A smart DNAzyme/graphene oxide nanosystem for fluorescent sensing of uranyl ion with high sensitivity and selectivity

Recently, more and more attentions have been paid to the sensitive and selective determination of uranyl ion (UO22+) in environmental water due to its high toxicity and radiotoxicity. The accurate and sensitive determination of UO22+ has been readily performed in the well-equipped laboratories; however, it is still a challenging task for the on-site analysis of UO22+. To address this issue, in the present work, a novel and smart nanosystem based on DNAzyme and graphene oxide (GO) is proposed for the turn-on fluorescent sensing of UO22+ by combining the excellent selectivity of DNAzyme toward UO22+, the super fluorescence quenching ability of GO, and the unique affinity of GO toward DNAs with different structures. The proposed DNAzyme/GO nanosystem displays outstanding analytical performance in terms of wide dynamic response range (0.1–40 nM), low limit of detection (25 pM) and good selectivity over other metal ions. Furthermore, this nanosystem is successfully applied for the UO22+ detection in water samples with satisfactory results, demonstrating its great potential in the environmental monitoring.