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Development of a Multi-Pathway Photosensitizer Cocktail for the Photodynamic Treatment of Harmful Algal Blooms

CSEF · 2023 Toxicology First Award

Kwok Christopher, Kwok Nicholas · 12

Overview

Greenhouse gases and nutrient loading have contributed to the proliferation of harmful algal blooms. The overgrowth of diatoms and dinoflagellates forms hypoxic dead zones and produces lethal toxins, threatening aquatic ecology and human health. Physical methods of remediating blooms are limited to small ponds, whereas commercial chemicals are slow, sensitive, and environmentally destructive. The project explores a more sustainable, targeted approach to control HABs through the novel development of a multi-pathway photosensitizer cocktail. Photodynamic therapy is a two-stage treatment involving a drug (photosensitizer) and light activation designed to kill target cells by generating reactive oxygen species and inducing apoptosis. The research was divided into three phases: Phase I synthesized and evaluated individual photosensitizers benzoporphyrin (carrier), anthraquinone (type I), and hypericin (type II) at 10 ppm and 20 ppm concentrations. Phase II combined the optimal concentrations of each photosensitizer to create different cocktail treatments for examination. Phase III performed toxicity assessments on the best cocktail treatment, analyzing phytotoxicity and cytotoxicity on non-algal cells. Microscopy and spectrophotometric assays of cell density and ROS yield discovered that a combination of benzoporphyrin 10 ppm + anthraquinone 20 ppm + hypericin 20 ppm most optimally inhibited algal colonies with a 98% efficacy. The low effective concentrations, good water solubility, and efficient sunlight activation created a multi-species treatment 20x faster and 400x cheaper than current algaecides. Non-toxic to non-algal cells and slow self-degradation prevents secondary residue. The project developed an environmental and economical HAB treatment that stops marine blooms.

Source coverage

This record comes from a published award list, not a complete project archive. Its abstract comes from CSEF's public project showcase as archived by the Internet Archive before judging (https://web.archive.org/web/20230401224130/https://ca-csef.zfairs.com/showcase/ShowcaseInfo?f=838e60b7-ea75-46e8-865c-fde4864244b3); the version presented may differ.

Awards (1)

Competition history

  • CSEF 2023 Toxicology · Entry S2106

Resources

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