Rylene Dye-Loaded Polymeric Nanoparticles for Photothermal Eradication of Harmful Dinoflagellates, Akashiwo sanguinea and Alexandrium pacificum

In the era of climate changes, harmful dinoflagellate outbreaks that produce potent algal toxins, odor, and water discoloration in aquatic environments have been increasingly reported. Thus, various treatments have been attempted for the mitigation and management of harmful blooms. Here, we report engineered nanoparticles that consist of two different types of rylene derivatives encapsulated in polymeric micelles. In addition, to avoid dissociation of the aggregate, the core of micelle was stabilized via semi-interpenetrating network (sIPN) formation. On two types of the marine red-tide dinoflagellates, Akashiwo sanguinea and Alexandrium pacificum, the nanoparticle uptake followed by fluorescence labeling and photothermal effect was conducted. Firstly, fluorescence microscopy enabled imaging of the dinoflagellates with the ultraviolet chromophore, Lumogen Violet. Lastly, near-infrared (NIR) laser irradiation was exposed on the Lumogen IR788 nanoparticle-treated Ak. Sanguinea. The irradiation resulted in reduced cell survival due to the photothermal effect in microalgae. The results suggested that the nanoparticle, IR788-sIPN, can be applied for potential red-tide algal elimination.