الفهرس 
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Abstract
The aim of the present study was to study the effect of gold nanoparticles prepared chemically and by green synthesis, using green coffee extract, as a radiosensitizer for gamma-rays- irradiated mice bearing Ehrlich ascites carcinoma.
To achieve this aim gold nanoparticles were prepared chemically by reduction of hydrogen tetrachloroaurate (HAuCl4.3H2O) by 1% trisodium citrate and by green coffee extract as a reducing agent for green synthesis. The prepared nanoparticles were characterized in terms of shape by transmission electron microscope, Size and charge by zeta analyzer and optical properties by scanning the plasmonic absorption band using uv-visible spectrophotometer.
For the evaluation of the effect of prepared gold nanoparticles as a radiosensitizer in vivo, sixty mice implanted with Ehrlich ascites carcinoma cells were divided into six main groups, each group consisting of 10 mice:
group I (Control group) (n=10), in which the animals were administrated saline solution.
group II (n=10), in which the animals were administrated citrate coated gold nanoparticles only.
group III (n=10), in which the animals were administrated gold nanoparticles prepared by green coffee extract.
group IV (n=10), in whi ch the animals were administrated saline solution and irradiated with 6 Gy gamma rays.
group V (n=10), in which the animals were administrated citrate coated gold nanoparticles and irradiated with 6 Gy gamma rays.
group VI (n=10), in which the animals were administrated gold nanoparticles prepared by green coffee extract and irradiated with 6 Gy gamma rays.
To study the radiosensitizing effect of gold nanoparticles in mice bearing Ehrlich Ascites Carcinoma on the tumor in different animal groups, the following parameters were estimated: tumor volume (mm3), tumor volume ratio (TVR), inhibition ratio of tumor, mice survival time and determination of total antioxidant (TAC) and malondialdehyde (MDA). Animal weight, and liver enzymes activity were assayed as general markers of toxicity.
Our results can be summarized as follow:
Perfectly spherical gold nanoparticles with discrete distribution at mean particle size to be around 45.6 nm were obtained by chemical reduction method with sodium citrate and 39.18 nm by green synthesis using green coffee extract. The zeta potential of prepared gold nanoparticles was -37.3 mv ± 4.8 with 0.68 mS/cm conductivity. The plasmon absorption of prepared AuNPs was clearly visible and its maximum absorption peak was at 520 nm.
Perfectly spherical gold nanoparticles with discrete distribution at mean particle size to be around 39.18 nm were obtained by green synthesis using green coffee extract. The zeta potential of prepared gold nanoparticles was 35.1 mv ± 7.88 with 2.16 mS/cm conductivity. The plasmon absorption of prepared AuNPs was clearly visible and its maximum absorption peak was at 550 nm.
After 7 days of irradiation, there were significant difference in tumor volume of animals of control group and animals injected with gold nanoparticles prepared chemically and by green synthesis. Animals injected with gold nanoparticles prior to 6 Gy Gamma ray irradiation showed significant reduction in tumor volume compared with animals irradiated with 6 Gy Gamma ray irradiation after 3 and 7 days.
The mean tumor volume ratio of animals irradiated with 6 Gy Gamma ray irradiation after 7 days of irradiation was 1.99 times greater than that after 24 hours post irradiation with tumor inhibition ratio of 56.5 compared with control group, the mean tumor volume ratio of animals injected with gold nanoparticles chemically prepared prior to 6 Gy Gamma ray irradiation after 7 days of irradiation was 1.56 times greater than that after 24 hours post irradiation with tumor inhibition ratio of 70.2 compared with control group. while the mean tumor volume ratio of animals injected with gold nanoparticles prepared by green synthesis prior to 6 Gy Gamma ray irradiation after 7 days of irradiation was 1.41 times greater than that after 24 hours post irradiation with tumor inhibition ratio of 76.5 compared with control group.
The mean survival time of mice injected intratumoral with GNPs prepared chemically or by green synthesis and irradiated with 6 Gy Gamma ray irradiation were significantly higher than that of control group, while no other groups showed significant difference.
Animals injected with GNP prepared by green synthesis prior to 6 Gy Gamma ray irradiation showed significant elevated concentration of MDA after 1 day post irradiation compared with control group with no significant difference after 3 and 7 days post irradiation.
Animals injected with GNPs chemically prepared prior to 6 Gy Gamma ray irradiation showed significant reduction in TAC levels after 1 day post irradiation compared with control group with no significant difference after 3 and 7 days post irradiation. Animals injected with GNPs prepared by green synthesis prior to 6 Gy Gamma ray irradiationirradiation (three times) showed non-significant difference in TAC levels after 1, 3 and 7 days post irradiation compared with control group, but was significantly higher at 3 and 7 days post irradiation compared with its corresponding injected with GNPs without gamma irradiation.
All animals were free of toxic clinical signs throughout the experiment period of 7 days. Mice injected intratumorally with GNPs chemicall prepared or those prepared by chemical synthesis prior to Gamma ray irradiation did not cause body weight changes compared with the control group during 7 days post irradition.