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  • 1.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Titanium Dioxide Photocatalysis in Biomaterials Applications2013Doctoral 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. 

    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, p. 491-499Article 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: 2018-02-08Bibliographically 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, p. 57715-57723Article 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: 2018-02-08Bibliographically 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, p. 418-431Article 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, p. 149-157Article 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, p. 62-67Article 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: 2018-02-08Bibliographically 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, p. 200-209Article 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
  • 2.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Analyzing the viability of bacteria after TiO2 induced photocatalysis2012In: Scandinavian Society for Biomaterials 5th annual meeting, 2012, Uppsala, Sweden, 2012Conference paper (Refereed)
  • 3.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Analyzing the viability of bacteria after TiO2 induced photocatalysis2012In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 23, no Suppl.5, p. 31-Article in journal (Refereed)
  • 4.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Biofilm susceptibility to photocatalytic dental mateirals2011In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 21, no Suppl.1, p. 55-Article in journal (Refereed)
  • 5.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    TiO2 surface for biofilm elimination, quantified by a novel method2012In: 9th World Biomaterials Congress, June 1-6, Chengdu, China, 2012Conference paper (Refereed)
  • 6.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Melhus, Åsa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Microbiology and Infectious Medicine, Clinical Bacteriology.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Photocatalytic inactivation of biofilms on bioactive dental adhesives2014In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 102, no 1, p. 62-67Article in journal (Refereed)
    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.

  • 7.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Disinfection Kinetics and Contribution ofReactive Oxygen Species When EliminatingBacteria with TiO2 Induced Photocatalysis2014In: Journal of Biomaterials and Nanobiotechnology, ISSN 2158-7027, E-ISSN 2158-7043, Vol. 5, no 3, p. 200-209Article in journal (Refereed)
    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.

  • 8.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Photocatalytic Antibacterial Effects Are Maintained on Resin-Based TiO2 Nanocomposites after Cessation of UV Irradiation2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 10, p. e75929-Article in journal (Refereed)
    Abstract [en]

    Photocatalysis induced by TiO2 and UV light constitutes a decontamination and antibacterial strategy utilized in many applications including self-cleaning environmental surfaces, water and air treatment. The present work reveals that antibacterial effects induced by photocatalysis can be maintained even after the cessation of UV irradiation. We show that resin-based composites containing 20% TiO2 nanoparticles continue to provide a pronounced antibacterial effect against the pathogens Escherichia coli, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus mutans and Enterococcus faecalis for up to two hours post UV. For biomaterials or implant coatings, where direct UV illumination is not feasible, a prolonged antibacterial effect after the cessation of the illumination would offer new unexplored treatment possibilities.

  • 9.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Photocatalysis induces bioactivity of an organic polymer based material2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 101, p. 57715-57723Article in journal (Refereed)
    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.

  • 10.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Bacteria viability assessment after photocatalytic treatment2014In: 3 Biotech, ISSN 2190-5738, E-ISSN 2190-5738, Vol. 4, no 2, p. 149-157Article in journal (Refereed)
    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

  • 11.
    Cai, Yanling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Melhus, Åsa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Bacteriology.
    A novel dental adhesive with bioactive and on-demand biofilm eliminating properties2010Conference paper (Refereed)
  • 12.
    Li, Cuiyan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhu, Yihua
    Ma, Mingguo
    Zheng, Wei
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Polyacrylamide-metal nanocomposites: one-pot synthesis, antibacterial properties, and thermal stability2013In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 15, no 9, p. UNSP 1922-Article in journal (Refereed)
    Abstract [en]

    The incorporation of inorganic nanoparticles into polymers is a hot research spot, since it endows the nanocomposites with new or improved properties by exploiting synergistic effects. Here we report a facile one-pot synthesis of polyacrylamide (PAM)-metal (M = Au, Ag, or Pd) nanocomposites in ethylene glycol (EG). The simultaneous polymerization of the acylamide (AM) monomer and formation of metal nanoparticles lead to a homogeneous distribution of metal nanoparticles in the PAM matrix. The sizes of Au, Ag, and Pd nanoparticles are 55.50 +/- 10.6, 14.15 +/- 2.57, and 7.74 +/- 1.82 nm, respectively. The reaction system only includes EG, AM monomer, and corresponding metal salt. EG acts as both the solvent and the reducing reagent. Also, no initiator for AM polymerization and no surfactant for stabilization of metal nanoparticles are used. Furthermore, this simple synthetic route does not rely on any special or expensive equipment, thus can be exploited to the synthesis of similar polymer-inorganic nanocomposites. Compared to PAM, the PAM-metal nanocomposites showed enhanced thermal stability and antibacterial properties.

