Korean researchers create AI-based microplastic detection kit

09 Oct 2023 --- Researchers have developed a technology to detect microplastics (MPs), which can cause human and genetic toxicity through environmental pollution and the food chain. The scientists say that their machine learning (ML)-based system is expected to be used for various MPs detection and environmentally hazardous substances, such as bacteria, viruses and fungi.

The research team was led by Dr. Ho Sang Jung of the Department of Nano-Bio Convergence at the Korea Institute of Materials Science, a research institute under the Ministry of Science and ICT, in collaboration with the Kotiti Testing & Research Institute.

Developing on-site applicable, facile and quick MP detection methods remains challenging, according to the study authors. The study uses 3D-plasmonic gold nanopocket (3D-PGNP) nanoarchitecture on a paper substrate for simultaneous MP filtration and detection.

The paper-based 3D-PGNP is integrated with a syringe filter device, and then MP-containing solutions are injected through the syringe. Subsequent detection of the MPs using surface-enhanced Raman scattering (SERS) successfully identifies the MPs without pretreatment.

The interface and volumetric hotspot generation of 3D-PGNP around the captured MPs significantly improves the sensitivity, confirmed by finite-difference time-domain simulation.

Then, the SERS mapping images obtained from a portable Raman spectrometer are transformed into digital signals via ML technique to identify and quantify the MP distribution. The developed SERS-ML-based MP detection kit is applied for mixture MPs and real matrix samples, demonstrating that the method provides improved accuracy.

SERS is an optical technology that amplifies the Raman scattering signals of molecules adsorbed on plasmonic materials. Raman spectrum shows molecule-specific vibrational signals and has been widely used for environmental, biological and medical sensing.

The scientists say the system is expected to be used for various MPs detection and environmentally hazardous substances.Overcoming limitations
Recent research using the SERS technique for MP detection focuses on the sensitive quantification of MP concentration, detection of various MP sizes and classification of the MP composition in the sample matrix.

But most of these studies use a SERS substrate comprising nanogaps, which limits the detection of large-sized MPs in the micro to submicrometer range because they are hard to place at the hotspot region, generating attenuated SERS signals far from the hotspot.

Furthermore, nanoparticle-mediated MP aggregation for SERS signal generation exhibits limitations regarding signal uniformity, which are induced by the heterogeneous attachment of nanoparticles to the MP surface.

Therefore, the development of substrate-type SERS materials that can capture and generate harmonized MP SERS signals can overcome conventional limitations. Multiple hotspots need to be generated at the SERS substrate-MP interface for sensitive MP detection. This can be achieved by constructing nanoarchitectures with large-sized pores that can capture and surround the MPs.

In addition, the concentration and the number of MPs in the sample are crucial to identifying various MP types. Therefore, the scientists say that a method that can verify the presence of MPs in a large area with a high resolution is required, as it can perform individual particle analysis providing shape information.

The research was published in Advanced Functional Materials.

By Natalie Schwertheim

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