Cucurbit[6]uril-based supramolecular assembly: its syntheses, structures, capture of heavy metal ions, and sensing properties

Multidimensional supramolecular assembly (CB[6]-PA) based on cucurbit[6]uril (CB[6]) was constructed via the outer-surface interactions of CB[6] with a structure-directing agent of pamoic acid (H₂PA). Most impressively, crystal CB[6]-PA exhibited satisfactory selectivity for the capture of Cd²⁺ and Hg²⁺ cations, and released Cd²⁺ and Hg²⁺ cations under acidic condition. This reversible process allows for capturing applications of Cd²⁺ and Hg²⁺ cations. Furthermore, crystalline CB[6]-PA-Cd demonstrated enhanced fluorescence properties compared with H₂PA ligands. CB[6]-PA-Cd could be employed for the precise detection of methylmalonic acid (EA or MMA) as a biomarker of septicemia. The introduction of EA resulted in the fluorescence quenching of CB[6]-PA-Cd, the mechanism of sensing EA was clearly elucidated. A portable detection platform was designed to augment the efficiency of EA detection. To promote biological applications, the exceptional probe capable of exactly detecting EA in serum samples had been substantiated. CB[6]-PA-Cd exhibited a negligible cytotoxicity, favorable cytocompatibility, and good hemocompatibility. Thus, these results will bring about new enlightenment for the fabrication of light-emitting materials and high-resolution bio-imaging probes based on cucurbit[n]urils.