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Cai, Yanling
Publications (10 of 18) Show all publications
Cai, Y., Strømme, M. & Welch, K. (2014). Bacteria viability assessment after photocatalytic treatment. 3 Biotech, 4(2), 149-157
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
Cai, Y., Strömme, M. & Welch, K. (2014). Disinfection Kinetics and Contribution ofReactive Oxygen Species When EliminatingBacteria with TiO2 Induced Photocatalysis. Journal of Biomaterials and Nanobiotechnology, 5(3), 200-209
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
Cai, Y., Strömme, M., Zhang, P., Engqvist, H. & Welch, K. (2014). Photocatalysis induces bioactivity of an organic polymer based material. RSC Advances, 4(101), 57715-57723
Open this publication in new window or tab >>Photocatalysis induces bioactivity of an organic polymer based material
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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
Li, C., Younesi, R., Cai, Y., Zhu, Y., Ma, M. & Zhu, J. (2014). Photocatalytic and antibacterial properties of Au-decorated Fe3O4@mTiO(2) core-shell microspheres. Applied Catalysis B: Environmental, 156, 314-322
Open this publication in new window or tab >>Photocatalytic and antibacterial properties of Au-decorated Fe3O4@mTiO(2) core-shell microspheres
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2014 (English)In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 156, p. 314-322Article in journal (Refereed) Published
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.

Keywords
Fe3O4 microsphere, Mesoporous TiO2, Core-shell structure, Au nanoparticle, Photocatalysis, Antibacterial effect, Recycle
National Category
Environmental Engineering
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-227241 (URN)10.1016/j.apcatb.2014.03.031 (DOI)000336013200035 ()
Available from: 2014-07-02 Created: 2014-06-24 Last updated: 2017-12-05Bibliographically approved
Cai, Y., Strömme, M., Melhus, Å., Engqvist, H. & Welch, K. (2014). Photocatalytic inactivation of biofilms on bioactive dental adhesives. Journal of Biomedical Materials Research. Part B - Applied biomaterials, 102(1), 62-67
Open this publication in new window or tab >>Photocatalytic inactivation of biofilms on bioactive dental adhesives
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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.

Keywords
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
Cai, Y., Strömme, M. & Welch, K. (2013). Photocatalytic Antibacterial Effects Are Maintained on Resin-Based TiO2 Nanocomposites after Cessation of UV Irradiation. PLoS ONE, 8(10), e75929
Open this publication in new window or tab >>Photocatalytic Antibacterial Effects Are Maintained on Resin-Based TiO2 Nanocomposites after Cessation of UV Irradiation
2013 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 10, p. e75929-Article in journal (Refereed) Published
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.

National Category
Natural Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-211454 (URN)10.1371/journal.pone.0075929 (DOI)000326022200004 ()
Available from: 2013-11-25 Created: 2013-11-25 Last updated: 2017-12-06Bibliographically approved
Li, C., Cai, Y., Zhu, Y., Ma, M., Zheng, W. & Zhu, J. (2013). Polyacrylamide-metal nanocomposites: one-pot synthesis, antibacterial properties, and thermal stability. Journal of nanoparticle research, 15(9), UNSP 1922
Open this publication in new window or tab >>Polyacrylamide-metal nanocomposites: one-pot synthesis, antibacterial properties, and thermal stability
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2013 (English)In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 15, no 9, p. UNSP 1922-Article in journal (Refereed) Published
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.

Keywords
Nanocomposite, One-pot synthesis, PAM, Noble metal, Antibacterial properties, Thermal stability
National Category
Natural Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials
Identifiers
urn:nbn:se:uu:diva-210735 (URN)10.1007/s11051-013-1922-9 (DOI)000324370200051 ()
Available from: 2013-11-14 Created: 2013-11-14 Last updated: 2017-12-06Bibliographically approved
Cai, Y. (2013). Titanium Dioxide Photocatalysis in Biomaterials Applications. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
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. p. 57
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1033
Keywords
titanium dioxide, photocatalysis, bioactivity, antibacterial effect, metabolic activity assay, biofilm, reactive oxygen species, disinfection kinetics, post-UV
National Category
Nano Technology
Identifiers
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)
Supervisors
Available from: 2013-04-26 Created: 2011-10-27 Last updated: 2013-08-30Bibliographically approved
Welch, K., Cai, Y. & Strömme, M. (2012). A Method for Quantitative Determination of Biofilm Viability. Journal of Functional Biomaterials, 3(2), 418-431
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
Cai, Y., Engqvist, H., Strømme, M. & Welch, K. (2012). Analyzing the viability of bacteria after TiO2 induced photocatalysis. In: Scandinavian Society for Biomaterials 5th annual meeting, 2012, Uppsala, Sweden. Paper presented at Scandinavian Society for Biomaterials 5th annual meeting, 2012, Uppsala, Sweden.
Open this publication in new window or tab >>Analyzing the viability of bacteria after TiO2 induced photocatalysis
2012 (English)In: Scandinavian Society for Biomaterials 5th annual meeting, 2012, Uppsala, Sweden, 2012Conference paper, Poster (with or without abstract) (Refereed)
National Category
Nano 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-179371 (URN)
Conference
Scandinavian Society for Biomaterials 5th annual meeting, 2012, Uppsala, Sweden
Available from: 2012-08-14 Created: 2012-08-14 Last updated: 2018-02-08
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