Positively charged Ag@Au core-shell nanoparticles as highly stable and enhanced fluorescence quenching platform for one-step nuclease activity detection

S1 nuclease plays an important role in DNA transcription, recombination and repair. Here, we synthesized a positively charged [email protected] core-shell nanoparticles ((+) [email protected] CSNPs) and used as highly stable and enhanced fluorescence quenching platform for one-step S1 nuclease activity detection. In the sensor, fluorophore labeled DNA was used as signal probe and its fluorescence signal could be effectively quenched based on the electrostatic interaction of it with (+) [email protected] CSNPs. In the presence of S1 nuclease, DNA probe was hydrolyzed into DNA fragments and cannot interact with (+) [email protected] CSNPs, inducing an obvious fluorescence signal increase that was proportional with S1 nuclease concentration in the range of 2.5 × 10 −4 –3.0 × 10 −2  U/mL. The enhanced quenching efficiency of (+) [email protected] CSNPs paved the way for sensitive S1 detection with a detection limit of 6.0 × 10 −5  U/mL. Moreover, the high stability of such nanocomposite can achieve the one-step detection of S1 in complex solution containing salt, protein or other metal ions. In addition, the method also exhibited high selectivity for nuclease detection, making our sensing platform has a potential application value in bioanalysis and clinical diagnosis.