Robust Natural Light-Absorbable and -Degradable AIE Photosensitizers for Fluorescence Labeling and Efficient Photodynamic Eradication of Algal Pollutants.

Abstract

Current water pollution caused by the excessive proliferation of harmful algae urges green methods that can efficiently utilize natural light to treat algal pollution. Herein, a series of aggregation-induced emission (AIE) photosensitizers that can efficiently harness sunshine were synthesized for the environmentally friendly and biocompatible treatment of algal pollution. By tuning the number of thiophene units and the electron conjugation degree, the photosensitizers' absorptions were broadened to cover the whole visible light range. The positive charges guided photosensitizers to aggregate on algal cell surfaces, resulting in a turn-on fluorescence signal and robust reactive oxygen species generation under sunshine, thereby achieving fluorescence labeling and photodynamic eradication of algae. The eradication outcomes demonstrated that the AIE photosensitizers significantly outperformed the commercial algaecide ALG. At 20 ppm photosensitizers, 90.4% and 94.2% killing rates were achieved for C. reinhardtii and C. vulgaris, respectively, 2.8- and 3.6-fold higher than those from the same concentration of ALG. Excellent performances in inhibiting algae growth were also verified with efficiency superior to that of ALG. Importantly, the photosensitizers can self-degrade into biocompatible fragments under irradiation to avoid secondary pollution. The developed photosensitizers that possess sunshine convertibility and degradability provide an efficient tool for algal treatment, showing broad research and application prospects.