Recently, the research team of Professor Young-Tae Chang (CHEM) and Doctor Sun Hyeok Lee of POSTECH Basic Science Research Institute (BSRI) succeeded in formulating fluorescent dye using a single-carbon molecule, formaldehyde, more cheaply and more efficiently than before. Their findings were published in a well-known academic journal in general chemistry, Angewandte Chemie International Edition on Sept. 18. 

Organic fluorescent molecules are substances that emit fluorescence by absorbing light of a specific wavelength and are widely used in the fields of medical diagnosis and bioimaging. However, synthesizing trimethine cyanine (Cy3), a common organic fluorescent molecule, requires a complex, large molecular-weight compound. Thus, it results in many by-products and low atom efficiency.

To solve this problem, the research team focused on formaldehyde (HCHO), which consists of one carbon (C) atom, two hydrogen atoms (H), and one oxygen (O) atom. Formaldehyde is often used as a useful tool to create carbon bonds in synthesis research.

The research team increased the overall efficiency of Cy3 synthesis by utilizing formaldehyde and a one-pot reaction. At the key step in Cy3 synthesis, the research team used formaldehyde rather than complex molecules to add carbon to the molecular chain, maximizing atomic efficiency. The one-pot reaction eliminated the need for additional steps, increasing the synthesis efficiency of asymmetric Cy3 synthesis. 

In addition, the research team focused on applying their findings in vivo. They applied their technology to rat small intestine tissue. They discovered that in the inflammation-induced group, the amount of formaldehyde required for Cy3 synthesis was relatively small due to inflammation. Hence, the fluorescence signal was weaker than that of the normal group. The research team’s method is not limited to in vitro synthesis but can also be used for in vivo synthesis.

Prof. Young-Tae Chang, who led the study, said, “This is the first case of synthesizing Cy3 molecules using formaldehyde,” and added, “This synthesis method not only has cost savings and high atomic efficiency but can also be used in vivo. Hence, it is expected to expand the scope of using organic fluorescent molecules in life science research and diagnostics.” 

Meanwhile, this study was sponsored by the Ministry of Science and ICT and the Glocal University 30 Project.