# Plasmonic Nanomaterials for Micro- and Nanoplastics Detection
## 4 SERS-Based MNPs Detection
### Detection of MNP Using SERS-Based Techniques  
Even though the application of SERS for micro and nanoplastics detection is still in its infancy, several works have been published on this topic, with increasing numbers over the last years. Among the different techniques based on plasmonic materials that we have cited so far, SERS-based approaches are receiving the greatest interest in the scientific literature. In Table 3, we tried to summarize the different examples of SERS-based materials for MNPs sensing and detection that can be found in the literature. The main characteristics and the relevant experimental parameters of each approach (i.e., the operating laser wavelength, the type of detected plastics, the limits of detection where available, etc.) are included in the table, while a more detailed discussion is reported in the following paragraphs. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Substrate** & **Plastics** & **EF** & \(\lambda_{\text{exc}}\) **(nm)** & **LOD (\(\mu\)g/mL)** & **Real Sample LOD** \\ \hline \multicolumn{6}{c}{Colloidal} \\ \hline \multicolumn{6}{c}{PS 100 nm: EF = 5 \(\times\) 10\({}^{2}\)} \\ \multicolumn{6}{c}{PS 100 nm: EF = 4 \(\times\) 10\({}^{4}\)} \\ \multicolumn{6}{c}{PS 100, 500 nm} \\ \multicolumn{6}{c}{in seawater:} \\ \multicolumn{6}{c}{PE 100 \(\mu\)m} \\ \multicolumn{6}{c}{PP 10 \(\mu\)m} \\ \multicolumn{6}{c}{PP 10 \(\mu\)m} \\ \multicolumn{6}{c}{(Equation (3))} \\ \hline AgNPs [68] & PS 1 \(\mu\)m, 50 nm & — & 785 nm & PS 1 \(\mu\)m, 50 nm: 5 \(\mu\)g/mL & 1 \(\mu\)m, 50 nm: 5 \(\mu\)g/mL \\ \hline \multicolumn{6}{c}{PS 20(+) nm:} \\ \multicolumn{6}{c}{AuNPs [71]} & PS 20(+), 20(\(-\)), 200(\(-\)) nm & PS 20(+) nm: EF = 3050 & PS 20(+) nm: 10 \(\mu\)g/mL & PS 100 \(\mu\)g/mL in NaCl \\ \multicolumn{6}{c}{PS 500 nm: EF = 6 \(\times\) 10\({}^{3}\)} \\ \multicolumn{6}{c}{(Equation (3))} \\ \hline Au & \multicolumn{6}{c}{PS 600 nm} \\ \multicolumn{6}{c}{[124]} \\ \multicolumn{6}{c}{AuNPs [82]} & PS 100 nm & — & 532 nm & 200 ug/mL & \multicolumn{1}{c}{–} \\ \hline \multicolumn{6}{c}{PS 50 nm: EF = 1 \(\times\) 10\({}^{4}\)} \\ \multicolumn{6}{c}{PS 100 nm: EF = 2.30 \(\times\) 10\({}^{4}\)} \\ \multicolumn{6}{c}{PS 50 02 nm: EF = 5.50 \(\times\) 10\({}^{3}\)} \\ \multicolumn{6}{c}{PS 500 nm: EF = 6 \(\times\) 10\({}^{3}\)} \\ \multicolumn{6}{c}{(Equation (3))} \\ \hline Elliptical & PS 350 nm, 1 \(\mu\)m & \multicolumn{1}{c}{–} & 632 nm & PS 350 nm: 6.25 ug/mL & \multicolumn{1}{c}{–} \\ \multicolumn{6}{c}{(Equation (2))} \\ \hline Au nanorods [125] & PS 30, 200 nm & PS 200 nm: EF = 10\({}^{2}\) & \multicolumn{1}{c}{–} & \multicolumn{1}{c}{–} \\ \multicolumn{6}{c}{(\(\overline{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \texttexttexttexttexttexttexttexttexttext       }}}}}}}}}}}}}}}\) \\ \multicolumn{1}{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \texttexttexttexttexttext {\texttexttext }}}}}}}}}}}}}}}}\) \\ \multicolumn{6}{c}{PMMA 300 nm} \\ \multicolumn{6}{c}{Device} \\ \hline \multicolumn{6}{c}{46 nm AuNPs:} \\ \multicolumn{6}{c}{PS 33 nm: 20 ug/mL} \\ \multicolumn{6}{c}{PS 161 nm: 10 ug/mL} \\ \multicolumn{6}{c}{AP 62 nm} \\ \multicolumn{6}{c}{PE 60–450 (Equation (3))} \\ \multicolumn{6}{c}{PE 62 nm} \\ \multicolumn{6}{c}{AP 62 nm} \\ \multicolumnWhen using SERS for MNPs detection, three main strategies can be identified:  
* SERS detection based on colloidal noble metal nanoparticles;
* SERS detection employing nanostructured devices;
* Hybrid SERS system capable of both the detection and remediation of MNPs. We describe each approach in detail as well as the relevant literature in the following sections.