Using visualization techniques to assess the accumulation of nanoplastics with varying surface modifications

Over the years, an increase in mass plastic production has caused growing concerns about the adverse effects that plastic nanoparticles (NPs) in the environment may have on human health. There are many knowledge gaps regarding the effects that NPs have on human health. Accurate studies prove challenging due to the hurdles in obtaining reliable model particles, performing accurate in vitro toxicology assessments, and visualizing results accurately. Numerous studies published in peer-reviewed literature have used commercially available NPs to represent environmental nanoplastic pollution. The commercial NPs with fluorescent tags were often used since they are easy to be monitored in cellular and organismal studies. However, the legitimacy of these commercial NP products has been questioned due to concerns about surface modifications altering interactions at the nano-bio interfaces, and the possibility that surface-bound fluorophores may detach and result in optical artifacts. Additionally, polystyrene is not the only polymer that should be investigated. We synthesized an orange, fluorescent organic dye and incorporated the dye into PMMA NPs to investigate skin cell uptake and in vivo biodistribution in a fish embryo model. We also compare the uptake results with that of the commonly used polystyrene particles and discuss possible mechanisms of uptake. Results revealed that 1) PMMA NPs can pass into embryos and potentially accumulate in larval bodies, and 2) commercially available sulfate-modified NPs and PMMA NPs accumulate similarly in fluorescently labeled fibroblast cells, however, PMMA NPs accumulate more localized intracellularly.