Construction of CDs@β-CD@CCM ratiometric fluorescence probe for FRET-based ClO-sensing.

β-Cyclodextrin (β-CD)-functionalized carbon quantum dots (CDs) loaded with curcumin (CCM) were used for ClOsensing with high sensitivity and selectivity. This fluorescence resonance energy transfer (FRET)-based sensor was created through attaching CCM to the CDs via β-CD linker. CCM could get into the interior of β-CD triggering the FRET from CDs to CCM, providing an 'off' state of the CDs. However, the effect of FRET was weakened by the ClO, because the o-methoxyphenol structure from CCM was oxidized to be benzoquinone. The fluorescence intensity of CDs@β-CD@CCM at 440 nm can be heightened and 520 nm from CCM can decrease along with the increased ClO. Therefore, a ratiometric fluorescence probe for ClOsensing is successfully constructed. It conforms to a polynomial curve equation which is I/I= -0.0268 + 0.0315 C+ 0.0055[C](= 0.9958) between 0 and 18.4M ClO. Furthermore, we also obtain excellent results using this spectrophotometric method for ClO-sensing in pure water and commercial disinfectants, which afford potential in the environment monitoring area. We expect this sensing platform could be helpful in other analogous probes in relevant fields.