Grafting polyethylenimine with quinoline derivatives for targeted imaging of intracellular Zn²⁺ and logic gate operations

In this study, a highly sensitive and selective fluorescent Zn²⁺ probe which exhibited excellent biocompatibility, water solubility, and cell-membrane permeability, was facilely synthesized in a single step by grafting polyethyleneimine (PEI) with quinoline derivatives. The primary amino groups in the branched PEI can increase water solubility and cell permeability of the probe PEIQ, while quinoline derivatives can specifically recognize Zn²⁺ and reduce the potential cytotoxicity of PEI. Basing on fluorescence off-on mechanism, PEIQ demonstrated excellent sensing capability towards Zn²⁺ in absolute aqueous solution, where a high sensitivity with a detection limit as low as 38.1 nM, and a high selectivity over competing metal ions and potential interfering amino acids, were achieved. Inspired by these results, elementary logic operations (YES, NOT and INHIBIT) have been constructed by employing PEIQ as the gate while Zn²⁺ and EDTA as chemical inputs. Together with the low cytotoxicity and good cell-permeability, the practical application of PEIQ in living cell imaging was satisfactorily demonstrated, emphasizing its wide application in fundamental biology research. - Graphical abstract: The fluorescent Zn²⁺ probe, PEIQ, is facilely synthesized by grafting PEI with 8-CAAQ, and demonstrated for the pratical applications in Zn²⁺ imaging and implementation of molecular logic operations within biological cells. - Highlights: • PEIQ, fluorescent Zn²⁺ probe, is synthesized by grafting PEI with quinoline derivatives. • PEIQ exhibits high sensitivity and selectivity in absolute aqueous solution. • PEIQ is biocompatible, water soluble, and cell-membrane permeable. • Elementary logic operations have been demonstrated for PEIQ/Zn²⁺/EDTA system. • The practical application of PEIQ in living cell imaging is demonstrated.