How to Make Better Sensors Using Living Cells

February 19, 2014

Christopher Tison, PhD, Research Scientist
Blaine Butler, Research Scientist
Biomedical Technologies Group

Living Cells as Chemical and Biological Sensors

The ability to monitor chemical or biological contamination of everything from the water we drink to the air we breathe is a critical concern for both civilian and military populations. Though there are dozens of options for rapid analysis of many toxins (toxic biological specimens) and toxicants (toxic chemicals), there is no single sensor that can accurately and sensitively respond to a true broad-spectrum of threats without previous knowledge of what you’re looking for. So, instead of relying on traditional sensors, Luna takes advantage of the unique properties of living cells to report on toxic exposure. These “living” sensors can also find application in the pharmaceutical industry, where monitoring toxicity and cell response to new drugs is critical.

Cells are the building blocks of tissue and are highly responsive to changes in their environment. They are therefore highly advantageous for use in “biologically inspired” sensors. However, they are traditionally very unstable at ambient conditions and therefore require significant and labor-intensive maintenance, making traditional cell-based techniques unsuitable for most applications. At Luna, we are remedying this problem by developing technologies to stabilize whole cells, and in the process are providing a valuable new tool for numerous potential customers.

Stabilizing Cells under Ambient Conditions

In order to enable cell-based sensing in a variety of conditions, we have been developing unique techniques capable of preserving (or, stabilizing) bacterial, fish, and even mammalian cells at ambient conditions for exceptionally long periods. Our technology is broadly applicable across diverse cell populations, easy to apply, and has been shown to be highly effective at preserving cellular viability and function. For example, we recently demonstrated that a bovine cell line known to be highly responsive to water toxins can be stabilized at room temperature for over 50 days! Without our stabilizing technology, this same cell line dies in less than 48 hours. Some fish cells we have been working with have even more dramatic responses, with cellular response observed after room temperature storage for well over 100 days. This drastic increase in cellular lifetime provides a truly unique enabling technology to the entire cell-based sensing field. 

We have shown room temperature stabilization of bovine lung cells for over 50 days. On the top, after 8 days of storage, non-stabilized cells (left) are losing cellular connections, contracting, and do not appear healthy, while stabilized cells (right) are exhibiting a characteristic healthy monolayer. On the bottom, we have used electrical impedance readings (in ohms) to monitor the viability of the cultured cells. Non-stabilized cells (blue) die quickly over the first 48 hours, while stabilized cells (red) exhibit exceptionally long lifetimes. *Experiments performed in collaborator Dr. Theresa Curtis’ Lab at SUNY, Cortland.
We have shown room temperature stabilization of bovine lung cells for over 50 days. On the top, after 8 days of storage, non-stabilized cells (left) are losing cellular connections, contracting, and do not appear healthy, while stabilized cells (right) are exhibiting a characteristic healthy monolayer. On the bottom, we have used electrical impedance readings (in ohms) to monitor the viability of the cultured cells. Non-stabilized cells (blue) die quickly over the first 48 hours, while stabilized cells (red) exhibit exceptionally long lifetimes.
*Experiments performed in collaborator Dr. Theresa Curtis’ Lab at SUNY, Cortland.

Using Long-term Stabilized Cells in Sensing Applications

In addition to stabilizing cells, we are also busy developing a variety of toxicant and toxin detection systems that rely on everything from electrical changes of cell monolayers to color changes of cells in response to environmental stress. The systems are designed to integrate directly with our stabilization technologies and will provide numerous solutions to our current partners. The goal of these research and development efforts is to create a single cell-based assay that can report on a variety of toxin and toxicant threats with no laborious media changes, no time-consuming upkeep, and negligible specialized training required for use. To this end, Luna is currently finalizing prototype development of its Portable Analysis of Toxic H2O Samples (PATH2OS) system –  a self-contained, cartridge-based technology that will allow rapid water toxicant analysis using the two characterization methods (impedance and colorimetric) described above. The kit will include stabilized cells for measuring response, internal controls and validations, and a user-friendly interface for response monitoring and recording of results. 

Our stabilization technology also permits the use of colorimetric sensing. Here, two different types of fish cells are responding to toxicants by aggregating in their presence. When the cells aggregate, the intensity of transmitted light increases (due to an increase in non-covered areas) and can therefore report on the presence of toxicants in the water. *Experiments performed in collaborator Dr. Janine Trempy’s Lab at Oregon State University.
Our stabilization technology also permits the use of colorimetric sensing. Here, two different types of fish cells are responding to toxicants by aggregating in their presence. When the cells aggregate, the intensity of transmitted light increases (due to an increase in non-covered areas) and can therefore report on the presence of toxicants in the water.
*Experiments performed in collaborator Dr. Janine Trempy’s Lab at Oregon State University.

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