A fluorescent signal-on sensor based on photoinduced electron transfer between copper nanoparticles and G-quadruplex/hemin

A novel fluorescence signal-on biosensing platform was developed by using photoinduced electron transfer (PET) between copper nanoclusters (CuNCs) and G-quadruplex/hemin. Hairpin DNA was chosen as an effective template to synthesize CuNCs. A split G-quadruplex sequence is linked to the end of the hairpin DNA template. In the presence of K+ and hemin, the split G-quadruplex sequence can form a Gquadruplex/ hemin complex and quench the fluorescence of CuNCs via PET. Target recognition causes split G-quadruplexes to move away from each other, and prevents the formation of a G-quadruplex/ hemin complex. Thus, a significant fluorescence signal increase is observed, because of the lower PET efficiency. This strategy is successfully applied for the detection of DNA. Otherwise, it can be used for developing a platform for detection of small molecules and proteins.