Current Technologies of Synthetic Biosensors for Disease Detection: Design, Classification and Future Perspectives.

Synthetic biology aims to endow living cells with new functions by incorporating functional gene networks into them. By overexpressing, blocking and rewiring native gene pathways, synthetic biologists have harnessed this promising technology to reprogram cells to perform diverse tasks such as drug discovery, biopharmaceutical manufacturing, gene therapy and tissue engineering, etc. In this review, we focus on current technologies of synthetic biosensors for disease detection. We start with the design principle of synthetic biosensors. Then we move towards the characteristics of simple synthetic biosensors, which can respond to a single input signal, and complex synthetic biosensors including Boolean gate biosensors, cascade biosensors, time-delay biosensors, oscillator biosensors and hysteretic biosensors, which can respond to more than two input signals and perform complex tasks. Synthetic biosensor has showed great potential in disease detection, but it is still in its infancy stage. More efforts should be made in identifying and constructing clinically relevant regulation systems. Computational tools are also needed in the design process in order to guarantee the precision of the synthetic biosensor. The ultimate goal of a synthetic biosensor is to act as a therapeutic sensor-effector device that connects diagnostic input with therapeutic output and therefore provides all-in-one diagnostic and therapeutic solutions for future gene- and cell-based therapies.