Presentation Information
[10a-P01-30]Detection and identification of single-digit nanoplastics using AuNP dimers
〇Rikiya Sodeyama1, Keiko Esashika1, Toshiharu Saiki1 (1.Keio Univ.)
Keywords:
raman enhancement,photonics,nanoplastics
In recent years, concern has grown over the health risks of nanoplastics. Significant amounts of plastic particles have been found in drinking water and food containers, indicating that oral ingestion is a major exposure route. Smaller particles are more readily absorbed, and those under 5 nm are particularly hazardous because they can penetrate cell membranes and evade immune detection. Therefore, identifying the types of single-digit nanoplastics in ingested materials is critically important. However, to our knowledge, no prior studies have spectroscopically detected or identified nanoplastics smaller than 10 nm.
In this study, we established a Raman spectroscopy-based method to detect and identify single-digit nanoplastics using gold nanoparticle (AuNP) dimers. The AuNPs, coated with citrate, carry a negative charge. Since different plastics have different surface charges, we optimized adsorption and dimer formation conditions for each plastic type.
We extracted nanoplastics from nylon 6 and polyethylene (PE) tea bags. Nylon 6, being positively charged, easily adsorbed onto negatively charged AuNPs in pure water, forming dimers spontaneously. In contrast, negatively charged PE repelled the AuNPs. Adding 20 mM NaCl neutralized the repulsion, promoting PE adsorption and dimerization.
After forming the dimers, we used agarose gel electrophoresis to isolate AuNP dimers with attached nanoplastics. We then conducted surface-enhanced Raman spectroscopy (SERS) on the collected samples. The spectra for nylon 6 and PE exhibited distinct, material-specific peaks, confirming successful detection and identification.
Transmission electron microscopy (TEM) showed that the interparticle gaps in the dimers—corresponding to plastic particle sizes—were all under 2 nm. This confirms that our method enables the detection and identification of single-digit nanoplastics, providing a new approach for analyzing nanoplastics in ingested materials.
In this study, we established a Raman spectroscopy-based method to detect and identify single-digit nanoplastics using gold nanoparticle (AuNP) dimers. The AuNPs, coated with citrate, carry a negative charge. Since different plastics have different surface charges, we optimized adsorption and dimer formation conditions for each plastic type.
We extracted nanoplastics from nylon 6 and polyethylene (PE) tea bags. Nylon 6, being positively charged, easily adsorbed onto negatively charged AuNPs in pure water, forming dimers spontaneously. In contrast, negatively charged PE repelled the AuNPs. Adding 20 mM NaCl neutralized the repulsion, promoting PE adsorption and dimerization.
After forming the dimers, we used agarose gel electrophoresis to isolate AuNP dimers with attached nanoplastics. We then conducted surface-enhanced Raman spectroscopy (SERS) on the collected samples. The spectra for nylon 6 and PE exhibited distinct, material-specific peaks, confirming successful detection and identification.
Transmission electron microscopy (TEM) showed that the interparticle gaps in the dimers—corresponding to plastic particle sizes—were all under 2 nm. This confirms that our method enables the detection and identification of single-digit nanoplastics, providing a new approach for analyzing nanoplastics in ingested materials.