LAUSR

Hydrogel beads of size 25-µm for immobilizing single photosynthetic cells of size approximately 5 µm were prepared by electrospraying and were characterized electrochemically using a microelectrode. A parametric study was then conducted on the size of the hydrogel beads containing the cells. In order to understand the electrochemical properties of the cells in the hydrogel bead, a microelectrode combined with a counter electrode was fabricated and characterized using microfabrication techniques; the electrochemical properties of the cells and beads were subsequently measured by chronoamperometry using this microelectrode system. The electrochemical properties of single cells immobilized in hydrogel were compared with those of single cells without immobilization by examining the oxygen-reduction currents for both cases. Changes in the oxygen-reduction current caused by photosynthesis in the cells show that an appropriate environment for cell survival is formed inside the hydrogel beads. We thus produced hydrogel beads containing photosynthetic cells that could be potentially useful for photosynthesis-based sensor applications.