Vacancy mediated CdZnS/SnIn4S8 heterojunction coupling Co3O4/CuO nanozymes: Artificial intelligence assisted ratiometric electrochemiluminescence sensing of tetracycline

Abstract

The accumulation of tetracycline (TC) residues in the environment poses a serious threat to public safety. Here, we developed a smartphone-integrated ratiometric electrochemiluminescence (RECL) sensing system for visual and point-of-care testing (POCT) of TC. Zero-dimensional CdZnS bonded in two-dimensional SnIn₄S₈ to construct the CdZnS/SnIn₄S₈ heterojunction with abundant sulfur vacancies (SVs) was designed by solvothermal method, which as the electrochemiluminescence (ECL) luminescent material for the cathode. Metal-organic framework-derived Co₃O₄/CuO nanozyme with multi-enzyme activity and abundant oxygen vacancies (OVs) were prepared by in-situ pyrolysis method, which is the ECL anode material. Interestingly, heterojunction-mediated SVs adjustment of charge transfer between CdZnS and SnIn₄S₈ for achieving enhanced regulation. The synthesized Co₃O₄/CuO nanozyme coupled luminol luminophore exhibited excellent ability in catalyzing hydrogen peroxide (H₂O₂) to superoxide anion (O₂^•−) and hydroxyl radical (^•OH). Thus, rational construction of CdZnS/SnIn₄S₈+Co₃O₄/CuO/luminol+H₂O₂ RECL system achieved high sensitivity and specificity for the detection of TC in the ranging from 1.0∼600 μmol l^-1 and the limit of detection was 0.827 μmol l^-1. More importantly, the RECL light signal can be captured by a smartphone based on the fast electrochemiluminescence judgment network (FEJ-Net), realizing a portable, intelligent, and POCT sensing novel method. Finally, this developed platform has obtained satisfactory results in the detection of real samples. Therefore, it is also expected to expand the potential of smartphone-integrated RECL in POCT.