We can't find the internet
Attempting to reconnect
Something went wrong!
Hang in there while we get back on track
A fluorescent counterstaining technique to differentiate microplastics from chitin using Nile red and calcofluor white in edible grasshoppers
Summary
Scientists developed a new dye technique that can accurately spot tiny plastic particles hiding in edible insects like grasshoppers, telling them apart from the insect's natural shell material (chitin), which often gets mistaken for plastic. This matters because as insects become a more popular protein source worldwide, we need reliable ways to check how much plastic contamination might be entering our food supply this way. The method is affordable and simple, making it a practical tool for future food safety testing.
Microplastics (MPs) are emerging contaminants of increasing environmental concern, and their detection in terrestrial organisms is essential for evaluating their impact, exposure and dynamics within ecosystems. Although insects represent a biologically relevant group for environmental monitoring and for estimating potential trophic transfer routes to humans, no standardized method currently exists for identifying MPs in these organisms. We have developed a detection protocol using edible grasshoppers (Sphenarium purpurascens) as study subjects. This combines Nile red (NR) and calcofluor white (CW) staining to distinguish added MPs from residual biological material (chitin). When NR was applied at 0.01 mg/mL, it successfully stained high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), expanded polystyrene (EPS), and polypropylene (PP), exhibiting polymer-dependent green or red fluorescence. A low NR concentration (0.01 mg/mL) was sufficient to ensure reliable visibility of the added MPs, while CW selectively stained chitin, emitting blue fluorescence under ultraviolet light. Counterstaining with both dyes provided a clear separation between MPs and biological structures, minimizing false positives. Furthermore, infrared spectroscopy (FTIR) confirmed the chemical composition of the added MPs (PP, EPS, ABS), complementing the limitations of NR staining. Thus, our NR-CW counterstaining protocol proved effective even for particles < 50 μm, and is cost-effective, simple to implement, and suitable for environmental studies involving organisms with chitin structures. Furthermore, it provides a reproducible tool suitable for estimating exposure and evaluating risks associated with MPs in terrestrial ecosystems.