Highly sensitive and reusable mercury (II) sensor based on fluorescence quenching of pyrene moiety in polyacrylamide-based cryogel

[Display omitted] •Pyrene functional, fluorescence active cryogel (PAAm-Pyr) was prepared by click chemistry and used as Hg2+ sensor.•PAAm-Pyr can sense very low concentrations of Hg2+ (2ppb) in aqueous solutions.•PAAm-Pyr can be reused many times after simple washing in pure water. A practically reusable fluorescent ion-sensing cryogel (PAAm-Pyr) was prepared through the post functionalization of macroporous polyacrylamide-based cryogel with pyrene moiety. PAAm-Pyr can sense very low concentration of Hg2+ (2ppb) in aqueous solutions and demonstrates a high selectivity for Hg2+ in the presence of various competing metal ions in pure water. Developed sensor can be used many times after simple washing in pure water.