Sedimentation study of bioink containing living cells

3D bioprinting has more and more applications in tissueengineering, in vitro drug testing, and regenerativemedicine. The bioink consisting of the biocompatiblepolymer (as extracellular matrix) and the living cells is thestarting material. Because the typical bioprinting processmay take several hours, the suspended cells in the bioinksediment with time, which significantly affects the bioinkstability as well as the following bioprinting quality andreliability. The cell sedimentation is determined by theintegral effects of drag force and buoyancy and gravity.The gravitational force is related to the cells, and the dragforce and buoyant force is related to the polymerconcentration. This paper is the first paper to quantify thecell sedimentation process of the bioink within 0.5% and1% (w/v) polymer concentrations respectively. The cellsedimentation phenomenon has been observed using thebioink within 0.5% and 1% (w/v) polymer concentrations.The cell sedimentation velocity has been estimated to be1.18 μm/s with the polymer concentrations to be 0.5%(w/v) and 0.88 μm/s for the bioink with the polymerconcentrations to be 1% (w/v). It is also found that the cellconcentration increases significantly at the bottom of thebioink reservoir, resulting in cell aggregates due to cell-cellinteraction.