The potential toxic impacts of different crystal phases of titania nanoparticles (TNPs) on freshwater biofilms, especially under ultraviolet C irradiation (UVC), are unknown. Here, adverse impacts of three phases (anatase, rutile, and P25, 50 mg L⁻¹ respectively) with UVC irradiation (An-UV, Ru-UV, and P25-UV) on freshwater biofilms were conducted. Characterization experiments revealed that rutile TNPs had a higher water environment stability than anatase and P25 TNPs, possessing a stronger photocatalytic activity under UVC irradiation. Phase-dependent inhibition of cell viability and significant decreases of four- and five-fold in algal biomass at 12 h of exposure were observed compared with unexposed biofilms. Moreover, phase-dependent oxidative stress resulted in remarkably significant reductions (P < 0.01) of the photosynthetic yields of the biofilms, to 40.32% (P25-UV), 48.39% (An-UV), and 46.77% (Ru-UV) of the plateau value obtained in the unexposed biofilms. A shift in community composition that manifested as a strong reduction in diatoms, indicating cyanobacteria and green algae were more tolerant than diatoms when exposed to TNPs. In terms of the toxic mechanisms, rutile TNPs resulted in apoptosis by inducing excessive intracellular reactive oxygen species (ROS) production, whereas P25 and anatase TNPs tended to catalyze enormous acellular ROS lead to cell necrosis under UVC irradiation.

未知二氧化钛纳米颗粒（TNP）的不同晶相对淡水生物膜的潜在毒性影响，尤其是在紫外线C辐射下的潜在毒性影响。此处，三个阶段（锐钛矿，金红石和P25，50 mg L ^-1）的不利影响分别在UVC辐照下（An-UV，Ru-UV和P25-UV）在淡水生物膜上进行。表征实验表明，金红石型TNPs比锐钛矿型和P25型TNPs具有更高的水环境稳定性，在UVC辐射下具有较强的光催化活性。与未暴露的生物膜相比，在暴露12 h时，观察到了细胞活力的阶段依赖性抑制以及藻类生物量的4倍和5倍显着下降。此外，依赖于相位的氧化应激导致生物膜的光合产量显着降低（P <0.01），分别降至40.32％（P25-UV），48.39％（An-UV）和46.77％（Ru-UV）在未暴露的生物膜中获得的平稳值的平均值。群落组成的变化表明硅藻的大量减少，表明当暴露于TNPs时，蓝藻和绿藻比硅藻更耐。就毒性机理而言，金红石型TNPs通过诱导过量的细胞内活性氧（ROS）产生而导致细胞凋亡，而P25和锐钛矿型TNPs倾向于催化大量的脱细胞ROS，从而在UVC辐射下导致细胞坏死。