5 Conclusion
The cell-free system with unique advantages provides a novel
design platform for the development of biosensors. Considering the
openness and rapid prototyping capability of CFPS, the CFPS system can
open up more design space for the construction and optimization of
biosensors and genetic circuits. Cell-free biosensors based on TF, RNA,
and toehold switch can reduce the number of cycles required to design
and help build complex genetic networks. CFPS system can also be
integrated with mathematical modeling and high technologies (e.g.,
automation and microfluidics) to unlock the potential of cell-free
biosensors.
In the practical applications of cell-free biosensors, the
lyophilization technology based on the portable paper platform can
maintain the stability of the system, which promotes its portable use
and reduces the cost. However, there are still many challenges to be
addressed. The decline of the activity after the storage is a problem
that needs to be further improved. To improve in situ detection,
multiplexing functions, the sensitivity, and the specificity of
cell-free biosensors need to be further
optimized.
In addition, cell-free biosensors can use
CFPS systems other than E. coli , such as yeast and mammalian
cells, to develop more sophisticated biosensors. By improving the sensor
recognition mechanisms and combining cell-free systems with other
materials (e.g., silicon), more types of functional cell-free biosensors
can be developed. It might expand the detection range of cell-free
biosensors to sense the odor, air, temperature, light, and osmotic
pressure. With further evolution of cell-free biosensors, besides
environmental monitoring and human health diagnosis, they will
increasingly expand their applications to food testing, classroom
education, and others, making them more practical and
commercial.