Whole-cell sensing systems in chemical and biological surveillance, in nano and microsensors for chemical and biological surveillance

Global security threats have become a major concern and represent a challenge to current technologies. The routine monitoring of the food and the environment for chemical and biological threat agents is not an easy task since available techniques usually require pure or clean samples and sophisticated equipment, thus being not suitable for field use. Alternatively, unconventional analytical tools that consent a rapid and low cost monitoring of complex matrices (e.g., water, food, soil) are provided by whole-cell biosensors. One property common to all chemical or biological threat agents is that they damage mammalian cells, thus several threat detection and classification methods based on the effects of compounds on cells, genetically engineered or not, have been developed. Whole-cell sensing systems measure a cell's response to an analyte, or a class of analytes. The response, which may include activation or inhibition of signal transduction pathways, is then converted into the expression of a reporter protein (eg., luciferase, green fluorescent protein, aequorin), giving a specific signal proportional to the amount of analyte present in the sample. Whole-cell biosensors found application in a variety of areas such as detection of biowarfare agents, waterborne and foodborne pathogens, and emerging infectious diseases. Considerable research has been done in the field of whole-cell sensing systems with the final goal of developing low-cost portable systems able to detect the presence of any toxic agent rapidly and with high sensitivity. To increase the robustness and portability of cell-based biosensors, several formats were employed combining the great potential of bio-chemiluminescence detection (high sensitivity, simple instrumentation) with the recent advancements in cell immobilization techniques to develop ready-to-use analytical devices. An up-to-date overview on the design, fabrication and analytical applications of whole-cell biosensors is provided in this chapter.