A glycosylation strategy to develop a low toxic naphthalimide fluorescent probe for the detection of Fe³⁺in aqueous medium

Abstract

A glycosylation strategy based on click chemistry was employed to develop a naphthalimide-based Fe³⁺ fluorescent probe with low cytotoxicity and good water-solubility. The selectivity and sensitivity to Fe³⁺ of three synthesized naphthalimide-based fluorescent probes follows a Nap-PZ < Nap-OH < Nap-Glc trend, because Nap-PZ was modified with a good water-soluble group. The cytotoxicity follows a Nap-PZ > Nap-OH > Nap-Glc trend, because the exposed toxic group of Nap-PZ was shielded by a good biocompatible group. The detection limit toward Fe³⁺ ion follows a Nap-PZ (7.40 × 10^-6 M) > Nap-OH (2.73 × 10^-7 M) > Nap-Glc (4.27 × 10^-8 M) trend. Moreover, Nap-Glc could be used to detect Fe³⁺ in living cells. The fluorescent "off-on" response of Nap-Glc towards Fe³⁺ could be recognized by the naked eye, and the "off-on" fluorescent mechanism also was demonstrated by theoretical calculations. Therefore, Nap-Glc is a novel glucosyl naphthalimide fluorescent probe for environmental or biological detection of Fe³⁺ with low cytotoxicity and good water-solubility.