Colorimetric and fluorescent dual‑channel responsive sensor array based on laccase-mimicking H₄TCPE@Cu/GMP nanozyme: Toward the discrimination and quantification of phenolic pollutants

Simultaneous identification and quantification of multiple phenolic pollutants remain significant challenges in environmental monitoring. This study presents a dual-channel cross-responsive sensor array, utilizing AIEgen-functionalized copper-based infinite coordination polymers (H₄TCPE@Cu/GMP ICP) nanozymes with laccase-mimicking activity. Based on theoretical insights into the catalytic mechanism for phenolic substrates via the chromogenic reaction of 4-aminoantipyrine (4-AAP), o-phenylenediamine (OPD) was strategically introduced to initiate a competitive redox reaction catalyzed by the nanozyme. This reaction produced yellow-colored 2,3-diaminophenazine (DAP) (A₄₁₀) while modulating the formation of red-colored quinone imide (A₅₁₀), thereby establishing dual-responsive signals in the colorimetric channel. Simultaneously, the inner filter arising from cross-influence of colorimetric and fluorescent channels suppressed the blue aggregation-induced emission (AIE) of H₄TCPE@Cu/GMP ICPs (F₄₃₅) and affected the orange-yellow emission of DAP (F₅₆₅), generating dual-responsive signals in the fluorescent channel. Established on the multivariate cross-responsive signals, the sensor array enabled accurate differentiation and quantification of 10 phenolic pollutants coexisting in real environmental samples, including monophenols and bisphenols, with the limit of detection (LOD) as low as the nM level. Furthermore, the unique ratiometric responses in dual channels produced distinct color variations amenable to digitally analyzed via a smartphone, facilitating on-site environmental monitoring. These findings highlight the potential of the proposed digital sensor array for high-efficiency, field-deployable monitoring of phenolic pollutants in complex wastewater environments.