Unlocking Self-Luminescence of Pyrene-Based Metal-Organic Gel for Sensitive Electrochemiluminescence Assay of Microplastics.

Pyrene (Py), an archetypal electrochemiluminescence (ECL) luminophore, suffers from inherent aggregation-caused quenching (ACQ) stemming from its planar π-conjugated structure and consequent intermolecular π-π stacking, severely restricting its practical utility. Herein, a gel confinement-induced emission enhancement (GCIEE) strategy is proposed to circumvent this limitation. At room temperature, 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) underwent a coordination reaction with Tb3+ to rapidly construct a Py-based metal-organic gel (Py-MOG). The rigid coordination framework of Py-MOG imposed spatial confinement on Py ligands, effectively suppressing their detrimental ACQ effect and thereby dramatically boosting the ECL efficiency. Significantly, the as-prepared Py-MOG exhibited a strong and stable ECL emission at -1.65 V without coreactants, and its ECL efficiency achieved a 3.39-fold enhancement relative to the H4TBAPy monomer. As a proof of concept, microplastics (MPs), a kind of persistent micropollutants that threaten ecosystems and human health even at trace levels due to their bioaccumulation and toxicity, were selected as the model target for evaluating the application of Py-MOG in ECL sensing. By coupling Py-MOG with an aptamer recognition-initiated Cas12a thrusting strand displacement reaction (CtSDR) amplification, a biosensor was constructed for the sensitive detection of polyvinyl chloride (PVC) and polystyrene (PS), displaying the limits of detection of 5.2 μg/L for PVC and 7.5 μg/L for PS, respectively. The GCIEE strategy provides a rapid, simple, and novel method to significantly improve the ECL efficiency of Py-based luminophores. The self-luminous Py-MOG establishes an ultrasensitive ECL platform for MPs detection without exogenous coreactants.