Chirlmin Joo

Chirlmin Joo studied physics at Seoul National University in Korea. He obtained his PhD in physics under the supervision of Taekjip Ha at the University of Illinois at Urbana-Champaign, USA. He studied a DNA repair process using single-molecule fluorescence techniques. During his PhD study, he advanced single-molecule techniques by innovating new tools including single-molecule multi-color FRET. As a post-doctoral fellow in Narry Kim’s lab at Seoul National University, Korea, he discovered novel proteins in microRNA biogenesis. 

In 2011, he started his faculty position in Department of Bionanoscience at Delft University of Technology in the Netherlands.  Chirlmin Joo has made significant advancements in the field of single-molecule biophysics by applying single-molecule FRET and developing the single-molecule pull-down method to explore the mechanisms of biological systems such as microRNA and CRISPR. In 2015, he reported the first single-molecule study of human Argonaute2 (Ago2), which mediates the interaction between microRNAs and their cellular targets, by monitoring single Ago2-miRNA complexes in real time and identifying biophysical properties of Ago2 that conventional biochemical approaches could not reveal (Chandradoss et al., Cell, 2015). In 2020, he visualized how bacteria update their adaptive immunity (CRISPR) through Cas1-Cas2-mediated prespacer selection and integration (Kim et al., Nature, 2020). In 2024, he published a pioneering high-throughput single-molecule fluorescence method that integrates next-generation DNA sequencing with single-molecule fluorescence (Severins et al., Science, 2024), enabling genome-wide and proteome-wide single-molecule studies. His single-molecule studies have been supported by ERC Starting Grant (microRNA, 2012-2017), NWO Vidi (CRISPR, 2015-2020), and ERC Consolidator Grant (DNA elimination, 2019-2024).

Additionally, understanding the need for a highly sensitive protein analysis tool, Prof. Joo aimed to develop high-resolution single-molecule techniques that could determine protein sequences at the single-molecule level. The first proof-of-concept paper demonstrating the use of fluorescence for this purpose was published in 2018 (van Ginkel et al, PNAS). This research was further expanded with a seminal publication in 2024 (Filius et al, Nature Nanotechnology). Leading a team of scientists in a Dutch national science program (NWO-FOM Vrije Programme, 2017-2023), Prof. Joo's group explored the biophysics of protein translocation and developed a novel technology to determine the sequence of proteins, molecule by molecule. His work in this area has resulted in five patents and numerous high-impact publications, cementing his leadership in the field of single-molecule protein analysis. This research has been supported by HFSP (2019-2023), NWO Vici (2021-2026) and Marie-Curie Doctoral Network (2022-2025).