Design of nuclease-based target recycling signal amplification in aptasensors

Compared with conventional antibody-based immunoassay methods, aptasensors based on nucleic acid aptamer have made at least two significant breakthroughs. One is that aptamers are more easily used for developing various simple and rapid homogeneous detection methods by "sample in signal out" without multi-step washing. The other is that aptamers are more easily employed for developing highly sensitive detection methods by using various nucleic acid-based signal amplification approaches. As many substances playing regulatory roles in physiology or pathology exist at an extremely low concentration and many chemical contaminants occur in trace amounts in food or environment, aptasensors for signal amplification contribute greatly to detection of such targets. Among the signal amplification approaches in highly sensitive aptasensors, the nuclease-based target recycling signal amplification has recently become a research focus because it shows easy design, simple operation, and rapid reaction and can be easily developed for homogenous assay. In this review, we summarized recent advances in the development of various nuclease-based target recycling signal amplification with the aim to provide a general guide for the design of aptamer-based ultrasensitive biosensing assays.