MnO2 Nanosheet-based Fluorescence Sensing Platform for Sensitive Detection of Endonuclease

A novel fluorescence sensing platform for ultrasensitive detection of SI nuclease activity has been constructed based on MnO2 nanosheets and FAM labeled single-stranded DNA (FAM-ssDNA). In this system, MnO2 nanosheets were found to have different adsorbent ability toward ssDNA and mono-or oligonucleotide fragments. FAM-ssDNA could adsorb on MnO2 nanosheets and resulted in significant fluorescence quenching through fluorescence resonance energy transfer (FRET), while mono- or oligonucleotide fragments could not adsorb on MnO2 nanosheets and still retained strong fluorescence emission. With the addition of S1 nuclease, FAM-ssDNA was cleaved into mono- or oligonucleotide fragments, which were not able to adsorb on MnO2 nanosheets and the fluorescence signal was never quenched. The different fluorescence intensity allowed for examination of Si nuclease activity. The developed method can detect S1 nuclease activity in the range of 0-20 U mL(-1)with a detection limit of 0.05 U mL(-1). Benefits of the system include less time-consuming processes and more simple design compared to other endonuclease assays. Satisfactory performance for S1 nuclease in complex samples has been successfully demonstrated with the system. The developed assay could potentially provide a new platform in bioimaging and clinical diagnosis.