A ratiometric fluorescent hydrogel of controlled thickness prepared continuously using microtomy for the detection and removal of Hg(II)

Mercury ions are one of the most toxic heavy metals and as such they can cause serious risk to the human body and environmental ecosystem. To effectively detect and remove Hg2+ from contaminated water, a new cellulose-based fluorescent hydrogel has been fabricated using a ratiometric probe with carbon dots as energy donor and rhodamine moiety as energy acceptor (CDs-Rho). The probe exhibits a sensitive and linear response to Hg2+ over a wide range from 0–100 μM with a limit detection of 2.19 × 10−9 M and exhibits high selectivity for Hg2+ over other cations. In addition, a series of cellulose-based fluorescent hydrogel slices containing CDs-Rho are continuously prepared using microtomy of a hydrogel, facilitating the large-scale fabrication of functionalized hydrogel slices with controlled thickness. The cellulose-based CDs-Rho (CCR) hydrogel exhibits good sensitivity and excellent adsorption capacity for Hg2+ with ~95% removal efficiency, meeting the requirements for sewage discharge. Moreover, the purified water is successfully used for cell culture and animal growth, demonstrating excellent biocompatibility. Our approach is expected to offer a novel concept for the construction of biocompatible fluorescent hydrogels for the detection of various metal ions and removal by simply swapping the current probe with suitable replacements for a variety of relevant applications.