Split aptamers are composed of two or more DNA strands that mimic segments of a larger parent aptamer. The ability of each component strand to bind targets will depend on the location of the nick and the secondary structures of the daughter strands, with the most prominent structures being three-way junctions. The presence of a target molecule can promote assembly of the DNA fragments. Once assembled, the strands can be chemically or enzymatically ligated into a single strand. Analytes for which split aptamers have been developed include the protein α-thrombin, ATP, and cocaine. Split aptamers are a potential template for biosensors in analogy to split protein systems.