Cucurbit[8]uril–guest–metal ion self-assemblies as fluorescence sensor arrays for discrimination and detection of physiological phosphates

In this study, a ThT@Q[8] host-guest complex was obtained <i>via</i> an interaction between cucurbit[8]uril (Q[8]) as the host and thioflavin T (ThT) as the guest. Then, ThT@Q[8]-Fe³⁺ and ThT@Q[8]-Hg²⁺ fluorescent probes were constructed based on metal ion stimuli-responsive supramolecular interactions. These probes exhibited distinct fluorescence responses toward five physiological phosphate anions (Pi, PPi, AMP, ADP, and ATP) due to electrostatic and coordinative interactions. A supramolecular fluorescence sensing array was thus developed using ThT@Q[8]-Fe³⁺ and ThT@Q[8]-Hg²⁺ as sensing units for the discrimination and detection of these phosphate anions. The array showed excellent anti-interference performance and successfully distinguished phosphate anions at low, medium, and high concentrations. A good linear relationship was observed between Factor 1 and anion concentration over the range from the limit of quantitation (LOQ) to 10 μM, with a limit of detection (LOD) as low as 0.13 μM. The array was also effective in discriminating the five phosphate anions in human serum. With advantages such as rich output signals, low cost, and simple preparation, this array holds considerable potential for detecting phosphate anions in biological systems. Furthermore, it enabled monitoring of ATP hydrolysis and evaluation of the energy charge in human serum.