Colorimetric and fluorescent dual-signals probes for naked-eye detection of hydrogen peroxide and applications in milk samples and in vivo

Excessive residual hydrogen peroxide (H2O2) disinfectant in food is harmful to human health. Therefore, it is necessary to develop efficient detection methods for H2O2 detection. In this work, we designed and synthesized five D-A molecules 3a-3e by introducing electron-donor substituents (-OCH3 and -CH3) to the electron-acceptor dicyanoisophorone skeleton in order to find out the suitable probes for H2O2 detection. Among them, two promising probes, 3a and 3c, are screened out according to structure-property relationships. Based on the principle of intramolecular charge transfer (ICT), 3a and 3c express colorimetric and fluorescent dual-signals towards H2O2 with low detection limits (0.20 μM and 0.14 μM) and rapid response (within 20 mins). The reaction mechanism between probes and H2O2 is determined by 1H NMR and HRMS. Density functional theory (DFT) calculations are measured to study the regulation mechanism of structure adjustment on probs performance. Furthermore, a smartphone RGB analysis is utilized as a portable platform for the quantitative detection of H2O2 without complicated instruments, indicating a high efficiency and on-site detection method for H2O2. In addition, probes are applied to detect H2O2 in milk samples, HepG-2 cells and zebrafish, suggesting the promising applications in food samples and physiological systems.