Hyoryung Nam

Control of charged droplets using electrohydrodynamic repulsion for circular droplet patterning

We report a novel method to form a circular pattern of monodisperse microdroplets using an electrohydrodynamic repulsion (EDR) mechanism. EDR is a phenomenon of electrostatical bounced microdroplets from an accumulated droplet on a bottom substrate. In addition to a regular EDR system, by placing a ring electrode between the capillary and ground substrate, two separate regions were created. A parameter study of two regions was carried out for droplet formation and falling velocity to control the radius of the generated droplets and the circular patterns independently. Based on energy conservation theory, our experimental results showed that the free-falling region exerted crucial influences on the sizes of the circular patterns.

Cell behaviour on a polyaniline nanoprotrusion structure surface

The extracellular matrix provides mechanical support and affects cell behaviour. Nanoscale structures have been shown to have functions similar to the extracellular matrix. In this study, we fabricated nanoprotrusion structures with polyaniline as cell culture plates using a simple method and determined the effects of these nanoprotrusion structures on cells.

Implantation of encapsulated human septal chondrocytes into immunocompetent mice using alginate microfibers

Cartilage regeneration is a major challenge for researchers because cartilage tissue has limited innate regenerative ability. Encapsulation within an alginate gel has been used widely for 3D scaffolds to generate cartilage-like tissue, but alginate gels have limitations such as poor mechanical properties. In this study, we fabricated alginate microfibers for human septal chondrocyte (HSC) encapsulation and identified the conditions that result in the optimal mechanical properties of the alginate microfibers. In vitro experiments showed that HSCs encapsulated within alginate microfibers maintained >90% viability for 7 days, and the 140μm condition was more effective in terms of HSC proliferation than the 330 and 520μm conditions. In vivo, HSCs differentiated gradually into cartilage tissue over 4 weeks in immunocompetent mice. Importantly, the alginate-encapsulated HSCs were isolated and protected from the host immune response despite xenograft implantation.