Resilience of Hybrid Bioelectrodes in an Ionizing Environment: A Space Simulation Study of <i>Limnospira indica</i> Under Gamma Radiation

Cyanobacteria possess unique biological properties and the ability to perform life-sustaining processes, which make them useful for applications in space exploration and colonization. Their potential use in bioelectricity and fuel production has garnered significant interest. This study explores the effects of ionizing radiation on the cyanobacterium <i>Limnospira indica</i> used in bioelectrodes. This is an important consideration as radiation levels in space are significantly higher than those experienced on Earth with its protective atmosphere and magnetosphere. In an approximate space radiation simulation setting, using gamma radiation, living cells of <i>L. indica</i> strain PCC 8005 (formerly known as <i>Arthrospira</i> sp.) were interfaced as bioelectrodes with boron-doped diamond (BDD)-coated and fluorine-doped tin oxide (FTO)-coated glass substrates and exposed to ⁶⁰Co gamma rays at an acute dose rate of 136 Gy.h^-1 for up to 14 h; electrogenic abilities (<i>i.e.</i>, respiration current in the dark) were measured by chronoamperometry. <i>Limnospira indica</i>-based bioelectrodes did not exhibit statistically significant changes in current generation even under high doses of 1.9 kGy gamma rays as compared with non-exposed bioelectrodes. Under radiation, bare FTO electrodes performed better than BDD electrodes, but negative gamma-induced effects in bare BDD electrodes were mitigated by cyanobacteria. The stable current generation under high-dose highlights the potential of biophotoelectrochemical and biophotovoltaic cells in radiation-intensive environments and applications in space.