An Electrochemiluminescence-Activated Amphiphilic Perylene Diimide Probe: Enabling Highly Sensitive and Selective Detection of Polypropylene Nanoplastics in the Environment

Nanoplastic pollution has emerged as a significant issue in both the environmental and human health fields. However, developing highly sensitive approaches to promptly identify and detect low concentrations of nanoplastics within complex systems remains a considerable challenge. Here, we utilized the amphiphilic perylene diimide (PDI-NH₂) as a probe in combination with electrochemiluminescence (ECL) for the sensitive detection of polypropylene (PP) nanoplastics. The PDI-NH₂ probe shows a remarkable enhancement of the ECL signal on PP in aqueous solutions, presenting a concentration-dependent response. This enables the ultrasensitive and specific detection of PP in aqueous solutions with a detection limit as low as 0.948 mg·L^-1. A series of comprehensive experiments indicate that PDI-NH₂ binds to PP through electrostatic and hydrophobic interactions. Moreover, isothermal titration calorimetry and density functional theory (DFT) calculations further confirm that the enhancement of the ECL signal can be attributed to the strong and significant affinity between PDI-NH₂ and nanoplastics. This strong affinity leads to a significantly high electron transfer rate. Additionally, it is notable that the ECL probe proved its effectiveness in detecting PP in actual samples, opening up possibilities for its application in monitoring and assessing nanoplastics pollution in various environmental and industrial settings.