Photocatalytic bactericidal action of fluorescent light in a titanium dioxide particle mixture: an in vitro study

Abstract

Traditional titanium dioxide (TiO 2 ) has photocatalytic bactericidal properties only under ultraviolet (UV) irradiation, which restricts its use in clinical treatment regimens. In this study, we evaluated the photocatalytic bactericidal effects of an aqueous system of TiO 2 particles irradiated by fluorescent light (FL) on Staphylococcus aureus. A TiO 2 particle mixture containing 19 ppm (0.019 mg/ mL) of TiO 2 was prepared. A bacterial solution of 1 × 10 5 CFU/mL was added one drop at a time to the TiO 2 mixture. The resulting product was then irradiated with FL. The bacterial survival rate decreased steadily in the TiO 2 mixture group, reaching 76.7% after 30 min of FL irradiation and 10.9% after 60 min. After 60 to 180 min, the bacterial survival ratio of the TiO 2 mixture group was significantly lower than that of the control group (P < 0.05). The present study indicates that treating the surfaces of surgical devices and the surgical field with a TiO 2 particle mixture can create a nearly sterile environment that can be maintained throughout surgery, even at low luminous intensities.When titanium dioxide (TiO 2 ) is exposed to ultraviolet (UV) light, various free radicals are released. These free radicals are a potent oxidant that can decompose bacteria and other organic substances (4, 7). In a previous study by the authors, a TiO 2 particle mixture was prepared in order to use its photocatalytic action to prevent postoperative infection. In comparison to the morphological characteristics of thin-film and large-particle TiO 2 formulations, the use of fine particles resulted in a greater surface area, improved UV exposure, and increased contact with the bacteria. This combination of factors provided potent antibacterial effects against Staphylococcus aureus (8). However, the physiological effects of the UV rays used to elicit photocatalysis must also be considered. This study evaluates the photocatalytic bactericidal effects on Staphylococcus aureus of an aqueous system of TiO 2 particles irradiated with fluorescent light (FL) containing no UV light whatsoever and having a lower luminous intensity than sunlight. TiO 2 particles were prepared from titanium (IV) chloride gas using the vapor phase method followed by annealing at room temperature. The surfaces of the particles were rutile (20%) while the interiors were anatase (80%). A powder was prepared by mixing these TiO 2 particles with other substances, mainly sodium percarbonate and citric acid, in order to adjust the aqueous pH and generate a reaction with the TiO 2 (MEK-01; Nanowave, Aichi, Japan). The TiO 2 concentration was 0.38%. The mixture

Effects of TiO2 NPs Coating-Titanium for Fibroblast Adhesion

“…Since the method of rapid colorimetric MTT is based on metabolic cell activity, the present study results can be more reliable than those reported by Sawase et al (2008), where counting the number of adherent cells was performed by laser microscopy and specialized software; on the other hand Onuki et al (2010) detached with trypsin adherent cells and cell counting was performed with hemocytometer and finally Koseki et al (2009) isolated cells from the surface with trypsin and ultrasonic waves, those methods previously reported are ineffective for correct estimate of the number of viable cells. However, the MTT method has a limitation, minimum cells still remain on the surface, underestimation due to lack of contact time MTT reagent with cells, therefore, in future research an increase in the incubation time of the reagent with cells is recommended.…”

“…The first report of the use of photocatalysis back to 1970 (Fujushima & Honda, 1972) several studies have focused on the antibacterial effects and sterilization with UV irradiation (Xu et al, 2006;Koseki et al, 2009). The present study confirms further that the UV light irradiation on the titanium plates for 20 min improves adhesion and proliferation of fibroblasts and significantly enhances the cell attachment when TiO 2 NPs were present on the Ti plates.…”

Synthesis and Determination of Antimicrobial Activity of Visible Light Activated TiO2 Nanoparticles with Polymethyl Methacrylate Denture Base Resin Against Staphylococcus Aureus

“…All these ensured that all the photocatalyst containing sites would be activated. Desai and Kaushik synthesized TiO 2 by sol-gel technique and studied its inhibitory photocatalytic activity against some common pathogenic micro organisms such as E. coli, P. aeruginosa, K. pnemoniae, S. aureus under visible illumination [24]. The antimicrobial activity of TiO 2 -PMMA combination is in accordance with the study conducted by Desai and Koseki et al which evaluated the photocatalytic bactericidal effects of TiO 2 on S. aureus when irradiated.…”

Clinical and Laboratory Evaluation of Anti-Microbial Efficacy of Photocatalysts

“…Böylece negatif yüklü elektron ve pozitif yüklü boşluk çifti meydana gelir ve sonuçta fotokatalizör çok güçlü redüksiyon ve oksidasyon yeteneği kazanır. Su ve oksijen molekülleri, fotokatalizör etkisi ile hidroksil ve süperoksit anyonları meydana getirirler [5][6][7]. Fotokatalizör sistemler, çevre ve insan için zararlı olan molekül-ler üzerindeki parçalayıcı etkisinin yanında, bakteriostatik ve bakterisit etkisini de serbest oksijen radikalleri aracılığı ile yaparlar.…”