This December 16, 2024 Nanowerk Spotlight article by Michael Berger highlights work where living cells are combined with nonliving materials (also called biohybrid materials or engineered living materials), Note: A link has been removed,

Chemical detection outside laboratory settings poses persistent technical challenges. Environmental monitoring, industrial quality control, and medical diagnostics require identifying specific molecules in complex mixtures. Current portable detectio n methods, such as test strips or electronic sensors, often lack sensitivity or struggle to detect multiple chemicals simultaneously. Traditional laboratory analysis provides precise results but requires expensive equipment, trained personnel, and days or weeks to process samples.

Living cells naturally detect and respond to chemicals with remarkable sensitivity. Their molecular detection systems, refined by evolution, can identify specific compounds at extremely low concentrations and process multiple signals simultaneously. Biologists have learned to harness these capabilities by engineering bacteria and yeast cells to produce visible signals when they encounter target molecules. These cellular sensors can detect compounds at concentrations far lower than conventional methods. However, using engineered cells outside the laboratory remains impractical because they require careful maintenance and protection from environmental stresses.

Materials scientists have recently developed new methods to protect living cells while preserving their functionality. Parallel advances in microfluidic technology enable precise control of tiny liquid volumes in miniature channels on portable chips. These developments create an opportunity to transform cellular sensors from laboratory curiosities into practical field devices.

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Berger goes into more detail about the technology, from his December 16, 2024 Nanowerk Spotlight article, Note: Links have been removed,

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The researchers first modified yeast and bacteria cells by adding genes that produce fluorescent proteins in response to specific chemicals. They precisely engineered these genetic circuits by controlling the number of receptor proteins on each cell’s surface. More receptors increase sensitivity but can also lead to false positives, while fewer receptors provide more selective detection. By optimizing this balance, they achieved detection of some compounds at concentrations as low as two nanomoles per liter – equivalent to finding a grain of salt dissolved in an Olympic swimming pool.

To protect these engineered cells, the team developed a two-layer encapsulation system. They embedded the cells in soft beads made from alginate, a natural polymer derived from seaweed. These beads provide a supportive environment while allowing chemicals to pass through. A tougher outer shell, combining alginate with polyacrylamide, adds physical protection. The resulting capsules, each about two millimeters wide, withstand significant compression without breaking and keep the cells alive and functional for over a month.

The researchers integrated these sensor capsules into a microfluidic chip with separate chambers for different sensors. ..

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This technology transforms living cells into practical sensors for field use. By combining synthetic biology, materials science, and microfluidic engineering, the researchers have created a system that preserves the sensitivity of cellular sensors while making them robust enough for real-world applications. …

Berger’s December 16, 2024 Nanowerk Spotlight article also includes details about field testing and possible future applications.

Here’s a link to and a citation for the paper,

On-Chip Engineered Living Materials as Field-Deployable Biosensing Laboratories for Multiplexed Detection by Benfeng Xu, Hui Tian, Xinrui Li, Qiya Hao, Yuying Ma, Ling Liu, Chunyang Lei, Ye Chen, Zhou Nie. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202416830 First published: 08 December 2024

This paper is behind a paywall.