Rapid and Highly Selective Detection of the Tire Antioxidant 6PPD in Water Samples via Dual-Mode Fluorescent and
Xiaonan Feng1, Xiaoduo Chen1, Kun Zhang1
1Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Abstract:
The pervasive presence of the tire antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) in aquatic environments, and its role as the precursor of the acutely toxic transformation product 6PPD-quinone, has raised substantial concerns regarding tire-derived chemical pollution and its ecological impacts. Despite growing regulatory attention, selective and interference-resistant methods for the rapid and reliable determination of 6PPD in environmental waters remain limited, largely due to the lack of specific molecular recognition mechanisms. In this study, we report the identification and mechanistic elucidation of a host-guest interaction between β-cyclodextrin (βCD) and 6PPD, enabled by cavity-size complementarity and favorable hydrogen-bonding interactions. Isothermal titration calorimetry, NMR spectroscopy, and molecular docking collectively confirmed the formation of a stable βCD-6PPD inclusion complex (Kd = 2.11 μM). Leveraging this recognition, two βCD-based sensing platforms were developed: a fluorescence "turn-on" sensor (LOD = 4.13 nM) and a self-powered photoelectrochemical sensor with enhanced selectivity (LOD = 3.19 nM). Both sensors were successfully applied to the quantification of 6PPD in road runoff rainwater samples, yielding results in excellent agreement with those of HPLC-MS/MS analysis. This work establishes cyclodextrin host-guest chemistry as an effective recognition strategy for tire-derived contaminants and provides a practical foundation for the rapid, low-cost, and potentially field-deployable monitoring of 6PPD in environmental waters.
