Usage of titanium dioxide nanoparticles (TiO₂ NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures in Allium cepa. Further, the toxicity of TiO₂ NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO₂ NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO₂), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC (EC₁₀ = 0.016 µmol/L) mixed with TiO₂ NPs significantly increased the toxicity for both UVA-TiO₂ and NI-TiO₂ NPs. Intracellular ROS generation was significantly high for UVA-TiO₂ NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential in A. cepa. Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO₂ NPs and TC showed the highest chromosomal aberrations (64.0%±1.26%) than the mixture with NI-TiO₂ or the individual contaminants. This decreased significantly after recovery (46.8%±1.92%), denoting the self-repair processes. This study proved that UVA-TiO₂ NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment.

在当前时代，二氧化钛纳米颗粒（TiO ₂ NPs）和四环素（TC）的使用已显着增加。这导致它们在环境中释放和积累。两种化合物都可能对植物产生不利的毒性作用。它们的二元混合物会增加这种程度的破坏。本研究旨在评估洋葱的单个和二元混合物中污染物的毒性。此外，还测量了TiO ₂ NPs在UVA预辐照下的毒性。结果表明，UVA预辐照的NPs（UVA-TiO ₂ NPs）与未辐照的对应物（NI-TiO _2）相比，细胞活力显着降低。），表示UVA预照射后光催化活性增加。极低浓度的TC（EC ₁₀ = 0.016 µmol / L）与TiO ₂ NP混合可显着提高UVA-TiO ₂和NI-TiO ₂ NP的毒性。UVA-TiO ₂ NPs的细胞内ROS生成明显较高。但是，TC对ROS的产生没有任何影响。两种化合物在洋葱曲霉中均显示出遗传毒性潜力。观察到了不同的染色体异常，如后期桥，末端桥，落后的染色体，双核细胞等。UVA-TiO ₂的二元混合物NPs和TC显示出最高的染色体畸变（64.0％±1.26％），高于与NI-TiO ₂的混合物或单个污染物的结合。恢复后，该值显着下降（46.8％±1.92％），表示自我修复过程。这项研究证明，与亚致死浓度的TC混合使用，UVA-TiO ₂ NPs更具毒性，并且可以进一步增强。这项工作将有助于评估两种化合物在环境中的风险。