Capturing Nanoplastics in Tap Water with Light: Breakthrough Research from Korea Institute

Raman-spectroscopy-based nanoplastic detection using the electric-optical tweezer and via surface-enhanced Raman scattering and the subsequent amplification of optical signals as well as the reduction of the accumulation time.Top right: Mimetic diagram of subsequent accumulation time reduction (blue: existing, red: current research)Bottom right: Mimetic diagram of subsequent amplification of optical signal accordingly (blue: existing, red: current research). Credit: Korea Institute of Science and Technology

The increasing amount of plastics in the environment is a global issue. Plastics, especially nanoplastics, have entered the ecosystem and pose a significant threat to human health and the environment. South Korea is among the countries with the highest concentration of microplastics in rivers globally. In addition, detecting nanoplastics is difficult because of their small size and low concentration. However, researchers at the Korea Institute of Science and Technology (KIST) have developed an innovative approach to capture and detect nanoplastics in real-time using electro-photonic tweezers and metal nanoparticles.

The Study

The study was conducted by a research team led by Dr. Yong-sang Ryu at the Brain Research Institute of KIST. The team used an electro-photonic tweezer along with metal nanoparticles to concentrate ultrafine nanoplastics in a short time period. They also developed a real-time detection system using light. The researchers supplied electricity to a large-area vertically-aligned metal sandwiched by a nanofilm insulator. They conducted Raman spectroscopy, which analyzes the energy difference between the incident and scattered light according to the frequency of the molecule. By combining the two techniques—electrical nanoparticle capture together with real-time Raman spectroscopy—the research team achieved the detection of a 30-nm 10 μg L-1 polystyrene particle with the help of gold nanoparticles via surface-enhanced Raman spectroscopy.

Results and Implications

The researchers were able to separate the particle from the sample through the dielectrophoresis phenomenon. This process reduced the entire process, including the collection, separation, and analysis, which previously required at least one day, to only several seconds. The study is published in the journal ACS Nano. The breakthrough research has significant implications for the detection of nanoplastics in water. The researchers stated that the proposed approach can be extended to the measurement of the microplastic concentration in various water resources and applied as a water resource securement technology.

Journal Information: Eui-Sang Yu et al, Real-Time Underwater Nanoplastic Detection beyond the Diffusion Limit and Low Raman Scattering Cross-Section via Electro-Photonic Tweezers, ACS Nano (2022). DOI: 10.1021/acsnano.2c07933