New study unveils novel technology for plasma separation using magnets

In their study, the research team used diamagnetic repulsion of blood cells to separate blood cells and blood plasma. Once superparamagnetic iron oxide nanoparticles (SPIONs) are supplemented to whole blood, the SPIONs turn the blood plasma into a paramagnetic condition, and thus, all blood cells are repelled by magnets. The research team collected hemolysis-free plasma without loss of plasma proteins, platelets, and exosomes.

"Many efforts have been made to develop various blood plasma separation methods. However, there always have been limitations, such as dilution of blood, blood cell impurity in plasma, and hemolysis," noted Professor Kang. "Our approach overcame these unmet challenges and we could provide a huge impact on in vitro diagnosis once this platform is translated into a commercial point-of-care device."

The developed blood plasma separation method achieved 100% of the plasma purity and 83.3% of the plasma volume recovery rate without noticeable hemolysis or loss of proteins in blood plasma, which was elusive with the conventional plasma separation devices. Moreover, this method enabled the greater recovery of bacterial DNA from the infected blood than centrifugation and immunoassays in whole blood without prior plasma separation.

"We have overcome the limitations of a filter-based blood plasma separation method that potentially could induce hemolysis or a microfluidic chip-based plasma separation method that has the problems in a plasma recovery rate and purity," says Research Professor Seyong Kwon in the Department of Biomedical Engineering at UNIST, the first co-author of the study.

The research team also developed an ultra-compact, low-cost, high-precision diagnostic chip that can test blood directly without plasma separation. The diagnostic chip detected prostate-specific antigen (PSA) protein, a biomarker for prostate cancer diagnosis.

The developed blood plasma separation method also allowed them to collect platelet rich plasma (PRP). This capability is important because recent studies have revealed that platelets could be used as a biomarker for diagnosis of cancer or diabetes. "Unlike a complex process of the conventional centrifugation method to collect PRP, our method can simply collect PRP by just tuning flow rates," says Jieung Oh, the first co-author of the study.

This study has been jointly carried out by Min Seok Lee in the Department of Biomedical Engineering at UNIST, together with Professor Joonwoo Jeong and Professor Eujin Um from the Department of Physics at UNIST.  This work has been supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, as well as Young Researcher Program by the Ministry of Science and ICT (MSIT).