Electron-bridge-mediated construction of flower-layered Cu@CuO@TCPP-Cu heterojunction from homogeneous copper precursor for integrated SERS and peroxidase-mimicking analysis

Cu@CuO@TCPP-Cu heterojunction with electronic bridge was fabricated. • Cu 2+ bridge boosts charge transfer and strengthens interfacial coupling in Cu@CuO@TCPP-Cu. • The heterojunction shows enhanced SERS performance and POD-like catalytic activity. • Dual-target strategies enable sensitive PAT and H 2 O 2 detection for food safety monitoring. Engineering heterojunctions with efficient carrier separation and interfacial charge transfer is crucial for high performance surface-enhanced Raman spectroscopy (SERS) and enzymatic catalytic activity. However, conventional asynchronous synthesized heterostructures suffer from insufficient interfacial contact, which severely restricts charge transfer kinetics and SERS/catalytic response. Here, we rationally engineer a novel flower-layered Cu@CuO@TCPP-Cu heterojunction mediated by an in situ formed “electron bridge” for high sensitivity sensing applications. A facile surface oxidation technique was employed to grow flower-like CuO in situ on a Cu foil, followed by surface-initiated encapsulation of two-dimensional MOF of TCPP-Cu through coordination between TCPP and Cu 2+ ions released from CuO. The dissociated Cu 2+ ions at the interface serve as an “electronic bridge” between CuO and TCPP-Cu, which drastically shortens the charge transfer distance and enhances interfacial coupling. This unique heterojunciton exhibits remarkable synergy in SERS signal enhancement and peroxidase (POD)-like catalytic activity, as confirmed by density functional theory (DFT) calculations. A robust solid-state SERS sensing chip was thereby constructed. Two distinct analytical strategies were subsequently established, including aptamer-mediated specific detection of patulin (PAT) and enzyme mimicking - amplified turn-on SERS assay for quantitative analysis of H 2 O 2 . The as-constructed sensing chip exhibits excellent analytical sensitivity and selectivity, achieving low limits of detection of 0.640 μg/L for PAT and 13.8 μg/L for H 2 O 2 , respectively. Furthermore, the chip successfully identified both analytes in complex food samples with high accuracy. This work provides a versatile engineering strategy for constructing high performance heterojunction toward advanced analytical and food safety applications. Herein, a novel flower-layered Cu@CuO@Cu-TCPP heterojunction is constructed via an electronic bridge strategy. The bridge-mediated interfacial electron transfer synergistically boots peroxidase-like catalytic activity and SERS performance. Integrating aptamer recognition with nanozyme amplified turn-on SERS sensing enables highly sensitive detection of PAT and H 2 O 2 , offering a universal heterojunction design paradigm and broadening applications in food safety monitoring. Download: Download high-res image (166KB) Download: Download full-size image