Comparison of TiO2 and ZnO nanoparticles for photocatalytic degradation of methylene blue and the correlated inactivation of gram-positive and gram-negative bacteria

  • Robert J. Barnes
  • Rodrigo Molina
  • Jianbin Xu
  • Peter J. Dobson
  • Ian P. ThompsonEmail author
Research Paper


Titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles are important photocatalysts and as such have been extensively studied for the removal of organic compounds from contaminated air and water and for microbial disinfection. Despite much research on the effect of TiO2 and ZnO nanoparticles on different bacterial species, uncertainties remain about which bacteria are more sensitive to these compounds. Very few studies have directly compared the toxicity of ZnO to TiO2 under both light and dark conditions. In addition, authors investigating the photocatalytic inactivation of TiO2 and ZnO nanoparticles on bacteria have failed to investigate the reactive oxygen species (ROS) generation of the nanoparticles, making it difficult to correlate killing action with the generation of ROS. In this study, three types of metal nanoparticle (ZnO < 50 nm, ZnO < 100 nm and TiO2) have been characterised and ROS production assessed through the degradation of methylene blue (MB). The photocatalytic killing potential of three nanoparticle concentrations (0.01, 0.1 and 1 g/L) was then assessed on four representative bacteria: two gram-positive (S. aureus and B. subtilis) and two gram-negative (E. coli and P. aeruginosa). Results showed that out of the three nanoparticles tested, the TiO2 nanoparticles generated more ROS than the ZnO nanoparticles, corresponding to a greater photocatalytic inactivation of three of the four species of bacteria examined. The MB decomposition results correlated well with the bacterial inactivation results with higher TiO2 nanoparticle concentrations leading to greater ROS production and increased loss of cell viability. Although producing less ROS than the TiO2 nanoparticles under ultraviolet light, the ZnO nanoparticles were toxic to two of the bacterial species even under dark conditions. In this study, no correlation between cell wall type and bacterial inactivation was observed for any of the nanoparticles tested although both gram-positive bacteria were sensitive to ROS production. P. aeruginosa cells were resistant to all types of treatment and highlight a potential limitation to the application of these nanoparticles for water treatment.


Nanoparticles Metal oxides Reactive oxygen species Toxicity Bacteria Photocatalysis 



Research was supported by NERC. The authors also thank Xin Zhao and Frank Cullen of the Department of Materials, University of Oxford, for TEM and XRD analyses.


