Synthesis, characterization and amoebicidal potential of locally synthesized TiO2 nanoparticles against pathogenic Acanthamoeba trophozoites in vitro

• Pure & Zn doped TiO2 were synthesized by two methods and used against Acanthamoeba.
• Sol–hydrothermally synthesized TiO2 exhibited ~ 60% amoebicidal effects while others ~ 40%.
• Zn doped TiO2 inhibited amoebic numbers up to 7 days in dose dependent manner.
• Optimal amoebicidal effects of TiO2 are at pH 7 which is relevant to amoebic growth conditions.
• First time we reported inhibitory potential of TiO2 on amoebic growth and viability.

Acanthamoeba is an opportunistic protozoan pathogen that plays a pivotal role in the ecosystem. It may cause blinding keratitis and fatal encephalitis involving the central nervous system. Here we synthesized pure and Zn doped TiO2 nanoparticles (~ 10–30 nm) via sol–gel and sol–hydrothermal methods and demonstrated its impact on the biological characteristics of pathogenic Acanthamoeba castellanii. Our results revealed that pure and Zn doped TiO2 nanoparticles synthesized by sol–hydrothermal methods (ranging 5, 10, 25 and 50 μg/ml) exhibited amoebicidal effects i.e., > 60% of trophozoites executed under normal light at maximum dose (50 μg/ml) within 1 h incubation. In contrast pure/doped TiO2 obtained via sol gel method showed ~ 40% amoeba damage. Furthermore, amoebae growth assay demonstrated that Zn doped TiO2 also inhibited Acanthamoeba numbers up to 7 days in dose dependent manner. It was interesting to note that all the tested TiO2 nanoparticles have shown maximum amoebicidal effects at pH 7 which is quite relevant to amoebic growth favorable conditions. Our results confirmed that TiO2 has inhibitory effects on Acanthamoeba growth and viability. Overall, we reported the amoebicidal and amoebic growth inhibition potential of pure and Zn doped TiO2 nanoparticles against Acanthamoeba due to attached OH− groups, reduced size and decreased band gap of sol hydrothermally synthesized TiO2 nanoparticles.

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