Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Titanium Dioxide Photocatalysis in Biomaterials Applications
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
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.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1033
Keyword [en]
titanium dioxide, photocatalysis, bioactivity, antibacterial effect, metabolic activity assay, biofilm, reactive oxygen species, disinfection kinetics, post-UV
National Category
Nano Technology
Identifiers
URN: urn:nbn:se:uu:diva-160634ISBN: 978-91-554-8634-1 (print)OAI: oai:DiVA.org:uu-160634DiVA: diva2:614342
Public defence
2013-05-22, Häggsalen, Ångström laboratory, Lägerhyddsvägen 1, Uppsala, 13:30 (English)
Supervisors
Available from: 2013-04-26 Created: 2011-10-27 Last updated: 2013-08-30Bibliographically approved
List of papers
1. Dental adhesives with bioactive and on-demand bactericidal properties
Open this publication in new window or tab >>Dental adhesives with bioactive and on-demand bactericidal properties
2010 (English)In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 26, no 5, 491-499 p.Article in journal (Refereed) Published
Abstract [en]

Objectives: The aim of the present work was to perform the first in vitro evaluation of a new interfacial bond-promoting material-and-method concept for on-demand long term bacteria inhibition in dental restoration procedures. Methods: The bioactivity, mechanical bonding strength and photocatalytic bactericidal properties, induced by low dose ultraviolet-A (UV-A) irradiation of dental adhesives containing crystalline titania nanoparticles (NPs), were analyzed. Results: Dental adhesives with a NP content of 20 wt% were shown to be bioactive in terms of spontaneous hydroxylapatite formation upon storage in simulated body fluid and the bioactivity was found to be promoted by chemical etching of the adhesives. The mechanical bonding strength between the adhesives and a HA tooth model was shown to be unaffected by the NPs up to a NP content of 30 wt%. Elimination of Staphylococcus epidermidis in contact with the adhesives was found to depend both on UV photocatalytic irradiation intensity and time. Efficient elimination of the bacteria could be achieved using a UV-A dose of 4.5 J/cm2 which is about 6 times below the safe maximum UV dose according to industry guidelines, and 20 times below the average UV-A dose received during an ordinary sun bed session. Significance: The combined features of bioactivity and on-demand bactericidal effect should open up the potential to create dental adhesives that reduce the incidence of secondary caries and promote closure of gaps forming at the interface towards the tooth via remineralization of adjacent tooth substance, as well as prevention of bacterial infections via on-demand UV-A irradiation.

Keyword
Antibacterial, Bioactivity, Dental adhesive, Nanoparticles, Photocatalysis, Titanium oxide
National Category
Engineering and Technology
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-121515 (URN)10.1016/j.dental.2010.01.008 (DOI)000275815300012 ()20189237 (PubMedID)
Available from: 2010-03-24 Created: 2010-03-24 Last updated: 2017-12-12Bibliographically approved
2. Photocatalysis induces bioactivity of an organic polymer based material
Open this publication in new window or tab >>Photocatalysis induces bioactivity of an organic polymer based material
Show others...
2014 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 101, 57715-57723 p.Article in journal (Refereed) Published
Abstract [en]

Several materials, like bioglasses, sintered hydroxyapatite and Ti metals and alloys, have the ability to bond to living bone in vivo, which is a desirable property of biomaterials called bioactivity. In this work, we present a novel strategy to develop bioactivity on the non-bioactive surface of a resin-TiO2 nanocomposite through photocatalysis. The results show that UV irradiation (365 nm, 10 mW cm(-2)) for 8 to 16 h on the resin-TiO2 nanocomposite immersed in water induces bioactivity as indicated by hydroxyapatite growth following immersion of the samples in Dulbecco's phosphate buffered saline for 7 days at 37 degrees C. While a nonirradiated resin-TiO2 surface did not show any hydroxyapatite deposition, a surface after 16 h of UV irradiation was fully covered by hydroxyapatite. In vitro cell adhesion of osteoblast-like MG63 cells confirmed the biocompatibility and bioactivity of the resin-TiO2 surfaces with a hydroxyapatite deposition layer, while the non-irradiated resin-TiO2 surface showed no cell adhesion. Resin-TiO2 nanocomposites, with or without UV irradiation, proved to be nontoxic to two human cell lines, human dermal fibroblasts (hDF) and MG63 cells. It was also shown that an increased dose of UV irradiation decreased bacterial adhesion, which is an additional benefit of the UV treatment and a favourable property for biomedical applications. The combined benefits of biocompatibility, bioactivity, decreased bacterial adhesion and the highly efficient disinfection property of TiO2 photocatalysis under UV light make this resin-TiO2 material an interesting candidate for implant and biomedical device applications.

