Folic acid (FA) is one of the essential vitamins for the growth and reproduction of human cells, and it is of great significance to detect FA in real time. In this study, we designed double-stranded DNA (dsDNA)-templated copper nanoclusters (CuNCs) as a nanoprobe for rapid, highly sensitive and selective detection of FA via the inner filter effect (IFE). The dsDNA-CuNCs nanoprobe with strong stability could be prepared facilely in only 5 min at room temperature and testing could be completed in 12.5 min. This method exhibited a satisfactory linear response to FA in the concentration range of 1...