(416i) Characterization of Polymeric Nanoparticles Via Microfluidic Interfacial Complexation

Micro/nano-plastics, micron to nanometer-sized particulate fragments of degraded polymeric waste, are increasingly prevalent in environmental waterways. The small size of these debris increases their bioavailability, posing unknown risks due to their ability to enter the food chain. But routine field-based monitoring of micro/nano-plastics is currently impossible because they can only be detected using laboratory-based analytical methods like infrared spectroscopy, Raman spectroscopy, electron microscopy, or pyrolysis gas chromatography/mass spectroscopy. Here we describe efforts to overcome these shortcomings by developing a portable continuous-sampling microfluidic platform capable of selectively quantifying micro/nano-plastics. The system works by co-injecting laminar streams of water containing polymeric nanoparticles and fluorescent tracers with specific chemical affinity to the plastics. Lateral diffusion-driven localized complexation between the polymeric particles and the tracer occurs at the interface between the two streams, generating a distinct fluorescence signature that can be easily detected and quantified. This approach enables continuous monitoring of concentration, size distribution, morphology, and polymeric composition. We demonstrate the operation of our system using polystyrene nanoparticles in the 20 – 100 nm size range to establish the fluorescent signal’s dependence on size and concentration, as well as to quantify sensitivity and detection limits. When combined with a physico-chemical reaction-diffusion model describing the underlying nanoparticle-tracer interactions, these data make it possible to establish a compositional profile that can be applied to perform field-based analysis of the transport and fate of micro/nano-plastics in the environment.