G-quadruplex DNA for construction of biosensors

DNA-based biosensors have been widely used for its stable chemical properties, cost-effectiveness, and easy modification. G-quadruplex (G4) DNA has attracted growing interest since it can be used for both target recognition and signal transduction. Much of G4 DNA's relevance in biosensors is related to its ability to bind specific metal ions, dyes and porphyrins, and these properties are first reviewed. Then, the role of G4 for molecular recognition is discussed including the sensing of metal ions, proteins and enzymes. Subsequently, G-quadruplex for signaling transduction is reviewed. In this part, G4 binds some substrate to enhance fluorescence, and binds hemin to show peroxidase-like activity. Finally, some sensors used G4 DNA for both target recognition and signaling. This review mainly contains specific examples of biosensors published in the last five years. Finally, some challenges in the field are discussed and a few future research opportunities are proposed.