Anodic cell-protein deposition on inverse inkjet printed micro structured gold surfaces

The transformation of fibrinogen into fibrin is biologically activated in a complex multi-step process known as the coagulation cascade. This transformation can also be triggered by anodic surfaces. It has been suggested that this mechanism is a result of an electron transfer from the anode to the fibrinogen molecule resulting in the formation of fibrin. In this study we used this pathway to simultaneously deposit vital cells (fibroblasts and keratinocytes) and fibrin on micro structured gold electrodes. The electrodes were produced using a novel inverse inkjet-printing technology in combination with subsequent gold-sputtering, resulting in minimal structure-sizes of 35 microm (+/-6 microm). Cell deposition and fibrin-coagulation were found to occur on the anode only, following exactly the micro structured electrode surface. Successful deposition was limited by the minimal voltage (0.8 V) needed for the formation of fibrin and the maximum voltage (1.85 V) resulting in the deterioration of the Au-electrodes due to electrolysis and possible damaging of the deposited cells due to the formation of molecular chlorine. Furthermore, it was demonstrated that this technique is suitable to co-cultivate different cell types in a layered fashion. Subsequent to the electrically mediated anodic cell-protein deposition, cells were cultivated for up to 4 days and then characterized by vital fluorescence staining, methyl violet-staining and scanning electron microscopy. Cell-vitality was found to be dependent on the experimental setup; in this study non-vital cells were only observed, when sequentially depositing two different cell types. Finally, the coagulation mechanism was studied using HPLC, SDS-gel-chromatography and ATR/FTIR.