Detecting Microplastics with Aptamer-Initiated HCR and AuNPs

Abstract

Microplastics (MPs) are plastic fragments smaller than five millimeters, existing in various mediums including drinking water, food, and within the human body. Previous research links the ingestion of microplastics to serious health issues including hormonal imbalances, infertility, and developmental abnormalities due to toxic phthalate esters (PEs), bisphenols, and heavy metals present in the MPs. Some of the most common MPs found in the environment include polystyrene (PS) and polyvinyl chloride (PVC) microplastics, accounting for over 36 million tons of waste in 2019. Despite all of this waste, current detection methods for these MPs in waterways are expensive, require extensive laboratory equipment and training, take a significant amount of time to produce results, lack sensitivity, and are overall inaccessible. This has resulted in a critical lack of MP tracking, making it difficult for preventative policies to be put into place had these metrics been known. In our study, we have designed an aptamer-based, enzyme free, colorimetric screening tool that can be used as a field-ready sensor to detect PVC and PS microplastics within drinking water. The signal generated by the aptamer adsorbing onto a microplastic is amplified using a Hybridization Chain Reaction (HCR) and then visualized with a colorimetric shift caused by the aggregation of gold nanoparticles (AuNPs). Thus, we provide a practical approach for microplastic detection and tracking, supporting efforts to reduce ingestion into the human body before serious health issues develop.