Microplastics Classifications, Toxicity, and Visual Detection Methods Based on Fluorescent Materials

Microplastics (MPs) have emerged as a significant global environmental concern over recent decades due to their widespread presence in oceans, bioavailability, and ability to transport toxic substances. The analysis of MPs in both environmental and experimental samples has become increasingly common. Among the analytical steps, detection is crucial, as it directly provides the results. With a growing preference for simple, rapid, and instrument-free methods, visual detection where results can be seen and interpreted by the naked eye has become essential. This critical review summarizes and discusses advanced visual detection techniques, emphasizing their potential for on-site microplastic monitoring based on carbon dots (CDs), nanozyme sensing assays, and fluorescent dyes. Finally, the review outlines key challenges and proposes potential future research directions in this field.