Real-Time Underwater Nanoplastic Detection beyond the Diffusion Limit and Low Raman Scattering Cross-Section via Electro-Photonic Tweezers

Abstract

Emerging as substantial concerns in the ecosystem, submicron plastics have attracted much attention for their considerable hazards. However, their effect and even amount in the environment remain unclear. Establishing a substantive analytic platform is essential to expand the understanding of nanoplastics. However, the issues of diffusion and detection limit that arise from ultradiluted concentration and extremely small scales of nanoplastics leave significant technical hurdles to analyze the nanoplastic pollutants. In this study, we obtain effective Raman signals in real time from underwater nanoplastics with ultralow concentrations via AC electro-osmotic flows and dielectrophoretic tweezing. This enables the field-induced active collection of nanoplastics toward the optical sensing area from remote areas in a rapid manner, integrating conventional technical skills of preconcentration, separation, and identification in a single process. A step further, synergetic combination with plasmonic nanorods, accomplishes the highest on-site detection performance so far.

On-the-Fly Monitoring of the Capture and Removal of Nanoplastics with Nanorobots

“…(Figure 4C) Overall, we propose a simple and fast method to detect nanoplastics, in comparison to currently used micro-FTIR, micro-RAMAN, and mass spectroscopy methods. [12][13][14][15]17 Using the proposed method demonstrates that nanorobots can remove nanoplastics from water in short treatment times.…”

“…The presented method is straightforward to implement in a chemical laboratory for the detection of nanoplastics, with the expectation that with further development it will overcome the challenges that current methodologies are faced with. To compare with similar studies, Yu et al 14 detected 30 nm polymer particles, using a very complex setup with a complicated surface to obtain the desired surface-enhanced Raman spectroscopy effect. On the other hand, in a study by Bianco et al 23 the detection limit was 600 nm, but a complex data treatment and expensive equipment were required to obtain the best results.…”

“…Microplastics detection is a well-studied field with a vast variety and complexity of methods that have been developed for their detection. Some examples are, pyrolysis gas-chromatography/mass spectroscopy, , Raman spectroscopy, − and micro-Fourier-transform infrared spectroscopy . One of the most used methods in microplastics detection and quantification relies on the staining of plastics with the fluorescent hydrophobic dye Nile Red. , This dye enables the observation and monitoring of a wide variety of plastic particles (polystyrene, polypropylene, and polyethylene, among others).…”

Integrated Passive Sensing Chip for Highly Sensitive and Reusable Detection of Differential-Charged Nanoplastics Concentration

“…10,11 In the laboratory research, ultraviolet, infrared, or total organic carbon (TOC) are commonly used. 12 However, the optical detection methods of ultraviolet and infrared are easily affected by the chromaticity of NPs solution, and TOC is easily affected by the dissolved organic matter in the system. 13,14 Currently, Raman spectroscopy is the primary method for the optical detection of NPs.…”

“…Although the harm of NPs is widely known, the microscopic nature of their particle sizes and the complexity of the natural environment make it challenging to detect NPs in the background. Therefore, laboratory research methods on the behavior of NPs can provide a reference for the monitoring research of NPs. , In the laboratory research, ultraviolet, infrared, or total organic carbon (TOC) are commonly used . However, the optical detection methods of ultraviolet and infrared are easily affected by the chromaticity of NPs solution, and TOC is easily affected by the dissolved organic matter in the system. , Currently, Raman spectroscopy is the primary method for the optical detection of NPs.…”