Popescu Traian, Lupu Andreea R, Raditoiu Valentin, Purcar Violeta, Teodorescu Valentin S
National Institute of Materials Physics, P.O. Box MG-7, 077125 Bucharest, Romania; University of Bucharest, Faculty of Physics, 077125 Bucharest, Romania.
Cantacuzino National Institute for Research and Development in Microbiology and Immunology, 050096 Bucharest, Romania; Victor Babes National Institute of Pathology, 050096 Bucharest, Romania.
J Colloid Interface Sci. 2015 Nov 1;457:108-20. doi: 10.1016/j.jcis.2015.07.005. Epub 2015 Jul 3.
The MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide] cell cytotoxicity indicator is photocatalytically reduced on the surface of TiO2 nanoparticles in phosphate-buffered-saline (PBS) environment. We hypothesize that specific phosphate adsorption may be used to modulate the efficiency of the TiO2-MTT reaction through colloidal and semiconductor-liquid interface processes.
The TiO2-MTT reaction kinetics was studied in PBS, with respect to photocatalyst and MTT concentrations and irradiation wavelength. The effects of PBS and electron scavengers (Fe(3+) ions) on reaction efficiency and the role of colloidal surface charge in the photocatalytic process were investigated. The structural and spectroscopic characteristics of relevant TiO2-formazan systems were studied by X-ray diffraction, transmission electron microscopy and IR-spectroscopy.
The reaction was pseudo-first order with respect to photocatalyst and showed a negative and fractional partial order with respect to MTT. Formazan production rates were directly proportional to radiation wavelength and TiO2 concentration and inversely proportional to the MTT initial concentration. The addition of Fe(3+) ions, as well as the absence of PBS, induced strong reaction inhibition. Reaction efficiency and catalyst Zeta potential were enhanced by Na2HPO4 (PBS component) and showed a maximum around the phosphate concentration 0.005 M. Structural/spectroscopic characterization confirmed the formation of amorphous MTT-formazan on the surface of TiO2 and the TiO2-phosphate binding.
在磷酸盐缓冲盐水（PBS）环境中，MTT [3 -（4,5 - 二甲基噻唑 - 2 - 基）- 2,5 - 二苯基四氮唑溴盐]细胞毒性指示剂在TiO2纳米颗粒表面发生光催化还原。我们假设特定的磷酸盐吸附可通过胶体和半导体 - 液体界面过程来调节TiO2 - MTT反应的效率。
在PBS中研究了TiO2 - MTT反应动力学，涉及光催化剂和MTT浓度以及照射波长。研究了PBS和电子清除剂（Fe(3+)离子）对反应效率的影响以及胶体表面电荷在光催化过程中的作用。通过X射线衍射、透射电子显微镜和红外光谱研究了相关TiO2 - 甲臜体系的结构和光谱特征。
该反应对光催化剂为准一级反应，对MTT为负的分数级反应。甲臜生成速率与辐射波长和TiO2浓度成正比，与MTT初始浓度成反比。添加Fe(3+)离子以及不存在PBS均会强烈抑制反应。Na2HPO4（PBS成分）提高了反应效率和催化剂的zeta电位，在磷酸盐浓度约0.005 M时达到最大值。结构/光谱表征证实了在TiO2表面形成无定形MTT - 甲臜以及TiO2 - 磷酸盐结合。
