"Lab-on-Double Confinement-Pipette Tip": CDsCu/Mn@MPDA-Driven Portable Intelligent Sensor for In-Situ Rapid Detection of Pesticide Residues.

Abstract

The development of high specificity, ultrasensitive, and portable detection technologies is conducive to monitoring pesticide residues in the environment, thereby promoting the scientific use of pesticides. Here, a dual-confined sensitization "lab-on-pipette tip" was developed for colorimetric-photothermal in-situ detection of carbosulfan by encapsulating nanomaterials within the hydrogel matrix on a pipette tip. As the signal transduction core, an interfacial-enhanced mesoporous polydopamine was loaded with dual-metal carbon dots (CDsCu/Mn@MPDA) to mimic high-efficiency peroxidase activity. The synergy between the bimetallic sites lowered the energy barrier for the reduction of H2O2, generating abundant hydroxyl radicals. Crucially, the reducing sulfur species generated from acidified carbosulfan inhibit the activity of CDsCu/Mn@MPDA by triggering radical-scavenging reactions, generating target concentration-dependent signals. Furthermore, CDsCu/Mn@MPDA was encapsulated in the hydrogel and gelled at the pipette tip to construct an integrated platform. The double-confinement effect enhanced reaction-component contact efficiency, resulting in a 40-fold compression of the linear response range for carbosulfan residue detection. The sensing platform exhibited a response range of 0-1200 µM in solution. Strikingly, this range was compressed to 0-30 µM within the spatially confined microcavity. This on-demand tunable range platform slashes per-assay costs by ∼99.7% vs liquid chromatography mass spectrometry, bridging the lab-to-field gap for environmental sensing.

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