Fabrication of cell plastics composed only of unicellular green alga Chlamydomonas reinhardtii as a raw material

Cell plastics in this study were fabricated with only unicellular green alga Chlamydomonas reinhardtii as raw materials. The sizes of cell-major axis as structures were 8.4 ± 1.2 µm, and the aspect ratios of those were 1.2 ± 0.1, showing homogeneous particle size. After optimizing extraction condition of intracellular contents, cell plastics were fabricated with the cells as ingredient components and the intracellular contents as matrix components. Those cell plastics were observed with scanning electron microscopy, displaying the smooth surfaces of the cell plastics at a low magnification level. However, the surface, especially exposed surface, were rough at high magnification level. Tensile strength test revealed that increasing the ratio of intracellular contents in the cell plastics until 21% led enhancing mechanical properties of Young's modulus and tensile strength; however, 25% of intracellular contents displayed decreases of those properties. As the optimal point, the cell plastic (21%), which contained 21% (w/w) of intracellular contents in cell plastics, showed 764 ± 100 MPa and 8.6 ± 5.2 MPa of Young's modulus and tensile strength. The cell plastics showed few plastic region and soon fractured, indicating the possibility that cells and intracellular contents could be electrostatically connected. Additionally, cells were shown as a negative charge and displayed the possibility to contribute electrically cell-gathering with intracellular ionic components. Therefore, cells and intracellular contents containing ionic metabolites could be electrostatically connected for giving the mechanical strength to cell plastics. In this study, we successfully demonstrated fabricating cell plastics with only cells for the first time and also showed the high possibility of conjugating each cell with the intracellular contents. KEY POINTS: • Cell plastics are fabricated with unicellular green algal cell directly. • Unicellular cells required to be conjugated for the fabrication with matrix. • Cells were conjugated with intracellular contents for cell-plastic fabrication.