  • 13.
    Li, Cuiyan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhu, Yihua
    Ma, Mingguo
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Photocatalytic and antibacterial properties of Au-decorated Fe3O4@mTiO(2) core-shell microspheres2014In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 156, p. 314-322Article in journal (Refereed)
    Abstract [en]

    A facile approach for the fabrication of Au-decorated mesoporous Fe3O4@TiO2 (Fe3O4@mTiO(2)) core-shell microspheres is demonstrated. The protocol involved the coating of a successive layer of TiO2 onto a magnetic Fe3O4 core via a sol-gel process, followed by TiO2 crystallization and mesopore-formation by a hydrothermal treatment, and then the deposition of Au nanoparticles onto Fe3O4@mTiO(2) microspheres through an in situ reduction of perchloric acid. The mesoporous microspheres (Fe3O4@mTiO(2)) showed stronger magnetic properties than the dense sample (Fe3O4@TiO2) before the hydrothermal treatment. The size and loading amount of Au nanoparticles were controlled by the reduction temperature and concentration of Au salt, respectively. Compared to unmodified Fe3O4@mTiO(2) microspheres, Fe3O4@mTiO(2)@Au microspheres showed higher photocatalytic activity for organic degradation and antibacterial action in water. These core-shell Fe3O4@mTiO(2)@Au microspheres can serve as efficient and recyclable photocatalysts, which have promising applications in environmental treatment.

  • 14.
    Unosson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jiang, Xiyuan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lööf, Jesper
    Doxa AB.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Antibacterial properties of contemporary dental luting agents2012In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 23, no S5, p. 64-64Article in journal (Refereed)
  • 15.
    Unosson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Jiang, Xiyuan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lööf, Jesper
    Doxa AB.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Antibacterial Properties of Dental Luting Agents: Potential to Hinder the Development of Secondary Caries2012In: International Journal of Dentistry, ISSN 1687-8736, Vol. 2012, p. 529495-Article in journal (Refereed)
    Abstract [en]

    A modified direct contact test was used to evaluate the antibacterial properties of four commercially available dental luting agents (RelyX Unicem, Ketac Cem, Ceramir Crown & Bridge and Harvard Cement) and two reference materials (glass-ionomer cement and calcium aluminate cement) compared to a negative-control material (PMMA). Streptococcus mutans bacteria were placed in direct contact with specimens that had been aged for 10 min, 1 day, and 7 days, in order to test the antibacterial properties of the materials. A metabolic assay containing resazurin was used to quantify the amount of viable bacteria remaining after the direct contact tests. The effects of pH and fluoride on bacteria proliferation were also evaluated. Strongest antibacterial properties were found for calcium aluminate cement, followed by Ceramir Crown & Bridge and RelyX Unicem. Ketac Cem, Harvard Cement, and the reference glass-ionomer cement showed bacteria content either higher than or not significantly different from the PMMA control in all instances. pH levels below 6.3 and above 9.0 were found to have negative effects on bacterial proliferation. No correlation between either acidic materials or fluoride release and antibacterial properties could be seen; rather, basic materials showed stronger antibacterial properties.

  • 16.
    Welch, Ken
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Dental adhesives with bioactive and on-demand bactericidal properties2010In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 26, no 5, p. 491-499Article in journal (Refereed)
    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.

  • 17.
    Welch, Ken
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    A Method for Quantitative Determination of Biofilm Viability2012In: Journal of Functional Biomaterials, ISSN 2079-4983, Vol. 3, no 2, p. 418-431Article in journal (Refereed)
  • 18.
    Xia, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Grandfield, Kathryn
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Hoess, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ballo, Ahmed
    BIOMATCELL, VINN excellence Center of Biomaterials and Cell Therapy, Göteborg, Dept of Biomaterials, Institute for Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Göteborg.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mesoporous titanium dioxide coating for metallic implants2012In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 100B, no 1, p. 82-93Article in journal (Refereed)
    Abstract [en]

    A bioactive mesoporous titanium dioxide (MT) coating for surface drug delivery has been investigated to develop a multifunctional implant coating, offering quick bone bonding and biological stability. An evaporation induced self-assembly (EISA) method was used to prepare a mesoporous titanium dioxide coating of the anatase phase with BET surface area of 172 m2/g and average pore diameter of 4.3 nm. Adhesion tests using the scratch method and an in situ screw-in/screw-out technique confirm that the MT coating bonds tightly with the metallic substrate, even after removal from bone. Because of its high surface area, the bioactivity of the MT coating is much better than that of a dense TiO2 coating of the same composition. Quick formation of hydroxyapatite (HA) in vitro can be related to enhance bonding with bone. The uptake of antibiotics by the MT coating reached 13.4 mg/cm3 within a 24 h loading process. A sustained release behavior has been obtained with a weak initial burst. By using Cephalothin as a model drug, drug loaded MT coating exhibits a sufficient antibacterial effect on the material surface, and within millimeters from material surface, against E.coli. Additionally, the coated and drug loaded surfaces showed no cytotoxic effect on cell cultures of the osteoblastic cell line MG-63. In conclusion, this study describes a novel, biocompatiblemesoporous implant coating, which has the ability to induce HA formation and could be used as a surface drug-delivery system.

1 - 18 of 18
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