Portable hydrogel kit driven by bimetallic carbon dots nanozyme for H2O2-self-supplying dual-modal monitoring of atmospheric CH3SH

Due to the typical volatility of gaseous pollutant methyl mercaptan (CH 3 SH), the development of a facile, reliable, and accurate onsite environmental surveillance of highly toxic CH 3 SH faces many challenges, but it is critical to environmental atmosphere assessment and safeguarding public health. Here, we prepared a novel bimetallic carbon dots (Fe&Cu@CDs) nanozyme with high peroxidase-mimicking activity to design a portable hydrogel kit for onsite visual H 2 O 2 -self-supplying enzymatic cascade catalytic colorimetric and photothermal signal synergistic amplification dual-modal monitoring of CH 3 SH in atmospheric environment. Assisted by alcohol oxidase (AOX), CH 3 SH could be specifically converted into H 2 O 2 for oxidizing chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) catalyzed by Fe&Cu@CDs to produce dark blue ox-TMB with absorption at 652 nm and photothermal characters. Consequently, a CH 3 SH concentration-dependent change both in naked-eye color and photothermal effect-triggered temperature were observed. By hybridizing AOX-assisted Fe&Cu@CDs + TMB with agarose, a H 2 O 2 -self-supplying colorimetric and photothermal signal synergistic amplification sensory hydrogel kit integrated with Color Picker APP-installed smartphone and 660 nm laser-equipped handheld thermal imager for CH 3 SH was proposed with acceptable results in atmospheric environment around wastepile ( e.g. , solid waste and food waste piles), which exhibited great potentials to further develop commercial onsite monitoring platforms in warning-early abnormal atmospheric CH 3 SH for safeguarding environmental health.