Impressions from Yonsei

Yonsei University (연세대학교), established in 1885, is one of the oldest and most renowned private universities in South Korea. It is consistently ranked within the global top 150 of the QS World University Rankings®and within the top 20 of the QS University Rankings: Asia. The Campus of Yonsei University is composed of the Main Campus in Seoul (Sinchon), Global Campus in Incheon (Songdo) and the Wonju Campus in Gangwon Province. In total, 26.613 undergraduate and 11.956 graduate students are enrolled at Yonsei University.

A report by Sascha Balakin

I have been at the Global Campus in Incheon from September 2017 until February 2018. There I worked in the group “Nano Convergence Systems” headed by Prof. Jong-Souk Yeo (http://ncs.yonsei.ac.kr/) in close cooperation with the Severance Hospital, Seoul. During my research stay we concentrated our work on two topics – (1) Immobilization and (2) bioconjugation of detonation nanodiamonds (NDs). In order to immobilize NDs on macroscopic surfaces, we utilized polyelectrolytes to control the electrostatic surface charge of various materials, including titanium, silicon, and silica glass. As shown in Figure 1, we demonstrated a homogenously coating of NDs with different densities using a manual coating procedure. The cytotoxicity of such multilayers was investigated at the Severance Hospital using MTT-assays, which provide the evidence to use ND-polyelectrolyte multilayers in biomedical applications.

 

 
Figure 1. Coating technique of NDs using polyelectrolyte multilayer films.

 

Based on the relevant literature of bioconjugation techniques, it is well known that the efficiency of an EDC/NHS mediated covalent coupling of nanomaterials is related to the amount of available carboxylic acid groups. At Yonsei University we determined the ratio of carboxylic acids to phenol and lactone surface groups of NDs, after applying wet and dry oxidation. The carboxylation of NDs consequently determines the resulting biomolecule loading capacity and describes a crucial point of the bioconjugation. In cooperation with Dr. Andreas Schubert (Fraunhofer IZI, Leipzig), we were able to bind antimicrobial peptides to the carboxylated NDs and correlate the obtain results. Figure 2 shows the bioconjugation of NDs using covalent coupling of antimicrobial peptides.

 
Figure 2. Antimicrobial peptide grating to NDs using thioester bridging.

 

In conclusion: It was a valuable adventure with tons of new impressions and challenges. Apart from the research topics, I am happy that I found new friends in Korea who always supported and advised me. I am looking forward to extend the collaboration on a professional and private level in the following years. Thanks to Prof. Jong-Souk Yeo and his generous team, I had a wonderful and valuable time in South Korea. I also would like to acknowledge Prof. Gianaurelio Cuniberti and the iEGSEMP project team as well as Dr. Jörg Opitz and Dr. Lotta Römhildt (Fraunhofer IKTS, Dresden). They provided me constant feedback and support regarding my research and traveling expenses.

 

Brief private impression of my stay in South Korea:

 

– Korean Japanese dinner –

– Chimaek (치맥) dinner –

– View from Lotte World Tower in Seoul –

– Hwaseong (화성) fortress in Suwon –

– Trade market in Busan –