Rapid single-particle chemical imaging of nanoplastics by SRS microscopy

Abstract

Plastics are now omnipresent in our daily lives. The existence of microplastics (1 µm to 5 mm in length) and possibly even nanoplastics (<1 μm) has recently raised health concerns. In particular, nanoplastics are believed to be more toxic since their smaller size renders them much more amenable, compared to microplastics, to enter the human body. However, detecting nanoplastics imposes tremendous analytical challenges on both the nano-level sensitivity and the plastic-identifying specificity, leading to a knowledge gap in this mysterious nanoworld surrounding us. To address these challenges, we developed a hyperspectral stimulated Raman scattering (SRS) imaging platform with an automated plastic identification algorithm that allows micro-nano plastic analysis at the single-particle level with high chemical specificity and throughput. We first validated the sensitivity enhancement of the narrow band of SRS to enable high-speed single nanoplastic detection below 100 nm. We then devised a data-driven spectral matching algorithm to address spectral identification challenges imposed by sensitive narrow-band hyperspectral imaging and achieve robust determination of common plastic polymers. With the established technique, we studied the micro-nano plastics from bottled water as a model system. We successfully detected and identified nanoplastics from major plastic types. Micro-nano plastics concentrations were estimated to be about 2.4 ± 1.3 × 10 5 particles per liter of bottled water, about 90% of which are nanoplastics. This is orders of magnitude more than the microplastic abundance reported previously in bottled water. High-throughput single-particle counting revealed extraordinary particle heterogeneity and nonorthogonality between plastic composition and morphologies; the resulting multidimensional profiling sheds light on the science of nanoplastics.

Optical tracking of the heterogeneous solvent diffusion dynamics and swelling kinetics of single polymer microspheres

“…1 illustrates the principle of bright-field imaging for determining the swelling kinetics of individual microplastic particles. To date, common microplastics such as polymethylmethacrylate (PMMA), polystyrene (PS), polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), and polyethylene (PE) 15,16 have come into use. These microplastic particles pose a tremendous risk to environmental safety and human health.…”

Toward Nano- and Microplastic Sensors: Identification of Nano- and Microplastic Particles via Artificial Intelligence Combined with a Plasmonic Probe Functionalized with an Estrogen Receptor

“…Optical and electrochemical sensing strategies integrated with discrimination capability for the particle size and type represent a growing field. , In particular, different optical and/or electrochemical platforms were developed for this purpose. − For instance, the coupling between optical tweezers and ML was demonstrated for microplastics classification in terms of both size and material . However, this approach was not proven for plastic nanoparticles and requires an expensive and complex experimental setup.…”

“…Along this line, Doi et al demonstrated the use of optical tweezers to distinguish nano- and microparticles but without the discrimination of the material type. A very recent work proposes a sensing approach by hyperspectral stimulated Raman scattering (SRS) microscopy, demonstrating the nanoplastics classification in terms of different materials in water samples, but in this case too, the approach requires complex and expensive instrumentation. Analytical methods for microplastics characterization exploiting FTIR analysis coupled with AI-based tools were also available. , Additionally, the use of surface enhanced Raman scattering (SERS) substrates paves the way for micro- and nanoplastics identification .…”

Development of Enzyme-Based Approaches for Recycling PET on an Industrial Scale

“…5 The majority (54%) of PET is utilized for the production of textiles and fibers, another 24 MMT (or 29%) for rigid containers and single-use bottles, with the rest used in films and other applications. 6 Multiple chemical recycling strategies for PET have been developed over the last several decades and, in some cases, scaled up. 7−9 Their aim is also to potentially include PET substrates such as textiles that are not currently recycled.…”

“…Among plastics, poly­(ethylene terephthalate) (PET), a conjugate of terephthalic acid (TPA) and ethylene glycol (EG), is the most abundantly produced synthetic polyester in circulation today. , Production of PET has reached 82 million metric tons (MMT) per year . The majority (54%) of PET is utilized for the production of textiles and fibers, another 24 MMT (or 29%) for rigid containers and single-use bottles, with the rest used in films and other applications …”