Abstract
It is of paramount importance to develop new probes that can selectively, sensitively, accurately and rapidly detect fluoride in aqueous media and biological systems, because F- is found to be closely related to many health and environmental concerns. Herein, a dual-emissive conjugated polyelectrolyte P1 containing phosphorescent iridium(III) complex was designed and synthesized, which can form ultrasmall polymer dots (Pdots) in aqueous media. The F--responsive tert-butyldiphenylsilyl moiety was introduced into iridium(III) complex as the signaling unit for sensing F− with the quenched phosphorescence. Thus, the dual-emissive Pdots can rapidly and accurately detect F− in aqueous media and live cells as a ratiometric probe by measuring the change in the ratio of the F−-sensitive red phosphorescence from iridium(III) complex to the F−-insensitive blue fluorescence from polyfluorene. Moreover, the interaction of Pdots with F− also changes its emission lifetime, and the lifetime-based detection of F− in live cells has been realized through photoluminescence lifetime imaging microscopy for the first time. Both the ratiometric luminescence and lifetime imaging have been demonstrated to be resistant to external influences, such as the probe’s concentration and excitation power. This study provides a new perspective for the design of promising Pdots-based probes for biological applications.
Highlights
As one of the important inorganic anions, fluoride anion (F−) plays a great role in many health and environmental concerns
The hydrodynamic diameter of the polymer dots (Pdots) was determined by dynamic light scattering (DLS), the mean diameter of the Pdots is about 16 nm (Fig. 3b)
It is reasonable that hydrodynamic diameter of the Pdots measured by DLS is larger than their size obtained by transmission electron microscopy (TEM), because the hydrodynamic diameter is the hydrated diameter combined by the Pdots cores together with the solvent coating layer, while for TEM, this hydration layer is not present[50]
Summary
As one of the important inorganic anions, fluoride anion (F−) plays a great role in many health and environmental concerns. It is of great importance to develop effective strategy that can selectively, sensitively, accurately and rapidly detect fluoride anion in aqueous media and biological systems. Compared to the sensors based on noncovalent and weak interaction, these specific reaction-based probes exhibit higher selectivity and stability[20] In spite of these merits, most of the reported probes are water-insoluble and usually suffer from long response time to ensure complete reaction, limiting their applications in real-time detection. By measuring the change in the ratio of the F−-sensitive red phosphorescence from iridium(III) complex to the F−-insensitive blue fluorescence from polyfluorene, the dual-emissive Pdots can rapidly and accurately detect F− in aqueous media and live cells as a ratiometric probe. The lifetime-based detection of F− in live cells has been realized through PLIM for the first time, and the advantages of lifetime detection have been demonstrated successfully
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