At 100 °C, only 10 min were required to get the highest absorbance (3.2) indicating the highest productivity of GNPs, this result was in agreement with previous studies [13]. The radiation-induced synthesis is one of the most promising strategies because it is

simple, clean and has harmless feature [58]. During radiation, when aqueous solution is exposed to gamma radiation, it creates solvated electrons which are able to reduce metal ions forming nano metals. Exposure of the extract see more to different doses of radiation was performed after addition of HAuCl4, surface plasmon resonance (SPR) band was noted for all doses, maximum absorbance (4) was found at a dose of 5 kGy, after which further increase in radiation dose resulted in decrease in absorbance at 550 nm, while no peak was recorded in blank sample (radiation before mixing with HAuCl4). The formation of GNPs can be attributed to the radiolytic reduction which generally involves

Ganetespib radiolysis of aqueous solutions that provides an efficient method to reduce metal ions. In the radiolytic method, when aqueous solutions are exposed to gamma rays, they create solvated electrons, which reduce the metal ions and the metal atoms eventually coalesce to form aggregates [59]. Exposure of water or aqueous solutions to ionizing radiation leads to formation of primary species H3O+, H , OH , H2O2. These free radicals have major importance in radiolytic chemical reactions. The combined effect of both radiolytic reduction and presence of peptide resulted in formation of GNPs by radiolytic reactions and stabilization by prevention of aggregates formation by “capping”. The higher concentration of GNPs indicated by in absorbance value of 4 with radiation compared to a value 4��8C of 3.2 with temperature, gave an obvious advantage for radiation over temperature in the production of GNPs. The volume of HAuCl4 added strongly affects the reaction. Absorbance increased with increase in volume HAuCl4, the best volume of HAuCl4 was 0.3 ml (10 mg/ml), which indicates increased rate of reaction by increasing the volume of HAuCl4 used, and further increase as reported causes decrease

in formation of GNPs used due to aggregation as reported previously [60]. From the above mentioned results we can conclude that laccase production by Pleurotus ostreatus has been shown to depend markedly on the composition of the culture medium, carbon, nitrogen content and inducer compounds. We were able to reach the conditions that helped in multiplying the enzyme concentration to almost 10 folds (compared to fermentation of wheat bran alone) indicating that factorial design can be a practical useful tool for optimizing the reaction parameters for enhancing the activity of laccase. Using the partially purified enzyme in the decolorization of five different reactive azo dyes, we were able to get relatively high percentage of decolorization, which underscores the importance of dye decolorization using fungal enzymes.