Proceedings of the 4 th International Conference on Nanostructures (ICNS4) 12-14 March, 2012, Kish Island, I.R. Iran Synthesis of TiO 2 -PEG-Folic acid nanocomposites for drug delivery and cancer therapy S. Naghibi a , H. R. Madaah Hosseini b , M. A. Faghihi Sani b a Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran b Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran Abstract: TiO 2 -PEG-Folic acid nanocomposites were synthesized by a hydrothermal route. The amount of crystallinity and crystallite size of PEG and Folic acid coated Anatase nanoparticles were investigated using a statistical design methodology. TiO 2 nanoparticles and the coated nanocomposites were characterized by X-ray diffraction method (XRD), transmission electron microscopy (TEM) and an UV-vis spectrophotometer. TiO 2 -PEG-Folic acid nanocomposite powders showed very high photocatalytic activity greater than P25 TiO 2 nanoparticles. Keywords: TiO 2 ; PEG; Folic acid; Hydrothermal; photocatalyst Introduction Photocatalytic property of titanium dioxide is being extensively utilized to rectify a variety of environmental pollution problems such as decomposition of unwanted and toxic organic compounds, degradation of pollutants from contaminated water and air and killing of harmful bacteria and cancer cells [1]. In recent years, many efforts have been allocated to the combining nanosized materials abilities with controlled drug delivery properties [2]. Among various methods for synthesising TiO 2 nanoparticles, hydrothermal route has many advantages such as producing a highly homogeneous crystalline product at relatively low temperature, decreasing in agglomeration between particles, narrow particle size distributions, phase homogeneity and controlled particle morphology [3]. In the present work, Taguchi method is used to optimize the hydrothermal process parameters to improveme the quality of the output without increasing the cost of experimentation by reducing the number of experiments [4]. TiO 2 nanoparticles were synthesized via hydrothermal process using titanium (IV) isopropoxide (TTIP), hydrochloric acid, isopropyl alcohol and triethylamine (TEA). Then, Polyethylene glycol (PEG) and Folic acid were coated on the surface of TiO 2 nanoparticles to prepare a nanocomposite for conjugating to an anticancer drug (Doxorubicin) in the next works. Experimental Titanium dioxide nanostructures were synthesized by adding TTIP (>98%, Merck), isopropyl alcohol (>99.5%, Merck), HCl (37%, Merck) and distilled water at pH 1.5. By addition of TTIP, a white precipitate was obtained. Stirring at room temperature for two days results in a homogeneous solution. TEA (>99%, Merck) was then dropped to the solution, increases the pH values to 7, 9, 10 and 11. The obtained white precipitate suspension was then placed in a Teflon recipient inside of stainless steel autoclave. Hydrothermal treatment was performed at different conditions. TiO 2 powders were obtained by filtering and repeatedly washing (3 times with distilled water). The obtained precipitates were then dried at 100 ºC for 8 h. The amount of starting materials and time and temperature conditions on the basis of L16 (4 5 ) orthogonal array in Taguchi method are shown in table 1. For preparing PEG coated TiO 2 nanoparticles, different concentrations of TiO 2 (0.01, 0.1, 1 & 5 mg/ml) and weight ratios of (PEG 6000, Merck)/TiO 2 (1/1, 1/2, 2/1) in distilled water were used. To evaluate the stability of the solutions, UV absorption of solutions were measured after sonicating for 4 h at different time intervals. The synthesis of TiO 2 -PEG-Folic acid nanocomposite performed by a two-step reaction: Folic acid activation and Folic acid capping. First, 4.5 mg Folic acid was activated by Dicyclohexylcarbodiimide (DCC, >99%, Merck) in 5 ml Dimethylsulfoxide (DMSO, 99%, Merck) at room temperature under nitrogen atmosphere for 2 h (weight ratio of DCC:Folic acid = 1:1). In the second step, PEG coated TiO 2 nanoparticles were added to the solution and the mixture was stirred under nitrogen for 2 h. Finally, the precipitations was washed with distilled water and freeze-dried. X-ray diffraction patterns (XRD) was obtained by a Bruker D8-advance X-ray diffractometer using monochromatized Cu K α (λ=1.5418 Å) radiation. Diffuse reflectance spectra were obtained by a UV–vis scanning spectrophotometer JASCO V-670 (195-600 nm Japan). Selected samples were also studied by using a Philips transmission electron microscope (TEM). The microscope was operating at an accelerating voltage of 120 kV. Samples were prepared by dipping a Cu grid into ultrasonic dispersion of the oxide powder in ethanol. The photocatalytic activities of TiO 2 -PEG and TiO 2 -PEG- Folic acid samples were evaluated by measuring the decomposition rate of methylene blue (MB) at room