Cell-Based Detection of Bacillus Cereus Anthrax Simulant Using Cell Impedance Sensing

We demonstrate a new approach to electrically sense pathogens using cells as the receptor-sensing element. Electrical cell-substrate Impedance Sensing (ECIS) was used to monitor the confluent growth of human dermal fibroblasts and their exposure to an anthrax simulant, namely Bacillus cereus. ECIS was conducted at frequencies between 4–64 kHz and it was found to be an excellent measure of cell growth, cell micro-motion, and overall intracellular and intercellular morphological responses to various agents. For instance, when cells were exposed to digestive enzyme trypsin, we observed an instantaneous and unambiguous change in the capacitance, of approximately 67% at 32 kHz. When cells were exposed to anthrax simulant Bacillus cereus spores, we observed no response during spore germination and a very small response when the spores thrived in the fibroblast growth media. The ECIS response was consistent with a live-dead assay whereby it was found that no cells had died and no significant morphological changes were observed. While Bacillus cereus is in the same genetic family as Bacillus anthracis, its pathological lethality on the cellular level for fibroblasts was negligible in our experimental conditions.