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Bacteria viability assessment after photocatalytic treatment
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
2014 (English)In: 3 Biotech, ISSN 2190-5738, Vol. 4, no 2, 149-157 p.Article in journal (Refereed) Published
Abstract [en]

The aim of the present work was to evaluate several methods for analyzing the viability of bacteria after antibacterial photocatalytic treatment. Colony-forming unit (CFU) counting, metabolic activity assays based on resazurin and phenol red and the Live/Dead® BacLight™ bacterial viability assay (Live/Dead staining) were employed to assess photocatalytically treated Staphylococcus epidermidis and Streptococcus mutans. The results showed conformity between CFU counting and the metabolic activity assays, while Live/Dead staining showed a significantly higher viability post-treatment. This indicates that the Live/Dead staining test may not be suitable for assessing bacterial viability after photocatalytic treatment and that, in general, care should be taken when selecting a method for determining the viability of bacteria subjected to photocatalysis. The present findings are expected to become valuable for the development and evaluation of photocatalytically based disinfection applications

Place, publisher, year, edition, pages
Springer, 2014. Vol. 4, no 2, 149-157 p.
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
URN: urn:nbn:se:uu:diva-197796DOI: 10.1007/s13205-013-0137-1OAI: diva2:614266
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2015-04-02Bibliographically approved
In thesis
1. Titanium Dioxide Photocatalysis in Biomaterials Applications
Open this publication in new window or tab >>Titanium Dioxide Photocatalysis in Biomaterials Applications
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Despite extensive preventative efforts, the problem of controlling infections associated with biomedical materials persists. Bacteria tend to colonize on biocompatible materials and form biofilms; thus, novel biomaterials with antibacterial properties are of great interest. In this thesis, titanium dioxide (TiO2)-associated photocatalysis under ultraviolet (UV) irradiation was investigated as a strategy for developing bioactivity and antibacterial properties on biomaterials. Although much of the work was specifically directed towards dental materials, the results presented are applicable to a wide range of biomaterial applications.

Most of the experimental work in the thesis was based on a resin-TiO2 nanocomposite that was prepared by adding 20 wt% TiO2 nanoparticles to a resin-based polymer material. Tests showed that the addition of the nanoparticles endowed the adhesive material with photocatalytic activity without affecting the functional bonding strength. Subsequent studies indicated a number of additional beneficial properties associated with the nanocomposite that appear promising for biomaterial applications. For example, irradiation with UV light induced bioactivity on the otherwise non-bioactive nanocomposite; this was indicated by hydroxyapatite formation on the surface following soaking in Dulbecco’s phosphate-buffered saline. Under UV irradiation, the resin-TiO2 nanocomposite provided effective antibacterial action against both planktonic and biofilm bacteria. UV irradiation of the nanocomposite also provided a prolonged antibacterial effect that continued after removal of the UV light source. UV treatment also reduced bacterial adhesion to the resin-TiO2 surface.

The mechanisms involved in the antibacterial effects of TiO2 photocatalysis were studied by investigating the specific contributions of the photocatalytic reaction products (the reactive oxygen species) and their disinfection kinetics. Methods of improving the viability analysis of bacteria subjected to photocatalysis were also developed. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 57 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1033
titanium dioxide, photocatalysis, bioactivity, antibacterial effect, metabolic activity assay, biofilm, reactive oxygen species, disinfection kinetics, post-UV
National Category
Nano Technology
urn:nbn:se:uu:diva-160634 (URN)978-91-554-8634-1 (ISBN)
Public defence
2013-05-22, Häggsalen, Ångström laboratory, Lägerhyddsvägen 1, Uppsala, 13:30 (English)
Available from: 2013-04-26 Created: 2011-10-27 Last updated: 2013-08-30Bibliographically approved

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