Hairpin loop-enhanced fluorescent copper nanoclusters and application in S1 nuclease detection.

Novel highly fluorescent copper nanoclusters (CuNCs) were prepared by using 24 adenine-thymine pair dsDNA (AT24) with six-base (X6) loops (AT24-X6-hairpin DNA) as an effective template. The AT24 double strand stem serves as a template for CuNC formation, and the six-base sequence loop acts as specific regions to enhance the fluorescence intensity of CuNCs. Relative to the AT24-CuNCs, AT24-X6-hairpin CuNCs have greater fluorescence (5 times enhancement).