An electrochemical biosensing approach for detection of microplastic beads

The rise in plastic packaging, household goods and single-use items has led to a significant increase in plastic production and pollution, including the generation of microplastics (MPs). These particles, widely dispersed in the environment, are being detected even in human blood and body fluids. The potential harm to the health of humans and other organism is an active area of research. Improved methods to detect MPs across different sizes is required to aid investigation into their dispersal, properties, and associated health risks. This study introduces an electrochemical, enzyme-based approach for MP monitoring inspired by biosensing. The approach employs horseradish peroxidase (HRP), a protein widely used as a molecular label, to physically adsorb onto PS particles and catalyze the redox reaction of a commercially available enzyme substrate that we show can be detected by chronoamperometric current measurements to infer the presence of PS MPs. Our electrochemical measurements were performed with low-cost printed electrodes and the results were corroborated by spectrophotometric measurements of the same substrate molecule. As a model study, different PS bead sizes and concentrations were used to characterize the sensitivity and the practical effectiveness of the approach. The overall results show that an enzyme-based electrochemical biosensing approach can lead to PS particle detection with signals generally increasing with bead concentration. Complex effects regarding sample processing as well as the size and exact properties of the particles, were also uncovered, which require further study.