Design and investigation of a biomimetic interface between nerve cells and technical substrates

With the advent of semiconductor technologies, great advances have been achieved with the combination of electronic device and biological system both in vitro and in vivo. The interface between cells and electronic device should be tailored to give proper cell viability, differentiation, migration, and strong adhesion. Tight adhesion is especially critical for electrical measurement to get good signal quality. Cell membrane is a dynamic barrier which keeps cytoplasm from extracellular material and the host of cell-cell interaction and signaling cascades. Because of the complex structure and composition of natural cell membrane, simplified in vitro models have been developed to study the cell membrane. Supported lipid bilayer (SLB) is one of the popular model system of cell membrane which shows the dynamic molecular processes at the interfaces. SLB has similar structural properties with cell membrane and easy to make in defined composition to study the interaction between cell membrane and proteins, viruses, lipids or other cells. These functionalized SLB can be constructed on functional surface and investigated with surface sensitive detection methods.In this work, biomimetic surface for neuronal culture was investigated, based on lipid bilayer. SLB formation on gold surface as a model electrode were investigated using lipid vesicle assembly. Typically, neutral lipid vesicles do not rupture on gold surface without surface modification. To fabricate SLB on gold surface, previously known methods such as surface modification of gold surface by self-assembled monolayer and vesicle rupture by forming peptide were shown. Lipid vesicles rupture on gold surface spontaneously when more than 30% of positively charged lipids were included. These SLB formation was monitored by quartz crystal microbalance with dissipation device. SLB formation process on these gold surface was studied using the measured mass and viscoelasticity. Functionalization of SLB with synaptic adhesion protein Ephrin A5 was also monitored. The positively charged lipid in SLB also supported viability of primary cortical neurons in a similar degree comparted to protein coated gold surface. When cells were cultured on highly charged SLB, lipid were transferred from SLB to cell membrane.In the brain, neurons are surrounded by glial cells and neurons. To provide biomimetic environment, SLB formation using cell membrane of glial cells were studied. Cell membrane was extracted by chemical vesiculation or direct contract printing and the extract was deposited on glass. But neuronal proliferation was observed only on chemically fixed astrocyte layer.This work shows the possibility of SLB as an interface between neuronal cells and electrodes with proper charge or protein immobilization. In future, neuronal interaction on these functionalized SLB can be measured by electrical and optical methods. And the biomimetic surface treatment can be also applied for implant devices to enhance biocompatibility and adhesion