  1. Adams LK, Lyon DY, Alvarez PJJ (2006) Comparative eco-toxicity of nanoscale TiO2, SiO2, and ZnO water suspensions. Water Res 40:3527–3532CrossRefGoogle Scholar
  2. Blake DM, Maness PC, Huang Z, Wolfrum EJ, Huang J (1999) Application of the photocatalytic chemistry of titanium dioxide to disinfection and the killing of cancer cells. Sep Purif Methods 28:1–50CrossRefGoogle Scholar
  3. Brayner R, Ferrari-Iliou R, Brivois N, Djediat S, Benedetti MF, Fiévet F (2006) Toxicological impact studies based on Escherichia coli bacteria in ultrafine ZnO nanoparticles colloidal medium. Nano Lett 6:866–870CrossRefGoogle Scholar
  4. Byrne JA, Eggins BR, Brown NMD, McKinnery B, Rouse M (1998) Immobilisation of TiO2 powder for the treatment of polluted water. Appl Catal B 17:25–36CrossRefGoogle Scholar
  5. Cho M, Chung H, Choi W, Yoon J (2004) Linear correlation between inactivation of E. coli and OH radical concentration in TiO2 photocatalytic disinfection. Water Res 38:1069–1077CrossRefGoogle Scholar
  6. Fu G, Vary PS, Lin C-T (2005) Anatase TiO2 nanocomposites for antimicrobial coatings. J Phys Chem B 109:8889–8898CrossRefGoogle Scholar
  7. Gaswami DY, Trivedi DM, Block SS (1997) Photocatalytic disinfection of indoor air. J Sol Energy Eng 119:92–96CrossRefGoogle Scholar
  8. Hariharan C (2006) Photocatalytic degradation of organic contaminants in water ZnO by nanoparticles: revisited. Appl Catal A 304:55–61CrossRefGoogle Scholar
  9. Hoffmann MR, Martin ST, Choi W, Bahnemann DW (1995) Environmental applications of semiconductor photocatalysis. Chem Rev 95:69–96CrossRefGoogle Scholar
  10. Huang Z, Zheng X, Yan D, Yin G, Liao X, Kang Y, Yao Y, Huang D, Hao B (2008) Toxicological effect of ZnO nanoparticles based on bacteria. Langmuir 24:4140–4144CrossRefGoogle Scholar
  11. Jacoby WA, Maness PC, Wolfrum EJ, Blake DM, Fennel JA (1998) Mineralization of bacterial cell mass on a photocatalytic surface in air. Environ Sci Technol 32:2650–2653CrossRefGoogle Scholar
  12. Jiang W, Mashayekhi H, Xing B (2009) Bacterial toxicity comparison between nano- and micro-scaled oxide particles. Environ Pollut 157:1619–1625CrossRefGoogle Scholar
  13. Johnson AC, Bowes MJ, Crossley A, Jarvie HP, Jurkschat K, Jürgens MD, Lawlor AJ, Park B, Rowland P, Spurgeon D, Svendsen C, Thompson IP, Barnes RJ, Williams RJ, Xu N (2011) An assessment of the fate, behaviour and environmental risk associated with sunscreen TiO2 nanoparticles in UK field scenarios. Sci Total Environ 409:2503–2510CrossRefGoogle Scholar
  14. Jones N, Ray B, Ranjit KT, Manna AC (2008) Antibacterial activity of ZnO nanoparticle suspensions on a broad spectrum of microorganisms. FEMS Microbiol Lett 279:71–76CrossRefGoogle Scholar
  15. Kwon CH, Shin H, Kim JH, Choi WS, Yoon KH (2004) Degradation of methylene blue via photocatalysis of titanium dioxide. Mater Chem Phys 86:78–82CrossRefGoogle Scholar
  16. Lakshmi S, Renganathan R, Fujita S (1995) Study on TiO2-mediated photocatalytic degradation of methylene blue. A 88:163–167Google Scholar
  17. Legrini O, Oliveros E, Braun AM (1993) Photochemical processes for water treatment. Chem Rev 93:671–698CrossRefGoogle Scholar
  18. Linsebigler AL, Lu G, Yates JT (1995) Photocatalysis on TiO2 surfaces: principles, mechanisms, and selected results. Chem Rev 95:735–758CrossRefGoogle Scholar
  19. Liu Y, He L, Mustapha A, Li H, Hu ZQ, Lin M (2009) Antibacterial activities of zinc oxide nanoparticles against Escherichia coli O157:H7. J Appl Microbiol 107:1193–1201CrossRefGoogle Scholar
  20. Maness PC, Smolinski S, Blake DM, Huang Z, Wolfrum EJ, Jacoby WA (1999) Bactericidal activity of photocatalytic TiO(2) reaction: toward an understanding of its killing mechanism. Appl Environ Microbiol 65:4094–4098Google Scholar
  21. Muggli DS, Ding L (2001) Photocatalytic performance of sulfated TiO2 and Degussa P-25 TiO2 during oxidation of organics. Appl Catal B 32:181–194CrossRefGoogle Scholar
  22. Padmavathy N, Vijayaraghavan R (2008) Enhanced bioactivity of ZnO nanoparticles-an antimicrobial study. Sci Technol Adv Mater 9:035004Google Scholar
  23. Premanathan M, Karthikeyan K, Jeyasubramanian K, Manivannan G (2011) Selective toxicity of ZnO nanoparticles toward Gram-positive bacteria and cancer cells by apoptosis through lipid peroxidation. Nanomedicine 7:184–192CrossRefGoogle Scholar
  24. Qamar M, Muneer M (2009) A comparative photocatalytic activity of titanium dioxide and zinc oxide by investigating the degradation of vanillin. Desalination 249:535–540CrossRefGoogle Scholar
  25. Rincon AG, Pulgarin C (2005) Use of coaxial photocatalytic reactor (CAPHORE) in the TiO2 photo-assisted treatment of mixed Escherichia coli and Bacillus subtilis and the bacterial community present in wastewater. Catal Today 101:331–344CrossRefGoogle Scholar
  26. Sawai J (2003) Quantitative evaluation of antibacterial activities of metallic oxide powders (ZnO, MgO and CaO) by conductimetric assay. J Microbiol Methods 54:177–182CrossRefGoogle Scholar
  27. Sawai J, Igarashi H, Hashimoto A, Kokugan T, Shimizu M (1995) Effect of ceramic powders on spores of Bacillus subtilis. J. Chem. Eng. Japan 28:288–293CrossRefGoogle Scholar
  28. Tayel AA, El-Tras WF, Moussa S, El-Baz AF, Mahrous H, Salem MF, Brimer L (2011) Antibacterial action of zinc oxide nanoparticles against foodborne pathogens. J Food Saf 31:211–218CrossRefGoogle Scholar
  29. Tsuang YH, Sun JS, Huang YC, Lu CH, Chang WH, Wang CC (2008) Studies of photokilling of bacteria using titanium dioxide nanoparticles. Artif Organs 32:167–174CrossRefGoogle Scholar
  30. Turchi CS, Ollis DF (1990) Photocatalytic degradation of organic water contaminants: mechanisms involving hydroxyl radical attack. J Catal 122:178–192CrossRefGoogle Scholar
  31. Wei C, Lin WY, Zaina Z, Williams NE, Zhu K, Kruzic AP, Smith RL, Rajeshwar K (1994) Bactericidal activity of TiO2 photocatalyst in aqueous media: toward a solar-assisted water disinfection system. Environ Sci Technol 28:934–938CrossRefGoogle Scholar
  32. Xu N, Shi Z, Fan Y, Dong J, Shi J, Hu MZ-C (1999) Effects of particle size of TiO2 on photocatalytic degradation of methylene blue in aqueous suspensions. Ind Eng Chem Res 38:373–379CrossRefGoogle Scholar
  33. Xue Z, Hessler CM, Panmanee W, Hassett DJ, Seo Y (2013) Pseudomonas aeruginosa inactivation mechanism is affected by capsular extracellular polymeric substance reactivity with chlorine and monochloramine. FEMS Microbiol Ecol 83:101–111Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Robert J. Barnes
    • 1
  • Rodrigo Molina
    • 1
  • Jianbin Xu
    • 1
  • Peter J. Dobson
    • 2
  • Ian P. Thompson
    • 1
    Email author
  1. 1.Department of Engineering ScienceOxford UniversityOxfordUK
  2. 2.Begbroke Directorate, Oxford University Begbroke Science ParkSandy LaneUK

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