiation, the particles assemble into two-dimensional ultra-bright nanolayers.

The process is not only gentle and controllable, it is also scalable to an industrial scale."

Robert Nissler, Nanomaterials in Health laboratory, Empa

Potential for diagnostics and therapy

Team leader Inge Herrmann is pleased: "The new hybrid material is suitable for real-time super-high-resolution imaging." For example, one could track the path of individual immune cells that have previously taken up the nano-pigment in tissues, the engineer explains. What has so far looked promising in laboratory experiments conducted in collaboration with imaging experts led by Daniel Razansky from ETH Zurich and the University of Zurich is set to be advanced toward clinical application in the next step. In addition to diagnostic possibilities, the researchers also see the potential here to couple therapeutic agents to the nano-pigment in order to develop novel therapies with integrated imaging.