Conjugated Polymer Nanoparticles as a Universal High-Affinity Probe for the Selective Detection of Microplastics

Abstract

Microplastic (MP) pollution is a global challenge that requires immediate mitigation practices. Monitoring is crucial for quantifying MPs, but their mitigation remains very challenging due to several factors, including the lack of selective materials to specific polymers, and the low sensitivity of the current detection techniques. In this work, we introduce a novel design for the selective detection of MPs through fluorescence spectroscopy by exploiting conjugated polymer nanoparticles (CPNs). Fluorescent diketopyrrolopyrrole nanoparticles were prepared by nanoprecipitation to incorporate peripheral hyaluronic acid to increase their affinity for various plastics. The affinity of the new ligand for various types of MPs was examined through several characterization techniques, including fluorescence spectroscopy and microscopy, nanoparticle tracking analysis and computational studies. The new CPN were shown to be highly fluorescent in the presence of typically abundant MPs, achieving very strong binding constants in the picomolar range. This very strong affinity for a broad family of plastics was found to be the results of cooperative supramolecular effects and topographical affinity, as probed by advanced microscopy and in silico studies. Furthermore, the new affinity probes were shown to be highly selective for MPs, allowing for their detection in heterogeneous samples, including soil debris and other organic contaminants. The new materials design introduced in this work constitute a promising platform for the development of novel MP detection devices directly useable at the point of collection. Moreover, it opens new avenue for the mitigation of this environmental hazard through tailorable materials.

Bright and Stable Nanomaterials for Imaging and Sensing

“…An alternative approach is to use polymer nanoparticles (PNPs) to incorporate the dyes. Although nanoparticles from conjugated polymers are intrinsically fluorescent and very bright [79][80][81][82], they have limited application because of poor biodegradability and cumbersome stabilization. On the other hand, nanoparticles of non-fluorescent polymers or copolymers can be used to encapsulate fluorescent dyes, offering huge versatility due to the large number of available monomers, the possibility to mix different monomers, and the incorporation of different groups in the polymer.…”

Surface Bio‐engineered Polymeric Nanoparticles

“…Successfully grafting biofunctional molecules onto nanoparticles modulates their surface characteristics and achieves desired biological activity such as biosensing, [34][35][36] bioimaging, [37,38] and targeted therapy [39,40] (Figure 1). For instance, nanoparticle structures specifically modified with ions, fluorophores, or antibodies can behave as nanoprobes for surface chemical fluctuations such as pH as well as sensors for reactive oxygen species (ROS) and biologically threatening agents.…”