Innovation of separation techniques
Study of weak intermolecular interactions on solid-liquid interphase and their applications to separation chemistry
On the one hand, HPLC has been widely used in various fields, particularly in pharmaceutical analysis, and has developed remarkably a core separation technique . On the other hand, there are still substances that are difficult to separate using conventional separation modes. Therefore, various π interactions arising from aromatic ring have attracted attention as a promising driving force for improved separations. However, the weak π interactions make experimental verification challenging, and theoretical explanation based on computational science and spectroscopic methods have been addressed.
We aim to quantitatively understand weak π interactions and to achieve effective separations of solutes that are difficult to be separated by optimizing both the design of stationary phases in a column and composition of a mobile phase in HPLC. To enhance π interaction in liquid phase separation, we focused on fullerenes, the smallest nano carbon materials and fabricated HPLC columns immobilized C60- and C70- fullerenes. As a result, we observed unique molecular recognition based on π-π interaction, spherical recognition, and CH (or OH) – π interaction in non-polarized solvents. Moreover, we achieved the separation of H/D isotope mixtures and the precise separation of unlabeled sugar chains, experimentally demonstrating halogen-π interactions between the C70 column and halogen atoms. These findings are not only the first experiment revealing π interactions but also the extremely important insight into a basic knowledge of intermolecular interactions.
Development of molecular recognition materials for selective separation, purification, and detection
To realize highly accurate quantitative analysis of target compounds in environmental and biological analytes from large amounts of contaminants, selective separation and enrichment techniques are demanded.
We focus on the specific molecular recognition capabilities of organic polymers. We have thus developed various methods for synthesizing separation media for targets ranging from low molecules to macromolecules by arranging molecularly imprinting technique. We have also established the highly selective screening method for toxic chemical substances using separation media mimicking receptor-like molecular recognition.
In addition, in recent studies, we have reported the selective adsorption of (glyco)proteins and their simple detection using hydrogels. This detection technology has contributed to application of simple onsite analysis.
Development of liquid phase separation for rapid and highly selective separation of biological substances
Miniaturization of substrates and further functionalization to improve separation performance are essential to develop separation media for liquid phase separation such as HPLC. Meanwhile, shorter operation times and lower costs are critical in pharmaceutical, environmental, and synthetic chemistry fields due to the growing number of analytes being analyzed.
To address these challenges, we focus on inexpensive, industrially produced materials, then developing porous macromolecules (spongy monolith) as novel separation media that enable high performance, high selectivity, low cost, and environmental sustainability. To further improve performance particularly in chromatographic method, we have addressed several challenges such as the complexity of purification processes for biopharmaceutical as well as the low recovery rate, poor reproducibility, and high analysis costs. As a result, we have achieved a simple and rapid separation method that overcomes these issues.
Currently, we are working on the development of multifunctional detection devices for specific antibodies of autoimmune diseases and selective separation and concentration of nanoparticles based on their chemical surface properties, such as vesicles (exosomes) and virus (SARS-CoV-2) . What is more, we are launching a startup from Kyoto University and Kyoto Prefectural University to commercialize our technology as a next-generation, high-performance purification system of biopharmaceuticals.
