ペットボトルの水に何が含まれているのか？数十万個の小さなプラスチック片が存在する可能性を示唆する研究結果(What’s in Your Bottled Water? Study Suggests There May Be Hundreds of Thousands of Tiny Plastic Bits)

2024-01-08 ラトガース大学

＜関連情報＞

• https://www.rutgers.edu/news/whats-your-bottled-water-study-suggests-there-may-be-hundreds-thousands-tiny-plastic-bits
• https://www.pnas.org/doi/10.1073/pnas.2300582121

SRS顕微鏡によるナノプラスチックの迅速な単一粒子化学イメージング Rapid single-particle chemical imaging of nanoplastics by SRS microscopy

Naixin Qian, Xin Gao, Xiaoqi Lang, +5, and Wei Min
Proceedings of the National Academy of Sciences  Published:January 8, 2024
DOI:https://doi.org/10.1073/pnas.2300582121

Significance

Micro-nano plastics originating from the prevalent usage of plastics have raised increasingly alarming concerns worldwide. However, there remains a fundamental knowledge gap in nanoplastics because of the lack of effective analytical techniques. This study developed a powerful optical imaging technique for rapid analysis of nanoplastics with unprecedented sensitivity and specificity. As a demonstration, micro-nano plastics in bottled water are analyzed with multidimensional profiling of individual plastic particles. Quantification suggests more than 10⁵ particles in each liter of bottled water, the majority of which are nanoplastics. This study holds the promise to bridge the knowledge gap on plastic pollution at the nano level.

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 × 10⁵ 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.