National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-197798 (URN)10.1039/c4ra08805k (DOI)000345651600048 ()
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2017-12-06Bibliographically approved
3. A Method for Quantitative Determination of Biofilm Viability
Open this publication in new window or tab >>A Method for Quantitative Determination of Biofilm Viability
2012 (English)In: Journal of Functional Biomaterials, ISSN 2079-4983, Vol. 3, no 2, 418-431 p.Article in journal (Refereed) Published
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-182501 (URN)10.3390/jfb3020418 (DOI)
Available from: 2012-10-11 Created: 2012-10-11 Last updated: 2016-11-30Bibliographically approved
4. Bacteria viability assessment after photocatalytic treatment
Open this publication in new window or tab >>Bacteria viability assessment after photocatalytic treatment
2014 (English)In: 3 Biotech, ISSN 2190-5738, E-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
National Category
Biomaterials Science Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-197796 (URN)10.1007/s13205-013-0137-1 (DOI)000358045200005 ()
Funder
Carl Tryggers foundation Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologySwedish Research CouncilVINNOVASwedish Foundation for Strategic Research
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2017-12-06Bibliographically approved
5. Photocatalytic inactivation of biofilms on bioactive dental adhesives
Open this publication in new window or tab >>Photocatalytic inactivation of biofilms on bioactive dental adhesives
Show others...
2014 (English)In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 102, no 1, 62-67 p.Article in journal (Refereed) Published
Abstract [en]

Biofilms are the most prevalent mode of microbial life in nature and are 10-1000 times more resistant to antibiotics than planktonic bacteria. Persistent biofilm growth associated at the margin of a dental restoration often leads to secondary caries, which remains a challenge in restorative dentistry. In this work, we present the first in vitro evaluation of on-demand photocatalytic inactivation of biofilm on a novel dental adhesive containing TiO2 nanoparticles. Streptococcus mutans biofilm was cultured on this photocatalytic surface for 16 h before photocatalytic treatment with ultraviolet-A (UV-A) light. UV-A doses ranging from 3 to 43 J/cm(2) were applied to the surface and the resulting viability of biofilms was evaluated with a metabolic activity assay incorporating phenol red that provided a quantitative measure of the reduction in viability due to the photocatalytic treatments. We show that an UV-A irradiation dose of 8.4 J/cm(2) leads to one order of magnitude reduction in the number of biofilm bacteria on the surface of the dental adhesives while as much as 5-6 orders of magnitude reduction in the corresponding number can be achieved with a dose of 43 J/cm(2). This material maintains its functional properties as an adhesive in restorative dentistry while offering the possibility of a novel dental procedure in the treatment or prevention of bacterial infections via on-demand UV-A irradiation. Similar materials could be developed for the treatment of additional indications such as peri-implantits.

Keyword
photocatalysis, titanium dioxide, biofilm inactivation, Streptococcus mutans, metabolic activity assay
National Category
Biomaterials Science Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-197797 (URN)10.1002/jbm.b.32980 (DOI)000328153100007 ()23847027 (PubMedID)
Funder
Carl Tryggers foundation Göran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologySwedish Research CouncilVINNOVASwedish Foundation for Strategic Research
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2017-07-05Bibliographically approved
6. Disinfection Kinetics and Contribution ofReactive Oxygen Species When EliminatingBacteria with TiO2 Induced Photocatalysis
Open this publication in new window or tab >>Disinfection Kinetics and Contribution ofReactive Oxygen Species When EliminatingBacteria with TiO2 Induced Photocatalysis
2014 (English)In: Journal of Biomaterials and Nanobiotechnology, ISSN 2158-7027, E-ISSN 2158-7043, Vol. 5, no 3, 200-209 p.Article in journal (Refereed) Published
Abstract [en]

Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfectionstrategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxylradicals (•OH), superoxide radicals ( •−2 O ) and hydrogen peroxide (H2O2), generated in thephotocatalytic reaction process are considered to be the active components prompting the bactericidaleffect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidisand specific contributions of •OH, •−2 O and H2O2 to the bactericidal process were studiedusing two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfacesand suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with alayer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficientROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-stepbehavior with an initial region having a lower disinfection rate followed by a higher rate regionafter 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria andphotocatalytic TiO2 nanoparticles, •OH and H2O2 showed equal significance in the bacterial inactivationhaving a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate.The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalyticdisinfection that are essential for designing specific antibacterial applications of photocatalyticmaterials.

National Category
Materials Engineering Nano Technology
Identifiers
urn:nbn:se:uu:diva-197799 (URN)10.4236/jbnb.2014.53024 (DOI)
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2017-12-06Bibliographically approved
7. Post-UV antibacterial properties of a resin-TiO2 nanocomposite
Open this publication in new window or tab >>Post-UV antibacterial properties of a resin-TiO2 nanocomposite
(English)Article in journal (Refereed) Submitted
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-197800 (URN)
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2013-08-30Bibliographically approved

Open Access in DiVA

fulltext(11321 kB)4049 downloads
File information
File name FULLTEXT01.pdfFile size 11321 kBChecksum SHA-512
16c8adc55587cc67a77396eef5bc2cad81fcc95bd03e7769a734f8386cff266e36b22fbdb0867f060fba2dde7956b1ed1a47986182cb864206b0a85deaecf1cd
Type fulltextMimetype application/pdf
Buy this publication >>

Search in DiVA

By author/editor
Cai, Yanling
By organisation
Nanotechnology and Functional Materials
Nano Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 4049 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1341 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf