A research team led by Professor Jae-Byum Chang of the Department of Materials Science and Engineering and Professor Young-Gyu Yoon of the School of Electrical Engineering announced on May 23 that it has developed a technology that allows ultra-multiplexed fluorescence imaging, named “PICASSO”. Biomarkers are biomolecules — proteins, DNA, RNA, and metabolites — that can be used to detect changes in the body. Thus, it is a useful tool for precise diagnosis of various diseases such as cancer, stroke, and dementia; the earlier the discovery, the better. Multiplexed imaging is a technique that allows simultaneous imaging of markers in a tissue, and PICASSO was able to overcome limitations previously inherent in the technique.

PICASSO is an acronym for “Process of ultra-multiplexed Imaging of biomolecules viA the unmixing of the Signals of the Specially Overlapping Fluorophores”. And as the name signifies, it can detect more than 15 markers that are spatially overlapping with one another by using an equal number of images and fluorophores. Each target protein would be assigned a fluorophore to enable advanced multiplexed imaging and bandpass filter-based microscopy. The research team developed methods to distinguish the emission spectra of different fluorophores, which could be cycled to detect more proteins. PICASSO provides the cheapest option among other biomarker-detecting techniques while detecting the greatest number of markers in the shortest time.

Previously, ultra-multiplexed fluorescence imaging showed difficulty with highly heterogeneous specimens such as brains, which created high variation among the emission spectra. There are other techniques like mass spectrometry imaging and fluorescent staining that are used for simultaneous imaging, but they have their own limitations. Mass spectrometry imaging can detect multiple protein markers simultaneously in a tissue, but it requires expensive special equipment, destroys tissues in the analysis process, and takes a long time throughout the entire process. And for fluorescent staining, only three protein markers can be observed at a time. PICASSO not only resolves these issues but also is highly accessible to researchers.

Recently, it has been found that protein markers expressed inside cancer tissues are unique for each patient, and it is this unique protein marker that determines the prognosis of cancer and the reactivity of anticancer drugs. Accordingly, the technology to simultaneously detect multiple protein markers in cancer tissues is essential. Since PICASSO technology does not require special reagents or expensive equipment, it is expected to be widely used for accurate diagnosis of cancer, development of anticancer drugs, and discovery of new protein markers.