Biosensors & Bioelectronics 16 (2001) 603 – 608 Engineering mammalian cells for solid-state sensor applications Fredric R. Bloom a,b , Paul Price a,b , Guifang Lao a,b , Jiu Lin Xia a,b , John H. Crowe c , John R. Battista d , Richard F. Helm e , Steve Slaughter e , Malcolm Potts e, * a Life Technologies —A Diision of Initrogen, Medical Center Drie, Rockille, MD 20850, USA b Life Technologies —A Diision of Initrogen, Grand Island, NY 14072, USA c Department of Molecular and Cell Biology, Uniersity of California, Dais, CA 95616, USA d Department of Biological Sciences, Louisiana State Uniersity, Baton Rouge, LA 70803, USA e Virginia Tech Center for Genomics, Virginia Tech, Blacksburg, VA 24061, USA Abstract A fundamental advance in the development and application of cell- and tissue-based biosensors would be the ability to achieve air-dry stabilization of mammalian (especially human) cells with subsequent recovery following rehydration. The would allow for the preparation of sensors with extended shelf lives, only requiring the addition of water for activation. By understanding and subsequently employing the tactics used by desiccation-tolerant extremophiles, it may be possible to design stabilized mammalian cell-based biosensors. The approaches required to realize this goal are discussed and illustrated with several examples. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Desiccation tolerance; Cyanobacteria; Sucrose; Anhydrophile; Hydrophilin www.elsevier.com/locate/bios 1. Introduction Many groups of organisms include representatives that tolerate desiccation (Potts, 1994; Crowe et al., 1997; Billi and Potts, 2000; Oliver et al., 2000). These anhydrobiotic organisms contain gene and gene prod- ucts, and employ physiological strategies, which can confer heightened resistance to desiccation. Such strate- gies provide long-term dormancy under a range of temperatures. These organisms are portable, durable, and can be reactivated through the simple addition of water. It is therefore of interest to investigate whether the principles these organisms employ for their protec- tion can be used to stabilize desiccation-intolerant cells of interest in biosensor fabrication, as robustness, resis- tance to environmental extremes, and portability are clearly important performance criteria for any field- based biosensor. The use of mammalian (human) cells as biosensors can provide responses that are of obvious relevance to human physiology and health, providing information with regards to the effect of a detected substance (Pan- crazio et al., 1999). However, such approaches are currently limited to physiologically-active cells (O’Con- ner et al., 2000), as it is not possible to store stable, dormant cells in a desiccated state. While several efforts are underway to provide desiccation tolerance to mam- malian cells (de Castro and Tunnacliffe, 2000; de Castro et al., 2000b; Eroglu et al., 2000; Guo et al., 2000), proof of desiccation tolerance is still a matter of debate. Finding the structural, physiological and molec- ular mechanism of desiccation tolerance in anhy- drophiles, as well as obtaining an understanding of why mammalian cells are sensitive to water deficit (there are no desiccation tolerant mammals), can provide the fundamental knowledge needed to model and engineer stress tolerance in desiccation sensitive cells and cell products. The synthesis of non-reducing disaccharides (such as trehalose and sucrose) is associated with the ability of anhydrophiles to withstand damage induced through water deficit (Billi et al., 2000; de Castro et al., 2000a). Intracellular trehalose improves the survival of cryopre- served mammalian cells (Eroglu et al., 2000). Whether * Corresponding author. Tel.: +1-540-231-6315; fax: +1-540-231- 9070. E-mail address: geordie@vt.edu (M. Potts). 0956-5663/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0956-5663(01)00175-0