Fe-Doped Piezoelectric Nanozyme UiO-66-NH2 with Enhanced Oxidase-like Activity for Fluorescence Detection of Glyphosate

Piezoelectric nanozymes have garnered considerable attention for their ability to drive catalytic reactions by generating localized electric fields through the piezoelectric effect, thereby eliminating reliance on traditional oxidants (such as H2O2) and effectively avoiding the problem of poor substrate stability. In this work, an Fe-doped piezoelectric nanozyme Fe/UiO-66-NH2 was developed. Under ultrasound (US) irradiation, owing to its noncentrosymmetric nature, UiO-66-NH2 promoted an internal electric field that enhanced electron-hole pairs separation, thereby enabling H2O2-free production of reactive oxygen species (ROS). Fe doping significantly boosted the piezoelectricity of UiO-66-NH2 by promoting electron transfer and facilitating the separation of electron-hole pairs; therefore, its piezoelectric constant (d33) increased from 24.3 to 36.3 pm V-1. The piezoelectric nanozyme Fe/UiO-66-NH2 driven by US could initiate the redox reactions with H2O and dissolved O2 to yield various ROS, which subsequently catalyzed the chromogenic reaction of o-phenylenediamine (OPD), yielding the fluorescent product 2,3-diaminophenazine (DAP). Since glyphosate (Gly) inhibited the piezoelectric effect by specifically binding to Fe/UiO-66-NH2, a fluorescence assay was developed for Gly detection. The proposed piezocatalytic sensing system allowed for rapid Gly detection within a period of 7 min, offering high sensitivity with a limit of detection of 70 ng/mL. This work offered a rational strategy for developing high-performance piezoelectric nanoenzymes, holding great potential in biochemical analysis.