Self-Immolative Polythiophene for Sunlight Inactivation of Harmful Cyanobacteria
Yunhe Lang, Ying Wang, Ronghui Zhou, Peng Wu
Abstract
Harmful cyanobacterial blooms and the released microcystins (MCs) caused serious environmental and public health concerns to drinking water safety. Photo-oxidation is an appealing treatment option and alternative to conventional flocculation and microbial antagonists, but the performances of current photosensitizers (either inorganic or organic) are unsatisfactory. Here, a polythiophene photosensitizer (PT10) with both high yield of reactive oxygen species (ROS) production (mainly 1 O 2, Φ Δ = 0.51, > 8 h continuous generation) and moderate photostability was used as a powerful algaecide to inhibit Microcystis aeruginosa . Due to the positive charge of PT10, the algal cells were quickly flocculated, followed by efficient inactivation in 4 h under white light irradiation (96.7%, 10 mW/cm 2 ). Meanwhile, PT10 was self-immolated in about 6 h. Upon biosafety evaluation with adult zebrafish, the low toxicity of PT10 and the degradation products of PT10 and algae (early logarithmic growth stage) were confirmed. In addition, microcystin-LR (MC-LR), a toxic microcystin that will be released during the destruction of the algal cells, was also degraded. Therefore, PT10-based photoinactivation of M. aeruginosa featured both high performance and low secondary pollution. In real-world aquatic systems, PT10 was confirmed to be capable of sunlight-assisted inactivation of M. aeruginosa and prevent algal blooms, thus making it appealing for environmental remediation.