الفهرس 
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Abstract
During the last decade, the world has paid great attention to energy, water, and food research. It has also returned to use of natural materials by green synthesis. Given the importance of preserving food with special specifications and maintaining its quality for the longest possible period, food additives are used. Titanium dioxide (TiO2) is a distinguished semiconductor with a white color that is used as coloring agent in many products including paints, plastics, inks, papers, cosmetic creams and food products. In food industry TiO2 Labelled as E171 according to the European Union legislation and it used in many products such as sugar confectionary, chewing gums , candies, some cheeses and sauces, low-fat products such as skimmed milk, ice-creams and pastries with a percentage up to 3.88 mg of TiO2 per g of product.
According to the literature around 36% of TiO2 E171 particles are nanoparticles (NPs), which can cross the intestinal barrier reaching the blood circulation then accumulate in the liver, spleen, kidneys, and lung tissues resulting in a serious damage to these organs.
In this study;
• Several techniques were used for characterization of the modified TiO2 E171 including (X-ray Diffraction (XRD), Transmission Electron Microscope (TEM) , UV spectroscopy, and Fourier-transform infrared spectroscopy (FTIR).
• DPPH assay was used to measure the antioxidant activity of the modified TiO2 E171, while MTT assay were used to assess their cytotoxicity.
• The aggregation state and zeta potential were measured to evaluate the fate of TiO2 E171after digestion using static standardized digestion model.
The obtained result of revealed that;
• the primary size of the three particles was 53.36 ± 9.52 nm, 90.5 ± 16.22, and 102.76 ± 27.6 for anatase TiO2 E171, rutile TiO2 E171, and food-grade TiO2 E171, respectively. After modification anatase and rutile TiO2 E171 showed an increase in the average particle size, while food-grade TiO2 E171 showed a decrease in the average particle size. The modification process of TiO2 E171 didn’t alter the structure of three types of TiO2 E171 on the contrary it improves the crystallinity and the plasmatic resonance.
• An enhancement in the cell viability for particles modified with both honey and thyme were observed . However, samples modified with honey showed lower cytotoxicity than those modified with thyme.
• Antioxidant activity results reflect an increase in the radical scavenging activity in the three types of TiO2 E171 after modification with honey and thyme with a higher activity of thyme modified TiO2 E171.
• Particle size distribution and zeta potential were measured to evaluate the behavior of TiO2 E171 after digestation. After each step of the three GIT steps the average particle size increased. The largest agglomeration was obtained at the intestinal phase for the three types of TiO2 E171 before modification due to the high acidity in the intestinal phase. The same trend was observed for three types of TiO2 E171 modified with honey and thyme flow, except. with a smaller value of agglomeration.
• The surface modification of TiO2 E171 affect its size and surface chemistry. As a sequence this will affect the formation of bio-corona, which alter its stability and absorption in the digestive media.
The present work amid to;
• we used honey and thyme as natural coating materials to reduce side effect of three types of TiO2 E171 (anatase, rutile and food grade).
• Evaluate of TiO2 E171 by using static digestion model.