A Lab-on-a-Filter Immunoassay for Detecting Polystyrene Microplastics

Abstract Microplastics (MPs), defined as plastic particles with a size range of less than 5 mm, have emerged as significant environmental and health concerns. Due to their small size, they can easily enter the food chain and human body, with potential consequences for human health, including blocking blood flow, inflammation, organ damage, and even carcinogenesis. The presence of MPs in blood highlights the urgent need for effective and reliable detection methods to assess human exposure. Currently, detection techniques are either time-consuming or require expensive equipment, limiting their practicality for large-scale or routine clinical analysis. In this study, we developed an innovative and cost-effective lab-on-a-filter immunoassay (LoFI) for detecting polystyrene (PS)-MPs. Briefly, samples containing PS-MPs were subjected to pass through a 0.2 μm syringe filter, which was pre-blocked with gelatine solution. This filter allowed the collection of PS-MPs. After extensive washing, Rabbit anti-PS serum was added to bind with PS-MPs. Addition of HRP conjugated goat anti-rabbit antibody generates chromic signal. Our results showed that the current LoFI assay could achieve a limit of detection down to 1.62 ng/mL for PS detection in PBS buffer. It is expected this LoFI method will provide a versatile tool for detecting MPs in clinical samples.