Detection of polystyrene nanoplastics in biological tissues with a fluorescent molecular rotor probe

The release of nanoplastics (NPs) from the weathering and degradation of plastics is an important environmental concern. Given their small sizes and their invasiveness in cells, methods for the detection of NPs in biological tissues are urgently needed. A simple fluorescence-based methodology for the detection of polystyrene NPs in biological tissues is proposed. The commercially available molecular rotor probe 9- (dicyanovinyl)-julolidine (DCVJ) has the properties to detect changes in hydrophobicity and microviscosity and was used to detect NPs. Increasing concentrations of 50 and 100 nm NPs in water and in tissue extracts were mixed with the DCVJ probe and the emission spectra determined between 480-800 nm at 450 nm excitation. The data revealed that NPs induces a second emission peak at 620 nm that differed from the normal spectra of the biological extract at 500 nm. A significant linear relationship was obtained for NPs of both sizes (r=0.98; P<0.001) with a theoretical limit of detection of 65 ng/mL. A simple and rapid microplate spectrofluorometric method for the semi-quantitative detection of polystyrene NPs in biological tissues is thus presented.