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 ClO^-sensing 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 ClO^-sensing is successfully constructed. It conforms to a polynomial curve equation which is I₄₄₀/I₅₂₀= -0.0268 + 0.0315 C_ClO^-+ 0.0055[C_ClO^-]²(R²= 0.9958) between 0 and 18.4μM 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.