Highly Sensitive Bioactivity Assessment of Thyroid-Disrupting Chemicals in Human Samples across the Entire Exposome Landscape

Human populations are exposed to numerous potentially hazardous compounds, but most of these compounds remain uncharacterized in the exposome of populations due to analytical challenges posed by limited sample volumes, complex matrices, and trace-level compound concentrations. Here, we developed a highly sensitive and high-throughput assay method for screening harmful compounds in human samples based on the mechanism underlying the toxicity of compounds that competitively bind to key peptides. A functional peptide was identified that mimics transthyretin (TTR)─thyroid hormone transport protein in plasma and cerebrospinal fluid─while achieving a 1000-fold cost reduction. The peptide was then conjugated to gold nanoparticles with enzyme-like activity (AuNPs@peptides) to facilitate the sensitive recognition of thyroid-disrupting chemicals (TDCs). Given the incompatibility of peptides with conventional acidic enzyme-catalyzed systems, we developed a novel alkaline-compatible, nanozyme-catalyzed, dopamine chromogenic assay that exploits the color of polydopamine intermediates to assess TDC bioactivity and elucidated the underlying enzymatic mechanisms. Compared with the recommended method, our method showed 96.3% consistency and 10-fold greater sensitivity. This method also demonstrated superior sensitivity for assessing TDC bioactivity at trace concentrations (nM) in human urine, enabling population-scale monitoring and a comprehensive risk assessment of endocrine-disrupting chemicals.